diff --git a/apps/zbugs/src/avatar-url-with-size.tsx b/apps/zbugs/src/avatar-url-with-size.ts
similarity index 100%
rename from apps/zbugs/src/avatar-url-with-size.tsx
rename to apps/zbugs/src/avatar-url-with-size.ts
diff --git a/apps/zbugs/src/comment-query.ts b/apps/zbugs/src/comment-query.ts
index 872ad5ef1b..16d0be9622 100644
--- a/apps/zbugs/src/comment-query.ts
+++ b/apps/zbugs/src/comment-query.ts
@@ -1,5 +1,5 @@
 import type {Zero} from '@rocicorp/zero';
-import type {IssueRow, Schema} from '../schema.js';
+import type {IssueRow, Schema} from '../schema.ts';
 
 export function commentQuery(z: Zero<Schema>, displayed: IssueRow | undefined) {
   return z.query.comment
diff --git a/apps/zbugs/src/components/avatar-image.tsx b/apps/zbugs/src/components/avatar-image.tsx
index d597ca43f5..5182dfff8f 100644
--- a/apps/zbugs/src/components/avatar-image.tsx
+++ b/apps/zbugs/src/components/avatar-image.tsx
@@ -1,6 +1,6 @@
 import {memo, type ImgHTMLAttributes} from 'react';
-import type {UserRow} from '../../schema.js';
-import {avatarURLWithSize} from '../avatar-url-with-size.js';
+import type {UserRow} from '../../schema.ts';
+import {avatarURLWithSize} from '../avatar-url-with-size.ts';
 
 interface AvatarImageProps extends ImgHTMLAttributes<HTMLImageElement> {
   user: UserRow;
diff --git a/apps/zbugs/src/components/button-with-login-check.tsx b/apps/zbugs/src/components/button-with-login-check.tsx
index 1c2e5eb56a..63a6af7f1a 100644
--- a/apps/zbugs/src/components/button-with-login-check.tsx
+++ b/apps/zbugs/src/components/button-with-login-check.tsx
@@ -1,7 +1,7 @@
 import {forwardRef, useCallback, useState, type ForwardedRef} from 'react';
-import {useLogin} from '../hooks/use-login.js';
-import {Button, type ButtonProps} from './button.jsx';
-import {NotLoggedInModal} from './not-logged-in-modal.js';
+import {useLogin} from '../hooks/use-login.tsx';
+import {Button, type ButtonProps} from './button.tsx';
+import {NotLoggedInModal} from './not-logged-in-modal.tsx';
 
 interface Props extends ButtonProps {
   loginMessage: string;
diff --git a/apps/zbugs/src/components/button.tsx b/apps/zbugs/src/components/button.tsx
index af9c8214d0..9533a613c9 100644
--- a/apps/zbugs/src/components/button.tsx
+++ b/apps/zbugs/src/components/button.tsx
@@ -5,8 +5,8 @@ import {
   type ForwardedRef,
   type ReactNode,
 } from 'react';
-import {isPrimaryMouseButton} from '../is-primary-mouse-button.js';
-import {umami} from '../umami.js';
+import {isPrimaryMouseButton} from '../is-primary-mouse-button.ts';
+import {umami} from '../umami.ts';
 
 export interface ButtonProps {
   onAction?: (() => void) | undefined;
diff --git a/apps/zbugs/src/components/can-edit.tsx b/apps/zbugs/src/components/can-edit.tsx
index 07b20f7dee..5a5816eaef 100644
--- a/apps/zbugs/src/components/can-edit.tsx
+++ b/apps/zbugs/src/components/can-edit.tsx
@@ -1,5 +1,5 @@
 import {memo} from 'react';
-import {useCanEdit} from '../hooks/use-can-edit.js';
+import {useCanEdit} from '../hooks/use-can-edit.ts';
 
 interface Props {
   children: React.ReactNode;
diff --git a/apps/zbugs/src/components/combobox.tsx b/apps/zbugs/src/components/combobox.tsx
index 93d4795c04..4cbbadd0f0 100644
--- a/apps/zbugs/src/components/combobox.tsx
+++ b/apps/zbugs/src/components/combobox.tsx
@@ -9,10 +9,10 @@ import {
   useState,
 } from 'react';
 import DropdownArrow from '../assets/icons/dropdown-arrow.svg?react';
-import {useClickOutside} from '../hooks/use-click-outside.js';
-import {umami} from '../umami.js';
+import {useClickOutside} from '../hooks/use-click-outside.ts';
+import {umami} from '../umami.ts';
 import styles from './combobox.module.css';
-import {fuzzySearch} from './fuzzySearch.js';
+import {fuzzySearch} from './fuzzy-search.ts';
 
 type Item<T> = {
   text: string;
diff --git a/apps/zbugs/src/components/confirm.tsx b/apps/zbugs/src/components/confirm.tsx
index 1c46b79afb..921d766c43 100644
--- a/apps/zbugs/src/components/confirm.tsx
+++ b/apps/zbugs/src/components/confirm.tsx
@@ -1,6 +1,6 @@
 import {useCallback} from 'react';
-import {Button} from './button.js';
-import {Modal, ModalActions, ModalText} from './modal.jsx';
+import {Button} from './button.tsx';
+import {Modal, ModalActions, ModalText} from './modal.tsx';
 
 interface Props {
   isOpen: boolean;
diff --git a/apps/zbugs/src/components/emoji-panel.tsx b/apps/zbugs/src/components/emoji-panel.tsx
index 3f2037ee02..45d70dc6f7 100644
--- a/apps/zbugs/src/components/emoji-panel.tsx
+++ b/apps/zbugs/src/components/emoji-panel.tsx
@@ -25,13 +25,13 @@ import {
   findEmojiForCreator,
   normalizeEmoji,
   type Emoji,
-} from '../emoji-utils.js';
-import {useLogin} from '../hooks/use-login.js';
-import {useZero} from '../hooks/use-zero.js';
-import {ButtonWithLoginCheck} from './button-with-login-check.js';
-import {type ButtonProps} from './button.js';
-import {EmojiPicker} from './emoji-picker.js';
-import {EmojiPill} from './emoji-pill.js';
+} from '../emoji-utils.ts';
+import {useLogin} from '../hooks/use-login.tsx';
+import {useZero} from '../hooks/use-zero.ts';
+import {ButtonWithLoginCheck} from './button-with-login-check.tsx';
+import {type ButtonProps} from './button.tsx';
+import {EmojiPicker} from './emoji-picker.tsx';
+import {EmojiPill} from './emoji-pill.tsx';
 
 const loginMessage = 'You need to be logged in to modify emoji reactions.';
 
diff --git a/apps/zbugs/src/components/emoji-picker.tsx b/apps/zbugs/src/components/emoji-picker.tsx
index dcecc77e4f..82070939aa 100644
--- a/apps/zbugs/src/components/emoji-picker.tsx
+++ b/apps/zbugs/src/components/emoji-picker.tsx
@@ -7,9 +7,9 @@ import type {
   SkinToneChangeEvent,
 } from 'emoji-picker-element/shared.js';
 import {createElement, memo, useRef, type RefCallback} from 'react';
-import {setUserPref, useUserPref} from '../hooks/use-user-pref.js';
-import {useZero} from '../hooks/use-zero.js';
-import {emojiDataSource} from './emoji-data-source.js';
+import {setUserPref, useUserPref} from '../hooks/use-user-pref.ts';
+import {useZero} from '../hooks/use-zero.ts';
+import {emojiDataSource} from './emoji-data-source.ts';
 
 export const SKIN_TONE_PREF = 'emojiSkinTone';
 
diff --git a/apps/zbugs/src/components/emoji-pill.tsx b/apps/zbugs/src/components/emoji-pill.tsx
index 930d4864b2..abc7b20f88 100644
--- a/apps/zbugs/src/components/emoji-pill.tsx
+++ b/apps/zbugs/src/components/emoji-pill.tsx
@@ -1,19 +1,19 @@
 import classNames from 'classnames';
 import {memo, useEffect, useState} from 'react';
 import {useIntersectionObserver} from 'usehooks-ts';
-import type {Emoji} from '../emoji-utils.js';
+import type {Emoji} from '../emoji-utils.ts';
 import {
   findEmojiForCreator,
   formatEmojiCreatorList,
   setSkinTone,
-} from '../emoji-utils.js';
-import {useDocumentHasFocus} from '../hooks/use-document-has-focus.js';
-import {useNumericPref} from '../hooks/use-user-pref.js';
-import {useZero} from '../hooks/use-zero.js';
-import {AvatarImage} from './avatar-image.js';
-import {ButtonWithLoginCheck} from './button-with-login-check.js';
-import {SKIN_TONE_PREF} from './emoji-picker.js';
-import {Tooltip, TooltipContent, TooltipTrigger} from './tooltip.jsx';
+} from '../emoji-utils.ts';
+import {useDocumentHasFocus} from '../hooks/use-document-has-focus.ts';
+import {useNumericPref} from '../hooks/use-user-pref.ts';
+import {useZero} from '../hooks/use-zero.ts';
+import {AvatarImage} from './avatar-image.tsx';
+import {ButtonWithLoginCheck} from './button-with-login-check.tsx';
+import {SKIN_TONE_PREF} from './emoji-picker.tsx';
+import {Tooltip, TooltipContent, TooltipTrigger} from './tooltip.tsx';
 
 const loginMessage = 'You need to be logged in to modify emoji reactions.';
 
diff --git a/apps/zbugs/src/components/filter.tsx b/apps/zbugs/src/components/filter.tsx
index 29f58eace8..3866861853 100644
--- a/apps/zbugs/src/components/filter.tsx
+++ b/apps/zbugs/src/components/filter.tsx
@@ -2,10 +2,10 @@ import {useQuery} from '@rocicorp/zero/react';
 import classNames from 'classnames';
 import {memo, useMemo, useState} from 'react';
 import labelIcon from '../assets/icons/label.svg';
-import {useZero} from '../hooks/use-zero.js';
-import {Button} from './button.js';
-import {Combobox} from './combobox.js';
-import {UserPicker} from './user-picker.js';
+import {useZero} from '../hooks/use-zero.ts';
+import {Button} from './button.tsx';
+import {Combobox} from './combobox.tsx';
+import {UserPicker} from './user-picker.tsx';
 
 export type Selection =
   | {creator: string}
diff --git a/apps/zbugs/src/components/fuzzySearch.tsx b/apps/zbugs/src/components/fuzzy-search.ts
similarity index 100%
rename from apps/zbugs/src/components/fuzzySearch.tsx
rename to apps/zbugs/src/components/fuzzy-search.ts
diff --git a/apps/zbugs/src/components/issue-link.tsx b/apps/zbugs/src/components/issue-link.tsx
index 7867cccda6..16c4f1e29f 100644
--- a/apps/zbugs/src/components/issue-link.tsx
+++ b/apps/zbugs/src/components/issue-link.tsx
@@ -1,5 +1,5 @@
-import {links, type ListContext} from '../routes.js';
-import {Link, type Props as LinkProps} from './link.js';
+import {links, type ListContext} from '../routes.ts';
+import {Link, type Props as LinkProps} from './link.tsx';
 
 export function IssueLink({
   issue,
diff --git a/apps/zbugs/src/components/label-picker.tsx b/apps/zbugs/src/components/label-picker.tsx
index ef1b583afd..9f8caeb18d 100644
--- a/apps/zbugs/src/components/label-picker.tsx
+++ b/apps/zbugs/src/components/label-picker.tsx
@@ -1,9 +1,9 @@
 import {useQuery} from '@rocicorp/zero/react';
 import classNames from 'classnames';
 import {useCallback, useRef, useState} from 'react';
-import {useClickOutside} from '../hooks/use-click-outside.js';
-import {useZero} from '../hooks/use-zero.js';
-import {Button} from './button.js';
+import {useClickOutside} from '../hooks/use-click-outside.ts';
+import {useZero} from '../hooks/use-zero.ts';
+import {Button} from './button.tsx';
 import style from './label-picker.module.css';
 
 const focusInput = (input: HTMLInputElement | null) => {
diff --git a/apps/zbugs/src/components/link.tsx b/apps/zbugs/src/components/link.tsx
index 338fef9ee4..652e4fe498 100644
--- a/apps/zbugs/src/components/link.tsx
+++ b/apps/zbugs/src/components/link.tsx
@@ -1,5 +1,5 @@
 import {memo, type ReactNode} from 'react';
-import type {ZbugsHistoryState} from '../routes.js';
+import type {ZbugsHistoryState} from '../routes.ts';
 
 export type Props = {
   children: ReactNode;
diff --git a/apps/zbugs/src/components/login-provider.tsx b/apps/zbugs/src/components/login-provider.tsx
index 865fab8fdb..0af3c7cc51 100644
--- a/apps/zbugs/src/components/login-provider.tsx
+++ b/apps/zbugs/src/components/login-provider.tsx
@@ -1,7 +1,7 @@
 import {useCallback, useSyncExternalStore} from 'react';
-import {loginContext} from '../hooks/use-login.js';
-import {clearJwt} from '../jwt.js';
-import {authRef} from '../zero-setup.js';
+import {loginContext} from '../hooks/use-login.tsx';
+import {clearJwt} from '../jwt.ts';
+import {authRef} from '../zero-setup.ts';
 
 export function LoginProvider({children}: {children: React.ReactNode}) {
   const loginState = useSyncExternalStore(
diff --git a/apps/zbugs/src/components/modal.tsx b/apps/zbugs/src/components/modal.tsx
index 73be62e9e8..c05fd4fe14 100644
--- a/apps/zbugs/src/components/modal.tsx
+++ b/apps/zbugs/src/components/modal.tsx
@@ -9,9 +9,9 @@ import React, {
 } from 'react';
 import ReactDOM from 'react-dom';
 import CloseIcon from '../assets/icons/close.svg?react';
-import {useKeypress} from '../hooks/use-keypress.js';
-import useLockBodyScroll from '../hooks/use-lock-body-scroll.js';
-import {Confirm} from './confirm.js';
+import {useKeypress} from '../hooks/use-keypress.ts';
+import useLockBodyScroll from '../hooks/use-lock-body-scroll.ts';
+import {Confirm} from './confirm.tsx';
 
 interface Props {
   title?: string | undefined;
diff --git a/apps/zbugs/src/components/nav.tsx b/apps/zbugs/src/components/nav.tsx
index 63c15f965d..dd548894f7 100644
--- a/apps/zbugs/src/components/nav.tsx
+++ b/apps/zbugs/src/components/nav.tsx
@@ -6,19 +6,19 @@ import {navigate, useHistoryState} from 'wouter/use-browser-location';
 import {useQuery} from 'zero-react/src/use-query.js';
 import logoURL from '../assets/images/logo.svg';
 import markURL from '../assets/images/mark.svg';
-import {useLogin} from '../hooks/use-login.js';
-import {useZero} from '../hooks/use-zero.js';
-import {IssueComposer} from '../pages/issue/issue-composer.js';
+import {useLogin} from '../hooks/use-login.tsx';
+import {useZero} from '../hooks/use-zero.ts';
+import {IssueComposer} from '../pages/issue/issue-composer.tsx';
 import {
   links,
   routes,
   type ListContext,
   type ZbugsHistoryState,
-} from '../routes.js';
-import {AvatarImage} from './avatar-image.js';
-import {ButtonWithLoginCheck} from './button-with-login-check.js';
-import {Button} from './button.js';
-import {Link} from './link.js';
+} from '../routes.ts';
+import {AvatarImage} from './avatar-image.tsx';
+import {ButtonWithLoginCheck} from './button-with-login-check.tsx';
+import {Button} from './button.tsx';
+import {Link} from './link.tsx';
 
 export const Nav = memo(() => {
   const search = useSearch();
diff --git a/apps/zbugs/src/components/not-logged-in-modal.tsx b/apps/zbugs/src/components/not-logged-in-modal.tsx
index 110218ad2d..033e7537b6 100644
--- a/apps/zbugs/src/components/not-logged-in-modal.tsx
+++ b/apps/zbugs/src/components/not-logged-in-modal.tsx
@@ -1,5 +1,5 @@
-import {links} from '../routes.js';
-import {Modal, ModalActions, ModalText} from './modal.js';
+import {links} from '../routes.ts';
+import {Modal, ModalActions, ModalText} from './modal.tsx';
 
 export interface Props {
   onDismiss: () => void;
diff --git a/apps/zbugs/src/components/user-picker.tsx b/apps/zbugs/src/components/user-picker.tsx
index 2e9e244c1d..025d3ee031 100644
--- a/apps/zbugs/src/components/user-picker.tsx
+++ b/apps/zbugs/src/components/user-picker.tsx
@@ -1,11 +1,11 @@
 import {type Row} from '@rocicorp/zero';
 import {useQuery} from '@rocicorp/zero/react';
 import {useEffect, useMemo, useState} from 'react';
-import {type Schema} from '../../schema.js';
+import {type Schema} from '../../schema.ts';
 import avatarIcon from '../assets/icons/avatar-default.svg';
-import {avatarURLWithSize} from '../avatar-url-with-size.js';
-import {useZero} from '../hooks/use-zero.js';
-import {Combobox} from './combobox.js';
+import {avatarURLWithSize} from '../avatar-url-with-size.ts';
+import {useZero} from '../hooks/use-zero.ts';
+import {Combobox} from './combobox.tsx';
 
 type Props = {
   onSelect?: ((user: User | undefined) => void) | undefined;
diff --git a/apps/zbugs/src/emoji-utils.test.ts b/apps/zbugs/src/emoji-utils.test.ts
index 1439ac5ba0..b7127c2392 100644
--- a/apps/zbugs/src/emoji-utils.test.ts
+++ b/apps/zbugs/src/emoji-utils.test.ts
@@ -1,7 +1,7 @@
 import type {Writable} from 'shared/src/writable.js';
 import {expect, test} from 'vitest';
-import type {Emoji} from './emoji-utils.js';
-import {formatEmojiCreatorList, formatEmojiTooltipText} from './emoji-utils.js';
+import type {Emoji} from './emoji-utils.ts';
+import {formatEmojiCreatorList, formatEmojiTooltipText} from './emoji-utils.ts';
 
 function makeEmoji(userID: string, login: string): Emoji {
   return {
diff --git a/apps/zbugs/src/emoji-utils.ts b/apps/zbugs/src/emoji-utils.ts
index 19dd8c1bab..048c23efbd 100644
--- a/apps/zbugs/src/emoji-utils.ts
+++ b/apps/zbugs/src/emoji-utils.ts
@@ -1,6 +1,6 @@
 import type {Row} from '@rocicorp/zero';
 import {assert} from 'shared/src/asserts.js';
-import type {Schema} from '../schema.js';
+import type {Schema} from '../schema.ts';
 
 export type Emoji = Row<Schema['tables']['emoji']> & {
   readonly creator: Row<Schema['tables']['user']> | undefined;
diff --git a/apps/zbugs/src/hooks/use-can-edit.ts b/apps/zbugs/src/hooks/use-can-edit.ts
index 32419dab63..c99546b985 100644
--- a/apps/zbugs/src/hooks/use-can-edit.ts
+++ b/apps/zbugs/src/hooks/use-can-edit.ts
@@ -1,6 +1,6 @@
 import {useQuery} from '@rocicorp/zero/react';
-import {useLogin} from './use-login.js';
-import {useZero} from './use-zero.js';
+import {useLogin} from './use-login.tsx';
+import {useZero} from './use-zero.ts';
 
 export function useCanEdit(ownerUserID: string | undefined): boolean {
   const login = useLogin();
diff --git a/apps/zbugs/src/hooks/use-document-has-focus.tsx b/apps/zbugs/src/hooks/use-document-has-focus.ts
similarity index 100%
rename from apps/zbugs/src/hooks/use-document-has-focus.tsx
rename to apps/zbugs/src/hooks/use-document-has-focus.ts
diff --git a/apps/zbugs/src/hooks/use-emoji-data-source-preload.ts b/apps/zbugs/src/hooks/use-emoji-data-source-preload.ts
index 667f35822d..527037e5b4 100644
--- a/apps/zbugs/src/hooks/use-emoji-data-source-preload.ts
+++ b/apps/zbugs/src/hooks/use-emoji-data-source-preload.ts
@@ -1,6 +1,6 @@
 import Database from 'emoji-picker-element/database.js';
 import {useEffect} from 'react';
-import {emojiDataSource} from '../components/emoji-data-source.js';
+import {emojiDataSource} from '../components/emoji-data-source.ts';
 
 export function useEmojiDataSourcePreload() {
   useEffect(() => {
diff --git a/apps/zbugs/src/hooks/use-login.tsx b/apps/zbugs/src/hooks/use-login.tsx
index 291bbd92b6..ecc02d5efc 100644
--- a/apps/zbugs/src/hooks/use-login.tsx
+++ b/apps/zbugs/src/hooks/use-login.tsx
@@ -1,5 +1,5 @@
 import {createContext, useContext} from 'react';
-import {type LoginState} from '../zero-setup.js';
+import {type LoginState} from '../zero-setup.ts';
 
 export type LoginContext = {
   logout: () => void;
diff --git a/apps/zbugs/src/hooks/use-softnav.ts b/apps/zbugs/src/hooks/use-softnav.ts
index 0029167845..470c8391e9 100644
--- a/apps/zbugs/src/hooks/use-softnav.ts
+++ b/apps/zbugs/src/hooks/use-softnav.ts
@@ -1,7 +1,7 @@
 import {useEffect} from 'react';
 import {navigate} from 'wouter/use-browser-location';
-import {isPrimaryMouseButton} from '../is-primary-mouse-button.js';
-import {umami} from '../umami.js';
+import {isPrimaryMouseButton} from '../is-primary-mouse-button.ts';
+import {umami} from '../umami.ts';
 
 // Implements softnav for all links.
 // We do it this way rather than in the Link component so that links inside
diff --git a/apps/zbugs/src/hooks/use-user-pref.ts b/apps/zbugs/src/hooks/use-user-pref.ts
index bd57ab21c8..c98cb15a38 100644
--- a/apps/zbugs/src/hooks/use-user-pref.ts
+++ b/apps/zbugs/src/hooks/use-user-pref.ts
@@ -1,7 +1,7 @@
 import type {Zero} from '@rocicorp/zero';
 import {useQuery} from '@rocicorp/zero/react';
-import type {Schema} from '../../schema.js';
-import {useZero} from './use-zero.js';
+import type {Schema} from '../../schema.ts';
+import {useZero} from './use-zero.ts';
 
 export function useUserPref(key: string): string | undefined {
   const z = useZero();
diff --git a/apps/zbugs/src/hooks/use-zero.ts b/apps/zbugs/src/hooks/use-zero.ts
index 833a6d02bc..fe78137dfc 100644
--- a/apps/zbugs/src/hooks/use-zero.ts
+++ b/apps/zbugs/src/hooks/use-zero.ts
@@ -1,3 +1,3 @@
 import {createUseZero} from '@rocicorp/zero/react';
-import type {Schema} from '../../schema.js';
+import type {Schema} from '../../schema.ts';
 export const useZero = createUseZero<Schema>();
diff --git a/apps/zbugs/src/main.tsx b/apps/zbugs/src/main.tsx
index e3a0cf8bc2..aaea324175 100644
--- a/apps/zbugs/src/main.tsx
+++ b/apps/zbugs/src/main.tsx
@@ -1,12 +1,12 @@
-import './zero-setup.js';
+import './zero-setup.ts';
 
 import {StrictMode} from 'react';
 import {createRoot} from 'react-dom/client';
 import 'react-toastify/dist/ReactToastify.css';
 import {must} from 'shared/src/must.js';
-import {LoginProvider} from './components/login-provider.js';
+import {LoginProvider} from './components/login-provider.tsx';
 import './index.css';
-import {Root} from './root.js';
+import {Root} from './root.tsx';
 
 createRoot(must(document.getElementById('root'))).render(
   <LoginProvider>
diff --git a/apps/zbugs/src/page-load-stats.ts b/apps/zbugs/src/page-load-stats.ts
index 9472d5c8f2..09a4f1c9e6 100644
--- a/apps/zbugs/src/page-load-stats.ts
+++ b/apps/zbugs/src/page-load-stats.ts
@@ -1,4 +1,4 @@
-import {umami} from './umami.js';
+import {umami} from './umami.ts';
 
 function assignLatencyToBucket(latencyMs: number): string {
   const buckets = [
diff --git a/apps/zbugs/src/pages/issue/comment-composer.tsx b/apps/zbugs/src/pages/issue/comment-composer.tsx
index 1de1d4c692..c5d2b76b3e 100644
--- a/apps/zbugs/src/pages/issue/comment-composer.tsx
+++ b/apps/zbugs/src/pages/issue/comment-composer.tsx
@@ -1,10 +1,10 @@
 import {nanoid} from 'nanoid';
 import {useEffect, useState} from 'react';
-import {Button} from '../../components/button.js';
-import {useLogin} from '../../hooks/use-login.js';
-import {useZero} from '../../hooks/use-zero.js';
-import {isCtrlEnter} from './is-ctrl-enter.js';
-import {maxCommentLength} from '../../limits.js';
+import {Button} from '../../components/button.tsx';
+import {useLogin} from '../../hooks/use-login.tsx';
+import {useZero} from '../../hooks/use-zero.ts';
+import {maxCommentLength} from '../../limits.ts';
+import {isCtrlEnter} from './is-ctrl-enter.ts';
 
 export function CommentComposer({
   id,
diff --git a/apps/zbugs/src/pages/issue/comment.tsx b/apps/zbugs/src/pages/issue/comment.tsx
index 0f36a67ed5..e4a8103e2e 100644
--- a/apps/zbugs/src/pages/issue/comment.tsx
+++ b/apps/zbugs/src/pages/issue/comment.tsx
@@ -1,20 +1,20 @@
 import type {Row} from '@rocicorp/zero';
 import classNames from 'classnames';
 import {memo, useState} from 'react';
-import {makePermalink} from '../../comment-permalink.js';
-import type {commentQuery} from '../../comment-query.js';
-import {AvatarImage} from '../../components/avatar-image.js';
-import {Button} from '../../components/button.js';
-import {CanEdit} from '../../components/can-edit.js';
-import {Confirm} from '../../components/confirm.js';
-import {EmojiPanel} from '../../components/emoji-panel.js';
-import {Link} from '../../components/link.js';
-import {Markdown} from '../../components/markdown.js';
-import {RelativeTime} from '../../components/relative-time.js';
-import {useHash} from '../../hooks/use-hash.js';
-import {useLogin} from '../../hooks/use-login.js';
-import {useZero} from '../../hooks/use-zero.js';
-import {CommentComposer} from './comment-composer.js';
+import {makePermalink} from '../../comment-permalink.ts';
+import type {commentQuery} from '../../comment-query.ts';
+import {AvatarImage} from '../../components/avatar-image.tsx';
+import {Button} from '../../components/button.tsx';
+import {CanEdit} from '../../components/can-edit.tsx';
+import {Confirm} from '../../components/confirm.tsx';
+import {EmojiPanel} from '../../components/emoji-panel.tsx';
+import {Link} from '../../components/link.tsx';
+import {Markdown} from '../../components/markdown.tsx';
+import {RelativeTime} from '../../components/relative-time.tsx';
+import {useHash} from '../../hooks/use-hash.ts';
+import {useLogin} from '../../hooks/use-login.tsx';
+import {useZero} from '../../hooks/use-zero.ts';
+import {CommentComposer} from './comment-composer.tsx';
 import style from './comment.module.css';
 
 type Props = {
diff --git a/apps/zbugs/src/pages/issue/is-ctrl-enter.tsx b/apps/zbugs/src/pages/issue/is-ctrl-enter.ts
similarity index 100%
rename from apps/zbugs/src/pages/issue/is-ctrl-enter.tsx
rename to apps/zbugs/src/pages/issue/is-ctrl-enter.ts
diff --git a/apps/zbugs/src/pages/issue/issue-composer.tsx b/apps/zbugs/src/pages/issue/issue-composer.tsx
index ded1ae669f..1f81942c0d 100644
--- a/apps/zbugs/src/pages/issue/issue-composer.tsx
+++ b/apps/zbugs/src/pages/issue/issue-composer.tsx
@@ -1,13 +1,13 @@
 import {nanoid} from 'nanoid';
 import {useCallback, useEffect, useState} from 'react';
-import {Button} from '../../components/button.js';
-import {Modal, ModalActions, ModalBody} from '../../components/modal.js';
-import {useZero} from '../../hooks/use-zero.js';
-import {isCtrlEnter} from './is-ctrl-enter.js';
+import {Button} from '../../components/button.tsx';
+import {Modal, ModalActions, ModalBody} from '../../components/modal.tsx';
+import {useZero} from '../../hooks/use-zero.ts';
 import {
   MAX_ISSUE_DESCRIPTION_LENGTH,
   MAX_ISSUE_TITLE_LENGTH,
-} from '../../limits.js';
+} from '../../limits.ts';
+import {isCtrlEnter} from './is-ctrl-enter.ts';
 
 interface Props {
   /** If id is defined the issue created by the composer. */
diff --git a/apps/zbugs/src/pages/issue/issue-page.tsx b/apps/zbugs/src/pages/issue/issue-page.tsx
index e938fbc483..54dc885dac 100644
--- a/apps/zbugs/src/pages/issue/issue-page.tsx
+++ b/apps/zbugs/src/pages/issue/issue-page.tsx
@@ -20,42 +20,42 @@ import {toast, ToastContainer} from 'react-toastify';
 import {assert} from 'shared/src/asserts.js';
 import {useParams} from 'wouter';
 import {navigate, useHistoryState} from 'wouter/use-browser-location';
-import {must} from '../../../../../packages/shared/src/must.js';
-import {difference} from '../../../../../packages/shared/src/set-utils.js';
-import type {CommentRow, IssueRow, Schema, UserRow} from '../../../schema.js';
+import {must} from '../../../../../packages/shared/src/must.ts';
+import {difference} from '../../../../../packages/shared/src/set-utils.ts';
+import type {CommentRow, IssueRow, Schema, UserRow} from '../../../schema.ts';
 import statusClosed from '../../assets/icons/issue-closed.svg';
 import statusOpen from '../../assets/icons/issue-open.svg';
-import {commentQuery} from '../../comment-query.js';
-import {AvatarImage} from '../../components/avatar-image.js';
-import {Button} from '../../components/button.js';
-import {CanEdit} from '../../components/can-edit.js';
-import {Combobox} from '../../components/combobox.js';
-import {Confirm} from '../../components/confirm.js';
-import {EmojiPanel} from '../../components/emoji-panel.js';
-import {LabelPicker} from '../../components/label-picker.js';
-import {Link} from '../../components/link.js';
-import {Markdown} from '../../components/markdown.js';
-import {RelativeTime} from '../../components/relative-time.js';
-import {UserPicker} from '../../components/user-picker.js';
-import {type Emoji} from '../../emoji-utils.js';
-import {useCanEdit} from '../../hooks/use-can-edit.js';
-import {useDocumentHasFocus} from '../../hooks/use-document-has-focus.js';
-import {useEmojiDataSourcePreload} from '../../hooks/use-emoji-data-source-preload.js';
-import {useIsScrolling} from '../../hooks/use-is-scrolling.js';
-import {useKeypress} from '../../hooks/use-keypress.js';
-import {useLogin} from '../../hooks/use-login.js';
-import {useZero} from '../../hooks/use-zero.js';
+import {commentQuery} from '../../comment-query.ts';
+import {AvatarImage} from '../../components/avatar-image.tsx';
+import {Button} from '../../components/button.tsx';
+import {CanEdit} from '../../components/can-edit.tsx';
+import {Combobox} from '../../components/combobox.tsx';
+import {Confirm} from '../../components/confirm.tsx';
+import {EmojiPanel} from '../../components/emoji-panel.tsx';
+import {LabelPicker} from '../../components/label-picker.tsx';
+import {Link} from '../../components/link.tsx';
+import {Markdown} from '../../components/markdown.tsx';
+import {RelativeTime} from '../../components/relative-time.tsx';
+import {UserPicker} from '../../components/user-picker.tsx';
+import {type Emoji} from '../../emoji-utils.ts';
+import {useCanEdit} from '../../hooks/use-can-edit.ts';
+import {useDocumentHasFocus} from '../../hooks/use-document-has-focus.ts';
+import {useEmojiDataSourcePreload} from '../../hooks/use-emoji-data-source-preload.ts';
+import {useIsScrolling} from '../../hooks/use-is-scrolling.ts';
+import {useKeypress} from '../../hooks/use-keypress.ts';
+import {useLogin} from '../../hooks/use-login.tsx';
+import {useZero} from '../../hooks/use-zero.ts';
 import {
   MAX_ISSUE_DESCRIPTION_LENGTH,
   MAX_ISSUE_TITLE_LENGTH,
-} from '../../limits.js';
-import {LRUCache} from '../../lru-cache.js';
-import {recordPageLoad} from '../../page-load-stats.js';
-import {links, type ListContext, type ZbugsHistoryState} from '../../routes.js';
-import {preload} from '../../zero-setup.js';
-import {CommentComposer} from './comment-composer.js';
-import {Comment} from './comment.js';
-import {isCtrlEnter} from './is-ctrl-enter.js';
+} from '../../limits.ts';
+import {LRUCache} from '../../lru-cache.ts';
+import {recordPageLoad} from '../../page-load-stats.ts';
+import {links, type ListContext, type ZbugsHistoryState} from '../../routes.ts';
+import {preload} from '../../zero-setup.ts';
+import {CommentComposer} from './comment-composer.tsx';
+import {Comment} from './comment.tsx';
+import {isCtrlEnter} from './is-ctrl-enter.ts';
 
 const emojiToastShowDuration = 3_000;
 
diff --git a/apps/zbugs/src/pages/list/list-page.tsx b/apps/zbugs/src/pages/list/list-page.tsx
index 0f56a5defa..33cf7ef0b3 100644
--- a/apps/zbugs/src/pages/list/list-page.tsx
+++ b/apps/zbugs/src/pages/list/list-page.tsx
@@ -14,20 +14,20 @@ import React, {
 import {useDebouncedCallback} from 'use-debounce';
 import {useSearch} from 'wouter';
 import {navigate} from 'wouter/use-browser-location';
-import {Button} from '../../components/button.js';
-import {Filter, type Selection} from '../../components/filter.js';
-import {IssueLink} from '../../components/issue-link.js';
-import {Link} from '../../components/link.js';
-import {RelativeTime} from '../../components/relative-time.js';
-import {useClickOutside} from '../../hooks/use-click-outside.js';
-import {useElementSize} from '../../hooks/use-element-size.js';
-import {useKeypress} from '../../hooks/use-keypress.js';
-import {useLogin} from '../../hooks/use-login.js';
-import {useZero} from '../../hooks/use-zero.js';
-import {recordPageLoad} from '../../page-load-stats.js';
-import {mark} from '../../perf-log.js';
-import type {ListContext} from '../../routes.js';
-import {preload} from '../../zero-setup.js';
+import {Button} from '../../components/button.tsx';
+import {Filter, type Selection} from '../../components/filter.tsx';
+import {IssueLink} from '../../components/issue-link.tsx';
+import {Link} from '../../components/link.tsx';
+import {RelativeTime} from '../../components/relative-time.tsx';
+import {useClickOutside} from '../../hooks/use-click-outside.ts';
+import {useElementSize} from '../../hooks/use-element-size.ts';
+import {useKeypress} from '../../hooks/use-keypress.ts';
+import {useLogin} from '../../hooks/use-login.tsx';
+import {useZero} from '../../hooks/use-zero.ts';
+import {recordPageLoad} from '../../page-load-stats.ts';
+import {mark} from '../../perf-log.ts';
+import type {ListContext} from '../../routes.ts';
+import {preload} from '../../zero-setup.ts';
 
 let firstRowRendered = false;
 const itemSize = 56;
diff --git a/apps/zbugs/src/root.tsx b/apps/zbugs/src/root.tsx
index 8c95579ebe..b913c470c5 100644
--- a/apps/zbugs/src/root.tsx
+++ b/apps/zbugs/src/root.tsx
@@ -1,13 +1,13 @@
 import {ZeroProvider} from '@rocicorp/zero/react';
 import {useCallback, useState, useSyncExternalStore} from 'react';
 import {Route, Switch} from 'wouter';
-import {Nav} from './components/nav.js';
-import {ErrorPage} from './pages/error/error-page.js';
-import {IssuePage} from './pages/issue/issue-page.js';
-import {ListPage} from './pages/list/list-page.js';
-import {routes} from './routes.js';
-import {zeroRef} from './zero-setup.js';
-import {useSoftNav} from './hooks/use-softnav.js';
+import {Nav} from './components/nav.tsx';
+import {useSoftNav} from './hooks/use-softnav.ts';
+import {ErrorPage} from './pages/error/error-page.tsx';
+import {IssuePage} from './pages/issue/issue-page.tsx';
+import {ListPage} from './pages/list/list-page.tsx';
+import {routes} from './routes.ts';
+import {zeroRef} from './zero-setup.ts';
 
 export function Root() {
   const z = useSyncExternalStore(
diff --git a/apps/zbugs/src/zero-setup.ts b/apps/zbugs/src/zero-setup.ts
index 6ad0f98a1b..020330c40c 100644
--- a/apps/zbugs/src/zero-setup.ts
+++ b/apps/zbugs/src/zero-setup.ts
@@ -1,9 +1,9 @@
 import {Zero} from '@rocicorp/zero';
-import {Atom} from './atom.js';
-import {type Schema, schema} from '../schema.js';
-import {clearJwt, getJwt, getRawJwt} from './jwt.js';
-import {mark} from './perf-log.js';
-import {INITIAL_COMMENT_LIMIT} from './pages/issue/issue-page.js';
+import {type Schema, schema} from '../schema.ts';
+import {Atom} from './atom.ts';
+import {clearJwt, getJwt, getRawJwt} from './jwt.ts';
+import {INITIAL_COMMENT_LIMIT} from './pages/issue/issue-page.tsx';
+import {mark} from './perf-log.ts';
 
 export type LoginState = {
   encoded: string;
diff --git a/apps/zbugs/vite.config.ts b/apps/zbugs/vite.config.ts
index 1034eeff77..e078d44c38 100644
--- a/apps/zbugs/vite.config.ts
+++ b/apps/zbugs/vite.config.ts
@@ -3,7 +3,7 @@ import {makeDefine} from 'shared/src/build.js';
 import {defineConfig, type ViteDevServer} from 'vite';
 import svgr from 'vite-plugin-svgr';
 import tsconfigPaths from 'vite-tsconfig-paths';
-import {fastify} from './api/index.js';
+import {fastify} from './api/index.ts';
 
 async function configureServer(server: ViteDevServer) {
   await fastify.ready();
diff --git a/apps/zbugs/vitest.config.ts b/apps/zbugs/vitest.config.ts
index 210c9615cc..4eb8ab6746 100644
--- a/apps/zbugs/vitest.config.ts
+++ b/apps/zbugs/vitest.config.ts
@@ -1,5 +1,5 @@
 import {mergeConfig} from 'vitest/config';
-import config from '../../packages/shared/src/tool/vitest-config.js';
+import config from '../../packages/shared/src/tool/vitest-config.ts';
 
 export default mergeConfig(config, {
   test: {
diff --git a/packages/datadog/src/datadog-log-sink.test.ts b/packages/datadog/src/datadog-log-sink.test.ts
index 50be182021..0bf86faee7 100644
--- a/packages/datadog/src/datadog-log-sink.test.ts
+++ b/packages/datadog/src/datadog-log-sink.test.ts
@@ -1,12 +1,12 @@
 import {resolver} from '@rocicorp/resolver';
-import type {ReadonlyJSONObject} from '../../shared/src/json.js';
 import {afterEach, beforeEach, expect, test, vi} from 'vitest';
+import type {ReadonlyJSONObject} from '../../shared/src/json.ts';
 import {
   DatadogLogSink,
   FORCE_FLUSH_THRESHOLD,
   MAX_ENTRY_CHARS,
   MAX_LOG_ENTRIES_PER_FLUSH,
-} from './datadog-log-sink.js';
+} from './datadog-log-sink.ts';
 
 const originalFetch = globalThis.fetch;
 const fetch = vi.fn<typeof originalFetch>();
diff --git a/packages/datadog/src/mod.ts b/packages/datadog/src/mod.ts
index a015bad1f2..31e01ba5d0 100644
--- a/packages/datadog/src/mod.ts
+++ b/packages/datadog/src/mod.ts
@@ -1,4 +1,4 @@
 export {
   DatadogLogSink,
   type DatadogLogSinkOptions,
-} from './datadog-log-sink.js';
+} from './datadog-log-sink.ts';
diff --git a/packages/datadog/vite.config.ts b/packages/datadog/vite.config.ts
index 960efc6d6b..12508b30d0 100644
--- a/packages/datadog/vite.config.ts
+++ b/packages/datadog/vite.config.ts
@@ -1 +1 @@
-export {default} from '../shared/src/tool/vitest-config.js';
+export {default} from '../shared/src/tool/vitest-config.ts';
diff --git a/packages/replicache-perf/src/bencher-metric-format.ts b/packages/replicache-perf/src/bencher-metric-format.ts
index e7df1fc081..1b757e4156 100644
--- a/packages/replicache-perf/src/bencher-metric-format.ts
+++ b/packages/replicache-perf/src/bencher-metric-format.ts
@@ -1,4 +1,4 @@
-import type {BenchmarkResult} from './benchmark.js';
+import type {BenchmarkResult} from './benchmark.ts';
 
 export type BencherMetricsFormat = {
   [k: string]: {
diff --git a/packages/replicache-perf/src/benchmarks/compare-utf8.ts b/packages/replicache-perf/src/benchmarks/compare-utf8.ts
index 0a9b11c506..7dc535b8dd 100644
--- a/packages/replicache-perf/src/benchmarks/compare-utf8.ts
+++ b/packages/replicache-perf/src/benchmarks/compare-utf8.ts
@@ -1,6 +1,6 @@
 import {compareUTF8} from 'compare-utf8';
-import type {Benchmark} from '../benchmark.js';
-import {makeRandomASCIIStrings, makeRandomStrings} from '../data.js';
+import type {Benchmark} from '../benchmark.ts';
+import {makeRandomASCIIStrings, makeRandomStrings} from '../data.ts';
 
 const encoder = new TextEncoder();
 
diff --git a/packages/replicache-perf/src/benchmarks/hash.ts b/packages/replicache-perf/src/benchmarks/hash.ts
index 47265f5649..abcd653a86 100644
--- a/packages/replicache-perf/src/benchmarks/hash.ts
+++ b/packages/replicache-perf/src/benchmarks/hash.ts
@@ -1,6 +1,6 @@
 import {createSHA512} from 'hash-wasm';
-import type {Benchmark} from '../benchmark.js';
-import {makeRandomStrings} from '../data.js';
+import type {Benchmark} from '../benchmark.ts';
+import {makeRandomStrings} from '../data.ts';
 
 const encoder = new TextEncoder();
 
diff --git a/packages/replicache-perf/src/benchmarks/idb.ts b/packages/replicache-perf/src/benchmarks/idb.ts
index 797d7a4c75..1cad697b8d 100644
--- a/packages/replicache-perf/src/benchmarks/idb.ts
+++ b/packages/replicache-perf/src/benchmarks/idb.ts
@@ -2,8 +2,8 @@ import {deleteDB, type IDBPDatabase, openDB} from 'idb/with-async-ittr';
 // eslint-disable-next-line @typescript-eslint/ban-ts-comment
 // @ts-ignore Invalid module when using node16 module resolution.
 import xbytes from 'xbytes';
-import type {Bencher, Benchmark} from '../benchmark.js';
-import {randomData, type RandomDataType} from '../data.js';
+import type {Bencher, Benchmark} from '../benchmark.ts';
+import {randomData, type RandomDataType} from '../data.ts';
 
 function benchmarkIDBReadGetAll(opts: {
   dataType: RandomDataType;
diff --git a/packages/replicache-perf/src/benchmarks/map-loop.ts b/packages/replicache-perf/src/benchmarks/map-loop.ts
index 5575ab7d31..41ece4e074 100644
--- a/packages/replicache-perf/src/benchmarks/map-loop.ts
+++ b/packages/replicache-perf/src/benchmarks/map-loop.ts
@@ -1,4 +1,4 @@
-import type {Benchmark} from '../benchmark.js';
+import type {Benchmark} from '../benchmark.ts';
 
 export function benchmarks(): Array<Benchmark> {
   return [forLoop(), forEach()];
diff --git a/packages/replicache-perf/src/benchmarks/replicache.ts b/packages/replicache-perf/src/benchmarks/replicache.ts
index 468d67a4f5..5ca77d6c3c 100644
--- a/packages/replicache-perf/src/benchmarks/replicache.ts
+++ b/packages/replicache-perf/src/benchmarks/replicache.ts
@@ -1,6 +1,6 @@
 import {resolver} from '@rocicorp/resolver';
-import {ReplicacheImpl} from '../../../replicache/src/impl.js';
-import {dropIDBStoreWithMemFallback} from '../../../replicache/src/kv/idb-store-with-mem-fallback.js';
+import {ReplicacheImpl} from '../../../replicache/src/impl.ts';
+import {dropIDBStoreWithMemFallback} from '../../../replicache/src/kv/idb-store-with-mem-fallback.ts';
 import type {
   IndexDefinitions,
   JSONValue,
@@ -9,18 +9,18 @@ import type {
   ReadTransaction,
   ReplicacheOptions,
   WriteTransaction,
-} from '../../../replicache/src/mod.js';
-import {assert} from '../../../shared/src/asserts.js';
-import {deepEqual} from '../../../shared/src/json.js';
-import {randomUint64} from '../../../shared/src/random-uint64.js';
-import type {Writable} from '../../../shared/src/writable.js';
-import type {Bencher, Benchmark} from '../benchmark.js';
+} from '../../../replicache/src/mod.ts';
+import {assert} from '../../../shared/src/asserts.ts';
+import {deepEqual} from '../../../shared/src/json.ts';
+import {randomUint64} from '../../../shared/src/random-uint64.ts';
+import type {Writable} from '../../../shared/src/writable.ts';
+import type {Bencher, Benchmark} from '../benchmark.ts';
 import {
   type TestDataObject,
   getTmcwData,
   jsonArrayTestData,
   jsonObjectTestData,
-} from '../data.js';
+} from '../data.ts';
 
 const valSize = 1024;
 
diff --git a/packages/replicache-perf/src/benchmarks/storage.ts b/packages/replicache-perf/src/benchmarks/storage.ts
index ac8ca7eced..a2a8acb630 100644
--- a/packages/replicache-perf/src/benchmarks/storage.ts
+++ b/packages/replicache-perf/src/benchmarks/storage.ts
@@ -1,5 +1,5 @@
-import type {Benchmark} from '../benchmark.js';
-import {randomString} from '../data.js';
+import type {Benchmark} from '../benchmark.ts';
+import {randomString} from '../data.ts';
 
 export function benchmarks(): Benchmark[] {
   return [localStorageRead(), localStorageWrite()];
diff --git a/packages/replicache-perf/src/data.ts b/packages/replicache-perf/src/data.ts
index f911b1d876..8da87b55fe 100644
--- a/packages/replicache-perf/src/data.ts
+++ b/packages/replicache-perf/src/data.ts
@@ -1,4 +1,4 @@
-import {getSizeOfValue} from '../../replicache/src/size-of-value.js';
+import {getSizeOfValue} from '../../replicache/src/size-of-value.ts';
 
 export type RandomDataType = 'string' | 'object' | 'arraybuffer' | 'blob';
 export type RandomDatum = string | Record<string, string> | ArrayBuffer | Blob;
diff --git a/packages/replicache-perf/src/format.ts b/packages/replicache-perf/src/format.ts
index c86da85327..dfdfabf303 100644
--- a/packages/replicache-perf/src/format.ts
+++ b/packages/replicache-perf/src/format.ts
@@ -1,4 +1,4 @@
-import type {BenchmarkResult} from './benchmark.js';
+import type {BenchmarkResult} from './benchmark.ts';
 
 export function formatAsReplicache(results: BenchmarkResult): string {
   const {name, runTimesStatistics: stats, sortedRunTimesMs: runs} = results;
diff --git a/packages/replicache-perf/src/github-action-benchmark.ts b/packages/replicache-perf/src/github-action-benchmark.ts
index c413d8611b..2225452470 100644
--- a/packages/replicache-perf/src/github-action-benchmark.ts
+++ b/packages/replicache-perf/src/github-action-benchmark.ts
@@ -1,5 +1,5 @@
-import type {BenchmarkResult} from './benchmark.js';
-import {formatAsReplicache, formatVariance} from './format.js';
+import type {BenchmarkResult} from './benchmark.ts';
+import {formatAsReplicache, formatVariance} from './format.ts';
 
 // See https://github.com/benchmark-action/github-action-benchmark#examples
 export type Entry = {
diff --git a/packages/replicache-perf/src/index.ts b/packages/replicache-perf/src/index.ts
index 1c53db1157..d0c14a3016 100644
--- a/packages/replicache-perf/src/index.ts
+++ b/packages/replicache-perf/src/index.ts
@@ -1,5 +1,5 @@
-import * as m from './perf.js';
-import {benchmarks, runAll} from './perf.js';
+import * as m from './perf.ts';
+import {benchmarks, runAll} from './perf.ts';
 
 // export all as globals
 for (const [n, v] of Object.entries(m)) {
diff --git a/packages/replicache-perf/src/perf.ts b/packages/replicache-perf/src/perf.ts
index 094a33e705..23444ce5dc 100644
--- a/packages/replicache-perf/src/perf.ts
+++ b/packages/replicache-perf/src/perf.ts
@@ -1,11 +1,11 @@
-import {type Benchmark, runBenchmark} from './benchmark.js';
-import {benchmarks as compareBenchmarks} from './benchmarks/compare-utf8.js';
-import {benchmarks as hashBenchmarks} from './benchmarks/hash.js';
-import {benchmarks as idbBenchmarks} from './benchmarks/idb.js';
-import {benchmarks as mapLoopBenchmarks} from './benchmarks/map-loop.js';
-import {benchmarks as replicacheBenchmarks} from './benchmarks/replicache.js';
-import {benchmarks as storageBenchmarks} from './benchmarks/storage.js';
-import {formatAsReplicache} from './format.js';
+import {type Benchmark, runBenchmark} from './benchmark.ts';
+import {benchmarks as compareBenchmarks} from './benchmarks/compare-utf8.ts';
+import {benchmarks as hashBenchmarks} from './benchmarks/hash.ts';
+import {benchmarks as idbBenchmarks} from './benchmarks/idb.ts';
+import {benchmarks as mapLoopBenchmarks} from './benchmarks/map-loop.ts';
+import {benchmarks as replicacheBenchmarks} from './benchmarks/replicache.ts';
+import {benchmarks as storageBenchmarks} from './benchmarks/storage.ts';
+import {formatAsReplicache} from './format.ts';
 
 export const benchmarks = [
   ...replicacheBenchmarks(),
diff --git a/packages/replicache-perf/src/runner.ts b/packages/replicache-perf/src/runner.ts
index 3574629ce5..fc0198940b 100644
--- a/packages/replicache-perf/src/runner.ts
+++ b/packages/replicache-perf/src/runner.ts
@@ -8,14 +8,14 @@ import process from 'node:process';
 import {fileURLToPath} from 'node:url';
 import * as playwright from 'playwright';
 import {createServer} from 'vite';
-import {assert} from '../../shared/src/asserts.js';
+import {assert} from '../../shared/src/asserts.ts';
 import {makeDefine} from '../../shared/src/build.js';
 import {
   type BencherMetricsFormat,
   toBencherMetricFormat,
-} from './bencher-metric-format.js';
-import {formatAsBenchmarkJS, formatAsReplicache} from './format.js';
-import {createGithubActionBenchmarkJSONEntries} from './github-action-benchmark.js';
+} from './bencher-metric-format.ts';
+import {formatAsBenchmarkJS, formatAsReplicache} from './format.ts';
+import {createGithubActionBenchmarkJSONEntries} from './github-action-benchmark.ts';
 
 type Format = 'benchmarkJS' | 'json' | 'replicache' | 'bmf';
 
diff --git a/packages/replicache-perf/tool/convert-old-file-sizes.js b/packages/replicache-perf/tool/convert-old-file-sizes.js
index 2f5e34c549..563088b5a8 100644
--- a/packages/replicache-perf/tool/convert-old-file-sizes.js
+++ b/packages/replicache-perf/tool/convert-old-file-sizes.js
@@ -9,7 +9,7 @@
 const branch = 'main';
 const testbed = 'localhost';
 const projectSlug = 'replicache-bundle-size';
-const jsURL = 'https://rocicorp.github.io/mono/bundle-sizes/data.js';
+const jsURL = 'https://rocicorp.github.io/mono/bundle-sizes/data.ts';
 const header = 'window.BENCHMARK_DATA = ';
 
 function benchesToBencher(benches) {
diff --git a/packages/replicache/src/array-compare.test.ts b/packages/replicache/src/array-compare.test.ts
index 8afd99dc64..e4eda343d4 100644
--- a/packages/replicache/src/array-compare.test.ts
+++ b/packages/replicache/src/array-compare.test.ts
@@ -1,5 +1,5 @@
 import {expect, test} from 'vitest';
-import {arrayCompare} from './array-compare.js';
+import {arrayCompare} from './array-compare.ts';
 
 test('array compare', () => {
   const t = <T>(a: ArrayLike<T>, b: ArrayLike<T>, expected: number) => {
diff --git a/packages/replicache/src/bg-interval.test.ts b/packages/replicache/src/bg-interval.test.ts
index ca49b9add4..00300c53e0 100644
--- a/packages/replicache/src/bg-interval.test.ts
+++ b/packages/replicache/src/bg-interval.test.ts
@@ -2,8 +2,8 @@ import {LogContext} from '@rocicorp/logger';
 import {resolver} from '@rocicorp/resolver';
 import sinon, {type SinonFakeTimers, useFakeTimers} from 'sinon';
 import {afterEach, beforeEach, expect, test} from 'vitest';
-import {TestLogSink} from '../../shared/src/logging-test-utils.js';
-import {initBgIntervalProcess} from './bg-interval.js';
+import {TestLogSink} from '../../shared/src/logging-test-utils.ts';
+import {initBgIntervalProcess} from './bg-interval.ts';
 
 let clock: SinonFakeTimers;
 beforeEach(() => {
diff --git a/packages/replicache/src/bg-interval.ts b/packages/replicache/src/bg-interval.ts
index 93a025662b..418fd0e83c 100644
--- a/packages/replicache/src/bg-interval.ts
+++ b/packages/replicache/src/bg-interval.ts
@@ -1,6 +1,6 @@
 import type {LogContext} from '@rocicorp/logger';
-import {AbortError} from '../../shared/src/abort-error.js';
-import {sleep} from '../../shared/src/sleep.js';
+import {AbortError} from '../../shared/src/abort-error.ts';
+import {sleep} from '../../shared/src/sleep.ts';
 
 export function initBgIntervalProcess(
   processName: string,
diff --git a/packages/replicache/src/binary-search.test.ts b/packages/replicache/src/binary-search.test.ts
index 83356a4a1a..08b79f30df 100644
--- a/packages/replicache/src/binary-search.test.ts
+++ b/packages/replicache/src/binary-search.test.ts
@@ -1,5 +1,5 @@
 import {expect, test} from 'vitest';
-import {binarySearch} from './binary-search.js';
+import {binarySearch} from './binary-search.ts';
 
 test('binarySearch', () => {
   // expect(binarySearch(0, () => -1)).to.equal(0);
diff --git a/packages/replicache/src/btree/diff.ts b/packages/replicache/src/btree/diff.ts
index e174a1cd40..1cd51150fb 100644
--- a/packages/replicache/src/btree/diff.ts
+++ b/packages/replicache/src/btree/diff.ts
@@ -1,6 +1,6 @@
-import {asyncIterableToArray} from '../async-iterable-to-array.js';
-import type {InternalDiff} from './node.js';
-import type {BTreeRead} from './read.js';
+import {asyncIterableToArray} from '../async-iterable-to-array.ts';
+import type {InternalDiff} from './node.ts';
+import type {BTreeRead} from './read.ts';
 
 export function diff(
   oldMap: BTreeRead,
diff --git a/packages/replicache/src/btree/node.test.ts b/packages/replicache/src/btree/node.test.ts
index f15773ceec..ad4998686d 100644
--- a/packages/replicache/src/btree/node.test.ts
+++ b/packages/replicache/src/btree/node.test.ts
@@ -1,21 +1,21 @@
 import {beforeEach, describe, expect, test} from 'vitest';
-import {assert} from '../../../shared/src/asserts.js';
-import type {Enum} from '../../../shared/src/enum.js';
-import type {ReadonlyJSONValue} from '../../../shared/src/json.js';
-import {toRefs} from '../dag/chunk.js';
-import type {Read, Store, Write} from '../dag/store.js';
-import {TestStore} from '../dag/test-store.js';
-import {ChainBuilder} from '../db/test-helpers.js';
-import * as FormatVersion from '../format-version-enum.js';
-import {type FrozenJSONValue, deepFreeze} from '../frozen-json.js';
+import {assert} from '../../../shared/src/asserts.ts';
+import type {Enum} from '../../../shared/src/enum.ts';
+import type {ReadonlyJSONValue} from '../../../shared/src/json.ts';
+import {toRefs} from '../dag/chunk.ts';
+import type {Read, Store, Write} from '../dag/store.ts';
+import {TestStore} from '../dag/test-store.ts';
+import {ChainBuilder} from '../db/test-helpers.ts';
+import * as FormatVersion from '../format-version-enum.ts';
+import {type FrozenJSONValue, deepFreeze} from '../frozen-json.ts';
 import {
   type Hash,
   emptyHash,
   fakeHash,
   makeNewFakeHashFunction,
-} from '../hash.js';
-import {getSizeOfEntry, getSizeOfValue} from '../size-of-value.js';
-import {withRead, withWrite} from '../with-transactions.js';
+} from '../hash.ts';
+import {getSizeOfEntry, getSizeOfValue} from '../size-of-value.ts';
+import {withRead, withWrite} from '../with-transactions.ts';
 import {
   type DataNode,
   type Diff,
@@ -28,9 +28,9 @@ import {
   parseBTreeNode,
   partition,
   toChunkData,
-} from './node.js';
-import {BTreeRead, NODE_HEADER_SIZE} from './read.js';
-import {BTreeWrite} from './write.js';
+} from './node.ts';
+import {BTreeRead, NODE_HEADER_SIZE} from './read.ts';
+import {BTreeWrite} from './write.ts';
 
 type FormatVersion = Enum<typeof FormatVersion>;
 
diff --git a/packages/replicache/src/btree/node.ts b/packages/replicache/src/btree/node.ts
index efb48502d8..2b1d6df3f2 100644
--- a/packages/replicache/src/btree/node.ts
+++ b/packages/replicache/src/btree/node.ts
@@ -4,27 +4,27 @@ import {
   assertArray,
   assertNumber,
   assertString,
-} from '../../../shared/src/asserts.js';
-import type {Enum} from '../../../shared/src/enum.js';
-import {joinIterables} from '../../../shared/src/iterables.js';
+} from '../../../shared/src/asserts.ts';
+import type {Enum} from '../../../shared/src/enum.ts';
+import {joinIterables} from '../../../shared/src/iterables.ts';
 import {
   type JSONValue,
   type ReadonlyJSONValue,
   assertJSONValue,
-} from '../../../shared/src/json.js';
-import {binarySearch as binarySearchWithFunc} from '../binary-search.js';
-import {skipBTreeNodeAsserts} from '../config.js';
-import type {IndexKey} from '../db/index.js';
-import * as FormatVersion from '../format-version-enum.js';
+} from '../../../shared/src/json.ts';
+import {binarySearch as binarySearchWithFunc} from '../binary-search.ts';
+import {skipBTreeNodeAsserts} from '../config.ts';
+import type {IndexKey} from '../db/index.ts';
+import * as FormatVersion from '../format-version-enum.ts';
 import {
   type FrozenJSONValue,
   type FrozenTag,
   assertDeepFrozen,
   deepFreeze,
-} from '../frozen-json.js';
-import {type Hash, emptyHash, newRandomHash} from '../hash.js';
-import type {BTreeRead} from './read.js';
-import type {BTreeWrite} from './write.js';
+} from '../frozen-json.ts';
+import {type Hash, emptyHash, newRandomHash} from '../hash.ts';
+import type {BTreeRead} from './read.ts';
+import type {BTreeWrite} from './write.ts';
 
 type FormatVersion = Enum<typeof FormatVersion>;
 
diff --git a/packages/replicache/src/btree/read.ts b/packages/replicache/src/btree/read.ts
index 8430daa2d1..930ee87bf4 100644
--- a/packages/replicache/src/btree/read.ts
+++ b/packages/replicache/src/btree/read.ts
@@ -1,10 +1,10 @@
-import type {Enum} from '../../../shared/src/enum.js';
-import {deepEqual} from '../../../shared/src/json.js';
-import type {Read} from '../dag/store.js';
-import * as FormatVersion from '../format-version-enum.js';
-import type {FrozenJSONValue} from '../frozen-json.js';
-import {type Hash, emptyHash} from '../hash.js';
-import {getSizeOfEntry} from '../size-of-value.js';
+import type {Enum} from '../../../shared/src/enum.ts';
+import {deepEqual} from '../../../shared/src/json.ts';
+import type {Read} from '../dag/store.ts';
+import * as FormatVersion from '../format-version-enum.ts';
+import type {FrozenJSONValue} from '../frozen-json.ts';
+import {type Hash, emptyHash} from '../hash.ts';
+import {getSizeOfEntry} from '../size-of-value.ts';
 import {
   DataNodeImpl,
   type Entry,
@@ -20,14 +20,14 @@ import {
   isDataNodeImpl,
   newNodeImpl,
   parseBTreeNode,
-} from './node.js';
+} from './node.ts';
 import {
   SPLICE_ADDED,
   SPLICE_AT,
   SPLICE_FROM,
   SPLICE_REMOVED,
   computeSplices,
-} from './splice.js';
+} from './splice.ts';
 
 type FormatVersion = Enum<typeof FormatVersion>;
 
diff --git a/packages/replicache/src/btree/splice.test.ts b/packages/replicache/src/btree/splice.test.ts
index 34ec4c5226..48b4ca7f69 100644
--- a/packages/replicache/src/btree/splice.test.ts
+++ b/packages/replicache/src/btree/splice.test.ts
@@ -1,6 +1,6 @@
 import {expect, test} from 'vitest';
-import type {ReadonlyJSONValue} from '../../../shared/src/json.js';
-import {computeSplices, type Splice} from './splice.js';
+import type {ReadonlyJSONValue} from '../../../shared/src/json.ts';
+import {computeSplices, type Splice} from './splice.ts';
 
 type Entry<V> = readonly [string, V];
 
diff --git a/packages/replicache/src/btree/splice.ts b/packages/replicache/src/btree/splice.ts
index 68646a15d7..fcc78d1ee5 100644
--- a/packages/replicache/src/btree/splice.ts
+++ b/packages/replicache/src/btree/splice.ts
@@ -1,4 +1,4 @@
-import {deepEqual, type ReadonlyJSONValue} from '../../../shared/src/json.js';
+import {deepEqual, type ReadonlyJSONValue} from '../../../shared/src/json.ts';
 
 export type Splice = [at: number, removed: number, added: number, from: number];
 
diff --git a/packages/replicache/src/btree/write.ts b/packages/replicache/src/btree/write.ts
index b8f6176980..63ac54ca0a 100644
--- a/packages/replicache/src/btree/write.ts
+++ b/packages/replicache/src/btree/write.ts
@@ -1,13 +1,13 @@
 import {Lock} from '@rocicorp/lock';
-import {assert} from '../../../shared/src/asserts.js';
-import type {Enum} from '../../../shared/src/enum.js';
-import type {ReadonlyJSONValue} from '../../../shared/src/json.js';
-import {type Chunk, type CreateChunk, toRefs} from '../dag/chunk.js';
-import type {Write} from '../dag/store.js';
-import * as FormatVersion from '../format-version-enum.js';
-import type {FrozenJSONValue} from '../frozen-json.js';
-import {type Hash, emptyHash, newRandomHash} from '../hash.js';
-import {getSizeOfEntry} from '../size-of-value.js';
+import {assert} from '../../../shared/src/asserts.ts';
+import type {Enum} from '../../../shared/src/enum.ts';
+import type {ReadonlyJSONValue} from '../../../shared/src/json.ts';
+import {type Chunk, type CreateChunk, toRefs} from '../dag/chunk.ts';
+import type {Write} from '../dag/store.ts';
+import * as FormatVersion from '../format-version-enum.ts';
+import type {FrozenJSONValue} from '../frozen-json.ts';
+import {type Hash, emptyHash, newRandomHash} from '../hash.ts';
+import {getSizeOfEntry} from '../size-of-value.ts';
 import {
   DataNodeImpl,
   type Entry,
@@ -18,8 +18,8 @@ import {
   newNodeImpl,
   partition,
   toChunkData,
-} from './node.js';
-import {BTreeRead} from './read.js';
+} from './node.ts';
+import {BTreeRead} from './read.ts';
 
 type FormatVersion = Enum<typeof FormatVersion>;
 
diff --git a/packages/replicache/src/call-default-fetch.ts b/packages/replicache/src/call-default-fetch.ts
index 9c6d012a8c..eba5d6567b 100644
--- a/packages/replicache/src/call-default-fetch.ts
+++ b/packages/replicache/src/call-default-fetch.ts
@@ -1,4 +1,4 @@
-import type {HTTPRequestInfo} from './http-request-info.js';
+import type {HTTPRequestInfo} from './http-request-info.ts';
 
 /**
  * Helper function for {@link getDefaultPuller} and {@link getDefaultPusher}.
diff --git a/packages/replicache/src/config.ts b/packages/replicache/src/config.ts
index b19e9c1052..fd73c75701 100644
--- a/packages/replicache/src/config.ts
+++ b/packages/replicache/src/config.ts
@@ -1,4 +1,4 @@
-import {isProd} from '../../shared/src/config.js';
+import {isProd} from '../../shared/src/config.ts';
 
 export {
   isProd as skipBTreeNodeAsserts,
diff --git a/packages/replicache/src/connection-loop-delegates.ts b/packages/replicache/src/connection-loop-delegates.ts
index b7316900d9..8e1dafde8f 100644
--- a/packages/replicache/src/connection-loop-delegates.ts
+++ b/packages/replicache/src/connection-loop-delegates.ts
@@ -1,5 +1,5 @@
-import type {ConnectionLoopDelegate} from './connection-loop.js';
-import type {ReplicacheImpl} from './replicache-impl.js';
+import type {ConnectionLoopDelegate} from './connection-loop.ts';
+import type {ReplicacheImpl} from './replicache-impl.ts';
 
 class ConnectionLoopDelegateImpl {
   readonly rep: ReplicacheImpl;
diff --git a/packages/replicache/src/connection-loop.test.ts b/packages/replicache/src/connection-loop.test.ts
index d2ce948e99..f31fef0f63 100644
--- a/packages/replicache/src/connection-loop.test.ts
+++ b/packages/replicache/src/connection-loop.test.ts
@@ -1,16 +1,16 @@
 import {LogContext} from '@rocicorp/logger';
 import {type SinonFakeTimers, useFakeTimers} from 'sinon';
 import {afterEach, beforeEach, describe, expect, test} from 'vitest';
-import {getDocumentVisibilityWatcher} from '../../shared/src/document-visible.js';
-import {promiseTrue} from '../../shared/src/resolved-promises.js';
-import {sleep} from '../../shared/src/sleep.js';
+import {getDocumentVisibilityWatcher} from '../../shared/src/document-visible.ts';
+import {promiseTrue} from '../../shared/src/resolved-promises.ts';
+import {sleep} from '../../shared/src/sleep.ts';
 import {
   ConnectionLoop,
   type ConnectionLoopDelegate,
   DEBOUNCE_DELAY_MS,
   MAX_DELAY_MS,
   MIN_DELAY_MS,
-} from './connection-loop.js';
+} from './connection-loop.ts';
 
 let clock: SinonFakeTimers;
 beforeEach(() => {
diff --git a/packages/replicache/src/connection-loop.ts b/packages/replicache/src/connection-loop.ts
index d08406df83..1e3ba8f223 100644
--- a/packages/replicache/src/connection-loop.ts
+++ b/packages/replicache/src/connection-loop.ts
@@ -1,7 +1,7 @@
 import type {LogContext} from '@rocicorp/logger';
 import {resolver} from '@rocicorp/resolver';
-import type {DocumentVisibilityWatcher} from '../../shared/src/document-visible.js';
-import {sleep} from '../../shared/src/sleep.js';
+import type {DocumentVisibilityWatcher} from '../../shared/src/document-visible.ts';
+import {sleep} from '../../shared/src/sleep.ts';
 
 export const DEBOUNCE_DELAY_MS = 10;
 
diff --git a/packages/replicache/src/cookies.test.ts b/packages/replicache/src/cookies.test.ts
index 814d7e2fd4..5e4b246860 100644
--- a/packages/replicache/src/cookies.test.ts
+++ b/packages/replicache/src/cookies.test.ts
@@ -1,5 +1,5 @@
 import {expect, test} from 'vitest';
-import {compareCookies, type Cookie} from './cookies.js';
+import {compareCookies, type Cookie} from './cookies.ts';
 
 test('compareCookies', () => {
   const t = (a: Cookie, b: Cookie, expected: number) => {
diff --git a/packages/replicache/src/cookies.ts b/packages/replicache/src/cookies.ts
index 532c63ac83..8ec82472bb 100644
--- a/packages/replicache/src/cookies.ts
+++ b/packages/replicache/src/cookies.ts
@@ -1,9 +1,9 @@
 import {
   assertJSONObject,
   type ReadonlyJSONValue,
-} from '../../shared/src/json.js';
-import {stringCompare} from '../../shared/src/string-compare.js';
-import type {FrozenJSONValue} from './frozen-json.js';
+} from '../../shared/src/json.ts';
+import {stringCompare} from '../../shared/src/string-compare.ts';
+import type {FrozenJSONValue} from './frozen-json.ts';
 
 /**
  * A cookie is a value that is used to determine the order of snapshots. It
diff --git a/packages/replicache/src/dag/chunk.test.ts b/packages/replicache/src/dag/chunk.test.ts
index 1ae073d5bf..dc527371f7 100644
--- a/packages/replicache/src/dag/chunk.test.ts
+++ b/packages/replicache/src/dag/chunk.test.ts
@@ -1,8 +1,8 @@
 import {expect, test} from 'vitest';
-import type {ReadonlyJSONValue} from '../../../shared/src/json.js';
-import {deepFreeze} from '../frozen-json.js';
-import {fakeHash, type Hash, makeNewFakeHashFunction} from '../hash.js';
-import {Chunk, createChunk, type Refs, toRefs} from './chunk.js';
+import type {ReadonlyJSONValue} from '../../../shared/src/json.ts';
+import {deepFreeze} from '../frozen-json.ts';
+import {fakeHash, type Hash, makeNewFakeHashFunction} from '../hash.ts';
+import {Chunk, createChunk, type Refs, toRefs} from './chunk.ts';
 
 test('round trip', () => {
   const chunkHasher = makeNewFakeHashFunction();
diff --git a/packages/replicache/src/dag/chunk.ts b/packages/replicache/src/dag/chunk.ts
index 0e2154c839..57759709ea 100644
--- a/packages/replicache/src/dag/chunk.ts
+++ b/packages/replicache/src/dag/chunk.ts
@@ -1,6 +1,6 @@
-import {assert, assertString} from '../../../shared/src/asserts.js';
-import {assertDeepFrozen} from '../frozen-json.js';
-import type {Hash} from '../hash.js';
+import {assert, assertString} from '../../../shared/src/asserts.ts';
+import {assertDeepFrozen} from '../frozen-json.ts';
+import type {Hash} from '../hash.ts';
 
 // By using declare we tell the type system that there is a unique symbol.
 // However, there is no such symbol but the type system does not care.
diff --git a/packages/replicache/src/dag/gc.test.ts b/packages/replicache/src/dag/gc.test.ts
index bfe51ae57a..59b312c9c3 100644
--- a/packages/replicache/src/dag/gc.test.ts
+++ b/packages/replicache/src/dag/gc.test.ts
@@ -1,6 +1,6 @@
 import {expect, test} from 'vitest';
-import {fakeHash, type Hash} from '../hash.js';
-import {computeRefCountUpdates, type RefCountUpdatesDelegate} from './gc.js';
+import {fakeHash, type Hash} from '../hash.ts';
+import {computeRefCountUpdates, type RefCountUpdatesDelegate} from './gc.ts';
 
 function createGraph(args: {
   graph: Record<string, string[]>;
diff --git a/packages/replicache/src/dag/gc.ts b/packages/replicache/src/dag/gc.ts
index b37f352f1d..ecef730035 100644
--- a/packages/replicache/src/dag/gc.ts
+++ b/packages/replicache/src/dag/gc.ts
@@ -1,7 +1,7 @@
-import {assert, assertNumber} from '../../../shared/src/asserts.js';
-import type {MaybePromise} from '../../../shared/src/types.js';
-import {skipGCAsserts} from '../config.js';
-import {type Hash, emptyHash} from '../hash.js';
+import {assert, assertNumber} from '../../../shared/src/asserts.ts';
+import type {MaybePromise} from '../../../shared/src/types.ts';
+import {skipGCAsserts} from '../config.ts';
+import {type Hash, emptyHash} from '../hash.ts';
 
 export type HeadChange = {
   new: Hash | undefined;
diff --git a/packages/replicache/src/dag/key.test.ts b/packages/replicache/src/dag/key.test.ts
index 4caa9a4c3b..d7b46296a1 100644
--- a/packages/replicache/src/dag/key.test.ts
+++ b/packages/replicache/src/dag/key.test.ts
@@ -1,6 +1,6 @@
 import {expect, test} from 'vitest';
-import {fakeHash} from '../hash.js';
-import * as KeyType from './key-type-enum.js';
+import {fakeHash} from '../hash.ts';
+import * as KeyType from './key-type-enum.ts';
 import {
   chunkDataKey,
   chunkMetaKey,
@@ -8,7 +8,7 @@ import {
   headKey,
   type Key,
   parse,
-} from './key.js';
+} from './key.ts';
 
 test('toString', () => {
   const hashEmptyString = fakeHash('');
diff --git a/packages/replicache/src/dag/key.ts b/packages/replicache/src/dag/key.ts
index 3839966543..6f3d4de04f 100644
--- a/packages/replicache/src/dag/key.ts
+++ b/packages/replicache/src/dag/key.ts
@@ -1,5 +1,5 @@
-import {type Hash, parse as parseHash} from '../hash.js';
-import * as KeyType from './key-type-enum.js';
+import {type Hash, parse as parseHash} from '../hash.ts';
+import * as KeyType from './key-type-enum.ts';
 
 export function chunkDataKey(hash: Hash): string {
   return `c/${hash}/d`;
diff --git a/packages/replicache/src/dag/lazy-store.test.ts b/packages/replicache/src/dag/lazy-store.test.ts
index ec231ae211..3604062795 100644
--- a/packages/replicache/src/dag/lazy-store.test.ts
+++ b/packages/replicache/src/dag/lazy-store.test.ts
@@ -1,14 +1,14 @@
 import {expect, test} from 'vitest';
-import {deepFreeze} from '../frozen-json.js';
-import {assertHash, fakeHash, makeNewFakeHashFunction} from '../hash.js';
+import {deepFreeze} from '../frozen-json.ts';
+import {assertHash, fakeHash, makeNewFakeHashFunction} from '../hash.ts';
 import {
   withRead,
   withWrite,
   withWriteNoImplicitCommit,
-} from '../with-transactions.js';
-import {asRefs, toRefs, type Chunk} from './chunk.js';
-import {TestLazyStore} from './test-lazy-store.js';
-import {TestStore} from './test-store.js';
+} from '../with-transactions.ts';
+import {asRefs, toRefs, type Chunk} from './chunk.ts';
+import {TestLazyStore} from './test-lazy-store.ts';
+import {TestStore} from './test-store.ts';
 
 const DEFAULT_VALUE_SIZE = 100;
 function getSizeOfChunkForTest(chunk: Chunk): number {
diff --git a/packages/replicache/src/dag/lazy-store.ts b/packages/replicache/src/dag/lazy-store.ts
index 33f664f84e..de4a803ebc 100644
--- a/packages/replicache/src/dag/lazy-store.ts
+++ b/packages/replicache/src/dag/lazy-store.ts
@@ -1,16 +1,16 @@
 import {RWLock} from '@rocicorp/lock';
-import {joinIterables} from '../../../shared/src/iterables.js';
-import {promiseVoid} from '../../../shared/src/resolved-promises.js';
-import type {MaybePromise} from '../../../shared/src/types.js';
-import type {Hash} from '../hash.js';
-import {getSizeOfValue} from '../size-of-value.js';
-import {Chunk, type ChunkHasher, type Refs, createChunk} from './chunk.js';
+import {joinIterables} from '../../../shared/src/iterables.ts';
+import {promiseVoid} from '../../../shared/src/resolved-promises.ts';
+import type {MaybePromise} from '../../../shared/src/types.ts';
+import type {Hash} from '../hash.ts';
+import {getSizeOfValue} from '../size-of-value.ts';
+import {Chunk, type ChunkHasher, type Refs, createChunk} from './chunk.ts';
 import {
   type HeadChange,
   type RefCountUpdatesDelegate,
   computeRefCountUpdates,
-} from './gc.js';
-import {type Read, type Store, type Write, mustGetChunk} from './store.js';
+} from './gc.ts';
+import {type Read, type Store, type Write, mustGetChunk} from './store.ts';
 
 /**
  * Dag Store which lazily loads values from a source store and then caches
diff --git a/packages/replicache/src/dag/store-impl.test.ts b/packages/replicache/src/dag/store-impl.test.ts
index 65829982c0..126f7b7425 100644
--- a/packages/replicache/src/dag/store-impl.test.ts
+++ b/packages/replicache/src/dag/store-impl.test.ts
@@ -1,26 +1,26 @@
 import {describe, expect, test} from 'vitest';
-import {assert} from '../../../shared/src/asserts.js';
-import type {ReadonlyJSONValue} from '../../../shared/src/json.js';
-import {deepFreeze} from '../frozen-json.js';
+import {assert} from '../../../shared/src/asserts.ts';
+import type {ReadonlyJSONValue} from '../../../shared/src/json.ts';
+import {deepFreeze} from '../frozen-json.ts';
 import {
   assertHash,
   fakeHash,
   type Hash,
   makeNewFakeHashFunction,
-} from '../hash.js';
-import type {Read, Store} from '../kv/store.js';
-import {TestMemStore} from '../kv/test-mem-store.js';
+} from '../hash.ts';
+import type {Read, Store} from '../kv/store.ts';
+import {TestMemStore} from '../kv/test-mem-store.ts';
 import {
   using,
   withRead,
   withWrite,
   withWriteNoImplicitCommit,
-} from '../with-transactions.js';
-import {Chunk, createChunk, type Refs, toRefs} from './chunk.js';
-import {chunkDataKey, chunkMetaKey, chunkRefCountKey, headKey} from './key.js';
-import {ReadImpl, StoreImpl, WriteImpl} from './store-impl.js';
-import {ChunkNotFoundError} from './store.js';
-import {TestStore} from './test-store.js';
+} from '../with-transactions.ts';
+import {Chunk, createChunk, type Refs, toRefs} from './chunk.ts';
+import {chunkDataKey, chunkMetaKey, chunkRefCountKey, headKey} from './key.ts';
+import {ReadImpl, StoreImpl, WriteImpl} from './store-impl.ts';
+import {ChunkNotFoundError} from './store.ts';
+import {TestStore} from './test-store.ts';
 
 describe('read', () => {
   test('has chunk', async () => {
diff --git a/packages/replicache/src/dag/store-impl.ts b/packages/replicache/src/dag/store-impl.ts
index f3a3a23c8b..09eec01c7c 100644
--- a/packages/replicache/src/dag/store-impl.ts
+++ b/packages/replicache/src/dag/store-impl.ts
@@ -1,21 +1,21 @@
-import {assertNumber} from '../../../shared/src/asserts.js';
-import type {ReadonlyJSONValue} from '../../../shared/src/json.js';
-import {type Hash, assertHash} from '../hash.js';
+import {assertNumber} from '../../../shared/src/asserts.ts';
+import type {ReadonlyJSONValue} from '../../../shared/src/json.ts';
+import {type Hash, assertHash} from '../hash.ts';
 import type {
   Read as KVRead,
   Store as KVStore,
   Write as KVWrite,
-} from '../kv/store.js';
+} from '../kv/store.ts';
 import {
   Chunk,
   type ChunkHasher,
   type Refs,
   assertRefs,
   createChunk,
-} from './chunk.js';
-import {type RefCountUpdatesDelegate, computeRefCountUpdates} from './gc.js';
-import {chunkDataKey, chunkMetaKey, chunkRefCountKey, headKey} from './key.js';
-import {type Read, type Store, type Write, mustGetChunk} from './store.js';
+} from './chunk.ts';
+import {type RefCountUpdatesDelegate, computeRefCountUpdates} from './gc.ts';
+import {chunkDataKey, chunkMetaKey, chunkRefCountKey, headKey} from './key.ts';
+import {type Read, type Store, type Write, mustGetChunk} from './store.ts';
 
 export class StoreImpl implements Store {
   readonly #kv: KVStore;
diff --git a/packages/replicache/src/dag/store.ts b/packages/replicache/src/dag/store.ts
index a148322ec6..b93278609a 100644
--- a/packages/replicache/src/dag/store.ts
+++ b/packages/replicache/src/dag/store.ts
@@ -1,7 +1,7 @@
-import {assert} from '../../../shared/src/asserts.js';
-import type {Hash} from '../hash.js';
-import type {Release} from '../with-transactions.js';
-import type {Chunk, Refs} from './chunk.js';
+import {assert} from '../../../shared/src/asserts.ts';
+import type {Hash} from '../hash.ts';
+import type {Release} from '../with-transactions.ts';
+import type {Chunk, Refs} from './chunk.ts';
 
 export interface Store {
   read(): Promise<Read>;
diff --git a/packages/replicache/src/dag/test-lazy-store.ts b/packages/replicache/src/dag/test-lazy-store.ts
index 9cc93fa907..6989f7fa19 100644
--- a/packages/replicache/src/dag/test-lazy-store.ts
+++ b/packages/replicache/src/dag/test-lazy-store.ts
@@ -1,6 +1,6 @@
-import type {Hash} from '../hash.js';
-import type {Chunk} from './chunk.js';
-import {LazyStore} from './lazy-store.js';
+import type {Hash} from '../hash.ts';
+import type {Chunk} from './chunk.ts';
+import {LazyStore} from './lazy-store.ts';
 
 export class TestLazyStore extends LazyStore {
   getRefCountsSnapshot(): Record<Hash, number> {
diff --git a/packages/replicache/src/dag/test-store.ts b/packages/replicache/src/dag/test-store.ts
index fa041f6866..8fccc458c5 100644
--- a/packages/replicache/src/dag/test-store.ts
+++ b/packages/replicache/src/dag/test-store.ts
@@ -1,21 +1,21 @@
-import {assertArray, assertString} from '../../../shared/src/asserts.js';
-import {stringCompare} from '../../../shared/src/string-compare.js';
-import type {Hash} from '../hash.js';
+import {assertArray, assertString} from '../../../shared/src/asserts.ts';
+import {stringCompare} from '../../../shared/src/string-compare.ts';
+import type {Hash} from '../hash.ts';
 import {
   assertHash,
   makeNewFakeHashFunction,
   parse as parseHash,
-} from '../hash.js';
-import {TestMemStore} from '../kv/test-mem-store.js';
+} from '../hash.ts';
+import {TestMemStore} from '../kv/test-mem-store.ts';
 import {
   Chunk,
   type ChunkHasher,
   type Refs,
   toRefs as chunkToRefs,
-} from './chunk.js';
-import * as KeyType from './key-type-enum.js';
-import {chunkMetaKey, parse as parseKey} from './key.js';
-import {StoreImpl} from './store-impl.js';
+} from './chunk.ts';
+import * as KeyType from './key-type-enum.ts';
+import {chunkMetaKey, parse as parseKey} from './key.ts';
+import {StoreImpl} from './store-impl.ts';
 
 export class TestStore extends StoreImpl {
   readonly kvStore: TestMemStore;
diff --git a/packages/replicache/src/dag/visitor.test.ts b/packages/replicache/src/dag/visitor.test.ts
index e222de18fc..7790463861 100644
--- a/packages/replicache/src/dag/visitor.test.ts
+++ b/packages/replicache/src/dag/visitor.test.ts
@@ -1,9 +1,9 @@
 import {expect, test} from 'vitest';
-import {assert} from '../../../shared/src/asserts.js';
-import {type Hash, fakeHash} from '../hash.js';
-import {Chunk, toRefs} from './chunk.js';
-import type {MustGetChunk} from './store.js';
-import {Visitor} from './visitor.js';
+import {assert} from '../../../shared/src/asserts.ts';
+import {type Hash, fakeHash} from '../hash.ts';
+import {Chunk, toRefs} from './chunk.ts';
+import type {MustGetChunk} from './store.ts';
+import {Visitor} from './visitor.ts';
 
 test('Ensure only visited once', async () => {
   const c1 = new Chunk(fakeHash('1'), 'data1', []);
diff --git a/packages/replicache/src/dag/visitor.ts b/packages/replicache/src/dag/visitor.ts
index b27f207b25..f25b72c7bb 100644
--- a/packages/replicache/src/dag/visitor.ts
+++ b/packages/replicache/src/dag/visitor.ts
@@ -1,6 +1,6 @@
-import type {Hash} from '../hash.js';
-import type {Chunk} from './chunk.js';
-import type {MustGetChunk} from './store.js';
+import type {Hash} from '../hash.ts';
+import type {Chunk} from './chunk.ts';
+import type {MustGetChunk} from './store.ts';
 
 /**
  * A visitor walks the DAG starting at a given root and visits each chunk.
diff --git a/packages/replicache/src/db/commit.test.ts b/packages/replicache/src/db/commit.test.ts
index bff60fe367..86c2f31e47 100644
--- a/packages/replicache/src/db/commit.test.ts
+++ b/packages/replicache/src/db/commit.test.ts
@@ -1,12 +1,12 @@
 import {describe, expect, test} from 'vitest';
-import {assert} from '../../../shared/src/asserts.js';
-import type {Enum} from '../../../shared/src/enum.js';
-import {Chunk, type Refs, toRefs} from '../dag/chunk.js';
-import {TestStore} from '../dag/test-store.js';
-import * as FormatVersion from '../format-version-enum.js';
-import {deepFreeze} from '../frozen-json.js';
-import {type Hash, fakeHash, makeNewFakeHashFunction} from '../hash.js';
-import {withRead} from '../with-transactions.js';
+import {assert} from '../../../shared/src/asserts.ts';
+import type {Enum} from '../../../shared/src/enum.ts';
+import {Chunk, type Refs, toRefs} from '../dag/chunk.ts';
+import {TestStore} from '../dag/test-store.ts';
+import * as FormatVersion from '../format-version-enum.ts';
+import {deepFreeze} from '../frozen-json.ts';
+import {type Hash, fakeHash, makeNewFakeHashFunction} from '../hash.ts';
+import {withRead} from '../with-transactions.ts';
 import {
   type ChunkIndexDefinition,
   Commit,
@@ -22,9 +22,9 @@ import {
   localMutations,
   localMutationsGreaterThan,
   makeCommitData,
-} from './commit.js';
-import * as MetaType from './meta-type-enum.js';
-import {ChainBuilder} from './test-helpers.js';
+} from './commit.ts';
+import * as MetaType from './meta-type-enum.ts';
+import {ChainBuilder} from './test-helpers.ts';
 
 type FormatVersion = Enum<typeof FormatVersion>;
 
diff --git a/packages/replicache/src/db/commit.ts b/packages/replicache/src/db/commit.ts
index ebb4ac2c53..3c92f1b41a 100644
--- a/packages/replicache/src/db/commit.ts
+++ b/packages/replicache/src/db/commit.ts
@@ -6,22 +6,22 @@ import {
   assertObject,
   assertString,
   unreachable,
-} from '../../../shared/src/asserts.js';
-import {assertJSONValue} from '../../../shared/src/json.js';
-import {skipCommitDataAsserts} from '../config.js';
-import {type FrozenCookie, compareCookies} from '../cookies.js';
-import {type Chunk, type CreateChunk, type Refs, toRefs} from '../dag/chunk.js';
-import {type MustGetChunk, type Read, mustGetHeadHash} from '../dag/store.js';
+} from '../../../shared/src/asserts.ts';
+import {assertJSONValue} from '../../../shared/src/json.ts';
+import {skipCommitDataAsserts} from '../config.ts';
+import {type FrozenCookie, compareCookies} from '../cookies.ts';
+import {type Chunk, type CreateChunk, type Refs, toRefs} from '../dag/chunk.ts';
+import {type MustGetChunk, type Read, mustGetHeadHash} from '../dag/store.ts';
 import {
   type FrozenJSONValue,
   type FrozenTag,
   assertDeepFrozen,
   deepFreeze,
-} from '../frozen-json.js';
-import {type Hash, assertHash} from '../hash.js';
-import type {IndexDefinition} from '../index-defs.js';
-import type {ClientID} from '../sync/ids.js';
-import * as MetaType from './meta-type-enum.js';
+} from '../frozen-json.ts';
+import {type Hash, assertHash} from '../hash.ts';
+import type {IndexDefinition} from '../index-defs.ts';
+import type {ClientID} from '../sync/ids.ts';
+import * as MetaType from './meta-type-enum.ts';
 
 export const DEFAULT_HEAD_NAME = 'main';
 
diff --git a/packages/replicache/src/db/index.test.ts b/packages/replicache/src/db/index.test.ts
index d50f9b0969..fcb132fecf 100644
--- a/packages/replicache/src/db/index.test.ts
+++ b/packages/replicache/src/db/index.test.ts
@@ -1,15 +1,15 @@
 import {LogContext} from '@rocicorp/logger';
 import {expect, test} from 'vitest';
-import type {Enum} from '../../../shared/src/enum.js';
-import type {JSONValue} from '../../../shared/src/json.js';
-import {stringCompare} from '../../../shared/src/string-compare.js';
-import {asyncIterableToArray} from '../async-iterable-to-array.js';
-import {BTreeWrite} from '../btree/write.js';
-import {TestStore} from '../dag/test-store.js';
-import * as FormatVersion from '../format-version-enum.js';
-import {deepFreeze} from '../frozen-json.js';
-import {withWrite} from '../with-transactions.js';
-import * as IndexOperation from './index-operation-enum.js';
+import type {Enum} from '../../../shared/src/enum.ts';
+import type {JSONValue} from '../../../shared/src/json.ts';
+import {stringCompare} from '../../../shared/src/string-compare.ts';
+import {asyncIterableToArray} from '../async-iterable-to-array.ts';
+import {BTreeWrite} from '../btree/write.ts';
+import {TestStore} from '../dag/test-store.ts';
+import * as FormatVersion from '../format-version-enum.ts';
+import {deepFreeze} from '../frozen-json.ts';
+import {withWrite} from '../with-transactions.ts';
+import * as IndexOperation from './index-operation-enum.ts';
 import {
   type IndexKey,
   KEY_SEPARATOR,
@@ -20,7 +20,7 @@ import {
   evaluateJSONPointer,
   getIndexKeys,
   indexValue,
-} from './index.js';
+} from './index.ts';
 
 type IndexOperation = Enum<typeof IndexOperation>;
 
diff --git a/packages/replicache/src/db/index.ts b/packages/replicache/src/db/index.ts
index 1035ec3387..8289e0e55f 100644
--- a/packages/replicache/src/db/index.ts
+++ b/packages/replicache/src/db/index.ts
@@ -1,11 +1,11 @@
 import type {LogContext} from '@rocicorp/logger';
-import type {Enum} from '../../../shared/src/enum.js';
-import type {BTreeRead} from '../btree/read.js';
-import type {BTreeWrite} from '../btree/write.js';
-import type {FrozenJSONObject, FrozenJSONValue} from '../frozen-json.js';
-import type {Hash} from '../hash.js';
-import type {IndexRecord} from './commit.js';
-import * as IndexOperation from './index-operation-enum.js';
+import type {Enum} from '../../../shared/src/enum.ts';
+import type {BTreeRead} from '../btree/read.ts';
+import type {BTreeWrite} from '../btree/write.ts';
+import type {FrozenJSONObject, FrozenJSONValue} from '../frozen-json.ts';
+import type {Hash} from '../hash.ts';
+import type {IndexRecord} from './commit.ts';
+import * as IndexOperation from './index-operation-enum.ts';
 
 type IndexOperation = Enum<typeof IndexOperation>;
 
diff --git a/packages/replicache/src/db/read.test.ts b/packages/replicache/src/db/read.test.ts
index bd67e19f6d..4e0e1cc149 100644
--- a/packages/replicache/src/db/read.test.ts
+++ b/packages/replicache/src/db/read.test.ts
@@ -1,13 +1,13 @@
 import {LogContext} from '@rocicorp/logger';
 import {describe, expect, test} from 'vitest';
-import type {Enum} from '../../../shared/src/enum.js';
-import {mustGetHeadHash} from '../dag/store.js';
-import {TestStore} from '../dag/test-store.js';
-import * as FormatVersion from '../format-version-enum.js';
-import {DEFAULT_HEAD_NAME} from './commit.js';
-import {readFromDefaultHead} from './read.js';
-import {initDB} from './test-helpers.js';
-import {newWriteLocal} from './write.js';
+import type {Enum} from '../../../shared/src/enum.ts';
+import {mustGetHeadHash} from '../dag/store.ts';
+import {TestStore} from '../dag/test-store.ts';
+import * as FormatVersion from '../format-version-enum.ts';
+import {DEFAULT_HEAD_NAME} from './commit.ts';
+import {readFromDefaultHead} from './read.ts';
+import {initDB} from './test-helpers.ts';
+import {newWriteLocal} from './write.ts';
 
 type FormatVersion = Enum<typeof FormatVersion>;
 
diff --git a/packages/replicache/src/db/read.ts b/packages/replicache/src/db/read.ts
index 9266e53760..c1ae851c41 100644
--- a/packages/replicache/src/db/read.ts
+++ b/packages/replicache/src/db/read.ts
@@ -1,17 +1,17 @@
-import type {Enum} from '../../../shared/src/enum.js';
-import {BTreeRead} from '../btree/read.js';
-import type {Read as DagRead} from '../dag/store.js';
-import * as FormatVersion from '../format-version-enum.js';
-import type {FrozenJSONValue} from '../frozen-json.js';
-import type {Hash} from '../hash.js';
+import type {Enum} from '../../../shared/src/enum.ts';
+import {BTreeRead} from '../btree/read.ts';
+import type {Read as DagRead} from '../dag/store.ts';
+import * as FormatVersion from '../format-version-enum.ts';
+import type {FrozenJSONValue} from '../frozen-json.ts';
+import type {Hash} from '../hash.ts';
 import {
   Commit,
   DEFAULT_HEAD_NAME,
   type Meta,
   commitFromHash,
   commitFromHead,
-} from './commit.js';
-import {IndexRead} from './index.js';
+} from './commit.ts';
+import {IndexRead} from './index.ts';
 
 type FormatVersion = Enum<typeof FormatVersion>;
 
diff --git a/packages/replicache/src/db/rebase.test.ts b/packages/replicache/src/db/rebase.test.ts
index 62023ebd8c..78e823023f 100644
--- a/packages/replicache/src/db/rebase.test.ts
+++ b/packages/replicache/src/db/rebase.test.ts
@@ -1,16 +1,16 @@
 import {LogContext} from '@rocicorp/logger';
 import sinon from 'sinon';
 import {afterEach, describe, expect, test} from 'vitest';
-import {assert} from '../../../shared/src/asserts.js';
-import type {Enum} from '../../../shared/src/enum.js';
-import {BTreeRead} from '../btree/read.js';
-import type {Read} from '../dag/store.js';
-import {TestStore} from '../dag/test-store.js';
-import * as FormatVersion from '../format-version-enum.js';
-import type {Hash} from '../hash.js';
-import {SYNC_HEAD_NAME} from '../sync/sync-head-name.js';
-import type {WriteTransaction} from '../transactions.js';
-import {withRead, withWriteNoImplicitCommit} from '../with-transactions.js';
+import {assert} from '../../../shared/src/asserts.ts';
+import type {Enum} from '../../../shared/src/enum.ts';
+import {BTreeRead} from '../btree/read.ts';
+import type {Read} from '../dag/store.ts';
+import {TestStore} from '../dag/test-store.ts';
+import * as FormatVersion from '../format-version-enum.ts';
+import type {Hash} from '../hash.ts';
+import {SYNC_HEAD_NAME} from '../sync/sync-head-name.ts';
+import type {WriteTransaction} from '../transactions.ts';
+import {withRead, withWriteNoImplicitCommit} from '../with-transactions.ts';
 import {
   Commit,
   type LocalMeta,
@@ -21,9 +21,9 @@ import {
   commitFromHead,
   commitIsLocal,
   commitIsLocalDD31,
-} from './commit.js';
-import {rebaseMutationAndCommit, rebaseMutationAndPutCommit} from './rebase.js';
-import {ChainBuilder} from './test-helpers.js';
+} from './commit.ts';
+import {rebaseMutationAndCommit, rebaseMutationAndPutCommit} from './rebase.ts';
+import {ChainBuilder} from './test-helpers.ts';
 
 type FormatVersion = Enum<typeof FormatVersion>;
 
diff --git a/packages/replicache/src/db/rebase.ts b/packages/replicache/src/db/rebase.ts
index fce3cc697c..b23eb9e35c 100644
--- a/packages/replicache/src/db/rebase.ts
+++ b/packages/replicache/src/db/rebase.ts
@@ -1,12 +1,12 @@
 import type {LogContext} from '@rocicorp/logger';
-import {assert} from '../../../shared/src/asserts.js';
-import type {Enum} from '../../../shared/src/enum.js';
-import type {Write as DagWrite} from '../dag/store.js';
-import * as FormatVersion from '../format-version-enum.js';
-import type {Hash} from '../hash.js';
-import type {ClientID} from '../sync/ids.js';
-import {WriteTransactionImpl} from '../transactions.js';
-import type {MutatorDefs} from '../types.js';
+import {assert} from '../../../shared/src/asserts.ts';
+import type {Enum} from '../../../shared/src/enum.ts';
+import type {Write as DagWrite} from '../dag/store.ts';
+import * as FormatVersion from '../format-version-enum.ts';
+import type {Hash} from '../hash.ts';
+import type {ClientID} from '../sync/ids.ts';
+import {WriteTransactionImpl} from '../transactions.ts';
+import type {MutatorDefs} from '../types.ts';
 import {
   Commit,
   type LocalMeta,
@@ -15,8 +15,8 @@ import {
   assertLocalMetaDD31,
   commitFromHash,
   isLocalMetaDD31,
-} from './commit.js';
-import {Write, newWriteLocal} from './write.js';
+} from './commit.ts';
+import {Write, newWriteLocal} from './write.ts';
 
 type FormatVersion = Enum<typeof FormatVersion>;
 
diff --git a/packages/replicache/src/db/scan.test.ts b/packages/replicache/src/db/scan.test.ts
index 0d6c4496ad..399c76f654 100644
--- a/packages/replicache/src/db/scan.test.ts
+++ b/packages/replicache/src/db/scan.test.ts
@@ -1,13 +1,13 @@
 import {expect, test} from 'vitest';
-import type {Enum} from '../../../shared/src/enum.js';
-import {BTreeWrite} from '../btree/write.js';
-import type {Write} from '../dag/store.js';
-import {TestStore} from '../dag/test-store.js';
-import * as FormatVersion from '../format-version-enum.js';
-import {fromKeyForIndexScanInternal} from '../scan-iterator.js';
-import {withWrite} from '../with-transactions.js';
-import {decodeIndexKey} from './index.js';
-import type {ScanItem} from './scan.js';
+import type {Enum} from '../../../shared/src/enum.ts';
+import {BTreeWrite} from '../btree/write.ts';
+import type {Write} from '../dag/store.ts';
+import {TestStore} from '../dag/test-store.ts';
+import * as FormatVersion from '../format-version-enum.ts';
+import {fromKeyForIndexScanInternal} from '../scan-iterator.ts';
+import {withWrite} from '../with-transactions.ts';
+import {decodeIndexKey} from './index.ts';
+import type {ScanItem} from './scan.ts';
 
 type FormatVersion = Enum<typeof FormatVersion>;
 
diff --git a/packages/replicache/src/db/scan.ts b/packages/replicache/src/db/scan.ts
index f783d77d99..c87863c207 100644
--- a/packages/replicache/src/db/scan.ts
+++ b/packages/replicache/src/db/scan.ts
@@ -1,4 +1,4 @@
-import type {ReadonlyJSONValue} from '../../../shared/src/json.js';
+import type {ReadonlyJSONValue} from '../../../shared/src/json.ts';
 
 // TODO(arv): Unify with src/scan-options.ts
 
diff --git a/packages/replicache/src/db/test-helpers.ts b/packages/replicache/src/db/test-helpers.ts
index 1b812845e4..280c271b4a 100644
--- a/packages/replicache/src/db/test-helpers.ts
+++ b/packages/replicache/src/db/test-helpers.ts
@@ -1,29 +1,29 @@
 import {LogContext} from '@rocicorp/logger';
 import {expect} from 'vitest';
-import {assert, assertNotUndefined} from '../../../shared/src/asserts.js';
-import type {Enum} from '../../../shared/src/enum.js';
-import type {JSONValue} from '../../../shared/src/json.js';
-import {emptyDataNode} from '../btree/node.js';
-import {BTreeWrite} from '../btree/write.js';
-import type {Cookie} from '../cookies.js';
-import type {Chunk} from '../dag/chunk.js';
+import {assert, assertNotUndefined} from '../../../shared/src/asserts.ts';
+import type {Enum} from '../../../shared/src/enum.ts';
+import type {JSONValue} from '../../../shared/src/json.ts';
+import {emptyDataNode} from '../btree/node.ts';
+import {BTreeWrite} from '../btree/write.ts';
+import type {Cookie} from '../cookies.ts';
+import type {Chunk} from '../dag/chunk.ts';
 import {
   type Write as DagWrite,
   type Store,
   mustGetHeadHash,
-} from '../dag/store.js';
-import {Visitor} from '../dag/visitor.js';
-import * as FormatVersion from '../format-version-enum.js';
-import {deepFreeze} from '../frozen-json.js';
-import {type Hash, emptyHash} from '../hash.js';
-import type {IndexDefinitions} from '../index-defs.js';
-import type {ClientID} from '../sync/ids.js';
-import {addSyncSnapshot} from '../sync/test-helpers.js';
+} from '../dag/store.ts';
+import {Visitor} from '../dag/visitor.ts';
+import * as FormatVersion from '../format-version-enum.ts';
+import {deepFreeze} from '../frozen-json.ts';
+import {type Hash, emptyHash} from '../hash.ts';
+import type {IndexDefinitions} from '../index-defs.ts';
+import type {ClientID} from '../sync/ids.ts';
+import {addSyncSnapshot} from '../sync/test-helpers.ts';
 import {
   withRead,
   withWrite,
   withWriteNoImplicitCommit,
-} from '../with-transactions.js';
+} from '../with-transactions.ts';
 import {
   Commit,
   DEFAULT_HEAD_NAME,
@@ -35,10 +35,10 @@ import {
   assertSnapshotCommitDD31,
   commitFromHead,
   toChunkIndexDefinition,
-} from './commit.js';
-import {IndexWrite} from './index.js';
-import * as MetaType from './meta-type-enum.js';
-import {Write, newWriteLocal, newWriteSnapshotDD31} from './write.js';
+} from './commit.ts';
+import {IndexWrite} from './index.ts';
+import * as MetaType from './meta-type-enum.ts';
+import {Write, newWriteLocal, newWriteSnapshotDD31} from './write.ts';
 
 type FormatVersion = Enum<typeof FormatVersion>;
 
diff --git a/packages/replicache/src/db/write.test.ts b/packages/replicache/src/db/write.test.ts
index 48bd9ebc3c..90bf6bb265 100644
--- a/packages/replicache/src/db/write.test.ts
+++ b/packages/replicache/src/db/write.test.ts
@@ -1,17 +1,17 @@
 import {LogContext} from '@rocicorp/logger';
 import {describe, expect, test} from 'vitest';
-import {assertNotUndefined} from '../../../shared/src/asserts.js';
-import type {Enum} from '../../../shared/src/enum.js';
-import {asyncIterableToArray} from '../async-iterable-to-array.js';
-import {BTreeRead} from '../btree/read.js';
-import {mustGetHeadHash} from '../dag/store.js';
-import {TestStore} from '../dag/test-store.js';
-import * as FormatVersion from '../format-version-enum.js';
-import {withRead, withWriteNoImplicitCommit} from '../with-transactions.js';
-import {DEFAULT_HEAD_NAME, commitFromHead} from './commit.js';
-import {readIndexesForRead} from './read.js';
-import {initDB} from './test-helpers.js';
-import {newWriteLocal} from './write.js';
+import {assertNotUndefined} from '../../../shared/src/asserts.ts';
+import type {Enum} from '../../../shared/src/enum.ts';
+import {asyncIterableToArray} from '../async-iterable-to-array.ts';
+import {BTreeRead} from '../btree/read.ts';
+import {mustGetHeadHash} from '../dag/store.ts';
+import {TestStore} from '../dag/test-store.ts';
+import * as FormatVersion from '../format-version-enum.ts';
+import {withRead, withWriteNoImplicitCommit} from '../with-transactions.ts';
+import {DEFAULT_HEAD_NAME, commitFromHead} from './commit.ts';
+import {readIndexesForRead} from './read.ts';
+import {initDB} from './test-helpers.ts';
+import {newWriteLocal} from './write.ts';
 
 type FormatVersion = Enum<typeof FormatVersion>;
 
diff --git a/packages/replicache/src/db/write.ts b/packages/replicache/src/db/write.ts
index bd57466f17..9c8b979ce0 100644
--- a/packages/replicache/src/db/write.ts
+++ b/packages/replicache/src/db/write.ts
@@ -1,19 +1,19 @@
 import type {LogContext} from '@rocicorp/logger';
-import {assert} from '../../../shared/src/asserts.js';
-import type {Enum} from '../../../shared/src/enum.js';
-import {diff} from '../btree/diff.js';
-import type {InternalDiff} from '../btree/node.js';
-import {BTreeRead, allEntriesAsDiff} from '../btree/read.js';
-import {BTreeWrite} from '../btree/write.js';
-import type {FrozenCookie} from '../cookies.js';
-import type {Write as DagWrite} from '../dag/store.js';
-import * as FormatVersion from '../format-version-enum.js';
-import type {FrozenJSONValue} from '../frozen-json.js';
-import {type Hash, emptyHash} from '../hash.js';
-import {lazy} from '../lazy.js';
-import type {DiffComputationConfig} from '../sync/diff.js';
-import {DiffsMap} from '../sync/diff.js';
-import type {ClientID} from '../sync/ids.js';
+import {assert} from '../../../shared/src/asserts.ts';
+import type {Enum} from '../../../shared/src/enum.ts';
+import {diff} from '../btree/diff.ts';
+import type {InternalDiff} from '../btree/node.ts';
+import {BTreeRead, allEntriesAsDiff} from '../btree/read.ts';
+import {BTreeWrite} from '../btree/write.ts';
+import type {FrozenCookie} from '../cookies.ts';
+import type {Write as DagWrite} from '../dag/store.ts';
+import * as FormatVersion from '../format-version-enum.ts';
+import type {FrozenJSONValue} from '../frozen-json.ts';
+import {type Hash, emptyHash} from '../hash.ts';
+import {lazy} from '../lazy.ts';
+import type {DiffComputationConfig} from '../sync/diff.ts';
+import {DiffsMap} from '../sync/diff.ts';
+import type {ClientID} from '../sync/ids.ts';
 import {
   Commit,
   type Meta as CommitMeta,
@@ -24,11 +24,11 @@ import {
   newLocalDD31 as commitNewLocalDD31,
   newSnapshotDD31 as commitNewSnapshotDD31,
   getMutationID,
-} from './commit.js';
-import * as IndexOperation from './index-operation-enum.js';
-import {IndexRead, IndexWrite, indexValue} from './index.js';
-import * as MetaType from './meta-type-enum.js';
-import {Read, readIndexesForRead} from './read.js';
+} from './commit.ts';
+import * as IndexOperation from './index-operation-enum.ts';
+import {IndexRead, IndexWrite, indexValue} from './index.ts';
+import * as MetaType from './meta-type-enum.ts';
+import {Read, readIndexesForRead} from './read.ts';
 
 type FormatVersion = Enum<typeof FormatVersion>;
 
diff --git a/packages/replicache/src/error-responses.ts b/packages/replicache/src/error-responses.ts
index e19d982a8c..0ef1fe6baf 100644
--- a/packages/replicache/src/error-responses.ts
+++ b/packages/replicache/src/error-responses.ts
@@ -1,4 +1,4 @@
-import {assert} from '../../shared/src/asserts.js';
+import {assert} from '../../shared/src/asserts.ts';
 
 function isError(obj: unknown, type: string): boolean {
   return (
diff --git a/packages/replicache/src/filter-async-iterable.test.ts b/packages/replicache/src/filter-async-iterable.test.ts
index d8380d09d8..228bca1648 100644
--- a/packages/replicache/src/filter-async-iterable.test.ts
+++ b/packages/replicache/src/filter-async-iterable.test.ts
@@ -1,7 +1,7 @@
 import {expect, test} from 'vitest';
-import {asyncIterableToArray} from './async-iterable-to-array.js';
-import {filterAsyncIterable} from './filter-async-iterable.js';
-import {makeAsyncIterable} from './merge-async-iterables.test.js';
+import {asyncIterableToArray} from './async-iterable-to-array.ts';
+import {filterAsyncIterable} from './filter-async-iterable.ts';
+import {makeAsyncIterable} from './merge-async-iterables.test.ts';
 
 test('filterAsyncIterable', async () => {
   const t = async <V>(
diff --git a/packages/replicache/src/filter-async-iterable.ts b/packages/replicache/src/filter-async-iterable.ts
index 3345b3cd31..68759b0ee6 100644
--- a/packages/replicache/src/filter-async-iterable.ts
+++ b/packages/replicache/src/filter-async-iterable.ts
@@ -1,4 +1,4 @@
-import type {IterableUnion} from './iterable-union.js';
+import type {IterableUnion} from './iterable-union.ts';
 
 /**
  * Filters an async iterable.
diff --git a/packages/replicache/src/format-version.ts b/packages/replicache/src/format-version.ts
index ddd77d3c5f..e827434e31 100644
--- a/packages/replicache/src/format-version.ts
+++ b/packages/replicache/src/format-version.ts
@@ -1,5 +1,5 @@
-import type {Enum} from '../../shared/src/enum.js';
-import * as FormatVersion from './format-version-enum.js';
+import type {Enum} from '../../shared/src/enum.ts';
+import * as FormatVersion from './format-version-enum.ts';
 
 type FormatVersion = Enum<typeof FormatVersion>;
 
diff --git a/packages/replicache/src/frozen-json.test.ts b/packages/replicache/src/frozen-json.test.ts
index 38f8340044..2722eac2ce 100644
--- a/packages/replicache/src/frozen-json.test.ts
+++ b/packages/replicache/src/frozen-json.test.ts
@@ -1,10 +1,10 @@
 import {expect, test} from 'vitest';
-import type {ReadonlyJSONValue} from '../../shared/src/json.js';
+import type {ReadonlyJSONValue} from '../../shared/src/json.ts';
 import {
   deepFreeze,
   deepFreezeAllowUndefined,
   isDeepFrozen,
-} from './frozen-json.js';
+} from './frozen-json.ts';
 
 test('deepFreeze', () => {
   expect(deepFreeze(null)).equal(null);
diff --git a/packages/replicache/src/frozen-json.ts b/packages/replicache/src/frozen-json.ts
index 3624774420..fe94bcefb3 100644
--- a/packages/replicache/src/frozen-json.ts
+++ b/packages/replicache/src/frozen-json.ts
@@ -1,12 +1,12 @@
-import {throwInvalidType} from '../../shared/src/asserts.js';
-import {skipAssertJSONValue} from '../../shared/src/config.js';
-import {hasOwn} from '../../shared/src/has-own.js';
+import {throwInvalidType} from '../../shared/src/asserts.ts';
+import {skipAssertJSONValue} from '../../shared/src/config.ts';
+import {hasOwn} from '../../shared/src/has-own.ts';
 import type {
   ReadonlyJSONObject,
   ReadonlyJSONValue,
-} from '../../shared/src/json.js';
-import {skipFreeze, skipFrozenAsserts} from './config.js';
-import type {Cookie, FrozenCookie} from './cookies.js';
+} from '../../shared/src/json.ts';
+import {skipFreeze, skipFrozenAsserts} from './config.ts';
+import type {Cookie, FrozenCookie} from './cookies.ts';
 
 declare const frozenJSONTag: unique symbol;
 
diff --git a/packages/replicache/src/get-default-puller.ts b/packages/replicache/src/get-default-puller.ts
index 7de05d5288..e3c5fe4644 100644
--- a/packages/replicache/src/get-default-puller.ts
+++ b/packages/replicache/src/get-default-puller.ts
@@ -2,22 +2,22 @@ import {
   assertNumber,
   assertObject,
   assertString,
-} from '../../shared/src/asserts.js';
-import {callDefaultFetch} from './call-default-fetch.js';
-import {assertCookie} from './cookies.js';
+} from '../../shared/src/asserts.ts';
+import {callDefaultFetch} from './call-default-fetch.ts';
+import {assertCookie} from './cookies.ts';
 import {
   isClientStateNotFoundResponse,
   isVersionNotSupportedResponse,
-} from './error-responses.js';
-import {assertHTTPRequestInfo} from './http-request-info.js';
-import {assertPatchOperations} from './patch-operation.js';
+} from './error-responses.ts';
+import {assertHTTPRequestInfo} from './http-request-info.ts';
+import {assertPatchOperations} from './patch-operation.ts';
 import type {
   PullResponseV1,
   Puller,
   PullerResult,
   PullerResultV1,
-} from './puller.js';
-import type {PullRequest} from './sync/pull.js';
+} from './puller.ts';
+import type {PullRequest} from './sync/pull.ts';
 
 /**
  * This creates a default puller which uses HTTP POST to send the pull request.
diff --git a/packages/replicache/src/get-default-pusher.ts b/packages/replicache/src/get-default-pusher.ts
index 4ee30b6973..03d53d2e0e 100644
--- a/packages/replicache/src/get-default-pusher.ts
+++ b/packages/replicache/src/get-default-pusher.ts
@@ -1,10 +1,10 @@
-import {callDefaultFetch} from './call-default-fetch.js';
+import {callDefaultFetch} from './call-default-fetch.ts';
 import {
   isClientStateNotFoundResponse,
   isVersionNotSupportedResponse,
-} from './error-responses.js';
-import type {Pusher, PusherResult} from './pusher.js';
-import type {PushRequest} from './sync/push.js';
+} from './error-responses.ts';
+import type {Pusher, PusherResult} from './pusher.ts';
+import type {PushRequest} from './sync/push.ts';
 
 /**
  * This creates a default pusher which uses HTTP POST to send the push request.
diff --git a/packages/replicache/src/hash.test.ts b/packages/replicache/src/hash.test.ts
index 2e34fa6927..165af817ee 100644
--- a/packages/replicache/src/hash.test.ts
+++ b/packages/replicache/src/hash.test.ts
@@ -1,5 +1,5 @@
 import {expect, test} from 'vitest';
-import * as valita from '../../shared/src/valita.js';
+import * as valita from '../../shared/src/valita.ts';
 import {
   type Hash,
   STRING_LENGTH,
@@ -10,7 +10,7 @@ import {
   makeNewFakeHashFunction,
   newRandomHash,
   parse,
-} from './hash.js';
+} from './hash.ts';
 
 const emptyUUID = '00000000-0000-4000-8000-000000000000';
 
diff --git a/packages/replicache/src/hash.ts b/packages/replicache/src/hash.ts
index 22b0286861..62a5ce1709 100644
--- a/packages/replicache/src/hash.ts
+++ b/packages/replicache/src/hash.ts
@@ -1,6 +1,6 @@
-import {assert} from '../../shared/src/asserts.js';
-import {randomUint64} from '../../shared/src/random-uint64.js';
-import * as valita from '../../shared/src/valita.js';
+import {assert} from '../../shared/src/asserts.ts';
+import {randomUint64} from '../../shared/src/random-uint64.ts';
+import * as valita from '../../shared/src/valita.ts';
 
 export const STRING_LENGTH = 22;
 
diff --git a/packages/replicache/src/http-request-info.ts b/packages/replicache/src/http-request-info.ts
index ea8a79d78e..e074808e28 100644
--- a/packages/replicache/src/http-request-info.ts
+++ b/packages/replicache/src/http-request-info.ts
@@ -2,7 +2,7 @@ import {
   assertNumber,
   assertObject,
   assertString,
-} from '../../shared/src/asserts.js';
+} from '../../shared/src/asserts.ts';
 
 export function assertHTTPRequestInfo(
   v: unknown,
diff --git a/packages/replicache/src/impl.ts b/packages/replicache/src/impl.ts
index 14bae5455e..6b598339bd 100644
--- a/packages/replicache/src/impl.ts
+++ b/packages/replicache/src/impl.ts
@@ -1,3 +1,3 @@
-export type {PatchOperationInternal} from './patch-operation.js';
-export {ReplicacheImpl, type ReplicacheImplOptions} from './replicache-impl.js';
-export type {PokeInternal} from './types.js';
+export type {PatchOperationInternal} from './patch-operation.ts';
+export {ReplicacheImpl, type ReplicacheImplOptions} from './replicache-impl.ts';
+export type {PokeInternal} from './types.ts';
diff --git a/packages/replicache/src/index-defs.test.ts b/packages/replicache/src/index-defs.test.ts
index b53cf11bf7..00114e70cd 100644
--- a/packages/replicache/src/index-defs.test.ts
+++ b/packages/replicache/src/index-defs.test.ts
@@ -4,7 +4,7 @@ import {
   indexDefinitionEqual,
   type IndexDefinitions,
   indexDefinitionsEqual,
-} from './index-defs.js';
+} from './index-defs.ts';
 
 test('indexDefinitionsEqual', () => {
   const t = (a: IndexDefinition, b: IndexDefinition = a) => {
diff --git a/packages/replicache/src/index-defs.ts b/packages/replicache/src/index-defs.ts
index 1a6d79f2d9..d942bdc566 100644
--- a/packages/replicache/src/index-defs.ts
+++ b/packages/replicache/src/index-defs.ts
@@ -1,4 +1,4 @@
-import * as valita from '../../shared/src/valita.js';
+import * as valita from '../../shared/src/valita.ts';
 
 /**
  * The definition of a single index.
diff --git a/packages/replicache/src/kv/idb-store-with-mem-fallback.test.ts b/packages/replicache/src/kv/idb-store-with-mem-fallback.test.ts
index 81508f6e26..ac9f235b63 100644
--- a/packages/replicache/src/kv/idb-store-with-mem-fallback.test.ts
+++ b/packages/replicache/src/kv/idb-store-with-mem-fallback.test.ts
@@ -1,17 +1,17 @@
 import {LogContext} from '@rocicorp/logger';
 import * as sinon from 'sinon';
 import {afterEach, expect, test} from 'vitest';
-import {assert} from '../../../shared/src/asserts.js';
+import {assert} from '../../../shared/src/asserts.ts';
 import {
   withRead,
   withWrite,
   withWriteNoImplicitCommit,
-} from '../with-transactions.js';
+} from '../with-transactions.ts';
 import {
   IDBStoreWithMemFallback,
   newIDBStoreWithMemFallback,
-} from './idb-store-with-mem-fallback.js';
-import {IDBStore} from './idb-store.js';
+} from './idb-store-with-mem-fallback.ts';
+import {IDBStore} from './idb-store.ts';
 
 afterEach(() => {
   sinon.restore();
diff --git a/packages/replicache/src/kv/idb-store-with-mem-fallback.ts b/packages/replicache/src/kv/idb-store-with-mem-fallback.ts
index a62df609ac..74c036febe 100644
--- a/packages/replicache/src/kv/idb-store-with-mem-fallback.ts
+++ b/packages/replicache/src/kv/idb-store-with-mem-fallback.ts
@@ -1,9 +1,9 @@
 import type {LogContext} from '@rocicorp/logger';
-import {navigator} from '../../../shared/src/navigator.js';
-import {promiseVoid} from '../../../shared/src/resolved-promises.js';
-import {IDBStore} from './idb-store.js';
-import {MemStore, dropMemStore} from './mem-store.js';
-import type {Read, Store, Write} from './store.js';
+import {navigator} from '../../../shared/src/navigator.ts';
+import {promiseVoid} from '../../../shared/src/resolved-promises.ts';
+import {IDBStore} from './idb-store.ts';
+import {MemStore, dropMemStore} from './mem-store.ts';
+import type {Read, Store, Write} from './store.ts';
 
 /**
  * This store uses an {@link IDBStore} by default. If the {@link IDBStore} fails
diff --git a/packages/replicache/src/kv/idb-store.test.ts b/packages/replicache/src/kv/idb-store.test.ts
index 354fe60bea..2e86cc2811 100644
--- a/packages/replicache/src/kv/idb-store.test.ts
+++ b/packages/replicache/src/kv/idb-store.test.ts
@@ -1,9 +1,9 @@
 import * as sinon from 'sinon';
 import {afterEach, beforeEach, describe, expect, test} from 'vitest';
-import {withRead, withWrite} from '../with-transactions.js';
-import {dropIDBStoreWithMemFallback} from './idb-store-with-mem-fallback.js';
-import {IDBNotFoundError, IDBStore} from './idb-store.js';
-import {runAll} from './store-test-util.js';
+import {withRead, withWrite} from '../with-transactions.ts';
+import {dropIDBStoreWithMemFallback} from './idb-store-with-mem-fallback.ts';
+import {IDBNotFoundError, IDBStore} from './idb-store.ts';
+import {runAll} from './store-test-util.ts';
 
 async function newRandomIDBStore() {
   const name = `test-idbstore-${Math.random()}`;
diff --git a/packages/replicache/src/kv/idb-store.ts b/packages/replicache/src/kv/idb-store.ts
index 3d91111a39..e0060723a6 100644
--- a/packages/replicache/src/kv/idb-store.ts
+++ b/packages/replicache/src/kv/idb-store.ts
@@ -1,13 +1,13 @@
 import {resolver} from '@rocicorp/resolver';
-import {assertNotNull} from '../../../shared/src/asserts.js';
-import {promiseVoid} from '../../../shared/src/resolved-promises.js';
+import {assertNotNull} from '../../../shared/src/asserts.ts';
+import {mustGetBrowserGlobal} from '../../../shared/src/browser-env.ts';
+import {promiseVoid} from '../../../shared/src/resolved-promises.ts';
 import {
   type FrozenJSONValue,
   deepFreezeAllowUndefined,
-} from '../frozen-json.js';
-import type {Read, Store, Write} from './store.js';
-import {WriteImplBase, deleteSentinel} from './write-impl-base.js';
-import {mustGetBrowserGlobal} from '../../../shared/src/browser-env.js';
+} from '../frozen-json.ts';
+import type {Read, Store, Write} from './store.ts';
+import {WriteImplBase, deleteSentinel} from './write-impl-base.ts';
 
 const RELAXED = {durability: 'relaxed'} as const;
 const OBJECT_STORE = 'chunks';
diff --git a/packages/replicache/src/kv/mem-store.test.ts b/packages/replicache/src/kv/mem-store.test.ts
index 111eba8007..0618b76434 100644
--- a/packages/replicache/src/kv/mem-store.test.ts
+++ b/packages/replicache/src/kv/mem-store.test.ts
@@ -1,8 +1,8 @@
 import {resolver} from '@rocicorp/resolver';
 import {beforeEach, expect, test} from 'vitest';
-import {withRead, withWrite} from '../with-transactions.js';
-import {MemStore, clearAllNamedMemStoresForTesting} from './mem-store.js';
-import {runAll} from './store-test-util.js';
+import {withRead, withWrite} from '../with-transactions.ts';
+import {MemStore, clearAllNamedMemStoresForTesting} from './mem-store.ts';
+import {runAll} from './store-test-util.ts';
 
 runAll('NamedMemStore', () => new MemStore('test'));
 
diff --git a/packages/replicache/src/kv/mem-store.ts b/packages/replicache/src/kv/mem-store.ts
index 4259916c11..700533ece3 100644
--- a/packages/replicache/src/kv/mem-store.ts
+++ b/packages/replicache/src/kv/mem-store.ts
@@ -1,9 +1,9 @@
 import {RWLock} from '@rocicorp/lock';
-import {promiseVoid} from '../../../shared/src/resolved-promises.js';
-import type {FrozenJSONValue} from '../frozen-json.js';
-import {ReadImpl} from './read-impl.js';
-import type {Read, Store, Write} from './store.js';
-import {WriteImpl} from './write-impl.js';
+import {promiseVoid} from '../../../shared/src/resolved-promises.ts';
+import type {FrozenJSONValue} from '../frozen-json.ts';
+import {ReadImpl} from './read-impl.ts';
+import type {Read, Store, Write} from './store.ts';
+import {WriteImpl} from './write-impl.ts';
 
 type StorageMap = Map<string, FrozenJSONValue>;
 
diff --git a/packages/replicache/src/kv/read-impl.ts b/packages/replicache/src/kv/read-impl.ts
index 94bd98efd0..47fbd6b4c1 100644
--- a/packages/replicache/src/kv/read-impl.ts
+++ b/packages/replicache/src/kv/read-impl.ts
@@ -1,5 +1,5 @@
-import type {FrozenJSONValue} from '../frozen-json.js';
-import type {Read} from './store.js';
+import type {FrozenJSONValue} from '../frozen-json.ts';
+import type {Read} from './store.ts';
 
 export class ReadImpl implements Read {
   readonly #map: Map<string, FrozenJSONValue>;
diff --git a/packages/replicache/src/kv/store-test-util.ts b/packages/replicache/src/kv/store-test-util.ts
index 936b6a4997..d6ea2ca967 100644
--- a/packages/replicache/src/kv/store-test-util.ts
+++ b/packages/replicache/src/kv/store-test-util.ts
@@ -1,12 +1,12 @@
 import {expect, test} from 'vitest';
-import type {ReadonlyJSONValue} from '../../../shared/src/json.js';
-import type {FrozenJSONValue} from '../frozen-json.js';
+import type {ReadonlyJSONValue} from '../../../shared/src/json.ts';
+import type {FrozenJSONValue} from '../frozen-json.ts';
 import {
   withRead,
   withWrite,
   withWriteNoImplicitCommit,
-} from '../with-transactions.js';
-import type {Read, Store, Write} from './store.js';
+} from '../with-transactions.ts';
+import type {Read, Store, Write} from './store.ts';
 
 class TestStore implements Store {
   readonly #store: Store;
diff --git a/packages/replicache/src/kv/store.ts b/packages/replicache/src/kv/store.ts
index 8561508fe7..724b902905 100644
--- a/packages/replicache/src/kv/store.ts
+++ b/packages/replicache/src/kv/store.ts
@@ -1,4 +1,4 @@
-import type {ReadonlyJSONValue} from '../../../shared/src/json.js';
+import type {ReadonlyJSONValue} from '../../../shared/src/json.ts';
 
 /**
  * Store defines a transactional key/value store that Replicache stores all data
diff --git a/packages/replicache/src/kv/test-mem-store.test.ts b/packages/replicache/src/kv/test-mem-store.test.ts
index 37f584f15f..3d7fdad978 100644
--- a/packages/replicache/src/kv/test-mem-store.test.ts
+++ b/packages/replicache/src/kv/test-mem-store.test.ts
@@ -1,4 +1,4 @@
-import {runAll} from './store-test-util.js';
-import {TestMemStore} from './test-mem-store.js';
+import {runAll} from './store-test-util.ts';
+import {TestMemStore} from './test-mem-store.ts';
 
 runAll('TestMemStore', () => new TestMemStore());
diff --git a/packages/replicache/src/kv/test-mem-store.ts b/packages/replicache/src/kv/test-mem-store.ts
index fe6da38eca..0fdc49ac68 100644
--- a/packages/replicache/src/kv/test-mem-store.ts
+++ b/packages/replicache/src/kv/test-mem-store.ts
@@ -1,10 +1,10 @@
 import {RWLock} from '@rocicorp/lock';
-import {promiseVoid} from '../../../shared/src/resolved-promises.js';
-import type {FrozenJSONValue} from '../frozen-json.js';
-import {stringCompare} from '../../../shared/src/string-compare.js';
-import {ReadImpl} from './read-impl.js';
-import type {Read, Store, Write} from './store.js';
-import {WriteImpl} from './write-impl.js';
+import {promiseVoid} from '../../../shared/src/resolved-promises.ts';
+import {stringCompare} from '../../../shared/src/string-compare.ts';
+import type {FrozenJSONValue} from '../frozen-json.ts';
+import {ReadImpl} from './read-impl.ts';
+import type {Read, Store, Write} from './store.ts';
+import {WriteImpl} from './write-impl.ts';
 
 export class TestMemStore implements Store {
   readonly #map: Map<string, FrozenJSONValue> = new Map();
diff --git a/packages/replicache/src/kv/write-impl-base.ts b/packages/replicache/src/kv/write-impl-base.ts
index 9487bb7d30..671e374269 100644
--- a/packages/replicache/src/kv/write-impl-base.ts
+++ b/packages/replicache/src/kv/write-impl-base.ts
@@ -1,15 +1,15 @@
-import type {ReadonlyJSONValue} from '../../../shared/src/json.js';
+import type {ReadonlyJSONValue} from '../../../shared/src/json.ts';
 import {
   promiseFalse,
   promiseTrue,
   promiseVoid,
-} from '../../../shared/src/resolved-promises.js';
+} from '../../../shared/src/resolved-promises.ts';
 import {
   type FrozenJSONValue,
   deepFreeze,
   deepFreezeAllowUndefined,
-} from '../frozen-json.js';
-import type {Read} from './store.js';
+} from '../frozen-json.ts';
+import type {Read} from './store.ts';
 
 export const deleteSentinel = Symbol();
 type DeleteSentinel = typeof deleteSentinel;
diff --git a/packages/replicache/src/kv/write-impl.ts b/packages/replicache/src/kv/write-impl.ts
index 4b13c1fce3..cb9387421b 100644
--- a/packages/replicache/src/kv/write-impl.ts
+++ b/packages/replicache/src/kv/write-impl.ts
@@ -1,8 +1,8 @@
-import {promiseVoid} from '../../../shared/src/resolved-promises.js';
-import type {FrozenJSONValue} from '../frozen-json.js';
-import {ReadImpl} from './read-impl.js';
-import type {Write} from './store.js';
-import {deleteSentinel, WriteImplBase} from './write-impl-base.js';
+import {promiseVoid} from '../../../shared/src/resolved-promises.ts';
+import type {FrozenJSONValue} from '../frozen-json.ts';
+import {ReadImpl} from './read-impl.ts';
+import type {Write} from './store.ts';
+import {deleteSentinel, WriteImplBase} from './write-impl-base.ts';
 
 export class WriteImpl extends WriteImplBase implements Write {
   readonly #map: Map<string, FrozenJSONValue>;
diff --git a/packages/replicache/src/merge-async-iterables.test.ts b/packages/replicache/src/merge-async-iterables.test.ts
index e0f1644784..25fd18a069 100644
--- a/packages/replicache/src/merge-async-iterables.test.ts
+++ b/packages/replicache/src/merge-async-iterables.test.ts
@@ -1,7 +1,7 @@
 import {expect, test} from 'vitest';
-import {stringCompare} from '../../shared/src/string-compare.js';
-import {asyncIterableToArray} from './async-iterable-to-array.js';
-import {mergeAsyncIterables} from './merge-async-iterables.js';
+import {stringCompare} from '../../shared/src/string-compare.ts';
+import {asyncIterableToArray} from './async-iterable-to-array.ts';
+import {mergeAsyncIterables} from './merge-async-iterables.ts';
 
 export async function* makeAsyncIterable<V>(
   values: Iterable<V>,
diff --git a/packages/replicache/src/merge-async-iterables.ts b/packages/replicache/src/merge-async-iterables.ts
index 34a3171325..babe17406a 100644
--- a/packages/replicache/src/merge-async-iterables.ts
+++ b/packages/replicache/src/merge-async-iterables.ts
@@ -1,4 +1,4 @@
-import {getIterator, type IterableUnion} from './iterable-union.js';
+import {getIterator, type IterableUnion} from './iterable-union.ts';
 
 /**
  * Merges an iterable on to another iterable.
diff --git a/packages/replicache/src/mod.ts b/packages/replicache/src/mod.ts
index 37dcdb3624..8165edb660 100644
--- a/packages/replicache/src/mod.ts
+++ b/packages/replicache/src/mod.ts
@@ -5,8 +5,8 @@ export type {
   JSONValue,
   ReadonlyJSONObject,
   ReadonlyJSONValue,
-} from '../../shared/src/json.js';
-export type {MaybePromise} from '../../shared/src/types.js';
+} from '../../shared/src/json.ts';
+export type {MaybePromise} from '../../shared/src/types.ts';
 export type {
   Diff as ExperimentalDiff,
   DiffOperation as ExperimentalDiffOperation,
@@ -15,20 +15,20 @@ export type {
   DiffOperationDel as ExperimentalDiffOperationDel,
   IndexDiff as ExperimentalIndexDiff,
   NoIndexDiff as ExperimentalNoIndexDiff,
-} from './btree/node.js';
-export type {Cookie} from './cookies.js';
-export type {IndexKey} from './db/index.js';
+} from './btree/node.ts';
+export type {Cookie} from './cookies.ts';
+export type {IndexKey} from './db/index.ts';
 export type {
   ClientStateNotFoundResponse,
   VersionNotSupportedResponse,
-} from './error-responses.js';
-export {filterAsyncIterable} from './filter-async-iterable.js';
-export {getDefaultPuller} from './get-default-puller.js';
-export {getDefaultPusher} from './get-default-pusher.js';
-export type {HTTPRequestInfo} from './http-request-info.js';
-export type {IndexDefinition, IndexDefinitions} from './index-defs.js';
-export type {IterableUnion} from './iterable-union.js';
-export {IDBNotFoundError} from './kv/idb-store.js';
+} from './error-responses.ts';
+export {filterAsyncIterable} from './filter-async-iterable.ts';
+export {getDefaultPuller} from './get-default-puller.ts';
+export {getDefaultPusher} from './get-default-pusher.ts';
+export type {HTTPRequestInfo} from './http-request-info.ts';
+export type {IndexDefinition, IndexDefinitions} from './index-defs.ts';
+export type {IterableUnion} from './iterable-union.ts';
+export {IDBNotFoundError} from './kv/idb-store.ts';
 export type {
   CreateStore as CreateKVStore,
   DropStore as DropKVStore,
@@ -36,35 +36,35 @@ export type {
   Store as KVStore,
   StoreProvider as KVStoreProvider,
   Write as KVWrite,
-} from './kv/store.js';
-export {mergeAsyncIterables} from './merge-async-iterables.js';
-export type {PatchOperation} from './patch-operation.js';
-export type {PendingMutation} from './pending-mutations.js';
+} from './kv/store.ts';
+export {mergeAsyncIterables} from './merge-async-iterables.ts';
+export type {PatchOperation} from './patch-operation.ts';
+export type {PendingMutation} from './pending-mutations.ts';
 export {
   deleteAllReplicacheData,
   dropAllDatabases,
   dropDatabase,
   type DropDatabaseOptions,
-} from './persist/collect-idb-databases.js';
-export type {Puller, PullerResult, PullResponse} from './puller.js';
-export type {Pusher, PusherResult, PushError, PushResponse} from './pusher.js';
-export type {ReplicacheOptions} from './replicache-options.js';
-export {makeIDBName, Replicache} from './replicache.js';
-export {makeScanResult} from './scan-iterator.js';
+} from './persist/collect-idb-databases.ts';
+export type {Puller, PullerResult, PullResponse} from './puller.ts';
+export type {Pusher, PusherResult, PushError, PushResponse} from './pusher.ts';
+export type {ReplicacheOptions} from './replicache-options.ts';
+export {makeIDBName, Replicache} from './replicache.ts';
+export {makeScanResult} from './scan-iterator.ts';
 export type {
   AsyncIterableIteratorToArray,
   GetIndexScanIterator,
   GetScanIterator,
   ScanResult,
-} from './scan-iterator.js';
-export {isScanIndexOptions} from './scan-options.js';
+} from './scan-iterator.ts';
+export {isScanIndexOptions} from './scan-options.ts';
 export type {
   KeyTypeForScanOptions,
   ScanIndexOptions,
   ScanNoIndexOptions,
   ScanOptionIndexedStartKey,
   ScanOptions,
-} from './scan-options.js';
+} from './scan-options.ts';
 export type {
   WatchCallbackForOptions as ExperimentalWatchCallbackForOptions,
   WatchIndexCallback as ExperimentalWatchIndexCallback,
@@ -73,13 +73,13 @@ export type {
   WatchNoIndexOptions as ExperimentalWatchNoIndexOptions,
   WatchOptions as ExperimentalWatchOptions,
   SubscribeOptions,
-} from './subscriptions.js';
-export type {ClientGroupID, ClientID} from './sync/ids.js';
-export {PullError} from './sync/pull-error.js';
-export type {PullRequest} from './sync/pull.js';
-export type {Mutation, PushRequest} from './sync/push.js';
-export {TEST_LICENSE_KEY} from './test-license-key.js';
-export {TransactionClosedError} from './transaction-closed-error.js';
+} from './subscriptions.ts';
+export type {ClientGroupID, ClientID} from './sync/ids.ts';
+export {PullError} from './sync/pull-error.ts';
+export type {PullRequest} from './sync/pull.ts';
+export type {Mutation, PushRequest} from './sync/push.ts';
+export {TEST_LICENSE_KEY} from './test-license-key.ts';
+export {TransactionClosedError} from './transaction-closed-error.ts';
 export type {
   CreateIndexDefinition,
   DeepReadonly,
@@ -89,7 +89,7 @@ export type {
   TransactionLocation,
   TransactionReason,
   WriteTransaction,
-} from './transactions.js';
+} from './transactions.ts';
 export type {
   MakeMutator,
   MakeMutators,
@@ -98,5 +98,5 @@ export type {
   Poke,
   RequestOptions,
   UpdateNeededReason,
-} from './types.js';
-export {version} from './version.js';
+} from './types.ts';
+export {version} from './version.ts';
diff --git a/packages/replicache/src/mutation-recovery-test-helper.ts b/packages/replicache/src/mutation-recovery-test-helper.ts
index e51192e8c4..f94ee8ff0c 100644
--- a/packages/replicache/src/mutation-recovery-test-helper.ts
+++ b/packages/replicache/src/mutation-recovery-test-helper.ts
@@ -1,23 +1,23 @@
 import {LogContext} from '@rocicorp/logger';
-import {assert} from '../../shared/src/asserts.js';
-import type {Enum} from '../../shared/src/enum.js';
-import type {ReadonlyJSONObject} from '../../shared/src/json.js';
-import {LazyStore} from './dag/lazy-store.js';
-import {StoreImpl} from './dag/store-impl.js';
-import type {Store} from './dag/store.js';
-import {type LocalMetaDD31, assertLocalMetaDD31} from './db/commit.js';
-import {ChainBuilder} from './db/test-helpers.js';
-import * as FormatVersion from './format-version-enum.js';
-import {assertHash, newRandomHash} from './hash.js';
-import {IDBStore} from './kv/idb-store.js';
-import {initClientWithClientID} from './persist/clients-test-helpers.js';
-import {IDBDatabasesStore} from './persist/idb-databases-store.js';
-import {persistDD31} from './persist/persist.js';
-import {makeIDBNameForTesting} from './replicache.js';
-import type {ClientGroupID, ClientID} from './sync/ids.js';
-import {PUSH_VERSION_DD31} from './sync/push.js';
-import {closeablesToClose, dbsToDrop} from './test-util.js';
-import type {MutatorDefs} from './types.js';
+import {assert} from '../../shared/src/asserts.ts';
+import type {Enum} from '../../shared/src/enum.ts';
+import type {ReadonlyJSONObject} from '../../shared/src/json.ts';
+import {LazyStore} from './dag/lazy-store.ts';
+import {StoreImpl} from './dag/store-impl.ts';
+import type {Store} from './dag/store.ts';
+import {type LocalMetaDD31, assertLocalMetaDD31} from './db/commit.ts';
+import {ChainBuilder} from './db/test-helpers.ts';
+import * as FormatVersion from './format-version-enum.ts';
+import {assertHash, newRandomHash} from './hash.ts';
+import {IDBStore} from './kv/idb-store.ts';
+import {initClientWithClientID} from './persist/clients-test-helpers.ts';
+import {IDBDatabasesStore} from './persist/idb-databases-store.ts';
+import {persistDD31} from './persist/persist.ts';
+import {makeIDBNameForTesting} from './replicache.ts';
+import type {ClientGroupID, ClientID} from './sync/ids.ts';
+import {PUSH_VERSION_DD31} from './sync/push.ts';
+import {closeablesToClose, dbsToDrop} from './test-util.ts';
+import type {MutatorDefs} from './types.ts';
 
 type FormatVersion = Enum<typeof FormatVersion>;
 
diff --git a/packages/replicache/src/mutation-recovery.ts b/packages/replicache/src/mutation-recovery.ts
index 46029878f6..3e0f13547d 100644
--- a/packages/replicache/src/mutation-recovery.ts
+++ b/packages/replicache/src/mutation-recovery.ts
@@ -1,40 +1,40 @@
 import type {LogContext} from '@rocicorp/logger';
-import {assert, assertNotUndefined} from '../../shared/src/asserts.js';
-import type {Enum} from '../../shared/src/enum.js';
-import type {MaybePromise} from '../../shared/src/types.js';
-import {throwChunkHasher} from './dag/chunk.js';
-import {LazyStore} from './dag/lazy-store.js';
-import {StoreImpl} from './dag/store-impl.js';
-import type {Store} from './dag/store.js';
-import {DEFAULT_HEAD_NAME} from './db/commit.js';
+import {assert, assertNotUndefined} from '../../shared/src/asserts.ts';
+import type {Enum} from '../../shared/src/enum.ts';
+import type {MaybePromise} from '../../shared/src/types.ts';
+import {throwChunkHasher} from './dag/chunk.ts';
+import {LazyStore} from './dag/lazy-store.ts';
+import {StoreImpl} from './dag/store-impl.ts';
+import type {Store} from './dag/store.ts';
+import {DEFAULT_HEAD_NAME} from './db/commit.ts';
 import {
   type ClientStateNotFoundResponse,
   type VersionNotSupportedResponse,
   isClientStateNotFoundResponse,
   isVersionNotSupportedResponse,
-} from './error-responses.js';
-import * as FormatVersion from './format-version-enum.js';
-import {parseReplicacheFormatVersion as parseFormatVersion} from './format-version.js';
-import {assertHash, newRandomHash} from './hash.js';
-import type {HTTPRequestInfo} from './http-request-info.js';
-import type {CreateStore} from './kv/store.js';
+} from './error-responses.ts';
+import * as FormatVersion from './format-version-enum.ts';
+import {parseReplicacheFormatVersion as parseFormatVersion} from './format-version.ts';
+import {assertHash, newRandomHash} from './hash.ts';
+import type {HTTPRequestInfo} from './http-request-info.ts';
+import type {CreateStore} from './kv/store.ts';
 import {
   type ClientGroup,
   type ClientGroupMap,
   getClientGroups,
   disableClientGroup as persistDisableClientGroup,
   setClientGroups,
-} from './persist/client-groups.js';
+} from './persist/client-groups.ts';
 import type {
   IDBDatabasesStore,
   IndexedDBDatabase,
-} from './persist/idb-databases-store.js';
-import type {PullResponseOKV1, PullResponseV1, Puller} from './puller.js';
-import type {PushResponse, Pusher} from './pusher.js';
-import type {ClientGroupID, ClientID} from './sync/ids.js';
-import {beginPullV1} from './sync/pull.js';
-import {PUSH_VERSION_DD31, push} from './sync/push.js';
-import {withRead, withWrite} from './with-transactions.js';
+} from './persist/idb-databases-store.ts';
+import type {PullResponseOKV1, PullResponseV1, Puller} from './puller.ts';
+import type {PushResponse, Pusher} from './pusher.ts';
+import type {ClientGroupID, ClientID} from './sync/ids.ts';
+import {beginPullV1} from './sync/pull.ts';
+import {PUSH_VERSION_DD31, push} from './sync/push.ts';
+import {withRead, withWrite} from './with-transactions.ts';
 
 type FormatVersion = Enum<typeof FormatVersion>;
 
diff --git a/packages/replicache/src/new-client-channel.test.ts b/packages/replicache/src/new-client-channel.test.ts
index d275f44686..8d565e1a63 100644
--- a/packages/replicache/src/new-client-channel.test.ts
+++ b/packages/replicache/src/new-client-channel.test.ts
@@ -1,16 +1,16 @@
 import {resolver} from '@rocicorp/resolver';
 import {describe, expect, test} from 'vitest';
-import {sleep} from '../../shared/src/sleep.js';
-import {BroadcastChannel} from './broadcast-channel.js';
-import {TestStore} from './dag/test-store.js';
-import {fakeHash} from './hash.js';
+import {sleep} from '../../shared/src/sleep.ts';
+import {BroadcastChannel} from './broadcast-channel.ts';
+import {TestStore} from './dag/test-store.ts';
+import {fakeHash} from './hash.ts';
 import {
   initNewClientChannel,
   makeChannelNameV0ForTesting,
   makeChannelNameV1ForTesting,
-} from './new-client-channel.js';
-import {setClientGroup} from './persist/client-groups.js';
-import {withWriteNoImplicitCommit} from './with-transactions.js';
+} from './new-client-channel.ts';
+import {setClientGroup} from './persist/client-groups.ts';
+import {withWriteNoImplicitCommit} from './with-transactions.ts';
 
 function getChannelMessagePromise(
   replicacheName: string,
diff --git a/packages/replicache/src/new-client-channel.ts b/packages/replicache/src/new-client-channel.ts
index 135e138d06..351721e79b 100644
--- a/packages/replicache/src/new-client-channel.ts
+++ b/packages/replicache/src/new-client-channel.ts
@@ -1,7 +1,7 @@
-import {BroadcastChannel} from './broadcast-channel.js';
-import type {Read, Store} from './dag/store.js';
-import {getClientGroup} from './persist/client-groups.js';
-import {withRead} from './with-transactions.js';
+import {BroadcastChannel} from './broadcast-channel.ts';
+import type {Read, Store} from './dag/store.ts';
+import {getClientGroup} from './persist/client-groups.ts';
+import {withRead} from './with-transactions.ts';
 
 // Older clients (<= replicache@13.0.1), listened on this channel name
 // and *asserted* that the messages received were an array containing exactly
diff --git a/packages/replicache/src/on-persist-channel.test.ts b/packages/replicache/src/on-persist-channel.test.ts
index 8179ce7135..ff6c0baf79 100644
--- a/packages/replicache/src/on-persist-channel.test.ts
+++ b/packages/replicache/src/on-persist-channel.test.ts
@@ -1,7 +1,7 @@
 import {resolver} from '@rocicorp/resolver';
 import {afterEach, describe, expect, test} from 'vitest';
-import {BroadcastChannel} from './broadcast-channel.js';
-import {initOnPersistChannel, type PersistInfo} from './on-persist-channel.js';
+import {BroadcastChannel} from './broadcast-channel.ts';
+import {initOnPersistChannel, type PersistInfo} from './on-persist-channel.ts';
 
 describe('initOnPersistChannel', () => {
   let channel: BroadcastChannel | undefined;
diff --git a/packages/replicache/src/on-persist-channel.ts b/packages/replicache/src/on-persist-channel.ts
index ffa1f45fae..b74964c62c 100644
--- a/packages/replicache/src/on-persist-channel.ts
+++ b/packages/replicache/src/on-persist-channel.ts
@@ -1,6 +1,6 @@
-import {assertObject, assertString} from '../../shared/src/asserts.js';
-import {BroadcastChannel} from './broadcast-channel.js';
-import type {ClientGroupID, ClientID} from './sync/ids.js';
+import {assertObject, assertString} from '../../shared/src/asserts.ts';
+import {BroadcastChannel} from './broadcast-channel.ts';
+import type {ClientGroupID, ClientID} from './sync/ids.ts';
 
 function makeChannelName(replicacheName: string): string {
   return `replicache-on-persist:${replicacheName}`;
diff --git a/packages/replicache/src/patch-operation.ts b/packages/replicache/src/patch-operation.ts
index 9fb8f20ab5..25eb96926c 100644
--- a/packages/replicache/src/patch-operation.ts
+++ b/packages/replicache/src/patch-operation.ts
@@ -2,13 +2,13 @@ import {
   assertArray,
   assertObject,
   assertString,
-} from '../../shared/src/asserts.js';
+} from '../../shared/src/asserts.ts';
 import {
   type ReadonlyJSONObject,
   type ReadonlyJSONValue,
   assertJSONObject,
   assertJSONValue,
-} from '../../shared/src/json.js';
+} from '../../shared/src/json.ts';
 
 export type PatchOperationInternal =
   | {
diff --git a/packages/replicache/src/peek-iterator.test.ts b/packages/replicache/src/peek-iterator.test.ts
index 0d03b6756f..587436cfe1 100644
--- a/packages/replicache/src/peek-iterator.test.ts
+++ b/packages/replicache/src/peek-iterator.test.ts
@@ -1,5 +1,5 @@
 import {expect, test} from 'vitest';
-import {PeekIterator} from './peek-iterator.js';
+import {PeekIterator} from './peek-iterator.ts';
 
 test('PeekIterator', () => {
   const c = new PeekIterator('abc'[Symbol.iterator]());
diff --git a/packages/replicache/src/pending-mutation.test.ts b/packages/replicache/src/pending-mutation.test.ts
index 9eb7fde30c..fcd32d188c 100644
--- a/packages/replicache/src/pending-mutation.test.ts
+++ b/packages/replicache/src/pending-mutation.test.ts
@@ -1,20 +1,20 @@
 import {expect, test} from 'vitest';
-import type {JSONValue} from '../../shared/src/json.js';
+import type {JSONValue} from '../../shared/src/json.ts';
 import {
   initReplicacheTesting,
   makePullResponseV1,
   replicacheForTesting,
   tickAFewTimes,
-} from './test-util.js';
-import type {WriteTransaction} from './transactions.js';
+} from './test-util.ts';
+import type {WriteTransaction} from './transactions.ts';
 // fetch-mock has invalid d.ts file so we removed that on npm install.
 // eslint-disable-next-line @typescript-eslint/ban-ts-comment
 // @ts-expect-error
 import fetchMock from 'fetch-mock/esm/client';
-import {TestStore} from './dag/test-store.js';
-import {ChainBuilder} from './db/test-helpers.js';
-import {pendingMutationsForAPI} from './pending-mutations.js';
-import {withRead} from './with-transactions.js';
+import {TestStore} from './dag/test-store.ts';
+import {ChainBuilder} from './db/test-helpers.ts';
+import {pendingMutationsForAPI} from './pending-mutations.ts';
+import {withRead} from './with-transactions.ts';
 
 initReplicacheTesting();
 
diff --git a/packages/replicache/src/pending-mutations.ts b/packages/replicache/src/pending-mutations.ts
index 27967bf8f1..47616823e8 100644
--- a/packages/replicache/src/pending-mutations.ts
+++ b/packages/replicache/src/pending-mutations.ts
@@ -1,7 +1,7 @@
-import type {ReadonlyJSONValue} from '../../shared/src/json.js';
-import {mustGetHeadHash, type Read} from './dag/store.js';
-import {DEFAULT_HEAD_NAME, localMutationsDD31} from './db/commit.js';
-import type {ClientID} from './sync/ids.js';
+import type {ReadonlyJSONValue} from '../../shared/src/json.ts';
+import {mustGetHeadHash, type Read} from './dag/store.ts';
+import {DEFAULT_HEAD_NAME, localMutationsDD31} from './db/commit.ts';
+import type {ClientID} from './sync/ids.ts';
 
 export type PendingMutation = {
   readonly name: string;
diff --git a/packages/replicache/src/persist/client-gc.test.ts b/packages/replicache/src/persist/client-gc.test.ts
index 18970a4154..6c1beefcc9 100644
--- a/packages/replicache/src/persist/client-gc.test.ts
+++ b/packages/replicache/src/persist/client-gc.test.ts
@@ -1,19 +1,19 @@
 import {LogContext} from '@rocicorp/logger';
 import {type SinonFakeTimers, useFakeTimers} from 'sinon';
 import {afterEach, beforeEach, expect, test} from 'vitest';
-import {assertNotUndefined} from '../../../shared/src/asserts.js';
-import type {Read} from '../dag/store.js';
-import {TestStore} from '../dag/test-store.js';
-import {newRandomHash} from '../hash.js';
-import {withRead, withWrite} from '../with-transactions.js';
+import {assertNotUndefined} from '../../../shared/src/asserts.ts';
+import type {Read} from '../dag/store.ts';
+import {TestStore} from '../dag/test-store.ts';
+import {newRandomHash} from '../hash.ts';
+import {withRead, withWrite} from '../with-transactions.ts';
 import {
   CLIENT_MAX_INACTIVE_TIME,
   GC_INTERVAL,
   getLatestGCUpdate,
   initClientGC,
-} from './client-gc.js';
-import {makeClientV4, setClientsForTesting} from './clients-test-helpers.js';
-import {type ClientMap, getClients, setClient} from './clients.js';
+} from './client-gc.ts';
+import {makeClientV4, setClientsForTesting} from './clients-test-helpers.ts';
+import {type ClientMap, getClients, setClient} from './clients.ts';
 
 let clock: SinonFakeTimers;
 const START_TIME = 0;
diff --git a/packages/replicache/src/persist/client-gc.ts b/packages/replicache/src/persist/client-gc.ts
index 499cd62c75..645090bbd7 100644
--- a/packages/replicache/src/persist/client-gc.ts
+++ b/packages/replicache/src/persist/client-gc.ts
@@ -1,9 +1,9 @@
 import type {LogContext} from '@rocicorp/logger';
-import {initBgIntervalProcess} from '../bg-interval.js';
-import type {Store} from '../dag/store.js';
-import type {ClientID} from '../sync/ids.js';
-import {withWrite} from '../with-transactions.js';
-import {type ClientMap, getClients, setClients} from './clients.js';
+import {initBgIntervalProcess} from '../bg-interval.ts';
+import type {Store} from '../dag/store.ts';
+import type {ClientID} from '../sync/ids.ts';
+import {withWrite} from '../with-transactions.ts';
+import {type ClientMap, getClients, setClients} from './clients.ts';
 
 /**
  * The maximum time a client can be inactive before it is garbage collected.
diff --git a/packages/replicache/src/persist/client-group-gc.test.ts b/packages/replicache/src/persist/client-group-gc.test.ts
index 31a57812fe..0be0fe8442 100644
--- a/packages/replicache/src/persist/client-group-gc.test.ts
+++ b/packages/replicache/src/persist/client-group-gc.test.ts
@@ -1,20 +1,20 @@
 import {LogContext} from '@rocicorp/logger';
 import {type SinonFakeTimers, useFakeTimers} from 'sinon';
 import {afterEach, beforeEach, expect, test} from 'vitest';
-import {assertNotUndefined} from '../../../shared/src/asserts.js';
-import type {Read} from '../dag/store.js';
-import {TestStore} from '../dag/test-store.js';
-import {fakeHash} from '../hash.js';
-import {withRead, withWriteNoImplicitCommit} from '../with-transactions.js';
-import {getLatestGCUpdate, initClientGroupGC} from './client-group-gc.js';
+import {assertNotUndefined} from '../../../shared/src/asserts.ts';
+import type {Read} from '../dag/store.ts';
+import {TestStore} from '../dag/test-store.ts';
+import {fakeHash} from '../hash.ts';
+import {withRead, withWriteNoImplicitCommit} from '../with-transactions.ts';
+import {getLatestGCUpdate, initClientGroupGC} from './client-group-gc.ts';
 import {
   type ClientGroup,
   type ClientGroupMap,
   getClientGroups,
   setClientGroup,
   setClientGroups,
-} from './client-groups.js';
-import {makeClientV6, setClientsForTesting} from './clients-test-helpers.js';
+} from './client-groups.ts';
+import {makeClientV6, setClientsForTesting} from './clients-test-helpers.ts';
 
 let clock: SinonFakeTimers;
 const START_TIME = 0;
diff --git a/packages/replicache/src/persist/client-group-gc.ts b/packages/replicache/src/persist/client-group-gc.ts
index 4c87d97dcd..8f3b2043bb 100644
--- a/packages/replicache/src/persist/client-group-gc.ts
+++ b/packages/replicache/src/persist/client-group-gc.ts
@@ -1,14 +1,14 @@
 import type {LogContext} from '@rocicorp/logger';
-import {initBgIntervalProcess} from '../bg-interval.js';
-import type {Store} from '../dag/store.js';
-import {withWrite} from '../with-transactions.js';
+import {initBgIntervalProcess} from '../bg-interval.ts';
+import type {Store} from '../dag/store.ts';
+import {withWrite} from '../with-transactions.ts';
 import {
   type ClientGroupMap,
   clientGroupHasPendingMutations,
   getClientGroups,
   setClientGroups,
-} from './client-groups.js';
-import {assertClientV6, getClients} from './clients.js';
+} from './client-groups.ts';
+import {assertClientV6, getClients} from './clients.ts';
 
 const GC_INTERVAL_MS = 5 * 60 * 1000; // 5 minutes
 
diff --git a/packages/replicache/src/persist/client-groups.test.ts b/packages/replicache/src/persist/client-groups.test.ts
index c3c6b3e839..828b0276f6 100644
--- a/packages/replicache/src/persist/client-groups.test.ts
+++ b/packages/replicache/src/persist/client-groups.test.ts
@@ -1,9 +1,9 @@
 import {expect, test} from 'vitest';
-import type {Read, Store, Write} from '../dag/store.js';
-import {TestStore} from '../dag/test-store.js';
-import {type Hash, assertHash, fakeHash} from '../hash.js';
-import type {ClientGroupID} from '../sync/ids.js';
-import {withRead, withWriteNoImplicitCommit} from '../with-transactions.js';
+import type {Read, Store, Write} from '../dag/store.ts';
+import {TestStore} from '../dag/test-store.ts';
+import {type Hash, assertHash, fakeHash} from '../hash.ts';
+import type {ClientGroupID} from '../sync/ids.ts';
+import {withRead, withWriteNoImplicitCommit} from '../with-transactions.ts';
 import {
   type ClientGroup,
   type ClientGroupMap,
@@ -15,7 +15,7 @@ import {
   mutatorNamesEqual,
   setClientGroup,
   setClientGroups,
-} from './client-groups.js';
+} from './client-groups.ts';
 
 const headClientGroup1Hash = fakeHash('b1');
 const headClientGroup2Hash = fakeHash('b2');
diff --git a/packages/replicache/src/persist/client-groups.ts b/packages/replicache/src/persist/client-groups.ts
index 48d568d9d2..e2f729f265 100644
--- a/packages/replicache/src/persist/client-groups.ts
+++ b/packages/replicache/src/persist/client-groups.ts
@@ -1,11 +1,11 @@
-import {assert, assertObject} from '../../../shared/src/asserts.js';
-import * as valita from '../../../shared/src/valita.js';
-import {toRefs} from '../dag/chunk.js';
-import type {Read, Write} from '../dag/store.js';
-import {deepFreeze, type FrozenJSONValue} from '../frozen-json.js';
-import {type Hash, hashSchema} from '../hash.js';
-import {indexDefinitionsEqual, indexDefinitionsSchema} from '../index-defs.js';
-import type {ClientGroupID} from '../sync/ids.js';
+import {assert, assertObject} from '../../../shared/src/asserts.ts';
+import * as valita from '../../../shared/src/valita.ts';
+import {toRefs} from '../dag/chunk.ts';
+import type {Read, Write} from '../dag/store.ts';
+import {deepFreeze, type FrozenJSONValue} from '../frozen-json.ts';
+import {type Hash, hashSchema} from '../hash.ts';
+import {indexDefinitionsEqual, indexDefinitionsSchema} from '../index-defs.ts';
+import type {ClientGroupID} from '../sync/ids.ts';
 
 export type ClientGroupMap = ReadonlyMap<ClientGroupID, ClientGroup>;
 
diff --git a/packages/replicache/src/persist/clients-test-helpers.ts b/packages/replicache/src/persist/clients-test-helpers.ts
index ab1787e4c6..b207131d6a 100644
--- a/packages/replicache/src/persist/clients-test-helpers.ts
+++ b/packages/replicache/src/persist/clients-test-helpers.ts
@@ -1,11 +1,11 @@
 import {LogContext} from '@rocicorp/logger';
-import {assert} from '../../../shared/src/asserts.js';
-import type {Enum} from '../../../shared/src/enum.js';
-import type {Store} from '../dag/store.js';
-import * as FormatVersion from '../format-version-enum.js';
-import type {IndexDefinitions} from '../index-defs.js';
-import type {ClientID} from '../sync/ids.js';
-import {withWrite} from '../with-transactions.js';
+import {assert} from '../../../shared/src/asserts.ts';
+import type {Enum} from '../../../shared/src/enum.ts';
+import type {Store} from '../dag/store.ts';
+import * as FormatVersion from '../format-version-enum.ts';
+import type {IndexDefinitions} from '../index-defs.ts';
+import type {ClientID} from '../sync/ids.ts';
+import {withWrite} from '../with-transactions.ts';
 import {
   type ClientMap,
   type ClientMapDD31,
@@ -15,7 +15,7 @@ import {
   getClients,
   initClientV6,
   setClients,
-} from './clients.js';
+} from './clients.ts';
 
 type FormatVersion = Enum<typeof FormatVersion>;
 
diff --git a/packages/replicache/src/persist/clients.test.ts b/packages/replicache/src/persist/clients.test.ts
index 25b08a3856..dd2b33e3e1 100644
--- a/packages/replicache/src/persist/clients.test.ts
+++ b/packages/replicache/src/persist/clients.test.ts
@@ -1,30 +1,30 @@
 import {LogContext} from '@rocicorp/logger';
 import {type SinonFakeTimers, useFakeTimers} from 'sinon';
 import {afterEach, beforeEach, describe, expect, test} from 'vitest';
-import {assert, assertNotUndefined} from '../../../shared/src/asserts.js';
-import {BTreeRead} from '../btree/read.js';
-import type {Read, Write} from '../dag/store.js';
-import {TestStore} from '../dag/test-store.js';
+import {assert, assertNotUndefined} from '../../../shared/src/asserts.ts';
+import {BTreeRead} from '../btree/read.ts';
+import type {Read, Write} from '../dag/store.ts';
+import {TestStore} from '../dag/test-store.ts';
 import {
   Commit,
   type SnapshotMetaDD31,
   commitFromHash,
   commitIsSnapshot,
   fromChunk,
-} from '../db/commit.js';
-import {ChainBuilder} from '../db/test-helpers.js';
-import * as FormatVersion from '../format-version-enum.js';
-import {deepFreeze} from '../frozen-json.js';
-import {assertHash, fakeHash, newRandomHash} from '../hash.js';
-import type {IndexDefinitions} from '../index-defs.js';
-import type {ClientGroupID, ClientID} from '../sync/ids.js';
-import {withRead, withWriteNoImplicitCommit} from '../with-transactions.js';
+} from '../db/commit.ts';
+import {ChainBuilder} from '../db/test-helpers.ts';
+import * as FormatVersion from '../format-version-enum.ts';
+import {deepFreeze} from '../frozen-json.ts';
+import {assertHash, fakeHash, newRandomHash} from '../hash.ts';
+import type {IndexDefinitions} from '../index-defs.ts';
+import type {ClientGroupID, ClientID} from '../sync/ids.ts';
+import {withRead, withWriteNoImplicitCommit} from '../with-transactions.ts';
 import {
   type ClientGroup,
   getClientGroup,
   setClientGroup,
-} from './client-groups.js';
-import {makeClientV6, setClientsForTesting} from './clients-test-helpers.js';
+} from './client-groups.ts';
+import {makeClientV6, setClientsForTesting} from './clients-test-helpers.ts';
 import {
   CLIENTS_HEAD_NAME,
   type ClientV5,
@@ -40,8 +40,8 @@ import {
   getClients,
   initClientV6,
   setClient,
-} from './clients.js';
-import {makeClientID} from './make-client-id.js';
+} from './clients.ts';
+import {makeClientID} from './make-client-id.ts';
 
 let clock: SinonFakeTimers;
 beforeEach(() => {
diff --git a/packages/replicache/src/persist/clients.ts b/packages/replicache/src/persist/clients.ts
index 550fa0fdb7..bb4ebbf1ff 100644
--- a/packages/replicache/src/persist/clients.ts
+++ b/packages/replicache/src/persist/clients.ts
@@ -1,13 +1,13 @@
 import type {LogContext} from '@rocicorp/logger';
-import {assert, assertObject} from '../../../shared/src/asserts.js';
-import type {Enum} from '../../../shared/src/enum.js';
-import {hasOwn} from '../../../shared/src/has-own.js';
-import * as valita from '../../../shared/src/valita.js';
-import {emptyDataNode} from '../btree/node.js';
-import {BTreeRead} from '../btree/read.js';
-import {type FrozenCookie, compareCookies} from '../cookies.js';
-import {type Refs, toRefs} from '../dag/chunk.js';
-import type {Read, Store, Write} from '../dag/store.js';
+import {assert, assertObject} from '../../../shared/src/asserts.ts';
+import type {Enum} from '../../../shared/src/enum.ts';
+import {hasOwn} from '../../../shared/src/has-own.ts';
+import * as valita from '../../../shared/src/valita.ts';
+import {emptyDataNode} from '../btree/node.ts';
+import {BTreeRead} from '../btree/read.ts';
+import {type FrozenCookie, compareCookies} from '../cookies.ts';
+import {type Refs, toRefs} from '../dag/chunk.ts';
+import type {Read, Store, Write} from '../dag/store.ts';
 import {
   type ChunkIndexDefinition,
   Commit,
@@ -19,26 +19,26 @@ import {
   getRefs,
   newSnapshotCommitDataDD31,
   toChunkIndexDefinition,
-} from '../db/commit.js';
-import {createIndexBTree} from '../db/write.js';
-import * as FormatVersion from '../format-version-enum.js';
-import {type FrozenJSONValue, deepFreeze} from '../frozen-json.js';
-import {type Hash, hashSchema} from '../hash.js';
-import {type IndexDefinitions, indexDefinitionsEqual} from '../index-defs.js';
+} from '../db/commit.ts';
+import {createIndexBTree} from '../db/write.ts';
+import * as FormatVersion from '../format-version-enum.ts';
+import {type FrozenJSONValue, deepFreeze} from '../frozen-json.ts';
+import {type Hash, hashSchema} from '../hash.ts';
+import {type IndexDefinitions, indexDefinitionsEqual} from '../index-defs.ts';
 import {
   type ClientGroupID,
   type ClientID,
   clientGroupIDSchema,
-} from '../sync/ids.js';
-import {withWriteNoImplicitCommit} from '../with-transactions.js';
+} from '../sync/ids.ts';
+import {withWriteNoImplicitCommit} from '../with-transactions.ts';
 import {
   type ClientGroup,
   getClientGroup,
   getClientGroups,
   mutatorNamesEqual,
   setClientGroup,
-} from './client-groups.js';
-import {makeClientID} from './make-client-id.js';
+} from './client-groups.ts';
+import {makeClientID} from './make-client-id.ts';
 
 type FormatVersion = Enum<typeof FormatVersion>;
 
diff --git a/packages/replicache/src/persist/collect-idb-databases.test.ts b/packages/replicache/src/persist/collect-idb-databases.test.ts
index 0ee420e686..b9410340c5 100644
--- a/packages/replicache/src/persist/collect-idb-databases.test.ts
+++ b/packages/replicache/src/persist/collect-idb-databases.test.ts
@@ -1,33 +1,33 @@
 import {LogContext} from '@rocicorp/logger';
 import {type SinonFakeTimers, useFakeTimers} from 'sinon';
 import {afterEach, beforeEach, describe, expect, test} from 'vitest';
-import {assertNotUndefined} from '../../../shared/src/asserts.js';
-import type {Store} from '../dag/store.js';
-import {TestStore} from '../dag/test-store.js';
-import * as FormatVersion from '../format-version-enum.js';
-import {fakeHash} from '../hash.js';
-import {IDBStore} from '../kv/idb-store.js';
-import {hasMemStore} from '../kv/mem-store.js';
-import {TestMemStore} from '../kv/test-mem-store.js';
-import {getKVStoreProvider} from '../replicache.js';
-import {withWrite, withWriteNoImplicitCommit} from '../with-transactions.js';
-import {type ClientGroupMap, setClientGroups} from './client-groups.js';
-import {makeClientGroupMap} from './client-groups.test.js';
+import {assertNotUndefined} from '../../../shared/src/asserts.ts';
+import type {Store} from '../dag/store.ts';
+import {TestStore} from '../dag/test-store.ts';
+import * as FormatVersion from '../format-version-enum.ts';
+import {fakeHash} from '../hash.ts';
+import {IDBStore} from '../kv/idb-store.ts';
+import {hasMemStore} from '../kv/mem-store.ts';
+import {TestMemStore} from '../kv/test-mem-store.ts';
+import {getKVStoreProvider} from '../replicache.ts';
+import {withWrite, withWriteNoImplicitCommit} from '../with-transactions.ts';
+import {makeClientGroupMap} from './client-groups.test.ts';
+import {type ClientGroupMap, setClientGroups} from './client-groups.ts';
 import {
   makeClientMapDD31,
   setClientsForTesting,
-} from './clients-test-helpers.js';
-import type {ClientMap} from './clients.js';
+} from './clients-test-helpers.ts';
+import type {ClientMap} from './clients.ts';
 import {
   collectIDBDatabases,
   dropAllDatabases,
   dropDatabase,
-} from './collect-idb-databases.js';
+} from './collect-idb-databases.ts';
 import {
   IDBDatabasesStore,
   type IndexedDBDatabase,
   type IndexedDBName,
-} from './idb-databases-store.js';
+} from './idb-databases-store.ts';
 
 describe('collectIDBDatabases', () => {
   let clock: SinonFakeTimers;
diff --git a/packages/replicache/src/persist/collect-idb-databases.ts b/packages/replicache/src/persist/collect-idb-databases.ts
index d76b8b81e9..2c520ec241 100644
--- a/packages/replicache/src/persist/collect-idb-databases.ts
+++ b/packages/replicache/src/persist/collect-idb-databases.ts
@@ -1,22 +1,22 @@
 import type {LogContext, LogLevel, LogSink} from '@rocicorp/logger';
-import {assert} from '../../../shared/src/asserts.js';
-import {initBgIntervalProcess} from '../bg-interval.js';
-import {StoreImpl} from '../dag/store-impl.js';
-import type {Store} from '../dag/store.js';
-import * as FormatVersion from '../format-version-enum.js';
-import {assertHash, newRandomHash} from '../hash.js';
-import {IDBStore} from '../kv/idb-store.js';
-import type {DropStore, StoreProvider} from '../kv/store.js';
-import {createLogContext} from '../log-options.js';
-import {getKVStoreProvider} from '../replicache.js';
-import {withRead} from '../with-transactions.js';
+import {assert} from '../../../shared/src/asserts.ts';
+import {initBgIntervalProcess} from '../bg-interval.ts';
+import {StoreImpl} from '../dag/store-impl.ts';
+import type {Store} from '../dag/store.ts';
+import * as FormatVersion from '../format-version-enum.ts';
+import {assertHash, newRandomHash} from '../hash.ts';
+import {IDBStore} from '../kv/idb-store.ts';
+import type {DropStore, StoreProvider} from '../kv/store.ts';
+import {createLogContext} from '../log-options.ts';
+import {getKVStoreProvider} from '../replicache.ts';
+import {withRead} from '../with-transactions.ts';
 import {
   clientGroupHasPendingMutations,
   getClientGroups,
-} from './client-groups.js';
-import {type ClientMap, getClients} from './clients.js';
-import type {IndexedDBDatabase} from './idb-databases-store.js';
-import {IDBDatabasesStore} from './idb-databases-store.js';
+} from './client-groups.ts';
+import {type ClientMap, getClients} from './clients.ts';
+import type {IndexedDBDatabase} from './idb-databases-store.ts';
+import {IDBDatabasesStore} from './idb-databases-store.ts';
 
 /**
  * How frequently to try to collect
diff --git a/packages/replicache/src/persist/gather-mem-only-visitor.test.ts b/packages/replicache/src/persist/gather-mem-only-visitor.test.ts
index 4d34da734a..8753263fc4 100644
--- a/packages/replicache/src/persist/gather-mem-only-visitor.test.ts
+++ b/packages/replicache/src/persist/gather-mem-only-visitor.test.ts
@@ -1,16 +1,16 @@
 import {describe, expect, test} from 'vitest';
-import {assert} from '../../../shared/src/asserts.js';
-import type {Enum} from '../../../shared/src/enum.js';
-import {LazyStore} from '../dag/lazy-store.js';
-import {TestLazyStore} from '../dag/test-lazy-store.js';
-import {TestStore} from '../dag/test-store.js';
-import {DEFAULT_HEAD_NAME} from '../db/commit.js';
-import * as MetaType from '../db/meta-type-enum.js';
-import {ChainBuilder} from '../db/test-helpers.js';
-import * as FormatVersion from '../format-version-enum.js';
-import {assertHash, fakeHash, makeNewFakeHashFunction} from '../hash.js';
-import {withRead, withWriteNoImplicitCommit} from '../with-transactions.js';
-import {GatherMemoryOnlyVisitor} from './gather-mem-only-visitor.js';
+import {assert} from '../../../shared/src/asserts.ts';
+import type {Enum} from '../../../shared/src/enum.ts';
+import {LazyStore} from '../dag/lazy-store.ts';
+import {TestLazyStore} from '../dag/test-lazy-store.ts';
+import {TestStore} from '../dag/test-store.ts';
+import {DEFAULT_HEAD_NAME} from '../db/commit.ts';
+import * as MetaType from '../db/meta-type-enum.ts';
+import {ChainBuilder} from '../db/test-helpers.ts';
+import * as FormatVersion from '../format-version-enum.ts';
+import {assertHash, fakeHash, makeNewFakeHashFunction} from '../hash.ts';
+import {withRead, withWriteNoImplicitCommit} from '../with-transactions.ts';
+import {GatherMemoryOnlyVisitor} from './gather-mem-only-visitor.ts';
 
 type FormatVersion = Enum<typeof FormatVersion>;
 
diff --git a/packages/replicache/src/persist/gather-mem-only-visitor.ts b/packages/replicache/src/persist/gather-mem-only-visitor.ts
index fbd5f75efa..de23db8d0d 100644
--- a/packages/replicache/src/persist/gather-mem-only-visitor.ts
+++ b/packages/replicache/src/persist/gather-mem-only-visitor.ts
@@ -1,8 +1,8 @@
-import {promiseVoid} from '../../../shared/src/resolved-promises.js';
-import type {Chunk} from '../dag/chunk.js';
-import type {LazyRead} from '../dag/lazy-store.js';
-import {Visitor} from '../dag/visitor.js';
-import type {Hash} from '../hash.js';
+import {promiseVoid} from '../../../shared/src/resolved-promises.ts';
+import type {Chunk} from '../dag/chunk.ts';
+import type {LazyRead} from '../dag/lazy-store.ts';
+import {Visitor} from '../dag/visitor.ts';
+import type {Hash} from '../hash.ts';
 
 export class GatherMemoryOnlyVisitor extends Visitor {
   readonly #gatheredChunks: Map<Hash, Chunk> = new Map();
diff --git a/packages/replicache/src/persist/gather-not-cached-visitor.test.ts b/packages/replicache/src/persist/gather-not-cached-visitor.test.ts
index 6e4deefcb9..59e3c2d5ae 100644
--- a/packages/replicache/src/persist/gather-not-cached-visitor.test.ts
+++ b/packages/replicache/src/persist/gather-not-cached-visitor.test.ts
@@ -1,11 +1,11 @@
 import {describe, expect, test} from 'vitest';
-import {LazyStore} from '../dag/lazy-store.js';
-import {TestStore} from '../dag/test-store.js';
-import * as MetaType from '../db/meta-type-enum.js';
-import {ChainBuilder} from '../db/test-helpers.js';
-import {assertHash, fakeHash, makeNewFakeHashFunction} from '../hash.js';
-import {withRead, withWriteNoImplicitCommit} from '../with-transactions.js';
-import {GatherNotCachedVisitor} from './gather-not-cached-visitor.js';
+import {LazyStore} from '../dag/lazy-store.ts';
+import {TestStore} from '../dag/test-store.ts';
+import * as MetaType from '../db/meta-type-enum.ts';
+import {ChainBuilder} from '../db/test-helpers.ts';
+import {assertHash, fakeHash, makeNewFakeHashFunction} from '../hash.ts';
+import {withRead, withWriteNoImplicitCommit} from '../with-transactions.ts';
+import {GatherNotCachedVisitor} from './gather-not-cached-visitor.ts';
 
 describe('GatherNotCachedVisitor', () => {
   test('when gatherSizeLimit not exceeded, if none cached gathers all, if all cached gathers none', async () => {
diff --git a/packages/replicache/src/persist/gather-not-cached-visitor.ts b/packages/replicache/src/persist/gather-not-cached-visitor.ts
index 7e8061bdb7..a99e5aa7a0 100644
--- a/packages/replicache/src/persist/gather-not-cached-visitor.ts
+++ b/packages/replicache/src/persist/gather-not-cached-visitor.ts
@@ -1,10 +1,10 @@
-import {promiseVoid} from '../../../shared/src/resolved-promises.js';
-import type {Chunk} from '../dag/chunk.js';
-import type {LazyStore} from '../dag/lazy-store.js';
-import type {Read} from '../dag/store.js';
-import {Visitor} from '../dag/visitor.js';
-import type {Hash} from '../hash.js';
-import {getSizeOfValue} from '../size-of-value.js';
+import {promiseVoid} from '../../../shared/src/resolved-promises.ts';
+import type {Chunk} from '../dag/chunk.ts';
+import type {LazyStore} from '../dag/lazy-store.ts';
+import type {Read} from '../dag/store.ts';
+import {Visitor} from '../dag/visitor.ts';
+import type {Hash} from '../hash.ts';
+import {getSizeOfValue} from '../size-of-value.ts';
 
 export type ChunkWithSize = {chunk: Chunk; size: number};
 
diff --git a/packages/replicache/src/persist/heartbeat.test.ts b/packages/replicache/src/persist/heartbeat.test.ts
index ea19af2196..a340ce803c 100644
--- a/packages/replicache/src/persist/heartbeat.test.ts
+++ b/packages/replicache/src/persist/heartbeat.test.ts
@@ -3,26 +3,26 @@ import {resolver} from '@rocicorp/resolver';
 import * as sinon from 'sinon';
 import {type SinonFakeTimers, useFakeTimers} from 'sinon';
 import {afterEach, beforeEach, expect, test} from 'vitest';
-import {assert, assertNotUndefined} from '../../../shared/src/asserts.js';
-import {StoreImpl} from '../dag/store-impl.js';
-import type {Read} from '../dag/store.js';
-import {TestStore} from '../dag/test-store.js';
-import {assertHash, fakeHash, newRandomHash} from '../hash.js';
-import {dropIDBStoreWithMemFallback} from '../kv/idb-store-with-mem-fallback.js';
-import {IDBNotFoundError, IDBStore} from '../kv/idb-store.js';
-import {withRead} from '../with-transactions.js';
-import {makeClientV5, setClientsForTesting} from './clients-test-helpers.js';
+import {assert, assertNotUndefined} from '../../../shared/src/asserts.ts';
+import {StoreImpl} from '../dag/store-impl.ts';
+import type {Read} from '../dag/store.ts';
+import {TestStore} from '../dag/test-store.ts';
+import {assertHash, fakeHash, newRandomHash} from '../hash.ts';
+import {dropIDBStoreWithMemFallback} from '../kv/idb-store-with-mem-fallback.ts';
+import {IDBNotFoundError, IDBStore} from '../kv/idb-store.ts';
+import {withRead} from '../with-transactions.ts';
+import {makeClientV5, setClientsForTesting} from './clients-test-helpers.ts';
 import {
   type ClientMap,
   ClientStateNotFoundError,
   getClients,
-} from './clients.js';
+} from './clients.ts';
 import {
   HEARTBEAT_INTERVAL,
   latestHeartbeatUpdate,
   startHeartbeats,
   writeHeartbeat,
-} from './heartbeat.js';
+} from './heartbeat.ts';
 
 let clock: SinonFakeTimers;
 const START_TIME = 100000;
diff --git a/packages/replicache/src/persist/heartbeat.ts b/packages/replicache/src/persist/heartbeat.ts
index 1e127a535f..d5011516a7 100644
--- a/packages/replicache/src/persist/heartbeat.ts
+++ b/packages/replicache/src/persist/heartbeat.ts
@@ -1,14 +1,14 @@
 import type {LogContext} from '@rocicorp/logger';
-import {initBgIntervalProcess} from '../bg-interval.js';
-import type {Store} from '../dag/store.js';
-import type {ClientID} from '../sync/ids.js';
-import {withWrite} from '../with-transactions.js';
+import {initBgIntervalProcess} from '../bg-interval.ts';
+import type {Store} from '../dag/store.ts';
+import type {ClientID} from '../sync/ids.ts';
+import {withWrite} from '../with-transactions.ts';
 import {
   type ClientMap,
   ClientStateNotFoundError,
   getClients,
   setClients,
-} from './clients.js';
+} from './clients.ts';
 
 export const HEARTBEAT_INTERVAL = 60 * 1000;
 
diff --git a/packages/replicache/src/persist/idb-databases-store-db-name.ts b/packages/replicache/src/persist/idb-databases-store-db-name.ts
index a3900f6fb8..19872e7c99 100644
--- a/packages/replicache/src/persist/idb-databases-store-db-name.ts
+++ b/packages/replicache/src/persist/idb-databases-store-db-name.ts
@@ -1,5 +1,5 @@
-import {randomUint64} from '../../../shared/src/random-uint64.js';
-import {dropIDBStoreWithMemFallback} from '../kv/idb-store-with-mem-fallback.js';
+import {randomUint64} from '../../../shared/src/random-uint64.ts';
+import {dropIDBStoreWithMemFallback} from '../kv/idb-store-with-mem-fallback.ts';
 
 const IDB_DATABASES_VERSION = 0;
 const IDB_DATABASES_DB_NAME = 'replicache-dbs-v' + IDB_DATABASES_VERSION;
diff --git a/packages/replicache/src/persist/idb-databases-store.test.ts b/packages/replicache/src/persist/idb-databases-store.test.ts
index 8e35f2a921..d71067ff62 100644
--- a/packages/replicache/src/persist/idb-databases-store.test.ts
+++ b/packages/replicache/src/persist/idb-databases-store.test.ts
@@ -1,10 +1,10 @@
 import * as sinon from 'sinon';
 import {afterEach, expect, test} from 'vitest';
-import {TestMemStore} from '../kv/test-mem-store.js';
+import {TestMemStore} from '../kv/test-mem-store.ts';
 import {
   IDBDatabasesStore,
   type IndexedDBDatabase,
-} from './idb-databases-store.js';
+} from './idb-databases-store.ts';
 
 afterEach(() => {
   sinon.restore();
diff --git a/packages/replicache/src/persist/idb-databases-store.ts b/packages/replicache/src/persist/idb-databases-store.ts
index 74a0e4a8fa..2ab06c6f50 100644
--- a/packages/replicache/src/persist/idb-databases-store.ts
+++ b/packages/replicache/src/persist/idb-databases-store.ts
@@ -3,12 +3,12 @@ import {
   assertNumber,
   assertObject,
   assertString,
-} from '../../../shared/src/asserts.js';
-import {deepFreeze} from '../frozen-json.js';
-import type {CreateStore, Read, Store} from '../kv/store.js';
-import {withRead, withWrite} from '../with-transactions.js';
-import {getIDBDatabasesDBName} from './idb-databases-store-db-name.js';
-import {makeClientID} from './make-client-id.js';
+} from '../../../shared/src/asserts.ts';
+import {deepFreeze} from '../frozen-json.ts';
+import type {CreateStore, Read, Store} from '../kv/store.ts';
+import {withRead, withWrite} from '../with-transactions.ts';
+import {getIDBDatabasesDBName} from './idb-databases-store-db-name.ts';
+import {makeClientID} from './make-client-id.ts';
 
 const DBS_KEY = 'dbs';
 const PROFILE_ID_KEY = 'profileId';
diff --git a/packages/replicache/src/persist/make-client-id.ts b/packages/replicache/src/persist/make-client-id.ts
index 221148a050..3e91bfb4a4 100644
--- a/packages/replicache/src/persist/make-client-id.ts
+++ b/packages/replicache/src/persist/make-client-id.ts
@@ -1,4 +1,4 @@
-import {randomUint64} from '../../../shared/src/random-uint64.js';
+import {randomUint64} from '../../../shared/src/random-uint64.ts';
 
 /**
  * Returns a random 18 character string encoded in base32 suitable as a client
diff --git a/packages/replicache/src/persist/persist.test.ts b/packages/replicache/src/persist/persist.test.ts
index 56197bf19e..063dcb49e3 100644
--- a/packages/replicache/src/persist/persist.test.ts
+++ b/packages/replicache/src/persist/persist.test.ts
@@ -5,13 +5,13 @@ import {
   assert,
   assertNotNull,
   assertNotUndefined,
-} from '../../../shared/src/asserts.js';
-import type {Enum} from '../../../shared/src/enum.js';
-import type {JSONValue} from '../../../shared/src/json.js';
-import {promiseVoid} from '../../../shared/src/resolved-promises.js';
-import {BTreeRead} from '../btree/read.js';
-import {LazyStore, LazyWrite} from '../dag/lazy-store.js';
-import {TestStore} from '../dag/test-store.js';
+} from '../../../shared/src/asserts.ts';
+import type {Enum} from '../../../shared/src/enum.ts';
+import type {JSONValue} from '../../../shared/src/json.ts';
+import {promiseVoid} from '../../../shared/src/resolved-promises.ts';
+import {BTreeRead} from '../btree/read.ts';
+import {LazyStore, LazyWrite} from '../dag/lazy-store.ts';
+import {TestStore} from '../dag/test-store.ts';
 import {
   Commit,
   DEFAULT_HEAD_NAME,
@@ -20,24 +20,24 @@ import {
   assertSnapshotCommitDD31,
   baseSnapshotFromHash,
   commitFromHash,
-} from '../db/commit.js';
+} from '../db/commit.ts';
 import {
   ChainBuilder,
   createMutatorName,
   getChunkSnapshot,
-} from '../db/test-helpers.js';
-import * as FormatVersion from '../format-version-enum.js';
-import {type Hash, assertHash, makeNewFakeHashFunction} from '../hash.js';
-import type {ClientGroupID, ClientID} from '../sync/ids.js';
-import type {WriteTransaction} from '../transactions.js';
-import type {MutatorDefs} from '../types.js';
-import {withRead, withWriteNoImplicitCommit} from '../with-transactions.js';
+} from '../db/test-helpers.ts';
+import * as FormatVersion from '../format-version-enum.ts';
+import {type Hash, assertHash, makeNewFakeHashFunction} from '../hash.ts';
+import type {ClientGroupID, ClientID} from '../sync/ids.ts';
+import type {WriteTransaction} from '../transactions.ts';
+import type {MutatorDefs} from '../types.ts';
+import {withRead, withWriteNoImplicitCommit} from '../with-transactions.ts';
 import {
   CLIENT_GROUPS_HEAD_NAME,
   type ClientGroup,
   getClientGroup,
   setClientGroup,
-} from './client-groups.js';
+} from './client-groups.ts';
 import {
   CLIENTS_HEAD_NAME,
   type Client,
@@ -48,10 +48,10 @@ import {
   getClients,
   initClientV6,
   setClients,
-} from './clients.js';
-import {makeClientID} from './make-client-id.js';
-import {persistDD31} from './persist.js';
-import * as PersistedExpectation from './persisted-expectation-enum.js';
+} from './clients.ts';
+import {makeClientID} from './make-client-id.ts';
+import {persistDD31} from './persist.ts';
+import * as PersistedExpectation from './persisted-expectation-enum.ts';
 
 type FormatVersion = Enum<typeof FormatVersion>;
 type PersistedExpectation = Enum<typeof PersistedExpectation>;
diff --git a/packages/replicache/src/persist/persist.ts b/packages/replicache/src/persist/persist.ts
index 9279a80bfb..7220fe7682 100644
--- a/packages/replicache/src/persist/persist.ts
+++ b/packages/replicache/src/persist/persist.ts
@@ -1,9 +1,9 @@
 import type {LogContext} from '@rocicorp/logger';
-import {assert} from '../../../shared/src/asserts.js';
-import type {Enum} from '../../../shared/src/enum.js';
-import type {Chunk} from '../dag/chunk.js';
-import type {LazyStore} from '../dag/lazy-store.js';
-import type {Read, Store, Write} from '../dag/store.js';
+import {assert} from '../../../shared/src/asserts.ts';
+import type {Enum} from '../../../shared/src/enum.ts';
+import type {Chunk} from '../dag/chunk.ts';
+import type {LazyStore} from '../dag/lazy-store.ts';
+import type {Read, Store, Write} from '../dag/store.ts';
 import {
   Commit,
   DEFAULT_HEAD_NAME,
@@ -16,26 +16,26 @@ import {
   compareCookiesForSnapshots,
   localMutationsDD31,
   localMutationsGreaterThan,
-} from '../db/commit.js';
-import {rebaseMutationAndPutCommit} from '../db/rebase.js';
-import * as FormatVersion from '../format-version-enum.js';
-import type {Hash} from '../hash.js';
-import type {ClientGroupID, ClientID} from '../sync/ids.js';
-import type {MutatorDefs} from '../types.js';
-import {withRead, withWrite} from '../with-transactions.js';
+} from '../db/commit.ts';
+import {rebaseMutationAndPutCommit} from '../db/rebase.ts';
+import * as FormatVersion from '../format-version-enum.ts';
+import type {Hash} from '../hash.ts';
+import type {ClientGroupID, ClientID} from '../sync/ids.ts';
+import type {MutatorDefs} from '../types.ts';
+import {withRead, withWrite} from '../with-transactions.ts';
 import {
   type ClientGroup,
   getClientGroup,
   setClientGroup,
-} from './client-groups.js';
+} from './client-groups.ts';
 import {
   assertClientV6,
   assertHasClientState,
   getClientGroupIDForClient,
   mustGetClient,
   setClient,
-} from './clients.js';
-import {GatherMemoryOnlyVisitor} from './gather-mem-only-visitor.js';
+} from './clients.ts';
+import {GatherMemoryOnlyVisitor} from './gather-mem-only-visitor.ts';
 
 type FormatVersion = Enum<typeof FormatVersion>;
 
diff --git a/packages/replicache/src/persist/refresh.test.ts b/packages/replicache/src/persist/refresh.test.ts
index 6287f65052..6b2edfb5ca 100644
--- a/packages/replicache/src/persist/refresh.test.ts
+++ b/packages/replicache/src/persist/refresh.test.ts
@@ -1,13 +1,13 @@
 import {LogContext} from '@rocicorp/logger';
 import {describe, expect, test} from 'vitest';
-import {assert, assertNotUndefined} from '../../../shared/src/asserts.js';
-import type {JSONValue, ReadonlyJSONValue} from '../../../shared/src/json.js';
-import type {Entry} from '../btree/node.js';
-import {BTreeWrite} from '../btree/write.js';
-import type {Cookie} from '../cookies.js';
-import {LazyStore} from '../dag/lazy-store.js';
-import type {Store} from '../dag/store.js';
-import {TestStore} from '../dag/test-store.js';
+import {assert, assertNotUndefined} from '../../../shared/src/asserts.ts';
+import type {JSONValue, ReadonlyJSONValue} from '../../../shared/src/json.ts';
+import type {Entry} from '../btree/node.ts';
+import {BTreeWrite} from '../btree/write.ts';
+import type {Cookie} from '../cookies.ts';
+import {LazyStore} from '../dag/lazy-store.ts';
+import type {Store} from '../dag/store.ts';
+import {TestStore} from '../dag/test-store.ts';
 import {
   Commit,
   DEFAULT_HEAD_NAME,
@@ -17,33 +17,33 @@ import {
   baseSnapshotHashFromHash,
   newLocalDD31,
   newSnapshotDD31,
-} from '../db/commit.js';
-import {ChainBuilder} from '../db/test-helpers.js';
-import * as FormatVersion from '../format-version-enum.js';
-import {deepFreeze} from '../frozen-json.js';
+} from '../db/commit.ts';
+import {ChainBuilder} from '../db/test-helpers.ts';
+import * as FormatVersion from '../format-version-enum.ts';
+import {deepFreeze} from '../frozen-json.ts';
 import {
   type Hash,
   assertHash,
   fakeHash,
   makeNewFakeHashFunction,
-} from '../hash.js';
+} from '../hash.ts';
 import {
   type ClientGroupMap,
   setClientGroup,
   setClientGroups,
-} from '../persist/client-groups.js';
+} from '../persist/client-groups.ts';
 import {
   type ClientV6,
   assertClientV6,
   getClient,
   setClient,
-} from '../persist/clients.js';
-import type {ClientID} from '../sync/ids.js';
-import {addData, testSubscriptionsManagerOptions} from '../test-util.js';
-import type {WriteTransaction} from '../transactions.js';
-import type {MutatorDefs} from '../types.js';
-import {withRead, withWriteNoImplicitCommit} from '../with-transactions.js';
-import {refresh} from './refresh.js';
+} from '../persist/clients.ts';
+import type {ClientID} from '../sync/ids.ts';
+import {addData, testSubscriptionsManagerOptions} from '../test-util.ts';
+import type {WriteTransaction} from '../transactions.ts';
+import type {MutatorDefs} from '../types.ts';
+import {withRead, withWriteNoImplicitCommit} from '../with-transactions.ts';
+import {refresh} from './refresh.ts';
 
 async function makeChain(
   store: Store,
diff --git a/packages/replicache/src/persist/refresh.ts b/packages/replicache/src/persist/refresh.ts
index 8780336e5d..3e93cbc0f7 100644
--- a/packages/replicache/src/persist/refresh.ts
+++ b/packages/replicache/src/persist/refresh.ts
@@ -1,8 +1,8 @@
 import type {LogContext} from '@rocicorp/logger';
-import type {Enum} from '../../../shared/src/enum.js';
-import {sleep} from '../../../shared/src/sleep.js';
-import type {LazyStore} from '../dag/lazy-store.js';
-import type {Store} from '../dag/store.js';
+import type {Enum} from '../../../shared/src/enum.ts';
+import {sleep} from '../../../shared/src/sleep.ts';
+import type {LazyStore} from '../dag/lazy-store.ts';
+import type {Store} from '../dag/store.ts';
 import {
   Commit,
   DEFAULT_HEAD_NAME,
@@ -15,18 +15,18 @@ import {
   commitFromHead,
   compareCookiesForSnapshots,
   localMutationsGreaterThan,
-} from '../db/commit.js';
-import {rebaseMutationAndPutCommit} from '../db/rebase.js';
-import * as FormatVersion from '../format-version-enum.js';
-import type {Hash} from '../hash.js';
+} from '../db/commit.ts';
+import {rebaseMutationAndPutCommit} from '../db/rebase.ts';
+import * as FormatVersion from '../format-version-enum.ts';
+import type {Hash} from '../hash.ts';
 import {
   type DiffComputationConfig,
   DiffsMap,
   diffCommits,
-} from '../sync/diff.js';
-import type {ClientID} from '../sync/ids.js';
-import type {MutatorDefs} from '../types.js';
-import {withRead, withWrite} from '../with-transactions.js';
+} from '../sync/diff.ts';
+import type {ClientID} from '../sync/ids.ts';
+import type {MutatorDefs} from '../types.ts';
+import {withRead, withWrite} from '../with-transactions.ts';
 import {
   ClientStateNotFoundError,
   type ClientV6,
@@ -34,11 +34,11 @@ import {
   getClientGroupForClient,
   mustGetClient,
   setClient,
-} from './clients.js';
+} from './clients.ts';
 import {
   type ChunkWithSize,
   GatherNotCachedVisitor,
-} from './gather-not-cached-visitor.js';
+} from './gather-not-cached-visitor.ts';
 
 type FormatVersion = Enum<typeof FormatVersion>;
 
diff --git a/packages/replicache/src/process-scheduler.test.ts b/packages/replicache/src/process-scheduler.test.ts
index 33d2a1204a..0ed0acb1d4 100644
--- a/packages/replicache/src/process-scheduler.test.ts
+++ b/packages/replicache/src/process-scheduler.test.ts
@@ -1,9 +1,9 @@
 import {resolver, type Resolver} from '@rocicorp/resolver';
 import sinon, {type SinonFakeTimers, useFakeTimers} from 'sinon';
 import {afterEach, beforeEach, describe, expect, test} from 'vitest';
-import {AbortError} from '../../shared/src/abort-error.js';
-import {ProcessScheduler} from './process-scheduler.js';
-import {expectPromiseToReject} from './test-util.js';
+import {AbortError} from '../../shared/src/abort-error.ts';
+import {ProcessScheduler} from './process-scheduler.ts';
+import {expectPromiseToReject} from './test-util.ts';
 
 describe('ProcessScheduler', () => {
   let clock: SinonFakeTimers;
diff --git a/packages/replicache/src/process-scheduler.ts b/packages/replicache/src/process-scheduler.ts
index 589b7b7709..ebe61d4f30 100644
--- a/packages/replicache/src/process-scheduler.ts
+++ b/packages/replicache/src/process-scheduler.ts
@@ -1,8 +1,8 @@
 import {type Resolver, resolver} from '@rocicorp/resolver';
-import {AbortError} from '../../shared/src/abort-error.js';
-import {assert} from '../../shared/src/asserts.js';
-import {sleep} from '../../shared/src/sleep.js';
-import {requestIdle as defaultRequestIdle} from './request-idle.js';
+import {AbortError} from '../../shared/src/abort-error.ts';
+import {assert} from '../../shared/src/asserts.ts';
+import {sleep} from '../../shared/src/sleep.ts';
+import {requestIdle as defaultRequestIdle} from './request-idle.ts';
 
 export class ProcessScheduler {
   readonly #process: () => Promise<void>;
diff --git a/packages/replicache/src/puller.ts b/packages/replicache/src/puller.ts
index 9e3cc9b8d5..d23d5fa6ab 100644
--- a/packages/replicache/src/puller.ts
+++ b/packages/replicache/src/puller.ts
@@ -1,15 +1,15 @@
-import type {Cookie} from './cookies.js';
+import type {Cookie} from './cookies.ts';
 import type {
   ClientStateNotFoundResponse,
   VersionNotSupportedResponse,
-} from './error-responses.js';
-import type {HTTPRequestInfo} from './http-request-info.js';
+} from './error-responses.ts';
+import type {HTTPRequestInfo} from './http-request-info.ts';
 import type {
   PatchOperation,
   PatchOperationInternal,
-} from './patch-operation.js';
-import type {ClientID} from './sync/ids.js';
-import type {PullRequest} from './sync/pull.js';
+} from './patch-operation.ts';
+import type {ClientID} from './sync/ids.ts';
+import type {PullRequest} from './sync/pull.ts';
 
 // TODO(arv): Does it really make sense to call this httpRequestInfo? It is
 // really the response status code and error message!
diff --git a/packages/replicache/src/pusher.ts b/packages/replicache/src/pusher.ts
index 837b1866fa..ef1dd5e7af 100644
--- a/packages/replicache/src/pusher.ts
+++ b/packages/replicache/src/pusher.ts
@@ -1,15 +1,15 @@
-import {assertObject} from '../../shared/src/asserts.js';
+import {assertObject} from '../../shared/src/asserts.ts';
 import {
   assertVersionNotSupportedResponse,
   type ClientStateNotFoundResponse,
   isClientStateNotFoundResponse,
   type VersionNotSupportedResponse,
-} from './error-responses.js';
+} from './error-responses.ts';
 import {
   assertHTTPRequestInfo,
   type HTTPRequestInfo,
-} from './http-request-info.js';
-import type {PushRequest} from './sync/push.js';
+} from './http-request-info.ts';
+import type {PushRequest} from './sync/push.ts';
 
 export type PusherResult = {
   response?: PushResponse | undefined;
diff --git a/packages/replicache/src/replicache-collect-idb-databases.test.ts b/packages/replicache/src/replicache-collect-idb-databases.test.ts
index d03aa272fd..ae1ed59849 100644
--- a/packages/replicache/src/replicache-collect-idb-databases.test.ts
+++ b/packages/replicache/src/replicache-collect-idb-databases.test.ts
@@ -1,10 +1,10 @@
 import {expect, test} from 'vitest';
-import {sleep} from '../../shared/src/sleep.js';
+import {sleep} from '../../shared/src/sleep.ts';
 import {
   clock,
   initReplicacheTesting,
   replicacheForTesting,
-} from './test-util.js';
+} from './test-util.ts';
 
 initReplicacheTesting();
 
diff --git a/packages/replicache/src/replicache-impl.ts b/packages/replicache/src/replicache-impl.ts
index 14db876bcb..d030de07f5 100644
--- a/packages/replicache/src/replicache-impl.ts
+++ b/packages/replicache/src/replicache-impl.ts
@@ -1,89 +1,89 @@
 import {Lock} from '@rocicorp/lock';
 import {consoleLogSink, LogContext} from '@rocicorp/logger';
 import {resolver} from '@rocicorp/resolver';
-import {AbortError} from '../../shared/src/abort-error.js';
-import {assert} from '../../shared/src/asserts.js';
-import {getBrowserGlobal} from '../../shared/src/browser-env.js';
-import {getDocumentVisibilityWatcher} from '../../shared/src/document-visible.js';
-import type {JSONValue, ReadonlyJSONValue} from '../../shared/src/json.js';
-import type {MaybePromise} from '../../shared/src/types.js';
-import {PullDelegate, PushDelegate} from './connection-loop-delegates.js';
-import {ConnectionLoop, MAX_DELAY_MS, MIN_DELAY_MS} from './connection-loop.js';
-import {assertCookie, type Cookie} from './cookies.js';
-import {LazyStore} from './dag/lazy-store.js';
-import {StoreImpl} from './dag/store-impl.js';
-import {ChunkNotFoundError, mustGetHeadHash, type Store} from './dag/store.js';
+import {AbortError} from '../../shared/src/abort-error.ts';
+import {assert} from '../../shared/src/asserts.ts';
+import {getBrowserGlobal} from '../../shared/src/browser-env.ts';
+import {getDocumentVisibilityWatcher} from '../../shared/src/document-visible.ts';
+import type {JSONValue, ReadonlyJSONValue} from '../../shared/src/json.ts';
+import type {MaybePromise} from '../../shared/src/types.ts';
+import {PullDelegate, PushDelegate} from './connection-loop-delegates.ts';
+import {ConnectionLoop, MAX_DELAY_MS, MIN_DELAY_MS} from './connection-loop.ts';
+import {assertCookie, type Cookie} from './cookies.ts';
+import {LazyStore} from './dag/lazy-store.ts';
+import {StoreImpl} from './dag/store-impl.ts';
+import {ChunkNotFoundError, mustGetHeadHash, type Store} from './dag/store.ts';
 import {
   baseSnapshotFromHash,
   DEFAULT_HEAD_NAME,
   isLocalMetaDD31,
   type LocalMeta,
-} from './db/commit.js';
-import {readFromDefaultHead} from './db/read.js';
-import {rebaseMutationAndCommit} from './db/rebase.js';
-import {newWriteLocal} from './db/write.js';
+} from './db/commit.ts';
+import {readFromDefaultHead} from './db/read.ts';
+import {rebaseMutationAndCommit} from './db/rebase.ts';
+import {newWriteLocal} from './db/write.ts';
 import {
   isClientStateNotFoundResponse,
   isVersionNotSupportedResponse,
   type VersionNotSupportedResponse,
-} from './error-responses.js';
-import * as FormatVersion from './format-version-enum.js';
-import {deepFreeze} from './frozen-json.js';
-import {getDefaultPuller, isDefaultPuller} from './get-default-puller.js';
-import {getDefaultPusher, isDefaultPusher} from './get-default-pusher.js';
-import {assertHash, emptyHash, type Hash, newRandomHash} from './hash.js';
-import type {HTTPRequestInfo} from './http-request-info.js';
-import type {IndexDefinitions} from './index-defs.js';
-import type {StoreProvider} from './kv/store.js';
-import {createLogContext} from './log-options.js';
-import {MutationRecovery} from './mutation-recovery.js';
-import {initNewClientChannel} from './new-client-channel.js';
+} from './error-responses.ts';
+import * as FormatVersion from './format-version-enum.ts';
+import {deepFreeze} from './frozen-json.ts';
+import {getDefaultPuller, isDefaultPuller} from './get-default-puller.ts';
+import {getDefaultPusher, isDefaultPusher} from './get-default-pusher.ts';
+import {assertHash, emptyHash, type Hash, newRandomHash} from './hash.ts';
+import type {HTTPRequestInfo} from './http-request-info.ts';
+import type {IndexDefinitions} from './index-defs.ts';
+import type {StoreProvider} from './kv/store.ts';
+import {createLogContext} from './log-options.ts';
+import {MutationRecovery} from './mutation-recovery.ts';
+import {initNewClientChannel} from './new-client-channel.ts';
 import {
   initOnPersistChannel,
   type OnPersist,
   type PersistInfo,
-} from './on-persist-channel.js';
+} from './on-persist-channel.ts';
 import {
   type PendingMutation,
   pendingMutationsForAPI,
-} from './pending-mutations.js';
+} from './pending-mutations.ts';
 import {
   CLIENT_MAX_INACTIVE_TIME,
   GC_INTERVAL,
   initClientGC,
-} from './persist/client-gc.js';
-import {initClientGroupGC} from './persist/client-group-gc.js';
-import {disableClientGroup} from './persist/client-groups.js';
+} from './persist/client-gc.ts';
+import {initClientGroupGC} from './persist/client-group-gc.ts';
+import {disableClientGroup} from './persist/client-groups.ts';
 import {
   ClientStateNotFoundError,
   initClientV6,
   hasClientState as persistHasClientState,
-} from './persist/clients.js';
+} from './persist/clients.ts';
 import {
   COLLECT_IDB_INTERVAL,
   initCollectIDBDatabases,
   INITIAL_COLLECT_IDB_DELAY,
   SDD_IDB_MAX_AGE,
-} from './persist/collect-idb-databases.js';
-import {HEARTBEAT_INTERVAL, startHeartbeats} from './persist/heartbeat.js';
+} from './persist/collect-idb-databases.ts';
+import {HEARTBEAT_INTERVAL, startHeartbeats} from './persist/heartbeat.ts';
 import {
   IDBDatabasesStore,
   type IndexedDBDatabase,
-} from './persist/idb-databases-store.js';
-import {makeClientID} from './persist/make-client-id.js';
-import {persistDD31} from './persist/persist.js';
-import {refresh} from './persist/refresh.js';
-import {ProcessScheduler} from './process-scheduler.js';
-import type {Puller} from './puller.js';
-import {type Pusher, PushError} from './pusher.js';
-import type {ReplicacheOptions} from './replicache-options.js';
+} from './persist/idb-databases-store.ts';
+import {makeClientID} from './persist/make-client-id.ts';
+import {persistDD31} from './persist/persist.ts';
+import {refresh} from './persist/refresh.ts';
+import {ProcessScheduler} from './process-scheduler.ts';
+import type {Puller} from './puller.ts';
+import {type Pusher, PushError} from './pusher.ts';
+import type {ReplicacheOptions} from './replicache-options.ts';
 import {
   getKVStoreProvider,
   httpStatusUnauthorized,
   makeIDBName,
   ReportError,
-} from './replicache.js';
-import {setIntervalWithSignal} from './set-interval-with-signal.js';
+} from './replicache.ts';
+import {setIntervalWithSignal} from './set-interval-with-signal.ts';
 import {
   type SubscribeOptions,
   SubscriptionImpl,
@@ -94,17 +94,17 @@ import {
   type WatchNoIndexCallback,
   type WatchOptions,
   WatchSubscription,
-} from './subscriptions.js';
-import * as HandlePullResponseResultEnum from './sync/handle-pull-response-result-type-enum.js';
-import type {ClientGroupID, ClientID} from './sync/ids.js';
-import {PullError} from './sync/pull-error.js';
-import {beginPullV1, handlePullResponseV1, maybeEndPull} from './sync/pull.js';
-import {push, PUSH_VERSION_DD31} from './sync/push.js';
-import {newRequestID} from './sync/request-id.js';
-import {SYNC_HEAD_NAME} from './sync/sync-head-name.js';
-import {throwIfClosed} from './transaction-closed-error.js';
-import type {ReadTransaction, WriteTransaction} from './transactions.js';
-import {ReadTransactionImpl, WriteTransactionImpl} from './transactions.js';
+} from './subscriptions.ts';
+import * as HandlePullResponseResultEnum from './sync/handle-pull-response-result-type-enum.ts';
+import type {ClientGroupID, ClientID} from './sync/ids.ts';
+import {PullError} from './sync/pull-error.ts';
+import {beginPullV1, handlePullResponseV1, maybeEndPull} from './sync/pull.ts';
+import {push, PUSH_VERSION_DD31} from './sync/push.ts';
+import {newRequestID} from './sync/request-id.ts';
+import {SYNC_HEAD_NAME} from './sync/sync-head-name.ts';
+import {throwIfClosed} from './transaction-closed-error.ts';
+import type {ReadTransaction, WriteTransaction} from './transactions.ts';
+import {ReadTransactionImpl, WriteTransactionImpl} from './transactions.ts';
 import type {
   BeginPullResult,
   MakeMutator,
@@ -115,13 +115,13 @@ import type {
   QueryInternal,
   RequestOptions,
   UpdateNeededReason,
-} from './types.js';
-import {version} from './version.js';
+} from './types.ts';
+import {version} from './version.ts';
 import {
   withRead,
   withWrite,
   withWriteNoImplicitCommit,
-} from './with-transactions.js';
+} from './with-transactions.ts';
 
 declare const TESTING: boolean;
 
diff --git a/packages/replicache/src/replicache-mutation-recovery-dd31.test.ts b/packages/replicache/src/replicache-mutation-recovery-dd31.test.ts
index e573b08b3b..5f0f922808 100644
--- a/packages/replicache/src/replicache-mutation-recovery-dd31.test.ts
+++ b/packages/replicache/src/replicache-mutation-recovery-dd31.test.ts
@@ -1,41 +1,41 @@
 import sinon from 'sinon';
 import {describe, expect, test} from 'vitest';
-import {assert} from '../../shared/src/asserts.js';
-import type {Enum} from '../../shared/src/enum.js';
-import {type JSONObject, assertJSONObject} from '../../shared/src/json.js';
-import {randomUint64} from '../../shared/src/random-uint64.js';
-import {LazyStore} from './dag/lazy-store.js';
-import {StoreImpl} from './dag/store-impl.js';
-import * as FormatVersion from './format-version-enum.js';
+import {assert} from '../../shared/src/asserts.ts';
+import type {Enum} from '../../shared/src/enum.ts';
+import {type JSONObject, assertJSONObject} from '../../shared/src/json.ts';
+import {randomUint64} from '../../shared/src/random-uint64.ts';
+import {LazyStore} from './dag/lazy-store.ts';
+import {StoreImpl} from './dag/store-impl.ts';
+import * as FormatVersion from './format-version-enum.ts';
 import {
   createAndPersistClientWithPendingLocalDD31,
   createPerdag,
   createPushRequestBodyDD31,
   persistSnapshotDD31,
-} from './mutation-recovery-test-helper.js';
+} from './mutation-recovery-test-helper.ts';
 import {
   disableClientGroup,
   getClientGroup,
   getClientGroups,
-} from './persist/client-groups.js';
-import {assertClientV6, getClient, getClients} from './persist/clients.js';
-import type {PullResponseV1} from './puller.js';
-import type {PushResponse} from './pusher.js';
-import type {ClientID} from './sync/ids.js';
-import {PULL_VERSION_DD31, type PullRequestV1} from './sync/pull.js';
+} from './persist/client-groups.ts';
+import {assertClientV6, getClient, getClients} from './persist/clients.ts';
+import type {PullResponseV1} from './puller.ts';
+import type {PushResponse} from './pusher.ts';
+import type {ClientID} from './sync/ids.ts';
+import {PULL_VERSION_DD31, type PullRequestV1} from './sync/pull.ts';
 import {
   PUSH_VERSION_DD31,
   type PushRequestV1,
   assertPushRequestV1,
-} from './sync/push.js';
+} from './sync/push.ts';
 import {
   clock,
   disableAllBackgroundProcesses,
   initReplicacheTesting,
   replicacheForTesting,
   tickAFewTimes,
-} from './test-util.js';
-import {withRead, withWriteNoImplicitCommit} from './with-transactions.js';
+} from './test-util.ts';
+import {withRead, withWriteNoImplicitCommit} from './with-transactions.ts';
 
 // fetch-mock has invalid d.ts file so we removed that on npm install.
 // eslint-disable-next-line @typescript-eslint/ban-ts-comment
diff --git a/packages/replicache/src/replicache-on-update-needed.test.ts b/packages/replicache/src/replicache-on-update-needed.test.ts
index f6ff72382e..d9d78937d5 100644
--- a/packages/replicache/src/replicache-on-update-needed.test.ts
+++ b/packages/replicache/src/replicache-on-update-needed.test.ts
@@ -3,7 +3,7 @@ import {
   initReplicacheTesting,
   replicacheForTesting,
   tickAFewTimes,
-} from './test-util.js';
+} from './test-util.ts';
 
 initReplicacheTesting();
 
diff --git a/packages/replicache/src/replicache-options.ts b/packages/replicache/src/replicache-options.ts
index 7ed08910ec..9437c7f129 100644
--- a/packages/replicache/src/replicache-options.ts
+++ b/packages/replicache/src/replicache-options.ts
@@ -1,9 +1,9 @@
 import type {LogLevel, LogSink} from '@rocicorp/logger';
-import type {IndexDefinitions} from './index-defs.js';
-import type {StoreProvider} from './kv/store.js';
-import type {Puller} from './puller.js';
-import type {Pusher} from './pusher.js';
-import type {MutatorDefs, RequestOptions} from './types.js';
+import type {IndexDefinitions} from './index-defs.ts';
+import type {StoreProvider} from './kv/store.ts';
+import type {Puller} from './puller.ts';
+import type {Pusher} from './pusher.ts';
+import type {MutatorDefs, RequestOptions} from './types.ts';
 
 /**
  * The options passed to {@link Replicache}.
diff --git a/packages/replicache/src/replicache-persist.test.ts b/packages/replicache/src/replicache-persist.test.ts
index dfe4dd2fb5..dab5d7990c 100644
--- a/packages/replicache/src/replicache-persist.test.ts
+++ b/packages/replicache/src/replicache-persist.test.ts
@@ -10,33 +10,33 @@ import {
   replicacheForTesting,
   ReplicacheTest,
   tickAFewTimes,
-} from './test-util.js';
+} from './test-util.ts';
 
 // fetch-mock has invalid d.ts file so we removed that on npm install.
 // eslint-disable-next-line @typescript-eslint/ban-ts-comment
 // @ts-expect-error
 import fetchMock from 'fetch-mock/esm/client';
-import {assert, assertNotUndefined} from '../../shared/src/asserts.js';
-import {sleep} from '../../shared/src/sleep.js';
-import {StoreImpl} from './dag/store-impl.js';
-import type {Store} from './dag/store.js';
-import {assertHash, newRandomHash} from './hash.js';
-import {dropIDBStoreWithMemFallback} from './kv/idb-store-with-mem-fallback.js';
-import {IDBNotFoundError, IDBStore} from './kv/idb-store.js';
+import {assert, assertNotUndefined} from '../../shared/src/asserts.ts';
+import {sleep} from '../../shared/src/sleep.ts';
+import {StoreImpl} from './dag/store-impl.ts';
+import type {Store} from './dag/store.ts';
+import {assertHash, newRandomHash} from './hash.ts';
+import {dropIDBStoreWithMemFallback} from './kv/idb-store-with-mem-fallback.ts';
+import {IDBNotFoundError, IDBStore} from './kv/idb-store.ts';
 import {
   type ClientGroup,
   deleteClientGroup,
   getClientGroup,
-} from './persist/client-groups.js';
-import {deleteClientForTesting} from './persist/clients-test-helpers.js';
+} from './persist/client-groups.ts';
+import {deleteClientForTesting} from './persist/clients-test-helpers.ts';
 import {
   assertClientV6,
   ClientStateNotFoundError,
   getClient,
-} from './persist/clients.js';
-import type {WriteTransaction} from './transactions.js';
-import type {MutatorDefs} from './types.js';
-import {withRead, withWriteNoImplicitCommit} from './with-transactions.js';
+} from './persist/clients.ts';
+import type {WriteTransaction} from './transactions.ts';
+import type {MutatorDefs} from './types.ts';
+import {withRead, withWriteNoImplicitCommit} from './with-transactions.ts';
 
 initReplicacheTesting();
 
diff --git a/packages/replicache/src/replicache-poke.test.ts b/packages/replicache/src/replicache-poke.test.ts
index 787304a650..4f0a9c36ff 100644
--- a/packages/replicache/src/replicache-poke.test.ts
+++ b/packages/replicache/src/replicache-poke.test.ts
@@ -1,15 +1,15 @@
 import * as sinon from 'sinon';
 import {expect, test} from 'vitest';
-import type {VersionNotSupportedResponse} from './error-responses.js';
+import type {VersionNotSupportedResponse} from './error-responses.ts';
 import {
   addData,
   disableAllBackgroundProcesses,
   initReplicacheTesting,
   makePullResponseV1,
   replicacheForTesting,
-} from './test-util.js';
-import type {WriteTransaction} from './transactions.js';
-import type {Poke, UpdateNeededReason} from './types.js';
+} from './test-util.ts';
+import type {WriteTransaction} from './transactions.ts';
+import type {Poke, UpdateNeededReason} from './types.ts';
 
 initReplicacheTesting();
 
diff --git a/packages/replicache/src/replicache-pull.test.ts b/packages/replicache/src/replicache-pull.test.ts
index 72da278934..668ce4de9d 100644
--- a/packages/replicache/src/replicache-pull.test.ts
+++ b/packages/replicache/src/replicache-pull.test.ts
@@ -1,11 +1,11 @@
 import {resolver} from '@rocicorp/resolver';
 import * as sinon from 'sinon';
 import {expect, test} from 'vitest';
-import type {VersionNotSupportedResponse} from './error-responses.js';
-import {getDefaultPuller} from './get-default-puller.js';
-import {type Hash, emptyHash} from './hash.js';
-import type {Puller} from './puller.js';
-import {httpStatusUnauthorized} from './replicache.js';
+import type {VersionNotSupportedResponse} from './error-responses.ts';
+import {getDefaultPuller} from './get-default-puller.ts';
+import {type Hash, emptyHash} from './hash.ts';
+import type {Puller} from './puller.ts';
+import {httpStatusUnauthorized} from './replicache.ts';
 import {
   disableAllBackgroundProcesses,
   expectConsoleLogContextStub,
@@ -15,9 +15,9 @@ import {
   requestIDLogContextRegex,
   tickAFewTimes,
   waitForSync,
-} from './test-util.js';
-import type {WriteTransaction} from './transactions.js';
-import type {UpdateNeededReason} from './types.js';
+} from './test-util.ts';
+import type {WriteTransaction} from './transactions.ts';
+import type {UpdateNeededReason} from './types.ts';
 
 // fetch-mock has invalid d.ts file so we removed that on npm install.
 // eslint-disable-next-line @typescript-eslint/ban-ts-comment
diff --git a/packages/replicache/src/replicache-push.test.ts b/packages/replicache/src/replicache-push.test.ts
index 1bccb7fe58..6eb378d4fb 100644
--- a/packages/replicache/src/replicache-push.test.ts
+++ b/packages/replicache/src/replicache-push.test.ts
@@ -1,21 +1,21 @@
 import * as sinon from 'sinon';
 import {expect, test} from 'vitest';
-import type {VersionNotSupportedResponse} from './error-responses.js';
-import type {Pusher} from './pusher.js';
+import type {VersionNotSupportedResponse} from './error-responses.ts';
+import type {Pusher} from './pusher.ts';
 import {
   disableAllBackgroundProcesses,
   initReplicacheTesting,
   replicacheForTesting,
   tickAFewTimes,
-} from './test-util.js';
-import type {WriteTransaction} from './transactions.js';
+} from './test-util.ts';
+import type {WriteTransaction} from './transactions.ts';
 
 // fetch-mock has invalid d.ts file so we removed that on npm install.
 // eslint-disable-next-line @typescript-eslint/ban-ts-comment
 // @ts-expect-error
 import fetchMock from 'fetch-mock/esm/client';
-import {getDefaultPusher} from './get-default-pusher.js';
-import type {UpdateNeededReason} from './types.js';
+import {getDefaultPusher} from './get-default-pusher.ts';
+import type {UpdateNeededReason} from './types.ts';
 
 initReplicacheTesting();
 
diff --git a/packages/replicache/src/replicache-subscribe.test.ts b/packages/replicache/src/replicache-subscribe.test.ts
index 2a76633b14..c302740ae9 100644
--- a/packages/replicache/src/replicache-subscribe.test.ts
+++ b/packages/replicache/src/replicache-subscribe.test.ts
@@ -1,12 +1,12 @@
 import {resolver} from '@rocicorp/resolver';
 import * as sinon from 'sinon';
-import type {JSONValue, ReadonlyJSONValue} from '../../shared/src/json.js';
-import {TestLogSink} from '../../shared/src/logging-test-utils.js';
-import {sleep} from '../../shared/src/sleep.js';
-import type {IndexKey} from './db/index.js';
-import type {IndexDefinitions} from './index-defs.js';
-import type {PatchOperation} from './patch-operation.js';
-import type {ScanOptions} from './scan-options.js';
+import type {JSONValue, ReadonlyJSONValue} from '../../shared/src/json.ts';
+import {TestLogSink} from '../../shared/src/logging-test-utils.ts';
+import {sleep} from '../../shared/src/sleep.ts';
+import type {IndexKey} from './db/index.ts';
+import type {IndexDefinitions} from './index-defs.ts';
+import type {PatchOperation} from './patch-operation.ts';
+import type {ScanOptions} from './scan-options.ts';
 import {
   clock,
   disableAllBackgroundProcesses,
@@ -15,8 +15,8 @@ import {
   replicacheForTesting,
   tickAFewTimes,
   tickUntil,
-} from './test-util.js';
-import type {ReadTransaction, WriteTransaction} from './transactions.js';
+} from './test-util.ts';
+import type {ReadTransaction, WriteTransaction} from './transactions.ts';
 
 // fetch-mock has invalid d.ts file so we removed that on npm install.
 // eslint-disable-next-line @typescript-eslint/ban-ts-comment
diff --git a/packages/replicache/src/replicache-types.test.ts b/packages/replicache/src/replicache-types.test.ts
index 44c8fc478e..dd0ee9d631 100644
--- a/packages/replicache/src/replicache-types.test.ts
+++ b/packages/replicache/src/replicache-types.test.ts
@@ -1,11 +1,11 @@
 /* eslint-disable require-await */
 
 import {test} from 'vitest';
-import {assert} from '../../shared/src/asserts.js';
-import type {ReadonlyJSONObject} from '../../shared/src/json.js';
-import type {IndexKey} from './db/index.js';
-import {Replicache} from './replicache.js';
-import type {DeepReadonly, WriteTransaction} from './transactions.js';
+import {assert} from '../../shared/src/asserts.ts';
+import type {ReadonlyJSONObject} from '../../shared/src/json.ts';
+import type {IndexKey} from './db/index.ts';
+import {Replicache} from './replicache.ts';
+import type {DeepReadonly, WriteTransaction} from './transactions.ts';
 
 function use(..._args: unknown[]) {
   // do nothing
diff --git a/packages/replicache/src/replicache.test.ts b/packages/replicache/src/replicache.test.ts
index 017de46ea3..1710882161 100644
--- a/packages/replicache/src/replicache.test.ts
+++ b/packages/replicache/src/replicache.test.ts
@@ -2,20 +2,20 @@ import type {Context, LogLevel} from '@rocicorp/logger';
 import {resolver} from '@rocicorp/resolver';
 import * as sinon from 'sinon';
 import {describe, expect, test} from 'vitest';
-import {assert, unreachable} from '../../shared/src/asserts.js';
-import type {JSONValue, ReadonlyJSONValue} from '../../shared/src/json.js';
-import {promiseVoid} from '../../shared/src/resolved-promises.js';
-import {sleep} from '../../shared/src/sleep.js';
-import {asyncIterableToArray} from './async-iterable-to-array.js';
-import {Write} from './db/write.js';
-import {TestMemStore} from './kv/test-mem-store.js';
-import type {PatchOperation} from './patch-operation.js';
-import {getClientGroup} from './persist/client-groups.js';
-import {deleteClientForTesting} from './persist/clients-test-helpers.js';
-import type {ReplicacheOptions} from './replicache-options.js';
-import {Replicache, httpStatusUnauthorized} from './replicache.js';
-import type {ScanOptions} from './scan-options.js';
-import type {ClientID} from './sync/ids.js';
+import {assert, unreachable} from '../../shared/src/asserts.ts';
+import type {JSONValue, ReadonlyJSONValue} from '../../shared/src/json.ts';
+import {promiseVoid} from '../../shared/src/resolved-promises.ts';
+import {sleep} from '../../shared/src/sleep.ts';
+import {asyncIterableToArray} from './async-iterable-to-array.ts';
+import {Write} from './db/write.ts';
+import {TestMemStore} from './kv/test-mem-store.ts';
+import type {PatchOperation} from './patch-operation.ts';
+import {getClientGroup} from './persist/client-groups.ts';
+import {deleteClientForTesting} from './persist/clients-test-helpers.ts';
+import type {ReplicacheOptions} from './replicache-options.ts';
+import {Replicache, httpStatusUnauthorized} from './replicache.ts';
+import type {ScanOptions} from './scan-options.ts';
+import type {ClientID} from './sync/ids.ts';
 import {
   MemStoreWithCounters,
   ReplicacheTest,
@@ -31,11 +31,11 @@ import {
   requestIDLogContextRegex,
   tickAFewTimes,
   tickUntil,
-} from './test-util.js';
-import {TransactionClosedError} from './transaction-closed-error.js';
-import type {ReadTransaction, WriteTransaction} from './transactions.js';
-import type {MutatorDefs, Poke} from './types.js';
-import {withRead} from './with-transactions.js';
+} from './test-util.ts';
+import {TransactionClosedError} from './transaction-closed-error.ts';
+import type {ReadTransaction, WriteTransaction} from './transactions.ts';
+import type {MutatorDefs, Poke} from './types.ts';
+import {withRead} from './with-transactions.ts';
 
 // fetch-mock has invalid d.ts file so we removed that on npm install.
 // eslint-disable-next-line @typescript-eslint/ban-ts-comment
diff --git a/packages/replicache/src/replicache.ts b/packages/replicache/src/replicache.ts
index 0ffe89c6e4..44320a6de9 100644
--- a/packages/replicache/src/replicache.ts
+++ b/packages/replicache/src/replicache.ts
@@ -1,31 +1,31 @@
 import type {LogContext} from '@rocicorp/logger';
-import type {MaybePromise} from '../../shared/src/types.js';
-import * as FormatVersion from './format-version-enum.js';
+import type {MaybePromise} from '../../shared/src/types.ts';
+import * as FormatVersion from './format-version-enum.ts';
 import {
   dropIDBStoreWithMemFallback,
   newIDBStoreWithMemFallback,
-} from './kv/idb-store-with-mem-fallback.js';
-import {MemStore, dropMemStore} from './kv/mem-store.js';
-import type {StoreProvider} from './kv/store.js';
-import type {PendingMutation} from './pending-mutations.js';
-import type {Puller} from './puller.js';
-import type {Pusher} from './pusher.js';
-import {ReplicacheImpl} from './replicache-impl.js';
-import type {ReplicacheOptions} from './replicache-options.js';
+} from './kv/idb-store-with-mem-fallback.ts';
+import {MemStore, dropMemStore} from './kv/mem-store.ts';
+import type {StoreProvider} from './kv/store.ts';
+import type {PendingMutation} from './pending-mutations.ts';
+import type {Puller} from './puller.ts';
+import type {Pusher} from './pusher.ts';
+import {ReplicacheImpl} from './replicache-impl.ts';
+import type {ReplicacheOptions} from './replicache-options.ts';
 import type {
   SubscribeOptions,
   WatchCallbackForOptions,
   WatchNoIndexCallback,
   WatchOptions,
-} from './subscriptions.js';
-import type {ReadTransaction} from './transactions.js';
+} from './subscriptions.ts';
+import type {ReadTransaction} from './transactions.ts';
 import type {
   MakeMutators,
   MutatorDefs,
   Poke,
   RequestOptions,
   UpdateNeededReason,
-} from './types.js';
+} from './types.ts';
 
 type MakeImpl = <MD extends MutatorDefs>(
   options: ReplicacheOptions<MD>,
diff --git a/packages/replicache/src/scan-iterator.test.ts b/packages/replicache/src/scan-iterator.test.ts
index 587c6bcc46..bf47c7ac9c 100644
--- a/packages/replicache/src/scan-iterator.test.ts
+++ b/packages/replicache/src/scan-iterator.test.ts
@@ -1,15 +1,15 @@
 import {expect, test} from 'vitest';
-import type {ReadonlyJSONValue} from '../../shared/src/json.js';
-import {asyncIterableToArray} from './async-iterable-to-array.js';
-import type {IndexKey} from './db/index.js';
+import type {ReadonlyJSONValue} from '../../shared/src/json.ts';
+import {asyncIterableToArray} from './async-iterable-to-array.ts';
+import type {IndexKey} from './db/index.ts';
 import {
   type Entry,
   type GetIndexScanIterator,
   type GetScanIterator,
   fromKeyForIndexScan,
   makeScanResult,
-} from './scan-iterator.js';
-import type {ScanIndexOptions, ScanOptions} from './scan-options.js';
+} from './scan-iterator.ts';
+import type {ScanIndexOptions, ScanOptions} from './scan-options.ts';
 
 test('makeScanResult', async () => {
   function getTestScanAsyncIterator(
diff --git a/packages/replicache/src/scan-iterator.ts b/packages/replicache/src/scan-iterator.ts
index c1902c3b2d..d399841efe 100644
--- a/packages/replicache/src/scan-iterator.ts
+++ b/packages/replicache/src/scan-iterator.ts
@@ -1,8 +1,8 @@
 import {greaterThan} from 'compare-utf8';
-import type {ReadonlyJSONValue} from '../../shared/src/json.js';
-import {asyncIterableToArray} from './async-iterable-to-array.js';
-import {type IndexKey, encodeIndexScanKey} from './db/index.js';
-import type {IterableUnion} from './iterable-union.js';
+import type {ReadonlyJSONValue} from '../../shared/src/json.ts';
+import {asyncIterableToArray} from './async-iterable-to-array.ts';
+import {type IndexKey, encodeIndexScanKey} from './db/index.ts';
+import type {IterableUnion} from './iterable-union.ts';
 import {
   type KeyTypeForScanOptions,
   type ScanIndexOptions,
@@ -10,9 +10,9 @@ import {
   type ScanOptions,
   isScanIndexOptions,
   normalizeScanOptionIndexedStartKey,
-} from './scan-options.js';
-import {type Closed, throwIfClosed} from './transaction-closed-error.js';
-import {type EntryForOptions, fromKeyForNonIndexScan} from './transactions.js';
+} from './scan-options.ts';
+import {type Closed, throwIfClosed} from './transaction-closed-error.ts';
+import {type EntryForOptions, fromKeyForNonIndexScan} from './transactions.ts';
 
 type ScanKey = string | IndexKey;
 
diff --git a/packages/replicache/src/scan-options.ts b/packages/replicache/src/scan-options.ts
index c9e963dd36..d561439412 100644
--- a/packages/replicache/src/scan-options.ts
+++ b/packages/replicache/src/scan-options.ts
@@ -1,5 +1,5 @@
-import type {IndexKey} from './db/index.js';
-import type {ScanOptions as DbScanOptions} from './db/scan.js';
+import type {IndexKey} from './db/index.ts';
+import type {ScanOptions as DbScanOptions} from './db/scan.ts';
 
 /**
  * Options for {@link ReadTransaction.scan | scan}
diff --git a/packages/replicache/src/size-of-value.test.ts b/packages/replicache/src/size-of-value.test.ts
index 6c2d27d19e..ab2300d541 100644
--- a/packages/replicache/src/size-of-value.test.ts
+++ b/packages/replicache/src/size-of-value.test.ts
@@ -1,5 +1,5 @@
 import {expect, test} from 'vitest';
-import {getSizeOfEntry, getSizeOfValue} from './size-of-value.js';
+import {getSizeOfEntry, getSizeOfValue} from './size-of-value.ts';
 
 test('getSizeOfValue', () => {
   expect(getSizeOfValue(null)).to.equal(1);
diff --git a/packages/replicache/src/size-of-value.ts b/packages/replicache/src/size-of-value.ts
index 6db8c640ea..f5dceb03bb 100644
--- a/packages/replicache/src/size-of-value.ts
+++ b/packages/replicache/src/size-of-value.ts
@@ -1,5 +1,5 @@
-import {hasOwn} from '../../shared/src/has-own.js';
-import type {ReadonlyJSONObject} from '../../shared/src/json.js';
+import {hasOwn} from '../../shared/src/has-own.ts';
+import type {ReadonlyJSONObject} from '../../shared/src/json.ts';
 
 const SIZE_TAG = 1;
 const SIZE_INT32 = 4;
diff --git a/packages/replicache/src/subscriptions.test.ts b/packages/replicache/src/subscriptions.test.ts
index 4e9001dcc9..5c17045401 100644
--- a/packages/replicache/src/subscriptions.test.ts
+++ b/packages/replicache/src/subscriptions.test.ts
@@ -2,7 +2,7 @@ import {expect, test} from 'vitest';
 import {
   SubscriptionImplForTesting,
   scanInfoMatchesKey,
-} from './subscriptions.js';
+} from './subscriptions.ts';
 
 test('scanInfoMatchesKey', () => {
   expect(scanInfoMatchesKey({options: {}}, '', 'a')).to.be.true;
diff --git a/packages/replicache/src/subscriptions.ts b/packages/replicache/src/subscriptions.ts
index 56cec1abbe..d39b06ac1d 100644
--- a/packages/replicache/src/subscriptions.ts
+++ b/packages/replicache/src/subscriptions.ts
@@ -1,9 +1,9 @@
 import type {LogContext} from '@rocicorp/logger';
 import {compareUTF8, greaterThan, lessThan, lessThanEq} from 'compare-utf8';
-import {assert} from '../../shared/src/asserts.js';
-import type {Enum} from '../../shared/src/enum.js';
-import {deepEqual} from '../../shared/src/json.js';
-import {binarySearch} from './binary-search.js';
+import {assert} from '../../shared/src/asserts.ts';
+import type {Enum} from '../../shared/src/enum.ts';
+import {deepEqual} from '../../shared/src/json.ts';
+import {binarySearch} from './binary-search.ts';
 import type {
   Diff,
   DiffOperation,
@@ -11,17 +11,17 @@ import type {
   InternalDiff,
   InternalDiffOperation,
   NoIndexDiff,
-} from './btree/node.js';
-import type {IndexKey} from './db/index.js';
-import {decodeIndexKey} from './db/index.js';
-import type {ScanOptions} from './db/scan.js';
-import * as InvokeKind from './invoke-kind-enum.js';
-import type {DiffComputationConfig, DiffsMap} from './sync/diff.js';
+} from './btree/node.ts';
+import type {IndexKey} from './db/index.ts';
+import {decodeIndexKey} from './db/index.ts';
+import type {ScanOptions} from './db/scan.ts';
+import * as InvokeKind from './invoke-kind-enum.ts';
+import type {DiffComputationConfig, DiffsMap} from './sync/diff.ts';
 import {
   type ReadTransaction,
   SubscriptionTransactionWrapper,
-} from './transactions.js';
-import type {QueryInternal} from './types.js';
+} from './transactions.ts';
+import type {QueryInternal} from './types.ts';
 
 type InvokeKind = Enum<typeof InvokeKind>;
 
diff --git a/packages/replicache/src/sync/diff.test.ts b/packages/replicache/src/sync/diff.test.ts
index f62e8f8000..311fbbb306 100644
--- a/packages/replicache/src/sync/diff.test.ts
+++ b/packages/replicache/src/sync/diff.test.ts
@@ -1,12 +1,12 @@
 import {expect, test} from 'vitest';
-import type {InternalDiff} from '../btree/node.js';
-import {TestStore} from '../dag/test-store.js';
-import {ChainBuilder} from '../db/test-helpers.js';
-import * as FormatVersion from '../format-version-enum.js';
-import type {IndexDefinitions} from '../index-defs.js';
-import {testSubscriptionsManagerOptions} from '../test-util.js';
-import {withRead} from '../with-transactions.js';
-import {diff} from './diff.js';
+import type {InternalDiff} from '../btree/node.ts';
+import {TestStore} from '../dag/test-store.ts';
+import {ChainBuilder} from '../db/test-helpers.ts';
+import * as FormatVersion from '../format-version-enum.ts';
+import type {IndexDefinitions} from '../index-defs.ts';
+import {testSubscriptionsManagerOptions} from '../test-util.ts';
+import {withRead} from '../with-transactions.ts';
+import {diff} from './diff.ts';
 
 type DiffsRecord = Record<string, InternalDiff>;
 
diff --git a/packages/replicache/src/sync/diff.ts b/packages/replicache/src/sync/diff.ts
index 172668d89e..1dbeafc7f3 100644
--- a/packages/replicache/src/sync/diff.ts
+++ b/packages/replicache/src/sync/diff.ts
@@ -1,13 +1,13 @@
-import {assert} from '../../../shared/src/asserts.js';
-import type {Enum} from '../../../shared/src/enum.js';
-import {diff as btreeDiff} from '../btree/diff.js';
-import type {InternalDiff} from '../btree/node.js';
-import {allEntriesAsDiff, BTreeRead} from '../btree/read.js';
-import type {Read} from '../dag/store.js';
-import {Commit, commitFromHash, type Meta} from '../db/commit.js';
-import {readIndexesForRead} from '../db/read.js';
-import * as FormatVersion from '../format-version-enum.js';
-import type {Hash} from '../hash.js';
+import {assert} from '../../../shared/src/asserts.ts';
+import type {Enum} from '../../../shared/src/enum.ts';
+import {diff as btreeDiff} from '../btree/diff.ts';
+import type {InternalDiff} from '../btree/node.ts';
+import {allEntriesAsDiff, BTreeRead} from '../btree/read.ts';
+import type {Read} from '../dag/store.ts';
+import {Commit, commitFromHash, type Meta} from '../db/commit.ts';
+import {readIndexesForRead} from '../db/read.ts';
+import * as FormatVersion from '../format-version-enum.ts';
+import type {Hash} from '../hash.ts';
 
 type FormatVersion = Enum<typeof FormatVersion>;
 
diff --git a/packages/replicache/src/sync/ids.ts b/packages/replicache/src/sync/ids.ts
index c18c766ef6..ea7016f38d 100644
--- a/packages/replicache/src/sync/ids.ts
+++ b/packages/replicache/src/sync/ids.ts
@@ -1,4 +1,4 @@
-import * as valita from '../../../shared/src/valita.js';
+import * as valita from '../../../shared/src/valita.ts';
 
 /**
  * The ID describing a group of clients. All clients in the same group share a
diff --git a/packages/replicache/src/sync/patch.test.ts b/packages/replicache/src/sync/patch.test.ts
index 5bbd28a3c3..a5ff224f75 100644
--- a/packages/replicache/src/sync/patch.test.ts
+++ b/packages/replicache/src/sync/patch.test.ts
@@ -1,19 +1,19 @@
 import {LogContext} from '@rocicorp/logger';
 import {describe, expect, test} from 'vitest';
-import {assert} from '../../../shared/src/asserts.js';
-import type {Enum} from '../../../shared/src/enum.js';
-import type {JSONValue} from '../../../shared/src/json.js';
-import {TestStore} from '../dag/test-store.js';
-import {ChainBuilder} from '../db/test-helpers.js';
-import {newWriteSnapshotDD31} from '../db/write.js';
-import * as FormatVersion from '../format-version-enum.js';
-import {deepFreeze} from '../frozen-json.js';
+import {assert} from '../../../shared/src/asserts.ts';
+import type {Enum} from '../../../shared/src/enum.ts';
+import type {JSONValue} from '../../../shared/src/json.ts';
+import {TestStore} from '../dag/test-store.ts';
+import {ChainBuilder} from '../db/test-helpers.ts';
+import {newWriteSnapshotDD31} from '../db/write.ts';
+import * as FormatVersion from '../format-version-enum.ts';
+import {deepFreeze} from '../frozen-json.ts';
 import {
   type PatchOperationInternal,
   assertPatchOperations,
-} from '../patch-operation.js';
-import {withWriteNoImplicitCommit} from '../with-transactions.js';
-import {apply} from './patch.js';
+} from '../patch-operation.ts';
+import {withWriteNoImplicitCommit} from '../with-transactions.ts';
+import {apply} from './patch.ts';
 
 type FormatVersion = Enum<typeof FormatVersion>;
 
diff --git a/packages/replicache/src/sync/patch.ts b/packages/replicache/src/sync/patch.ts
index aa7a74a8f3..1157659f1d 100644
--- a/packages/replicache/src/sync/patch.ts
+++ b/packages/replicache/src/sync/patch.ts
@@ -1,16 +1,16 @@
 import type {LogContext} from '@rocicorp/logger';
-import {assertObject} from '../../../shared/src/asserts.js';
+import {assertObject} from '../../../shared/src/asserts.ts';
 import type {
   ReadonlyJSONObject,
   ReadonlyJSONValue,
-} from '../../../shared/src/json.js';
-import type {Write} from '../db/write.js';
+} from '../../../shared/src/json.ts';
+import type {Write} from '../db/write.ts';
 import {
   type FrozenJSONObject,
   type FrozenJSONValue,
   deepFreeze,
-} from '../frozen-json.js';
-import type {PatchOperationInternal} from '../patch-operation.js';
+} from '../frozen-json.ts';
+import type {PatchOperationInternal} from '../patch-operation.ts';
 
 export async function apply(
   lc: LogContext,
diff --git a/packages/replicache/src/sync/pull.test.ts b/packages/replicache/src/sync/pull.test.ts
index abefdeb02e..5de72e57f1 100644
--- a/packages/replicache/src/sync/pull.test.ts
+++ b/packages/replicache/src/sync/pull.test.ts
@@ -4,14 +4,14 @@ import {
   assert,
   assertObject,
   assertString,
-} from '../../../shared/src/asserts.js';
-import type {Enum} from '../../../shared/src/enum.js';
-import type {ReadonlyJSONValue} from '../../../shared/src/json.js';
-import {stringCompare} from '../../../shared/src/string-compare.js';
-import {asyncIterableToArray} from '../async-iterable-to-array.js';
-import {BTreeRead} from '../btree/read.js';
-import type {Cookie, FrozenCookie} from '../cookies.js';
-import {TestStore} from '../dag/test-store.js';
+} from '../../../shared/src/asserts.ts';
+import type {Enum} from '../../../shared/src/enum.ts';
+import type {ReadonlyJSONValue} from '../../../shared/src/json.ts';
+import {stringCompare} from '../../../shared/src/string-compare.ts';
+import {asyncIterableToArray} from '../async-iterable-to-array.ts';
+import {BTreeRead} from '../btree/read.ts';
+import type {Cookie, FrozenCookie} from '../cookies.ts';
+import {TestStore} from '../dag/test-store.ts';
 import {
   DEFAULT_HEAD_NAME,
   assertSnapshotCommitDD31,
@@ -19,36 +19,36 @@ import {
   commitFromHead,
   commitIsLocal,
   snapshotMetaParts,
-} from '../db/commit.js';
-import {encodeIndexKey} from '../db/index.js';
-import {readFromDefaultHead, readFromHead} from '../db/read.js';
-import {ChainBuilder} from '../db/test-helpers.js';
-import {newWriteLocal, newWriteSnapshotDD31} from '../db/write.js';
+} from '../db/commit.ts';
+import {encodeIndexKey} from '../db/index.ts';
+import {readFromDefaultHead, readFromHead} from '../db/read.ts';
+import {ChainBuilder} from '../db/test-helpers.ts';
+import {newWriteLocal, newWriteSnapshotDD31} from '../db/write.ts';
 import {
   isClientStateNotFoundResponse,
   isVersionNotSupportedResponse,
-} from '../error-responses.js';
-import * as FormatVersion from '../format-version-enum.js';
-import {type FrozenJSONValue, deepFreeze} from '../frozen-json.js';
-import {assertPullResponseV1} from '../get-default-puller.js';
-import {assertHash, emptyHash, fakeHash} from '../hash.js';
-import type {HTTPRequestInfo} from '../http-request-info.js';
-import type {IndexDefinitions} from '../index-defs.js';
-import type {PatchOperation} from '../patch-operation.js';
+} from '../error-responses.ts';
+import * as FormatVersion from '../format-version-enum.ts';
+import {type FrozenJSONValue, deepFreeze} from '../frozen-json.ts';
+import {assertPullResponseV1} from '../get-default-puller.ts';
+import {assertHash, emptyHash, fakeHash} from '../hash.ts';
+import type {HTTPRequestInfo} from '../http-request-info.ts';
+import type {IndexDefinitions} from '../index-defs.ts';
+import type {PatchOperation} from '../patch-operation.ts';
 import type {
   PullResponseOKV1,
   PullResponseV1,
   Puller,
   PullerResultV1,
-} from '../puller.js';
-import {testSubscriptionsManagerOptions} from '../test-util.js';
+} from '../puller.ts';
+import {testSubscriptionsManagerOptions} from '../test-util.ts';
 import {
   withRead,
   withWrite,
   withWriteNoImplicitCommit,
-} from '../with-transactions.js';
-import type {DiffsMap} from './diff.js';
-import * as HandlePullResponseResultEnum from './handle-pull-response-result-type-enum.js';
+} from '../with-transactions.ts';
+import type {DiffsMap} from './diff.ts';
+import * as HandlePullResponseResultEnum from './handle-pull-response-result-type-enum.ts';
 import {
   type BeginPullResponseV1,
   PULL_VERSION_DD31,
@@ -57,8 +57,8 @@ import {
   handlePullResponseV1,
   isPullRequestV1,
   maybeEndPull,
-} from './pull.js';
-import {SYNC_HEAD_NAME} from './sync-head-name.js';
+} from './pull.ts';
+import {SYNC_HEAD_NAME} from './sync-head-name.ts';
 
 type FormatVersion = Enum<typeof FormatVersion>;
 type HandlePullResponseResultEnum = Enum<typeof HandlePullResponseResultEnum>;
diff --git a/packages/replicache/src/sync/pull.ts b/packages/replicache/src/sync/pull.ts
index bbda4f3174..acfad3d124 100644
--- a/packages/replicache/src/sync/pull.ts
+++ b/packages/replicache/src/sync/pull.ts
@@ -1,10 +1,10 @@
 import type {LogContext} from '@rocicorp/logger';
-import {assert} from '../../../shared/src/asserts.js';
-import {deepEqual} from '../../../shared/src/json.js';
-import {diff} from '../btree/diff.js';
-import {BTreeRead} from '../btree/read.js';
-import {compareCookies, type Cookie} from '../cookies.js';
-import type {Store} from '../dag/store.js';
+import {assert} from '../../../shared/src/asserts.ts';
+import {deepEqual} from '../../../shared/src/json.ts';
+import {diff} from '../btree/diff.ts';
+import {BTreeRead} from '../btree/read.ts';
+import {compareCookies, type Cookie} from '../cookies.ts';
+import type {Store} from '../dag/store.ts';
 import {
   assertSnapshotMetaDD31,
   baseSnapshotFromHash,
@@ -15,34 +15,34 @@ import {
   type LocalMeta,
   localMutations as localMutations_1,
   snapshotMetaParts,
-} from '../db/commit.js';
-import {newWriteSnapshotDD31} from '../db/write.js';
-import {isErrorResponse} from '../error-responses.js';
-import * as FormatVersion from '../format-version-enum.js';
-import {deepFreeze, type FrozenJSONValue} from '../frozen-json.js';
-import {assertPullerResultV1} from '../get-default-puller.js';
-import {emptyHash, type Hash} from '../hash.js';
-import type {HTTPRequestInfo} from '../http-request-info.js';
+} from '../db/commit.ts';
+import {newWriteSnapshotDD31} from '../db/write.ts';
+import {isErrorResponse} from '../error-responses.ts';
+import * as FormatVersion from '../format-version-enum.ts';
+import {deepFreeze, type FrozenJSONValue} from '../frozen-json.ts';
+import {assertPullerResultV1} from '../get-default-puller.ts';
+import {emptyHash, type Hash} from '../hash.ts';
+import type {HTTPRequestInfo} from '../http-request-info.ts';
 import type {
   Puller,
   PullerResult,
   PullerResultV1,
   PullResponseOKV1Internal,
   PullResponseV1,
-} from '../puller.js';
-import {ReportError} from '../replicache.js';
-import {toError} from '../to-error.js';
-import {withRead, withWriteNoImplicitCommit} from '../with-transactions.js';
+} from '../puller.ts';
+import {ReportError} from '../replicache.ts';
+import {toError} from '../to-error.ts';
+import {withRead, withWriteNoImplicitCommit} from '../with-transactions.ts';
 import {
   addDiffsForIndexes,
   type DiffComputationConfig,
   DiffsMap,
-} from './diff.js';
-import * as HandlePullResponseResultType from './handle-pull-response-result-type-enum.js';
-import type {ClientGroupID, ClientID} from './ids.js';
-import * as patch from './patch.js';
-import {PullError} from './pull-error.js';
-import {SYNC_HEAD_NAME} from './sync-head-name.js';
+} from './diff.ts';
+import * as HandlePullResponseResultType from './handle-pull-response-result-type-enum.ts';
+import type {ClientGroupID, ClientID} from './ids.ts';
+import * as patch from './patch.ts';
+import {PullError} from './pull-error.ts';
+import {SYNC_HEAD_NAME} from './sync-head-name.ts';
 
 type FormatVersion = (typeof FormatVersion)[keyof typeof FormatVersion];
 
diff --git a/packages/replicache/src/sync/push.test.ts b/packages/replicache/src/sync/push.test.ts
index ae66f4b650..a1c9b0bd6f 100644
--- a/packages/replicache/src/sync/push.test.ts
+++ b/packages/replicache/src/sync/push.test.ts
@@ -1,21 +1,21 @@
 import {LogContext} from '@rocicorp/logger';
 import {expect, test} from 'vitest';
-import {TestStore} from '../dag/test-store.js';
-import {DEFAULT_HEAD_NAME} from '../db/commit.js';
-import {readFromDefaultHead} from '../db/read.js';
-import {ChainBuilder} from '../db/test-helpers.js';
-import * as FormatVersion from '../format-version-enum.js';
-import {deepFreeze} from '../frozen-json.js';
-import type {Pusher, PusherResult} from '../pusher.js';
-import {withRead, withWrite} from '../with-transactions.js';
-import type {ClientGroupID} from './ids.js';
+import {TestStore} from '../dag/test-store.ts';
+import {DEFAULT_HEAD_NAME} from '../db/commit.ts';
+import {readFromDefaultHead} from '../db/read.ts';
+import {ChainBuilder} from '../db/test-helpers.ts';
+import * as FormatVersion from '../format-version-enum.ts';
+import {deepFreeze} from '../frozen-json.ts';
+import type {Pusher, PusherResult} from '../pusher.ts';
+import {withRead, withWrite} from '../with-transactions.ts';
+import type {ClientGroupID} from './ids.ts';
 import {
   PUSH_VERSION_DD31,
   type PushRequest,
   type PushRequestV1,
   push,
-} from './push.js';
-import {SYNC_HEAD_NAME} from './sync-head-name.js';
+} from './push.ts';
+import {SYNC_HEAD_NAME} from './sync-head-name.ts';
 
 type FakePusherArgs = {
   expPush: boolean;
diff --git a/packages/replicache/src/sync/push.ts b/packages/replicache/src/sync/push.ts
index 836e21d057..99a1c69949 100644
--- a/packages/replicache/src/sync/push.ts
+++ b/packages/replicache/src/sync/push.ts
@@ -1,31 +1,31 @@
 import type {LogContext} from '@rocicorp/logger';
-import {assert} from '../../../shared/src/asserts.js';
-import {jsonSchema} from '../../../shared/src/json-schema.js';
-import type {ReadonlyJSONValue} from '../../../shared/src/json.js';
-import * as valita from '../../../shared/src/valita.js';
-import type {Store} from '../dag/store.js';
+import {assert} from '../../../shared/src/asserts.ts';
+import {jsonSchema} from '../../../shared/src/json-schema.ts';
+import type {ReadonlyJSONValue} from '../../../shared/src/json.ts';
+import * as valita from '../../../shared/src/valita.ts';
+import type {Store} from '../dag/store.ts';
 import {
   DEFAULT_HEAD_NAME,
   type LocalMetaDD31,
   commitIsLocalDD31,
   localMutations,
-} from '../db/commit.js';
-import type {FrozenJSONValue} from '../frozen-json.js';
+} from '../db/commit.ts';
+import type {FrozenJSONValue} from '../frozen-json.ts';
 import {
   PushError,
   type Pusher,
   type PusherResult,
   assertPusherResult,
-} from '../pusher.js';
-import {ReportError} from '../replicache.js';
-import {toError} from '../to-error.js';
-import {withRead} from '../with-transactions.js';
+} from '../pusher.ts';
+import {ReportError} from '../replicache.ts';
+import {toError} from '../to-error.ts';
+import {withRead} from '../with-transactions.ts';
 import {
   type ClientGroupID,
   type ClientID,
   clientGroupIDSchema,
   clientIDSchema,
-} from './ids.js';
+} from './ids.ts';
 
 export const PUSH_VERSION_SDD = 0;
 export const PUSH_VERSION_DD31 = 1;
diff --git a/packages/replicache/src/sync/request-id.test.ts b/packages/replicache/src/sync/request-id.test.ts
index 2b669da3ca..8ed322a01f 100644
--- a/packages/replicache/src/sync/request-id.test.ts
+++ b/packages/replicache/src/sync/request-id.test.ts
@@ -1,5 +1,5 @@
 import {expect, test} from 'vitest';
-import {newRequestID} from './request-id.js';
+import {newRequestID} from './request-id.ts';
 
 test('newRequestID()', () => {
   {
diff --git a/packages/replicache/src/sync/request-id.ts b/packages/replicache/src/sync/request-id.ts
index ba717eaaa6..f1b8422f1f 100644
--- a/packages/replicache/src/sync/request-id.ts
+++ b/packages/replicache/src/sync/request-id.ts
@@ -1,5 +1,5 @@
-import {getNonCryptoRandomValues} from '../../../shared/src/random-values.js';
-import type {ClientID} from './ids.js';
+import {getNonCryptoRandomValues} from '../../../shared/src/random-values.ts';
+import type {ClientID} from './ids.ts';
 
 let sessionID = '';
 function getSessionID() {
diff --git a/packages/replicache/src/sync/test-helpers.ts b/packages/replicache/src/sync/test-helpers.ts
index 121117ee8d..b8e9052842 100644
--- a/packages/replicache/src/sync/test-helpers.ts
+++ b/packages/replicache/src/sync/test-helpers.ts
@@ -1,18 +1,18 @@
 import {expect} from 'vitest';
-import {assert} from '../../../shared/src/asserts.js';
-import type {Store} from '../dag/store.js';
+import {assert} from '../../../shared/src/asserts.ts';
+import type {Store} from '../dag/store.ts';
 import {
   Commit,
   type SnapshotMeta,
   commitFromHead,
   commitIsSnapshot,
-} from '../db/commit.js';
-import type {Chain} from '../db/test-helpers.js';
-import {newWriteSnapshotDD31} from '../db/write.js';
-import * as FormatVersion from '../format-version-enum.js';
-import {withRead, withWriteNoImplicitCommit} from '../with-transactions.js';
-import type {ClientID} from './ids.js';
-import {SYNC_HEAD_NAME} from './sync-head-name.js';
+} from '../db/commit.ts';
+import type {Chain} from '../db/test-helpers.ts';
+import {newWriteSnapshotDD31} from '../db/write.ts';
+import * as FormatVersion from '../format-version-enum.ts';
+import {withRead, withWriteNoImplicitCommit} from '../with-transactions.ts';
+import type {ClientID} from './ids.ts';
+import {SYNC_HEAD_NAME} from './sync-head-name.ts';
 
 type FormatVersion = (typeof FormatVersion)[keyof typeof FormatVersion];
 
diff --git a/packages/replicache/src/test-util.ts b/packages/replicache/src/test-util.ts
index 764238a487..5c9b3e6962 100644
--- a/packages/replicache/src/test-util.ts
+++ b/packages/replicache/src/test-util.ts
@@ -2,32 +2,32 @@ import {resolver} from '@rocicorp/resolver';
 import * as sinon from 'sinon';
 import {type SinonFakeTimers, useFakeTimers} from 'sinon';
 import {afterEach, beforeEach, expect} from 'vitest';
-import type {JSONValue} from '../../shared/src/json.js';
-import {must} from '../../shared/src/must.js';
-import {randomUint64} from '../../shared/src/random-uint64.js';
-import type {Cookie} from './cookies.js';
-import type {Store} from './dag/store.js';
-import type {Hash} from './hash.js';
-import {dropIDBStoreWithMemFallback} from './kv/idb-store-with-mem-fallback.js';
-import {MemStore} from './kv/mem-store.js';
-import type {Store as KVStore} from './kv/store.js';
-import type {PatchOperation} from './patch-operation.js';
+import type {JSONValue} from '../../shared/src/json.ts';
+import {must} from '../../shared/src/must.ts';
+import {randomUint64} from '../../shared/src/random-uint64.ts';
+import type {Cookie} from './cookies.ts';
+import type {Store} from './dag/store.ts';
+import type {Hash} from './hash.ts';
+import {dropIDBStoreWithMemFallback} from './kv/idb-store-with-mem-fallback.ts';
+import {MemStore} from './kv/mem-store.ts';
+import type {Store as KVStore} from './kv/store.ts';
+import type {PatchOperation} from './patch-operation.ts';
 import {
   setupForTest as setupIDBDatabasesStoreForTest,
   teardownForTest as teardownIDBDatabasesStoreForTest,
-} from './persist/idb-databases-store-db-name.js';
-import type {PullResponseV1} from './puller.js';
-import {ReplicacheImpl, type ReplicacheImplOptions} from './replicache-impl.js';
-import type {ReplicacheOptions} from './replicache-options.js';
+} from './persist/idb-databases-store-db-name.ts';
+import type {PullResponseV1} from './puller.ts';
+import {ReplicacheImpl, type ReplicacheImplOptions} from './replicache-impl.ts';
+import type {ReplicacheOptions} from './replicache-options.ts';
 import {
   Replicache,
   restoreMakeImplForTest,
   setMakeImplForTest,
-} from './replicache.js';
-import type {DiffComputationConfig} from './sync/diff.js';
-import type {ClientID} from './sync/ids.js';
-import type {WriteTransaction} from './transactions.js';
-import type {BeginPullResult, MutatorDefs} from './types.js';
+} from './replicache.ts';
+import type {DiffComputationConfig} from './sync/diff.ts';
+import type {ClientID} from './sync/ids.ts';
+import type {WriteTransaction} from './transactions.ts';
+import type {BeginPullResult, MutatorDefs} from './types.ts';
 
 // fetch-mock has invalid d.ts file so we removed that on npm install.
 // eslint-disable-next-line @typescript-eslint/ban-ts-comment
diff --git a/packages/replicache/src/transactions.ts b/packages/replicache/src/transactions.ts
index 129a651e0d..93ad3a221a 100644
--- a/packages/replicache/src/transactions.ts
+++ b/packages/replicache/src/transactions.ts
@@ -1,13 +1,13 @@
 import type {LogContext} from '@rocicorp/logger';
 import {greaterThan} from 'compare-utf8';
-import type {JSONValue, ReadonlyJSONValue} from '../../shared/src/json.js';
-import {type IndexKey, decodeIndexKey} from './db/index.js';
-import type {Read} from './db/read.js';
-import type {Write} from './db/write.js';
-import {deepFreeze} from './frozen-json.js';
-import type {IndexDefinition} from './index-defs.js';
-import type {ScanResult} from './scan-iterator.js';
-import {ScanResultImpl, fromKeyForIndexScanInternal} from './scan-iterator.js';
+import type {JSONValue, ReadonlyJSONValue} from '../../shared/src/json.ts';
+import {type IndexKey, decodeIndexKey} from './db/index.ts';
+import type {Read} from './db/read.ts';
+import type {Write} from './db/write.ts';
+import {deepFreeze} from './frozen-json.ts';
+import type {IndexDefinition} from './index-defs.ts';
+import type {ScanResult} from './scan-iterator.ts';
+import {ScanResultImpl, fromKeyForIndexScanInternal} from './scan-iterator.ts';
 import {
   type KeyTypeForScanOptions,
   type ScanIndexOptions,
@@ -15,10 +15,10 @@ import {
   type ScanOptions,
   isScanIndexOptions,
   toDbScanOptions,
-} from './scan-options.js';
-import type {ScanSubscriptionInfo} from './subscriptions.js';
-import type {ClientID} from './sync/ids.js';
-import {rejectIfClosed, throwIfClosed} from './transaction-closed-error.js';
+} from './scan-options.ts';
+import type {ScanSubscriptionInfo} from './subscriptions.ts';
+import type {ClientID} from './sync/ids.ts';
+import {rejectIfClosed, throwIfClosed} from './transaction-closed-error.ts';
 
 export type TransactionEnvironment = 'client' | 'server';
 export type TransactionLocation = TransactionEnvironment;
diff --git a/packages/replicache/src/types.ts b/packages/replicache/src/types.ts
index f07b41046a..11aa630525 100644
--- a/packages/replicache/src/types.ts
+++ b/packages/replicache/src/types.ts
@@ -1,8 +1,8 @@
-import type {MaybePromise} from '../../shared/src/types.js';
-import type {Hash} from './hash.js';
-import type {ReadonlyJSONValue, WriteTransaction} from './mod.js';
-import type {PullResponseV1, PullResponseV1Internal} from './puller.js';
-import type {ReadTransactionImpl} from './transactions.js';
+import type {MaybePromise} from '../../shared/src/types.ts';
+import type {Hash} from './hash.ts';
+import type {ReadonlyJSONValue, WriteTransaction} from './mod.ts';
+import type {PullResponseV1, PullResponseV1Internal} from './puller.ts';
+import type {ReadTransactionImpl} from './transactions.ts';
 
 export type BeginPullResult = {
   requestID: string;
diff --git a/packages/replicache/src/version.test.ts b/packages/replicache/src/version.test.ts
index 31baebad01..01ccd1da49 100644
--- a/packages/replicache/src/version.test.ts
+++ b/packages/replicache/src/version.test.ts
@@ -1,5 +1,5 @@
 import {expect, test} from 'vitest';
-import {version} from './version.js';
+import {version} from './version.ts';
 
 test('version', async () => {
   expect(version).is.string;
diff --git a/packages/replicache/src/watch.test.ts b/packages/replicache/src/watch.test.ts
index a8eb5d8a13..30a4ba1b17 100644
--- a/packages/replicache/src/watch.test.ts
+++ b/packages/replicache/src/watch.test.ts
@@ -1,14 +1,14 @@
 import * as sinon from 'sinon';
 import {describe, expect, test} from 'vitest';
-import type {JSONValue} from '../../shared/src/json.js';
-import {Queue} from '../../shared/src/queue.js';
+import type {JSONValue} from '../../shared/src/json.ts';
+import {Queue} from '../../shared/src/queue.ts';
 import {
   disableAllBackgroundProcesses,
   initReplicacheTesting,
   replicacheForTesting,
   tickAFewTimes,
-} from './test-util.js';
-import type {WriteTransaction} from './transactions.js';
+} from './test-util.ts';
+import type {WriteTransaction} from './transactions.ts';
 
 initReplicacheTesting();
 
diff --git a/packages/replicache/src/worker-test.ts b/packages/replicache/src/worker-test.ts
index d37028cf1a..b329001168 100644
--- a/packages/replicache/src/worker-test.ts
+++ b/packages/replicache/src/worker-test.ts
@@ -1,10 +1,10 @@
 // This test file is loaded by worker.test.ts
 
-import {assert} from '../../shared/src/asserts.js';
-import {deepEqual, type JSONValue} from '../../shared/src/json.js';
-import {asyncIterableToArray} from './async-iterable-to-array.js';
-import {Replicache} from './replicache.js';
-import type {ReadTransaction, WriteTransaction} from './transactions.js';
+import {assert} from '../../shared/src/asserts.ts';
+import {deepEqual, type JSONValue} from '../../shared/src/json.ts';
+import {asyncIterableToArray} from './async-iterable-to-array.ts';
+import {Replicache} from './replicache.ts';
+import type {ReadTransaction, WriteTransaction} from './transactions.ts';
 
 onmessage = async (e: MessageEvent) => {
   const {name} = e.data;
diff --git a/packages/replicache/src/worker.test.ts b/packages/replicache/src/worker.test.ts
index 8e2e1c89c0..c619464a2f 100644
--- a/packages/replicache/src/worker.test.ts
+++ b/packages/replicache/src/worker.test.ts
@@ -1,6 +1,6 @@
 import {afterEach, expect, test} from 'vitest';
-import {sleep} from '../../shared/src/sleep.js';
-import {closeAllReps, dbsToDrop, deleteAllDatabases} from './test-util.js';
+import {sleep} from '../../shared/src/sleep.ts';
+import {closeAllReps, dbsToDrop, deleteAllDatabases} from './test-util.ts';
 
 afterEach(async () => {
   await closeAllReps();
diff --git a/packages/replicache/vitest.config.ts b/packages/replicache/vitest.config.ts
index 960efc6d6b..12508b30d0 100644
--- a/packages/replicache/vitest.config.ts
+++ b/packages/replicache/vitest.config.ts
@@ -1 +1 @@
-export {default} from '../shared/src/tool/vitest-config.js';
+export {default} from '../shared/src/tool/vitest-config.ts';
diff --git a/packages/shared/src/arrays.test.ts b/packages/shared/src/arrays.test.ts
index 5fd8ad44c6..6cd02d5c43 100644
--- a/packages/shared/src/arrays.test.ts
+++ b/packages/shared/src/arrays.test.ts
@@ -1,5 +1,5 @@
 import {describe, expect, test} from 'vitest';
-import {defined} from './arrays.js';
+import {defined} from './arrays.ts';
 
 describe('shared/arrays', () => {
   type Case = {
diff --git a/packages/shared/src/base62.test.ts b/packages/shared/src/base62.test.ts
index fb9720d02e..b9bcc4b20d 100644
--- a/packages/shared/src/base62.test.ts
+++ b/packages/shared/src/base62.test.ts
@@ -1,5 +1,5 @@
 import {expect, test} from 'vitest';
-import {encode} from './base62.js';
+import {encode} from './base62.ts';
 
 test('it should encode base62', () => {
   expect(encode(0n)).toBe('0');
diff --git a/packages/shared/src/btree-set.test.ts b/packages/shared/src/btree-set.test.ts
index 210dcb8dbe..a90e27b574 100644
--- a/packages/shared/src/btree-set.test.ts
+++ b/packages/shared/src/btree-set.test.ts
@@ -1,7 +1,7 @@
 import {compareUTF8} from 'compare-utf8';
 import fc, {assert, property} from 'fast-check';
 import {expect, suite, test} from 'vitest';
-import {BTreeSet} from './btree-set.js';
+import {BTreeSet} from './btree-set.ts';
 
 test('delete', () => {
   const t = new BTreeSet<number>((a, b) => a - b);
diff --git a/packages/shared/src/btree-set.ts b/packages/shared/src/btree-set.ts
index 19c5ca30c5..c84041840d 100644
--- a/packages/shared/src/btree-set.ts
+++ b/packages/shared/src/btree-set.ts
@@ -1,4 +1,4 @@
-import {assert} from './asserts.js';
+import {assert} from './asserts.ts';
 
 const MAX_NODE_SIZE = 32;
 
diff --git a/packages/shared/src/buffer-sizer.test.ts b/packages/shared/src/buffer-sizer.test.ts
index f7869725e0..63a8e1329a 100644
--- a/packages/shared/src/buffer-sizer.test.ts
+++ b/packages/shared/src/buffer-sizer.test.ts
@@ -1,6 +1,6 @@
 import {LogContext} from '@rocicorp/logger';
 import {describe, expect, test} from 'vitest';
-import {BufferSizer} from './buffer-sizer.js';
+import {BufferSizer} from './buffer-sizer.ts';
 
 type Case = {
   name: string;
diff --git a/packages/shared/src/buffer-sizer.ts b/packages/shared/src/buffer-sizer.ts
index 8e9ea073dd..4db03cd931 100644
--- a/packages/shared/src/buffer-sizer.ts
+++ b/packages/shared/src/buffer-sizer.ts
@@ -1,5 +1,5 @@
 import type {LogContext} from '@rocicorp/logger';
-import {assert} from './asserts.js';
+import {assert} from './asserts.ts';
 
 export class BufferSizer {
   #bufferSizeMs: number;
diff --git a/packages/shared/src/deep-clone.test.ts b/packages/shared/src/deep-clone.test.ts
index 4bad2a8b0f..85027e5458 100644
--- a/packages/shared/src/deep-clone.test.ts
+++ b/packages/shared/src/deep-clone.test.ts
@@ -1,6 +1,6 @@
 import {expect, test} from 'vitest';
-import {deepClone} from './deep-clone.js';
-import type {JSONValue, ReadonlyJSONValue} from './json.js';
+import {deepClone} from './deep-clone.ts';
+import type {JSONValue, ReadonlyJSONValue} from './json.ts';
 
 test('deepClone', () => {
   const t = (v: ReadonlyJSONValue) => {
diff --git a/packages/shared/src/deep-clone.ts b/packages/shared/src/deep-clone.ts
index 2ba014cabb..453d329113 100644
--- a/packages/shared/src/deep-clone.ts
+++ b/packages/shared/src/deep-clone.ts
@@ -1,5 +1,5 @@
-import {hasOwn} from './has-own.js';
-import type {JSONValue, ReadonlyJSONValue} from './json.js';
+import {hasOwn} from './has-own.ts';
+import type {JSONValue, ReadonlyJSONValue} from './json.ts';
 
 export function deepClone(value: ReadonlyJSONValue): JSONValue {
   const seen: Array<ReadonlyJSONValue> = [];
diff --git a/packages/shared/src/document-visible.test.ts b/packages/shared/src/document-visible.test.ts
index f2c861b21e..e057995ff2 100644
--- a/packages/shared/src/document-visible.test.ts
+++ b/packages/shared/src/document-visible.test.ts
@@ -1,5 +1,5 @@
 import {afterEach, beforeEach, expect, test, vi} from 'vitest';
-import {getDocumentVisibilityWatcher} from './document-visible.js';
+import {getDocumentVisibilityWatcher} from './document-visible.ts';
 
 beforeEach(() => {
   vi.useFakeTimers();
diff --git a/packages/shared/src/events/connection-seconds.ts b/packages/shared/src/events/connection-seconds.ts
index 10c7ea79f3..0ef355d8f6 100644
--- a/packages/shared/src/events/connection-seconds.ts
+++ b/packages/shared/src/events/connection-seconds.ts
@@ -1,4 +1,4 @@
-import * as v from '../valita.js';
+import * as v from '../valita.ts';
 
 // Increment when making non-backwards compatible changes to the schema.
 const SCHEMA_VERSION = 2;
diff --git a/packages/shared/src/float-to-ordered-string.test.ts b/packages/shared/src/float-to-ordered-string.test.ts
index b5bc19edc5..adc0a8b6ae 100644
--- a/packages/shared/src/float-to-ordered-string.test.ts
+++ b/packages/shared/src/float-to-ordered-string.test.ts
@@ -3,7 +3,7 @@ import {expect, test} from 'vitest';
 import {
   decodeFloat64AsString,
   encodeFloat64AsString,
-} from './float-to-ordered-string.js';
+} from './float-to-ordered-string.ts';
 
 const cases = [
   [-0, '1y2p0ij32e8e7'],
diff --git a/packages/shared/src/float-to-ordered-string.ts b/packages/shared/src/float-to-ordered-string.ts
index f4754076bf..633af9fa09 100644
--- a/packages/shared/src/float-to-ordered-string.ts
+++ b/packages/shared/src/float-to-ordered-string.ts
@@ -1,5 +1,5 @@
-import {assert} from './asserts.js';
-import {parseBigInt} from './parse-big-int.js';
+import {assert} from './asserts.ts';
+import {parseBigInt} from './parse-big-int.ts';
 
 const view = new DataView(new ArrayBuffer(8));
 
diff --git a/packages/shared/src/headers.test.ts b/packages/shared/src/headers.test.ts
index a0d375f6e7..443d6b60b8 100644
--- a/packages/shared/src/headers.test.ts
+++ b/packages/shared/src/headers.test.ts
@@ -1,5 +1,5 @@
-import {test, expect} from 'vitest';
-import {decodeHeaderValue, encodeHeaderValue} from './headers.js';
+import {expect, test} from 'vitest';
+import {decodeHeaderValue, encodeHeaderValue} from './headers.ts';
 
 function testEncodeDecodeHeaderValue(value: string, expected: string): void {
   const encoded = encodeHeaderValue(value);
diff --git a/packages/shared/src/iterables.test.ts b/packages/shared/src/iterables.test.ts
index 4477e60f85..14f8e46061 100644
--- a/packages/shared/src/iterables.test.ts
+++ b/packages/shared/src/iterables.test.ts
@@ -1,6 +1,6 @@
-import {describe, expect, test} from 'vitest';
-import {mergeIterables, wrapIterable} from './iterables.js';
 import fc from 'fast-check';
+import {describe, expect, test} from 'vitest';
+import {mergeIterables, wrapIterable} from './iterables.ts';
 
 function* range(start = 0, end = Infinity, step = 1) {
   for (let i = start; i < end; i += step) {
diff --git a/packages/shared/src/iterables.ts b/packages/shared/src/iterables.ts
index e2560dff87..a6b097bb4e 100644
--- a/packages/shared/src/iterables.ts
+++ b/packages/shared/src/iterables.ts
@@ -1,4 +1,4 @@
-import {assert} from './asserts.js';
+import {assert} from './asserts.ts';
 
 export function* joinIterables<T>(...iters: Iterable<T>[]) {
   for (const iter of iters) {
diff --git a/packages/shared/src/json-schema.test.ts b/packages/shared/src/json-schema.test.ts
index 4be597c5d2..28c92ccce1 100644
--- a/packages/shared/src/json-schema.test.ts
+++ b/packages/shared/src/json-schema.test.ts
@@ -1,8 +1,8 @@
 import {expect, test} from 'vitest';
-import {assert} from './asserts.js';
-import {jsonObjectSchema, jsonSchema} from './json-schema.js';
-import * as v from './valita.js';
-import {parse} from './valita.js';
+import {assert} from './asserts.ts';
+import {jsonObjectSchema, jsonSchema} from './json-schema.ts';
+import * as v from './valita.ts';
+import {parse} from './valita.ts';
 
 test('json schema', () => {
   const t = <T>(s: v.Type<T>, v: unknown, message?: string) => {
diff --git a/packages/shared/src/json-schema.ts b/packages/shared/src/json-schema.ts
index 27f9bcfab1..b4358416ca 100644
--- a/packages/shared/src/json-schema.ts
+++ b/packages/shared/src/json-schema.ts
@@ -1,8 +1,8 @@
 import * as valita from '@badrap/valita';
-import {skipAssertJSONValue} from './config.js';
-import type {ReadonlyJSONObject, ReadonlyJSONValue} from './json.js';
-import {isJSONObject, isJSONValue} from './json.js';
-import * as v from './valita.js';
+import {skipAssertJSONValue} from './config.ts';
+import type {ReadonlyJSONObject, ReadonlyJSONValue} from './json.ts';
+import {isJSONObject, isJSONValue} from './json.ts';
+import * as v from './valita.ts';
 
 const path: (string | number)[] = [];
 
diff --git a/packages/shared/src/json.test.ts b/packages/shared/src/json.test.ts
index 4d1c90a8e5..0a984036a9 100644
--- a/packages/shared/src/json.test.ts
+++ b/packages/shared/src/json.test.ts
@@ -4,7 +4,7 @@ import {
   assertJSONValue,
   deepEqual,
   isJSONValue,
-} from './json.js';
+} from './json.ts';
 
 test('JSON deep equal', () => {
   const t = (
diff --git a/packages/shared/src/json.ts b/packages/shared/src/json.ts
index 2ae835d662..639439efcb 100644
--- a/packages/shared/src/json.ts
+++ b/packages/shared/src/json.ts
@@ -1,6 +1,6 @@
-import {assertObject, throwInvalidType} from './asserts.js';
-import {skipAssertJSONValue} from './config.js';
-import {hasOwn} from './has-own.js';
+import {assertObject, throwInvalidType} from './asserts.ts';
+import {skipAssertJSONValue} from './config.ts';
+import {hasOwn} from './has-own.ts';
 
 /** The values that can be represented in JSON */
 export type JSONValue =
diff --git a/packages/shared/src/mirror/is-supported-semver-range.test.ts b/packages/shared/src/mirror/is-supported-semver-range.test.ts
index b2c9ab2dc1..f3055d766b 100644
--- a/packages/shared/src/mirror/is-supported-semver-range.test.ts
+++ b/packages/shared/src/mirror/is-supported-semver-range.test.ts
@@ -1,6 +1,6 @@
 import {Range} from 'semver';
 import {expect, test} from 'vitest';
-import {isSupportedSemverRange} from './is-supported-semver-range.js';
+import {isSupportedSemverRange} from './is-supported-semver-range.ts';
 
 test('isSupportedSemverRange', () => {
   const t = (range: string, expected: boolean) =>
diff --git a/packages/shared/src/options.test.ts b/packages/shared/src/options.test.ts
index 3d3e66def4..20b70550a6 100644
--- a/packages/shared/src/options.test.ts
+++ b/packages/shared/src/options.test.ts
@@ -9,8 +9,8 @@ import {
   parseOptionsAdvanced,
   type Config,
   type Options,
-} from './options.js';
-import * as v from './valita.js';
+} from './options.ts';
+import * as v from './valita.ts';
 
 const options = {
   port: {
diff --git a/packages/shared/src/options.ts b/packages/shared/src/options.ts
index df61f6a88c..06ef37a422 100644
--- a/packages/shared/src/options.ts
+++ b/packages/shared/src/options.ts
@@ -6,9 +6,9 @@ import commandLineUsage from 'command-line-usage';
 import {createDefu} from 'defu';
 import {toKebabCase, toSnakeCase} from 'kasi';
 import {stripVTControlCharacters as stripAnsi} from 'node:util';
-import {assert} from './asserts.js';
-import {must} from './must.js';
-import * as v from './valita.js';
+import {assert} from './asserts.ts';
+import {must} from './must.ts';
+import * as v from './valita.ts';
 
 type Primitive = number | string | boolean;
 type Value = Primitive | Array<Primitive>;
diff --git a/packages/shared/src/parse-big-int.test.ts b/packages/shared/src/parse-big-int.test.ts
index aa06d6bca0..22b063fe9d 100644
--- a/packages/shared/src/parse-big-int.test.ts
+++ b/packages/shared/src/parse-big-int.test.ts
@@ -1,6 +1,6 @@
 import fc from 'fast-check';
 import {expect, test} from 'vitest';
-import {parseBigInt} from './parse-big-int.js';
+import {parseBigInt} from './parse-big-int.ts';
 
 const cases = [
   ['0', 10, 0n],
diff --git a/packages/shared/src/queue.test.ts b/packages/shared/src/queue.test.ts
index 0848cbcbde..9e418daea5 100644
--- a/packages/shared/src/queue.test.ts
+++ b/packages/shared/src/queue.test.ts
@@ -1,6 +1,6 @@
 import {resolver} from '@rocicorp/resolver';
 import {describe, expect, test} from 'vitest';
-import {Queue} from './queue.js';
+import {Queue} from './queue.ts';
 
 describe('Queue', () => {
   test('dequeues enqueued value', async () => {
diff --git a/packages/shared/src/queue.ts b/packages/shared/src/queue.ts
index ccadee52ea..2288df08c5 100644
--- a/packages/shared/src/queue.ts
+++ b/packages/shared/src/queue.ts
@@ -1,5 +1,5 @@
 import {resolver, type Resolver} from '@rocicorp/resolver';
-import {assert} from './asserts.js';
+import {assert} from './asserts.ts';
 
 /**
  * A Queue allows the consumers to await (possibly future) values,
diff --git a/packages/shared/src/set-util.test.ts b/packages/shared/src/set-util.test.ts
index de5e63cebd..e113ccf89b 100644
--- a/packages/shared/src/set-util.test.ts
+++ b/packages/shared/src/set-util.test.ts
@@ -5,7 +5,7 @@ import {
   intersection,
   symmetricDifferences,
   union,
-} from './set-utils.js';
+} from './set-utils.ts';
 
 describe('Set', () => {
   test('equals', () => {
diff --git a/packages/shared/src/sleep.test.ts b/packages/shared/src/sleep.test.ts
index 692c65636e..d551a90181 100644
--- a/packages/shared/src/sleep.test.ts
+++ b/packages/shared/src/sleep.test.ts
@@ -1,7 +1,7 @@
 import {type SinonFakeTimers, useFakeTimers} from 'sinon';
 import {afterEach, beforeEach, expect, test} from 'vitest';
-import {AbortError} from './abort-error.js';
-import {sleep, sleepWithAbort} from './sleep.js';
+import {AbortError} from './abort-error.ts';
+import {sleep, sleepWithAbort} from './sleep.ts';
 
 let clock: SinonFakeTimers;
 beforeEach(() => {
diff --git a/packages/shared/src/sleep.ts b/packages/shared/src/sleep.ts
index a37eaee8f8..fa3be5e437 100644
--- a/packages/shared/src/sleep.ts
+++ b/packages/shared/src/sleep.ts
@@ -1,5 +1,5 @@
 import {resolver} from '@rocicorp/resolver';
-import {AbortError} from './abort-error.js';
+import {AbortError} from './abort-error.ts';
 
 const promiseVoid = Promise.resolve();
 const promiseNever = new Promise<void>(() => undefined);
diff --git a/packages/shared/src/sorted-entries.ts b/packages/shared/src/sorted-entries.ts
index 8936a6cd59..328e86ee58 100644
--- a/packages/shared/src/sorted-entries.ts
+++ b/packages/shared/src/sorted-entries.ts
@@ -1,4 +1,4 @@
-import {stringCompare} from './string-compare.js';
+import {stringCompare} from './string-compare.ts';
 
 // eslint-disable-next-line @typescript-eslint/no-explicit-any
 export function sortedEntries<T extends Record<string, any>>(
diff --git a/packages/shared/src/tool/get-external-from-package-json.js b/packages/shared/src/tool/get-external-from-package-json.js
index d3483aeabe..64a9326e32 100644
--- a/packages/shared/src/tool/get-external-from-package-json.js
+++ b/packages/shared/src/tool/get-external-from-package-json.js
@@ -3,9 +3,9 @@
 /* eslint-env es2022 */
 
 import {readFile} from 'node:fs/promises';
-import {packageUp} from 'package-up';
 import {resolve as resolvePath} from 'node:path';
 import {fileURLToPath} from 'node:url';
+import {packageUp} from 'package-up';
 import {isInternalPackage} from './internal-packages.js';
 
 /**
diff --git a/packages/shared/src/valita.test.ts b/packages/shared/src/valita.test.ts
index 838d998eb4..b6c257b890 100644
--- a/packages/shared/src/valita.test.ts
+++ b/packages/shared/src/valita.test.ts
@@ -1,7 +1,7 @@
 import {expect, test} from 'vitest';
-import {assert} from './asserts.js';
-import * as v from './valita.js';
-import {parse} from './valita.js';
+import {assert} from './asserts.ts';
+import * as v from './valita.ts';
+import {parse} from './valita.ts';
 
 const t = <T>(s: v.Type<T>, val: unknown, message?: string) => {
   const r1 = v.test(val, s);
diff --git a/packages/zero-advanced/src/mod.ts b/packages/zero-advanced/src/mod.ts
index 7ae96a0739..463a0728d4 100644
--- a/packages/zero-advanced/src/mod.ts
+++ b/packages/zero-advanced/src/mod.ts
@@ -1,8 +1,8 @@
-export type {Change} from '../../zql/src/ivm/change.js';
-export type {Input, Output} from '../../zql/src/ivm/operator.js';
-export {applyChange} from '../../zql/src/ivm/view-apply-change.js';
-export type {Entry, Format, View, ViewFactory} from '../../zql/src/ivm/view.js';
-export type {AdvancedQuery} from '../../zql/src/query/query-internal.js';
-export type {Query, HumanReadable} from '../../zql/src/query/query.js';
-export type {TableSchema} from '../../zero-schema/src/table-schema.js';
-export type {ZeroAdvancedOptions} from '../../zero-client/src/client/options.js';
+export type {ZeroAdvancedOptions} from '../../zero-client/src/client/options.ts';
+export type {TableSchema} from '../../zero-schema/src/table-schema.ts';
+export type {Change} from '../../zql/src/ivm/change.ts';
+export type {Input, Output} from '../../zql/src/ivm/operator.ts';
+export {applyChange} from '../../zql/src/ivm/view-apply-change.ts';
+export type {Entry, Format, View, ViewFactory} from '../../zql/src/ivm/view.ts';
+export type {AdvancedQuery} from '../../zql/src/query/query-internal.ts';
+export type {HumanReadable, Query} from '../../zql/src/query/query.ts';
diff --git a/packages/zero-cache/bench/bench.ts b/packages/zero-cache/bench/bench.ts
index d277ac7cec..876d76b86a 100644
--- a/packages/zero-cache/bench/bench.ts
+++ b/packages/zero-cache/bench/bench.ts
@@ -1,4 +1,4 @@
 import 'dotenv/config';
-import {bench} from './benchmark.js';
+import {bench} from './benchmark.ts';
 
 bench({dbFile: '/tmp/bench/zbugs-sync-replica.db'});
diff --git a/packages/zero-cache/bench/benchmark.ts b/packages/zero-cache/bench/benchmark.ts
index 2772d300c6..08917349e2 100644
--- a/packages/zero-cache/bench/benchmark.ts
+++ b/packages/zero-cache/bench/benchmark.ts
@@ -1,15 +1,15 @@
 // create a zql query
 
-import {assert} from '../../shared/src/asserts.js';
-import {createSilentLogContext} from '../../shared/src/logging-test-utils.js';
-import {MemoryStorage} from '../../zql/src/ivm/memory-storage.js';
-import type {Source} from '../../zql/src/ivm/source.js';
-import {newQuery, type QueryDelegate} from '../../zql/src/query/query-impl.js';
-import {Database} from '../../zqlite/src/db.js';
-import {TableSource} from '../../zqlite/src/table-source.js';
-import {computeZqlSpecs} from '../src/db/lite-tables.js';
-import {mapLiteDataTypeToZqlSchemaValue} from '../src/types/lite.js';
-import {schema} from './schema.js';
+import {assert} from '../../shared/src/asserts.ts';
+import {createSilentLogContext} from '../../shared/src/logging-test-utils.ts';
+import {MemoryStorage} from '../../zql/src/ivm/memory-storage.ts';
+import type {Source} from '../../zql/src/ivm/source.ts';
+import {newQuery, type QueryDelegate} from '../../zql/src/query/query-impl.ts';
+import {Database} from '../../zqlite/src/db.ts';
+import {TableSource} from '../../zqlite/src/table-source.ts';
+import {computeZqlSpecs} from '../src/db/lite-tables.ts';
+import {mapLiteDataTypeToZqlSchemaValue} from '../src/types/lite.ts';
+import {schema} from './schema.ts';
 
 type Options = {
   dbFile: string;
diff --git a/packages/zero-cache/bench/double.ts b/packages/zero-cache/bench/double.ts
index dc5b8af387..8b4071815a 100644
--- a/packages/zero-cache/bench/double.ts
+++ b/packages/zero-cache/bench/double.ts
@@ -1,6 +1,6 @@
 import 'dotenv/config';
-import {createSilentLogContext} from '../../shared/src/logging-test-utils.js';
-import {Database} from '../../zqlite/src/db.js';
+import {createSilentLogContext} from '../../shared/src/logging-test-utils.ts';
+import {Database} from '../../zqlite/src/db.ts';
 
 type Options = {
   dbFile: string;
diff --git a/packages/zero-cache/bench/schema.ts b/packages/zero-cache/bench/schema.ts
index dc41787f46..b5c5a1ad94 100644
--- a/packages/zero-cache/bench/schema.ts
+++ b/packages/zero-cache/bench/schema.ts
@@ -1,10 +1,10 @@
-import {relationships} from '../../zero-schema/src/builder/relationship-builder.js';
-import {createSchema} from '../../zero-schema/src/builder/schema-builder.js';
+import {relationships} from '../../zero-schema/src/builder/relationship-builder.ts';
+import {createSchema} from '../../zero-schema/src/builder/schema-builder.ts';
 import {
   number,
   string,
   table,
-} from '../../zero-schema/src/builder/table-builder.js';
+} from '../../zero-schema/src/builder/table-builder.ts';
 
 const member = table('member')
   .columns({
diff --git a/packages/zero-cache/bench/wal-bench.ts b/packages/zero-cache/bench/wal-bench.ts
index f7ca8b1db9..2fec5e0808 100644
--- a/packages/zero-cache/bench/wal-bench.ts
+++ b/packages/zero-cache/bench/wal-bench.ts
@@ -1,5 +1,5 @@
 import 'dotenv/config';
-import {walBenchmark} from './wal-benchmark.js';
+import {walBenchmark} from './wal-benchmark.ts';
 
 walBenchmark({
   dbFile: '/tmp/bench/zbugs-sync-replica.db',
diff --git a/packages/zero-cache/bench/wal-benchmark.ts b/packages/zero-cache/bench/wal-benchmark.ts
index 6e71d16b84..c62e6f928a 100644
--- a/packages/zero-cache/bench/wal-benchmark.ts
+++ b/packages/zero-cache/bench/wal-benchmark.ts
@@ -1,8 +1,8 @@
 import {statSync} from 'fs';
-import {createSilentLogContext} from '../../shared/src/logging-test-utils.js';
-import {randInt} from '../../shared/src/rand.js';
-import {Database, Statement} from '../../zqlite/src/db.js';
-import {bench} from './benchmark.js';
+import {createSilentLogContext} from '../../shared/src/logging-test-utils.ts';
+import {randInt} from '../../shared/src/rand.ts';
+import {Database, Statement} from '../../zqlite/src/db.ts';
+import {bench} from './benchmark.ts';
 
 const lc = createSilentLogContext();
 
diff --git a/packages/zero-cache/bench/wal2-bench.ts b/packages/zero-cache/bench/wal2-bench.ts
index 6deb99bae0..59fd1810ef 100644
--- a/packages/zero-cache/bench/wal2-bench.ts
+++ b/packages/zero-cache/bench/wal2-bench.ts
@@ -1,5 +1,5 @@
 import 'dotenv/config';
-import {walBenchmark} from './wal-benchmark.js';
+import {walBenchmark} from './wal-benchmark.ts';
 
 walBenchmark({
   dbFile: '/tmp/bench/zbugs-sync-replica.db',
diff --git a/packages/zero-cache/src/auth/jwt.test.ts b/packages/zero-cache/src/auth/jwt.test.ts
index 0e3fdf92dd..3b27b1447b 100644
--- a/packages/zero-cache/src/auth/jwt.test.ts
+++ b/packages/zero-cache/src/auth/jwt.test.ts
@@ -1,8 +1,8 @@
-import {describe, expect, test} from 'vitest';
-import type {AuthConfig} from '../config/zero-config.js';
-import {verifyToken} from './jwt.js';
 import {exportJWK, generateKeyPair, SignJWT, type JWTPayload} from 'jose';
-import {must} from '../../../shared/src/must.js';
+import {describe, expect, test} from 'vitest';
+import {must} from '../../../shared/src/must.ts';
+import type {AuthConfig} from '../config/zero-config.ts';
+import {verifyToken} from './jwt.ts';
 
 async function generateJwkKeys() {
   const {publicKey, privateKey} = await generateKeyPair('PS256');
diff --git a/packages/zero-cache/src/auth/jwt.ts b/packages/zero-cache/src/auth/jwt.ts
index c6b8911b0e..51df0edd92 100644
--- a/packages/zero-cache/src/auth/jwt.ts
+++ b/packages/zero-cache/src/auth/jwt.ts
@@ -6,7 +6,7 @@ import {
   type JWTPayload,
   type KeyLike,
 } from 'jose';
-import type {AuthConfig} from '../config/zero-config.js';
+import type {AuthConfig} from '../config/zero-config.ts';
 
 export function authIsConfigured(config: AuthConfig) {
   return (
diff --git a/packages/zero-cache/src/auth/load-schema.ts b/packages/zero-cache/src/auth/load-schema.ts
index baffb46850..dd9c190ac9 100644
--- a/packages/zero-cache/src/auth/load-schema.ts
+++ b/packages/zero-cache/src/auth/load-schema.ts
@@ -1,9 +1,9 @@
-import path from 'node:path';
-import {type PermissionsConfig} from '../../../zero-schema/src/compiled-permissions.js';
-import type {Schema} from '../../../zero-schema/src/builder/schema-builder.js';
 import {readFile} from 'node:fs/promises';
-import type {ZeroConfig} from '../config/zero-config.js';
-import {parseSchema} from '../../../zero-schema/src/schema-config.js';
+import path from 'node:path';
+import type {Schema} from '../../../zero-schema/src/builder/schema-builder.ts';
+import {type PermissionsConfig} from '../../../zero-schema/src/compiled-permissions.ts';
+import {parseSchema} from '../../../zero-schema/src/schema-config.ts';
+import type {ZeroConfig} from '../config/zero-config.ts';
 
 let loadedSchema:
   | Promise<{
diff --git a/packages/zero-cache/src/auth/read-authorizer.query.test.ts b/packages/zero-cache/src/auth/read-authorizer.query.test.ts
index c7b498a723..1db7e11ff9 100644
--- a/packages/zero-cache/src/auth/read-authorizer.query.test.ts
+++ b/packages/zero-cache/src/auth/read-authorizer.query.test.ts
@@ -1,47 +1,47 @@
 /* eslint-disable @typescript-eslint/naming-convention */
 /* eslint-disable arrow-body-style */
 import {beforeEach, describe, expect, test} from 'vitest';
-import {assert} from '../../../shared/src/asserts.js';
-import {createSilentLogContext} from '../../../shared/src/logging-test-utils.js';
-import {must} from '../../../shared/src/must.js';
+import {assert} from '../../../shared/src/asserts.ts';
+import {createSilentLogContext} from '../../../shared/src/logging-test-utils.ts';
+import {must} from '../../../shared/src/must.ts';
 import type {
   DeleteOp,
   InsertOp,
   UpdateOp,
-} from '../../../zero-protocol/src/push.js';
-import {definePermissions} from '../../../zero-schema/src/permissions.js';
-import type {ValueType} from '../../../zero-schema/src/table-schema.js';
+} from '../../../zero-protocol/src/push.ts';
+import {relationships} from '../../../zero-schema/src/builder/relationship-builder.ts';
+import {
+  createSchema,
+  type Schema as ZeroSchema,
+} from '../../../zero-schema/src/builder/schema-builder.ts';
+import {
+  boolean,
+  number,
+  string,
+  table,
+} from '../../../zero-schema/src/builder/table-builder.ts';
+import {definePermissions} from '../../../zero-schema/src/permissions.ts';
+import type {ValueType} from '../../../zero-schema/src/table-schema.ts';
 import {
   bindStaticParameters,
   buildPipeline,
-} from '../../../zql/src/builder/builder.js';
-import {Catch} from '../../../zql/src/ivm/catch.js';
-import type {Node} from '../../../zql/src/ivm/data.js';
-import {MemoryStorage} from '../../../zql/src/ivm/memory-storage.js';
-import type {Source} from '../../../zql/src/ivm/source.js';
-import type {ExpressionBuilder} from '../../../zql/src/query/expression.js';
+} from '../../../zql/src/builder/builder.ts';
+import {Catch} from '../../../zql/src/ivm/catch.ts';
+import type {Node} from '../../../zql/src/ivm/data.ts';
+import {MemoryStorage} from '../../../zql/src/ivm/memory-storage.ts';
+import type {Source} from '../../../zql/src/ivm/source.ts';
+import type {ExpressionBuilder} from '../../../zql/src/query/expression.ts';
 import {
   completedAstSymbol,
   newQuery,
   QueryImpl,
   type QueryDelegate,
-} from '../../../zql/src/query/query-impl.js';
-import type {Query, Row} from '../../../zql/src/query/query.js';
-import {Database} from '../../../zqlite/src/db.js';
-import {TableSource} from '../../../zqlite/src/table-source.js';
-import {transformQuery} from './read-authorizer.js';
-import {WriteAuthorizerImpl} from './write-authorizer.js';
-import {
-  boolean,
-  number,
-  string,
-  table,
-} from '../../../zero-schema/src/builder/table-builder.js';
-import {relationships} from '../../../zero-schema/src/builder/relationship-builder.js';
-import {
-  createSchema,
-  type Schema as ZeroSchema,
-} from '../../../zero-schema/src/builder/schema-builder.js';
+} from '../../../zql/src/query/query-impl.ts';
+import type {Query, Row} from '../../../zql/src/query/query.ts';
+import {Database} from '../../../zqlite/src/db.ts';
+import {TableSource} from '../../../zqlite/src/table-source.ts';
+import {transformQuery} from './read-authorizer.ts';
+import {WriteAuthorizerImpl} from './write-authorizer.ts';
 
 const user = table('user')
   .columns({
diff --git a/packages/zero-cache/src/auth/read-authorizer.test.ts b/packages/zero-cache/src/auth/read-authorizer.test.ts
index 59dd5fb163..bcb4df06e8 100644
--- a/packages/zero-cache/src/auth/read-authorizer.test.ts
+++ b/packages/zero-cache/src/auth/read-authorizer.test.ts
@@ -1,19 +1,19 @@
 import {describe, expect, test} from 'vitest';
-import {definePermissions} from '../../../zero-schema/src/permissions.js';
-import type {ExpressionBuilder} from '../../../zql/src/query/expression.js';
+import {must} from '../../../shared/src/must.ts';
+import {relationships} from '../../../zero-schema/src/builder/relationship-builder.ts';
+import type {Schema as ZeroSchema} from '../../../zero-schema/src/builder/schema-builder.ts';
+import {createSchema} from '../../../zero-schema/src/builder/schema-builder.ts';
+import {string, table} from '../../../zero-schema/src/builder/table-builder.ts';
+import {definePermissions} from '../../../zero-schema/src/permissions.ts';
+import type {ExpressionBuilder} from '../../../zql/src/query/expression.ts';
 import {
   astForTestingSymbol,
   newQuery,
   QueryImpl,
   type QueryDelegate,
-} from '../../../zql/src/query/query-impl.js';
-import type {Query} from '../../../zql/src/query/query.js';
-import {transformQuery} from './read-authorizer.js';
-import {must} from '../../../shared/src/must.js';
-import {string, table} from '../../../zero-schema/src/builder/table-builder.js';
-import {relationships} from '../../../zero-schema/src/builder/relationship-builder.js';
-import {createSchema} from '../../../zero-schema/src/builder/schema-builder.js';
-import type {Schema as ZeroSchema} from '../../../zero-schema/src/builder/schema-builder.js';
+} from '../../../zql/src/query/query-impl.ts';
+import type {Query} from '../../../zql/src/query/query.ts';
+import {transformQuery} from './read-authorizer.ts';
 
 const mockDelegate = {} as QueryDelegate;
 
diff --git a/packages/zero-cache/src/auth/read-authorizer.ts b/packages/zero-cache/src/auth/read-authorizer.ts
index ef80261ae0..3eefa2a2e5 100644
--- a/packages/zero-cache/src/auth/read-authorizer.ts
+++ b/packages/zero-cache/src/auth/read-authorizer.ts
@@ -1,10 +1,10 @@
 import type {JWTPayload} from 'jose';
-import {hashOfAST} from '../../../zero-protocol/src/ast-hash.js';
-import type {AST, Condition} from '../../../zero-protocol/src/ast.js';
-import type {PermissionsConfig} from '../../../zero-schema/src/compiled-permissions.js';
-import {bindStaticParameters} from '../../../zql/src/builder/builder.js';
-import {dnf} from '../../../zql/src/query/dnf.js';
-import type {JSONValue} from '../../../shared/src/json.js';
+import type {JSONValue} from '../../../shared/src/json.ts';
+import {hashOfAST} from '../../../zero-protocol/src/ast-hash.ts';
+import type {AST, Condition} from '../../../zero-protocol/src/ast.ts';
+import type {PermissionsConfig} from '../../../zero-schema/src/compiled-permissions.ts';
+import {bindStaticParameters} from '../../../zql/src/builder/builder.ts';
+import {dnf} from '../../../zql/src/query/dnf.ts';
 
 export type TransformedAndHashed =
   | {
diff --git a/packages/zero-cache/src/auth/write-authorizer.test.ts b/packages/zero-cache/src/auth/write-authorizer.test.ts
index 6481dbd092..bd1fd1be66 100644
--- a/packages/zero-cache/src/auth/write-authorizer.test.ts
+++ b/packages/zero-cache/src/auth/write-authorizer.test.ts
@@ -1,15 +1,15 @@
 import {beforeEach, describe, expect, test} from 'vitest';
-import {createSilentLogContext} from '../../../shared/src/logging-test-utils.js';
-import {Database} from '../../../zqlite/src/db.js';
-import {WriteAuthorizerImpl} from './write-authorizer.js';
-import type {Rule} from '../../../zero-schema/src/compiled-permissions.js';
+import {createSilentLogContext} from '../../../shared/src/logging-test-utils.ts';
 import type {
   DeleteOp,
   InsertOp,
   UpdateOp,
-} from '../../../zero-protocol/src/push.js';
-import {createSchema} from '../../../zero-schema/src/builder/schema-builder.js';
-import {string, table} from '../../../zero-schema/src/builder/table-builder.js';
+} from '../../../zero-protocol/src/push.ts';
+import {createSchema} from '../../../zero-schema/src/builder/schema-builder.ts';
+import {string, table} from '../../../zero-schema/src/builder/table-builder.ts';
+import type {Rule} from '../../../zero-schema/src/compiled-permissions.ts';
+import {Database} from '../../../zqlite/src/db.ts';
+import {WriteAuthorizerImpl} from './write-authorizer.ts';
 
 const lc = createSilentLogContext();
 
diff --git a/packages/zero-cache/src/auth/write-authorizer.ts b/packages/zero-cache/src/auth/write-authorizer.ts
index 4d3642dddf..fdcba80434 100644
--- a/packages/zero-cache/src/auth/write-authorizer.ts
+++ b/packages/zero-cache/src/auth/write-authorizer.ts
@@ -4,47 +4,47 @@ import type {JWTPayload} from 'jose';
 import {tmpdir} from 'node:os';
 import path from 'node:path';
 import {pid} from 'node:process';
-import {assert} from '../../../shared/src/asserts.js';
-import type {JSONValue} from '../../../shared/src/json.js';
-import {randInt} from '../../../shared/src/rand.js';
-import * as v from '../../../shared/src/valita.js';
-import type {Condition} from '../../../zero-protocol/src/ast.js';
+import {assert} from '../../../shared/src/asserts.ts';
+import type {JSONValue} from '../../../shared/src/json.ts';
+import {randInt} from '../../../shared/src/rand.ts';
+import * as v from '../../../shared/src/valita.ts';
+import type {Condition} from '../../../zero-protocol/src/ast.ts';
 import type {
   CRUDOp,
   DeleteOp,
   InsertOp,
   UpdateOp,
   UpsertOp,
-} from '../../../zero-protocol/src/mod.js';
+} from '../../../zero-protocol/src/mod.ts';
 import {
   primaryKeyValueSchema,
   type PrimaryKeyValue,
-} from '../../../zero-protocol/src/primary-key.js';
-import type {Schema} from '../../../zero-schema/src/builder/schema-builder.js';
+} from '../../../zero-protocol/src/primary-key.ts';
+import type {Schema} from '../../../zero-schema/src/builder/schema-builder.ts';
 import type {
   PermissionsConfig,
   Policy,
-} from '../../../zero-schema/src/compiled-permissions.js';
-import type {BuilderDelegate} from '../../../zql/src/builder/builder.js';
+} from '../../../zero-schema/src/compiled-permissions.ts';
+import type {BuilderDelegate} from '../../../zql/src/builder/builder.ts';
 import {
   bindStaticParameters,
   buildPipeline,
-} from '../../../zql/src/builder/builder.js';
-import {AuthQuery, authQuery} from '../../../zql/src/query/auth-query.js';
-import {dnf} from '../../../zql/src/query/dnf.js';
-import type {Query} from '../../../zql/src/query/query.js';
-import {Database} from '../../../zqlite/src/db.js';
-import {compile, sql} from '../../../zqlite/src/internal/sql.js';
+} from '../../../zql/src/builder/builder.ts';
+import {AuthQuery, authQuery} from '../../../zql/src/query/auth-query.ts';
+import {dnf} from '../../../zql/src/query/dnf.ts';
+import type {Query} from '../../../zql/src/query/query.ts';
+import {Database} from '../../../zqlite/src/db.ts';
+import {compile, sql} from '../../../zqlite/src/internal/sql.ts';
 import {
   fromSQLiteTypes,
   TableSource,
-} from '../../../zqlite/src/table-source.js';
-import type {ZeroConfig} from '../config/zero-config.js';
-import {computeZqlSpecs} from '../db/lite-tables.js';
-import type {LiteAndZqlSpec} from '../db/specs.js';
-import {StatementRunner} from '../db/statements.js';
-import {DatabaseStorage} from '../services/view-syncer/database-storage.js';
-import {mapLiteDataTypeToZqlSchemaValue} from '../types/lite.js';
+} from '../../../zqlite/src/table-source.ts';
+import type {ZeroConfig} from '../config/zero-config.ts';
+import {computeZqlSpecs} from '../db/lite-tables.ts';
+import type {LiteAndZqlSpec} from '../db/specs.ts';
+import {StatementRunner} from '../db/statements.ts';
+import {DatabaseStorage} from '../services/view-syncer/database-storage.ts';
+import {mapLiteDataTypeToZqlSchemaValue} from '../types/lite.ts';
 
 type Phase = 'preMutation' | 'postMutation';
 
diff --git a/packages/zero-cache/src/config/zero-config.test.ts b/packages/zero-cache/src/config/zero-config.test.ts
index fc3398a493..4606d9c9d5 100644
--- a/packages/zero-cache/src/config/zero-config.test.ts
+++ b/packages/zero-cache/src/config/zero-config.test.ts
@@ -1,7 +1,7 @@
 import {stripVTControlCharacters as stripAnsi} from 'node:util';
 import {expect, test, vi} from 'vitest';
-import {parseOptions} from '../../../shared/src/options.js';
-import {zeroOptions} from './zero-config.js';
+import {parseOptions} from '../../../shared/src/options.ts';
+import {zeroOptions} from './zero-config.ts';
 
 class ExitAfterUsage extends Error {}
 const exit = () => {
diff --git a/packages/zero-cache/src/config/zero-config.ts b/packages/zero-cache/src/config/zero-config.ts
index d678634c50..2bf5f27cb5 100644
--- a/packages/zero-cache/src/config/zero-config.ts
+++ b/packages/zero-cache/src/config/zero-config.ts
@@ -2,10 +2,10 @@
  * These types represent the _compiled_ config whereas `define-config` types represent the _source_ config.
  */
 
-import {parseOptions, type Config} from '../../../shared/src/options.js';
-import * as v from '../../../shared/src/valita.js';
-import {runtimeDebugFlags} from '../../../zqlite/src/runtime-debug.js';
-import {singleProcessMode} from '../types/processes.js';
+import {parseOptions, type Config} from '../../../shared/src/options.ts';
+import * as v from '../../../shared/src/valita.ts';
+import {runtimeDebugFlags} from '../../../zqlite/src/runtime-debug.ts';
+import {singleProcessMode} from '../types/processes.ts';
 
 /**
  * Configures the view of the upstream database replicated to this zero-cache.
diff --git a/packages/zero-cache/src/db/begin-concurrent.test.ts b/packages/zero-cache/src/db/begin-concurrent.test.ts
index 5ff53b44c8..1607c44909 100644
--- a/packages/zero-cache/src/db/begin-concurrent.test.ts
+++ b/packages/zero-cache/src/db/begin-concurrent.test.ts
@@ -1,6 +1,6 @@
 import {afterEach, beforeEach, describe, expect, test} from 'vitest';
-import {createSilentLogContext} from '../../../shared/src/logging-test-utils.js';
-import {DbFile} from '../test/lite.js';
+import {createSilentLogContext} from '../../../shared/src/logging-test-utils.ts';
+import {DbFile} from '../test/lite.ts';
 
 describe('db/begin-concurrent', () => {
   let dbFile: DbFile;
diff --git a/packages/zero-cache/src/db/create.pg-test.ts b/packages/zero-cache/src/db/create.pg-test.ts
index fc56b3ffe2..4c3b249737 100644
--- a/packages/zero-cache/src/db/create.pg-test.ts
+++ b/packages/zero-cache/src/db/create.pg-test.ts
@@ -1,15 +1,15 @@
 import type postgres from 'postgres';
 import {afterAll, afterEach, beforeEach, describe, expect, test} from 'vitest';
-import {createSilentLogContext} from '../../../shared/src/logging-test-utils.js';
-import {Database} from '../../../zqlite/src/db.js';
-import {getPublicationInfo} from '../services/change-source/pg/schema/published.js';
-import {testDBs} from '../test/db.js';
-import {createTableStatement} from './create.js';
-import {listTables} from './lite-tables.js';
-import {mapPostgresToLite} from './pg-to-lite.js';
-import * as PostgresTypeClass from './postgres-type-class-enum.js';
-import {stripCommentsAndWhitespace} from './query-test-util.js';
-import {type LiteTableSpec, type TableSpec} from './specs.js';
+import {createSilentLogContext} from '../../../shared/src/logging-test-utils.ts';
+import {Database} from '../../../zqlite/src/db.ts';
+import {getPublicationInfo} from '../services/change-source/pg/schema/published.ts';
+import {testDBs} from '../test/db.ts';
+import {createTableStatement} from './create.ts';
+import {listTables} from './lite-tables.ts';
+import {mapPostgresToLite} from './pg-to-lite.ts';
+import * as PostgresTypeClass from './postgres-type-class-enum.ts';
+import {stripCommentsAndWhitespace} from './query-test-util.ts';
+import {type LiteTableSpec, type TableSpec} from './specs.ts';
 
 describe('tables/create', () => {
   type Case = {
diff --git a/packages/zero-cache/src/db/create.ts b/packages/zero-cache/src/db/create.ts
index d2746cc447..760ee2c03a 100644
--- a/packages/zero-cache/src/db/create.ts
+++ b/packages/zero-cache/src/db/create.ts
@@ -1,10 +1,10 @@
-import {id, idList} from '../types/sql.js';
+import {id, idList} from '../types/sql.ts';
 import type {
   ColumnSpec,
   LiteIndexSpec,
   LiteTableSpec,
   TableSpec,
-} from './specs.js';
+} from './specs.ts';
 
 export function columnDef(spec: ColumnSpec) {
   const parts = [id(spec.dataType)];
diff --git a/packages/zero-cache/src/db/lite-tables.test.ts b/packages/zero-cache/src/db/lite-tables.test.ts
index c9106f0521..b195d82b01 100644
--- a/packages/zero-cache/src/db/lite-tables.test.ts
+++ b/packages/zero-cache/src/db/lite-tables.test.ts
@@ -1,8 +1,8 @@
 import {describe, expect, test} from 'vitest';
-import {createSilentLogContext} from '../../../shared/src/logging-test-utils.js';
-import {Database} from '../../../zqlite/src/db.js';
-import {computeZqlSpecs, listIndexes, listTables} from './lite-tables.js';
-import type {LiteIndexSpec, LiteTableSpec} from './specs.js';
+import {createSilentLogContext} from '../../../shared/src/logging-test-utils.ts';
+import {Database} from '../../../zqlite/src/db.ts';
+import {computeZqlSpecs, listIndexes, listTables} from './lite-tables.ts';
+import type {LiteIndexSpec, LiteTableSpec} from './specs.ts';
 
 describe('lite/tables', () => {
   type Case = {
diff --git a/packages/zero-cache/src/db/lite-tables.ts b/packages/zero-cache/src/db/lite-tables.ts
index 965fb22e44..57979bf9a3 100644
--- a/packages/zero-cache/src/db/lite-tables.ts
+++ b/packages/zero-cache/src/db/lite-tables.ts
@@ -1,21 +1,21 @@
 import type {LogContext} from '@rocicorp/logger';
-import {must} from '../../../shared/src/must.js';
-import {difference} from '../../../shared/src/set-utils.js';
-import * as v from '../../../shared/src/valita.js';
-import {primaryKeySchema} from '../../../zero-protocol/src/primary-key.js';
-import type {Database} from '../../../zqlite/src/db.js';
+import {must} from '../../../shared/src/must.ts';
+import {difference} from '../../../shared/src/set-utils.ts';
+import * as v from '../../../shared/src/valita.ts';
+import {primaryKeySchema} from '../../../zero-protocol/src/primary-key.ts';
+import type {Database} from '../../../zqlite/src/db.ts';
 import {
   dataTypeToZqlValueType,
   mapLiteDataTypeToZqlSchemaValue,
   nullableUpstream,
-} from '../types/lite.js';
+} from '../types/lite.ts';
 import type {
   LiteAndZqlSpec,
   LiteIndexSpec,
   LiteTableSpec,
   MutableLiteIndexSpec,
   MutableLiteTableSpec,
-} from './specs.js';
+} from './specs.ts';
 
 type ColumnInfo = {
   table: string;
diff --git a/packages/zero-cache/src/db/migration-lite.test.ts b/packages/zero-cache/src/db/migration-lite.test.ts
index 08632a2666..20507725ba 100644
--- a/packages/zero-cache/src/db/migration-lite.test.ts
+++ b/packages/zero-cache/src/db/migration-lite.test.ts
@@ -1,15 +1,15 @@
 import type {LogContext} from '@rocicorp/logger';
 import {afterEach, beforeEach, describe, expect, test} from 'vitest';
-import {createSilentLogContext} from '../../../shared/src/logging-test-utils.js';
-import type {Database as Db} from '../../../zqlite/src/db.js';
-import {DbFile} from '../test/lite.js';
+import {createSilentLogContext} from '../../../shared/src/logging-test-utils.ts';
+import type {Database as Db} from '../../../zqlite/src/db.ts';
+import {DbFile} from '../test/lite.ts';
 import {
   type IncrementalMigrationMap,
   type Migration,
   type VersionHistory,
   getVersionHistory,
   runSchemaMigrations,
-} from './migration-lite.js';
+} from './migration-lite.ts';
 
 describe('db/migration-lite', () => {
   const debugName = 'debug-name';
diff --git a/packages/zero-cache/src/db/migration-lite.ts b/packages/zero-cache/src/db/migration-lite.ts
index 4fe1464d83..39aecbf445 100644
--- a/packages/zero-cache/src/db/migration-lite.ts
+++ b/packages/zero-cache/src/db/migration-lite.ts
@@ -1,9 +1,9 @@
 import type {LogContext} from '@rocicorp/logger';
-import {assert} from '../../../shared/src/asserts.js';
-import {randInt} from '../../../shared/src/rand.js';
-import * as v from '../../../shared/src/valita.js';
-import type {Database as Db} from '../../../zqlite/src/db.js';
-import {Database} from '../../../zqlite/src/db.js';
+import {assert} from '../../../shared/src/asserts.ts';
+import {randInt} from '../../../shared/src/rand.ts';
+import * as v from '../../../shared/src/valita.ts';
+import type {Database as Db} from '../../../zqlite/src/db.ts';
+import {Database} from '../../../zqlite/src/db.ts';
 
 type Operations = (log: LogContext, tx: Db) => Promise<void> | void;
 
diff --git a/packages/zero-cache/src/db/migration.pg-test.ts b/packages/zero-cache/src/db/migration.pg-test.ts
index 602188ea65..960635a18f 100644
--- a/packages/zero-cache/src/db/migration.pg-test.ts
+++ b/packages/zero-cache/src/db/migration.pg-test.ts
@@ -1,16 +1,16 @@
 import type {LogContext} from '@rocicorp/logger';
 import type postgres from 'postgres';
 import {afterEach, beforeEach, describe, expect, test} from 'vitest';
-import {createSilentLogContext} from '../../../shared/src/logging-test-utils.js';
-import {testDBs} from '../test/db.js';
-import type {PostgresDB} from '../types/pg.js';
+import {createSilentLogContext} from '../../../shared/src/logging-test-utils.ts';
+import {testDBs} from '../test/db.ts';
+import type {PostgresDB} from '../types/pg.ts';
 import {
   type IncrementalMigrationMap,
   type Migration,
   type VersionHistory,
   getVersionHistory,
   runSchemaMigrations,
-} from './migration.js';
+} from './migration.ts';
 
 describe('db/migration', () => {
   const schemaName = '_zero';
diff --git a/packages/zero-cache/src/db/migration.ts b/packages/zero-cache/src/db/migration.ts
index 651e0187ec..d86c44a6fa 100644
--- a/packages/zero-cache/src/db/migration.ts
+++ b/packages/zero-cache/src/db/migration.ts
@@ -1,9 +1,9 @@
 import type {LogContext} from '@rocicorp/logger';
 import type postgres from 'postgres';
-import {assert} from '../../../shared/src/asserts.js';
-import {randInt} from '../../../shared/src/rand.js';
-import * as v from '../../../shared/src/valita.js';
-import type {PostgresDB, PostgresTransaction} from '../types/pg.js';
+import {assert} from '../../../shared/src/asserts.ts';
+import {randInt} from '../../../shared/src/rand.ts';
+import * as v from '../../../shared/src/valita.ts';
+import type {PostgresDB, PostgresTransaction} from '../types/pg.ts';
 
 type Operations = (log: LogContext, tx: PostgresTransaction) => Promise<void>;
 
diff --git a/packages/zero-cache/src/db/pg-to-lite.test.ts b/packages/zero-cache/src/db/pg-to-lite.test.ts
index 119bd5b468..b90d897add 100644
--- a/packages/zero-cache/src/db/pg-to-lite.test.ts
+++ b/packages/zero-cache/src/db/pg-to-lite.test.ts
@@ -1,7 +1,7 @@
 import {expect, test} from 'vitest';
-import {mapPostgresToLite, mapPostgresToLiteColumn} from './pg-to-lite.js';
-import * as PostgresTypeClass from './postgres-type-class-enum.js';
-import {type ColumnSpec} from './specs.js';
+import {mapPostgresToLite, mapPostgresToLiteColumn} from './pg-to-lite.ts';
+import * as PostgresTypeClass from './postgres-type-class-enum.ts';
+import {type ColumnSpec} from './specs.ts';
 
 test('postgres to lite table spec', () => {
   expect(
diff --git a/packages/zero-cache/src/db/pg-to-lite.ts b/packages/zero-cache/src/db/pg-to-lite.ts
index 61346d38a6..7cf4b83a16 100644
--- a/packages/zero-cache/src/db/pg-to-lite.ts
+++ b/packages/zero-cache/src/db/pg-to-lite.ts
@@ -1,20 +1,20 @@
 import type {LogContext} from '@rocicorp/logger';
-import {ZERO_VERSION_COLUMN_NAME} from '../services/replicator/schema/replication-state.js';
+import {ZERO_VERSION_COLUMN_NAME} from '../services/replicator/schema/replication-state.ts';
 import {
   dataTypeToZqlValueType,
   liteTypeString,
   upstreamDataType,
   type LiteTypeString,
-} from '../types/lite.js';
-import {liteTableName} from '../types/names.js';
-import * as PostgresTypeClass from './postgres-type-class-enum.js';
+} from '../types/lite.ts';
+import {liteTableName} from '../types/names.ts';
+import * as PostgresTypeClass from './postgres-type-class-enum.ts';
 import {
   type ColumnSpec,
   type IndexSpec,
   type LiteIndexSpec,
   type LiteTableSpec,
   type TableSpec,
-} from './specs.js';
+} from './specs.ts';
 
 export const ZERO_VERSION_COLUMN_SPEC: ColumnSpec = {
   pos: Number.MAX_SAFE_INTEGER, // i.e. last
diff --git a/packages/zero-cache/src/db/queries.pg-test.ts b/packages/zero-cache/src/db/queries.pg-test.ts
index c89d345143..16d0a6334b 100644
--- a/packages/zero-cache/src/db/queries.pg-test.ts
+++ b/packages/zero-cache/src/db/queries.pg-test.ts
@@ -1,9 +1,9 @@
 import pg from 'pg';
 import {afterEach, beforeEach, describe, expect, test} from 'vitest';
-import {testDBs} from '../test/db.js';
-import type {PostgresDB} from '../types/pg.js';
-import type {RowKey} from '../types/row-key.js';
-import {lookupRowsWithKeys} from './queries.js';
+import {testDBs} from '../test/db.ts';
+import type {PostgresDB} from '../types/pg.ts';
+import type {RowKey} from '../types/row-key.ts';
+import {lookupRowsWithKeys} from './queries.ts';
 
 const {
   types: {builtins},
diff --git a/packages/zero-cache/src/db/queries.ts b/packages/zero-cache/src/db/queries.ts
index 518e278906..a90d8a4704 100644
--- a/packages/zero-cache/src/db/queries.ts
+++ b/packages/zero-cache/src/db/queries.ts
@@ -1,7 +1,7 @@
 import {compareUTF8} from 'compare-utf8';
 import type postgres from 'postgres';
-import {type PostgresDB, typeNameByOID} from '../types/pg.js';
-import type {RowKey, RowKeyType} from '../types/row-key.js';
+import {type PostgresDB, typeNameByOID} from '../types/pg.ts';
+import type {RowKey, RowKeyType} from '../types/row-key.ts';
 
 /**
  * Efficient lookup of multiple rows from a table from row keys.
diff --git a/packages/zero-cache/src/db/short-lived-client.pg-test.ts b/packages/zero-cache/src/db/short-lived-client.pg-test.ts
index abc1af8c5f..7e44dd74e1 100644
--- a/packages/zero-cache/src/db/short-lived-client.pg-test.ts
+++ b/packages/zero-cache/src/db/short-lived-client.pg-test.ts
@@ -1,10 +1,10 @@
 import {LogContext} from '@rocicorp/logger';
 import {afterAll, beforeAll, describe, expect, test} from 'vitest';
-import {TestLogSink} from '../../../shared/src/logging-test-utils.js';
-import {sleep} from '../../../shared/src/sleep.js';
-import {getConnectionURI, testDBs} from '../test/db.js';
-import type {PostgresDB} from '../types/pg.js';
-import {ShortLivedClient} from './short-lived-client.js';
+import {TestLogSink} from '../../../shared/src/logging-test-utils.ts';
+import {sleep} from '../../../shared/src/sleep.ts';
+import {getConnectionURI, testDBs} from '../test/db.ts';
+import type {PostgresDB} from '../types/pg.ts';
+import {ShortLivedClient} from './short-lived-client.ts';
 
 describe('short-lived-client', () => {
   let db: PostgresDB;
diff --git a/packages/zero-cache/src/db/short-lived-client.ts b/packages/zero-cache/src/db/short-lived-client.ts
index c020c71441..a3d84a1898 100644
--- a/packages/zero-cache/src/db/short-lived-client.ts
+++ b/packages/zero-cache/src/db/short-lived-client.ts
@@ -1,5 +1,5 @@
 import type {LogContext} from '@rocicorp/logger';
-import {pgClient, type PostgresDB} from '../types/pg.js';
+import {pgClient, type PostgresDB} from '../types/pg.ts';
 
 /**
  * Manages on-demand short-lived connections to a DB, shutting down after
diff --git a/packages/zero-cache/src/db/specs-type-test.ts b/packages/zero-cache/src/db/specs-type-test.ts
index d578ef0b52..2b30d38009 100644
--- a/packages/zero-cache/src/db/specs-type-test.ts
+++ b/packages/zero-cache/src/db/specs-type-test.ts
@@ -1,7 +1,7 @@
-import type {Enum} from '../../../shared/src/enum.js';
-import type * as v from '../../../shared/src/valita.js';
-import * as PostgresTypeClass from './postgres-type-class-enum.js';
-import type {pgTypeClassSchema} from './specs.js';
+import type {Enum} from '../../../shared/src/enum.ts';
+import type * as v from '../../../shared/src/valita.ts';
+import * as PostgresTypeClass from './postgres-type-class-enum.ts';
+import type {pgTypeClassSchema} from './specs.ts';
 
 type PostgresTypeClass = Enum<typeof PostgresTypeClass>;
 
diff --git a/packages/zero-cache/src/db/specs.ts b/packages/zero-cache/src/db/specs.ts
index 0d3f3d8f41..ed71c7fa51 100644
--- a/packages/zero-cache/src/db/specs.ts
+++ b/packages/zero-cache/src/db/specs.ts
@@ -1,9 +1,9 @@
-import type {DeepReadonly} from '../../../shared/src/json.js';
-import * as v from '../../../shared/src/valita.js';
-import type {PrimaryKey} from '../../../zero-protocol/src/primary-key.js';
-import type {SchemaValue} from '../../../zero-schema/src/table-schema.js';
-import * as PostgresReplicaIdentity from './postgres-replica-identity-enum.js';
-import * as PostgresTypeClass from './postgres-type-class-enum.js';
+import type {DeepReadonly} from '../../../shared/src/json.ts';
+import * as v from '../../../shared/src/valita.ts';
+import type {PrimaryKey} from '../../../zero-protocol/src/primary-key.ts';
+import type {SchemaValue} from '../../../zero-schema/src/table-schema.ts';
+import * as PostgresReplicaIdentity from './postgres-replica-identity-enum.ts';
+import * as PostgresTypeClass from './postgres-type-class-enum.ts';
 
 export const pgTypeClassSchema = v.union(
   v.literal(PostgresTypeClass.Base),
diff --git a/packages/zero-cache/src/db/statements.test.ts b/packages/zero-cache/src/db/statements.test.ts
index 1e7b8072d2..2708136dec 100644
--- a/packages/zero-cache/src/db/statements.test.ts
+++ b/packages/zero-cache/src/db/statements.test.ts
@@ -1,8 +1,8 @@
-import {createSilentLogContext} from '../../../shared/src/logging-test-utils.js';
 import {beforeEach, describe, expect, test} from 'vitest';
-import {Database} from '../../../zqlite/src/db.js';
-import {expectTables} from '../test/lite.js';
-import {StatementRunner} from './statements.js';
+import {createSilentLogContext} from '../../../shared/src/logging-test-utils.ts';
+import {Database} from '../../../zqlite/src/db.ts';
+import {expectTables} from '../test/lite.ts';
+import {StatementRunner} from './statements.ts';
 
 describe('db/statements', () => {
   let db: StatementRunner;
diff --git a/packages/zero-cache/src/db/statements.ts b/packages/zero-cache/src/db/statements.ts
index 51cdd5138d..9fc34fd221 100644
--- a/packages/zero-cache/src/db/statements.ts
+++ b/packages/zero-cache/src/db/statements.ts
@@ -1,6 +1,6 @@
 import type {RunResult} from '@rocicorp/zero-sqlite3';
-import {Database} from '../../../zqlite/src/db.js';
-import {StatementCache} from '../../../zqlite/src/internal/statement-cache.js';
+import {Database} from '../../../zqlite/src/db.ts';
+import {StatementCache} from '../../../zqlite/src/internal/statement-cache.ts';
 
 /**
  * A stateless wrapper around a {@link StatementCache} that facilitates single-line
diff --git a/packages/zero-cache/src/db/transaction-pool.pg-test.ts b/packages/zero-cache/src/db/transaction-pool.pg-test.ts
index d7c1a6be17..c7fee35fda 100644
--- a/packages/zero-cache/src/db/transaction-pool.pg-test.ts
+++ b/packages/zero-cache/src/db/transaction-pool.pg-test.ts
@@ -2,13 +2,13 @@ import {PG_UNIQUE_VIOLATION} from '@drdgvhbh/postgres-error-codes';
 import type {LogContext} from '@rocicorp/logger';
 import postgres from 'postgres';
 import {afterEach, beforeEach, describe, expect, test} from 'vitest';
-import type {Enum} from '../../../shared/src/enum.js';
-import {createSilentLogContext} from '../../../shared/src/logging-test-utils.js';
-import {Queue} from '../../../shared/src/queue.js';
-import {sleep} from '../../../shared/src/sleep.js';
-import {expectTables, testDBs} from '../test/db.js';
-import type {PostgresDB} from '../types/pg.js';
-import * as Mode from './mode-enum.js';
+import type {Enum} from '../../../shared/src/enum.ts';
+import {createSilentLogContext} from '../../../shared/src/logging-test-utils.ts';
+import {Queue} from '../../../shared/src/queue.ts';
+import {sleep} from '../../../shared/src/sleep.ts';
+import {expectTables, testDBs} from '../test/db.ts';
+import type {PostgresDB} from '../types/pg.ts';
+import * as Mode from './mode-enum.ts';
 import {
   importSnapshot,
   sharedSnapshot,
@@ -16,7 +16,7 @@ import {
   TIMEOUT_TASKS,
   TransactionPool,
   type Task,
-} from './transaction-pool.js';
+} from './transaction-pool.ts';
 
 type Mode = Enum<typeof Mode>;
 
diff --git a/packages/zero-cache/src/db/transaction-pool.ts b/packages/zero-cache/src/db/transaction-pool.ts
index 0db7fde8c9..60d5ec3b13 100644
--- a/packages/zero-cache/src/db/transaction-pool.ts
+++ b/packages/zero-cache/src/db/transaction-pool.ts
@@ -1,11 +1,11 @@
 import type {LogContext} from '@rocicorp/logger';
 import {type Resolver, resolver} from '@rocicorp/resolver';
 import type postgres from 'postgres';
-import {assert} from '../../../shared/src/asserts.js';
-import type {Enum} from '../../../shared/src/enum.js';
-import {Queue} from '../../../shared/src/queue.js';
-import type {PostgresDB, PostgresTransaction} from '../types/pg.js';
-import * as Mode from './mode-enum.js';
+import {assert} from '../../../shared/src/asserts.ts';
+import type {Enum} from '../../../shared/src/enum.ts';
+import {Queue} from '../../../shared/src/queue.ts';
+import type {PostgresDB, PostgresTransaction} from '../types/pg.ts';
+import * as Mode from './mode-enum.ts';
 
 type Mode = Enum<typeof Mode>;
 
diff --git a/packages/zero-cache/src/db/wal-checkpoint.test.ts b/packages/zero-cache/src/db/wal-checkpoint.test.ts
index 83e4f5ee49..4e4faa08cd 100644
--- a/packages/zero-cache/src/db/wal-checkpoint.test.ts
+++ b/packages/zero-cache/src/db/wal-checkpoint.test.ts
@@ -1,8 +1,8 @@
 import {resolver} from '@rocicorp/resolver';
 import {afterEach, beforeEach, describe, expect, test} from 'vitest';
 import {Worker} from 'worker_threads';
-import {createSilentLogContext} from '../../../shared/src/logging-test-utils.js';
-import {DbFile} from '../test/lite.js';
+import {createSilentLogContext} from '../../../shared/src/logging-test-utils.ts';
+import {DbFile} from '../test/lite.ts';
 
 describe('db/wal-checkpoint', () => {
   let dbFile: DbFile;
diff --git a/packages/zero-cache/src/integration/integration.pg-test.ts b/packages/zero-cache/src/integration/integration.pg-test.ts
index d191e9cbc5..827b4b5fc3 100644
--- a/packages/zero-cache/src/integration/integration.pg-test.ts
+++ b/packages/zero-cache/src/integration/integration.pg-test.ts
@@ -11,18 +11,18 @@ import {
   vi,
 } from 'vitest';
 import WebSocket from 'ws';
-import {assert} from '../../../shared/src/asserts.js';
-import {Queue} from '../../../shared/src/queue.js';
-import {randInt} from '../../../shared/src/rand.js';
-import type {AST} from '../../../zero-protocol/src/ast.js';
-import type {ChangeDesiredQueriesMessage} from '../../../zero-protocol/src/change-desired-queries.js';
-import type {InitConnectionMessage} from '../../../zero-protocol/src/connect.js';
-import type {PokeStartMessage} from '../../../zero-protocol/src/poke.js';
-import {PROTOCOL_VERSION} from '../../../zero-protocol/src/protocol-version.js';
-import {getConnectionURI, testDBs} from '../test/db.js';
-import {DbFile} from '../test/lite.js';
-import type {PostgresDB} from '../types/pg.js';
-import {childWorker, type Worker} from '../types/processes.js';
+import {assert} from '../../../shared/src/asserts.ts';
+import {Queue} from '../../../shared/src/queue.ts';
+import {randInt} from '../../../shared/src/rand.ts';
+import type {AST} from '../../../zero-protocol/src/ast.ts';
+import type {ChangeDesiredQueriesMessage} from '../../../zero-protocol/src/change-desired-queries.ts';
+import type {InitConnectionMessage} from '../../../zero-protocol/src/connect.ts';
+import type {PokeStartMessage} from '../../../zero-protocol/src/poke.ts';
+import {PROTOCOL_VERSION} from '../../../zero-protocol/src/protocol-version.ts';
+import {getConnectionURI, testDBs} from '../test/db.ts';
+import {DbFile} from '../test/lite.ts';
+import type {PostgresDB} from '../types/pg.ts';
+import {childWorker, type Worker} from '../types/processes.ts';
 
 // Adjust to debug.
 const LOG_LEVEL: LogLevel = 'error';
diff --git a/packages/zero-cache/src/scripts/run-query.ts b/packages/zero-cache/src/scripts/run-query.ts
index fb4308ba6e..b01378ba6c 100644
--- a/packages/zero-cache/src/scripts/run-query.ts
+++ b/packages/zero-cache/src/scripts/run-query.ts
@@ -1,21 +1,21 @@
 /* eslint-disable no-console */
 import 'dotenv/config';
 
-import {getDebugConfig} from '../config/zero-config.js';
-import {getSchema} from '../auth/load-schema.js';
-import {must} from '../../../shared/src/must.js';
-import {Database} from '../../../zqlite/src/db.js';
-import {createSilentLogContext} from '../../../shared/src/logging-test-utils.js';
-import {type QueryDelegate} from '../../../zql/src/query/query-impl.js';
-import {TableSource} from '../../../zqlite/src/table-source.js';
-import {MemoryStorage} from '../../../zql/src/ivm/memory-storage.js';
-import type {AST} from '../../../zero-protocol/src/ast.js';
-import {buildPipeline} from '../../../zql/src/builder/builder.js';
-import {Catch} from '../../../zql/src/ivm/catch.js';
+import {createSilentLogContext} from '../../../shared/src/logging-test-utils.ts';
+import {must} from '../../../shared/src/must.ts';
+import type {AST} from '../../../zero-protocol/src/ast.ts';
+import {buildPipeline} from '../../../zql/src/builder/builder.ts';
+import {Catch} from '../../../zql/src/ivm/catch.ts';
+import {MemoryStorage} from '../../../zql/src/ivm/memory-storage.ts';
+import {type QueryDelegate} from '../../../zql/src/query/query-impl.ts';
+import {Database} from '../../../zqlite/src/db.ts';
 import {
   runtimeDebugFlags,
   runtimeDebugStats,
-} from '../../../zqlite/src/runtime-debug.js';
+} from '../../../zqlite/src/runtime-debug.ts';
+import {TableSource} from '../../../zqlite/src/table-source.ts';
+import {getSchema} from '../auth/load-schema.ts';
+import {getDebugConfig} from '../config/zero-config.ts';
 
 const config = getDebugConfig();
 const schemaAndPermissions = await getSchema(config);
diff --git a/packages/zero-cache/src/scripts/transform-query.ts b/packages/zero-cache/src/scripts/transform-query.ts
index 6b15695739..fe9736e33f 100644
--- a/packages/zero-cache/src/scripts/transform-query.ts
+++ b/packages/zero-cache/src/scripts/transform-query.ts
@@ -1,12 +1,12 @@
 /* eslint-disable no-console */
 import 'dotenv/config';
 
-import {getDebugConfig} from '../config/zero-config.js';
-import {getSchema} from '../auth/load-schema.js';
-import {transformAndHashQuery} from '../auth/read-authorizer.js';
-import {must} from '../../../shared/src/must.js';
-import {pgClient} from '../types/pg.js';
 import {consoleLogSink, LogContext} from '@rocicorp/logger';
+import {must} from '../../../shared/src/must.ts';
+import {getSchema} from '../auth/load-schema.ts';
+import {transformAndHashQuery} from '../auth/read-authorizer.ts';
+import {getDebugConfig} from '../config/zero-config.ts';
+import {pgClient} from '../types/pg.ts';
 
 const config = getDebugConfig();
 const schema = await getSchema(config);
diff --git a/packages/zero-cache/src/server/change-streamer.ts b/packages/zero-cache/src/server/change-streamer.ts
index 4c3d340aad..f3cdf0ef21 100644
--- a/packages/zero-cache/src/server/change-streamer.ts
+++ b/packages/zero-cache/src/server/change-streamer.ts
@@ -1,21 +1,21 @@
-import {assert} from '../../../shared/src/asserts.js';
-import {must} from '../../../shared/src/must.js';
-import {DatabaseInitError} from '../../../zqlite/src/db.js';
-import {getZeroConfig} from '../config/zero-config.js';
-import {deleteLiteDB} from '../db/delete-lite-db.js';
-import {initializeChangeSource} from '../services/change-source/pg/change-source.js';
-import {ChangeStreamerHttpServer} from '../services/change-streamer/change-streamer-http.js';
-import {initializeStreamer} from '../services/change-streamer/change-streamer-service.js';
-import type {ChangeStreamerService} from '../services/change-streamer/change-streamer.js';
-import {AutoResetSignal} from '../services/change-streamer/schema/tables.js';
-import {exitAfter, runUntilKilled} from '../services/life-cycle.js';
-import {pgClient} from '../types/pg.js';
+import {assert} from '../../../shared/src/asserts.ts';
+import {must} from '../../../shared/src/must.ts';
+import {DatabaseInitError} from '../../../zqlite/src/db.ts';
+import {getZeroConfig} from '../config/zero-config.ts';
+import {deleteLiteDB} from '../db/delete-lite-db.ts';
+import {initializeChangeSource} from '../services/change-source/pg/change-source.ts';
+import {ChangeStreamerHttpServer} from '../services/change-streamer/change-streamer-http.ts';
+import {initializeStreamer} from '../services/change-streamer/change-streamer-service.ts';
+import type {ChangeStreamerService} from '../services/change-streamer/change-streamer.ts';
+import {AutoResetSignal} from '../services/change-streamer/schema/tables.ts';
+import {exitAfter, runUntilKilled} from '../services/life-cycle.ts';
+import {pgClient} from '../types/pg.ts';
 import {
   parentWorker,
   singleProcessMode,
   type Worker,
-} from '../types/processes.js';
-import {createLogContext} from './logging.js';
+} from '../types/processes.ts';
+import {createLogContext} from './logging.ts';
 
 export default async function runWorker(
   parent: Worker,
diff --git a/packages/zero-cache/src/server/logging.ts b/packages/zero-cache/src/server/logging.ts
index 9d0521d8e1..42e79fb19f 100644
--- a/packages/zero-cache/src/server/logging.ts
+++ b/packages/zero-cache/src/server/logging.ts
@@ -6,8 +6,8 @@ import {
   type LogSink,
 } from '@rocicorp/logger';
 import {pid} from 'node:process';
-import {type LogConfig, type ZeroConfig} from '../config/zero-config.js';
-import {stringify} from '../types/bigint-json.js';
+import {type LogConfig, type ZeroConfig} from '../config/zero-config.ts';
+import {stringify} from '../types/bigint-json.ts';
 
 function createLogSink(config: LogConfig) {
   return config.format === 'json' ? consoleJsonLogSink : consoleLogSink;
diff --git a/packages/zero-cache/src/server/main.ts b/packages/zero-cache/src/server/main.ts
index 5aa31bcc12..5707797a09 100644
--- a/packages/zero-cache/src/server/main.ts
+++ b/packages/zero-cache/src/server/main.ts
@@ -1,38 +1,38 @@
 import {resolver} from '@rocicorp/resolver';
 import {availableParallelism} from 'node:os';
 import path from 'node:path';
-import {must} from '../../../shared/src/must.js';
-import {getZeroConfig} from '../config/zero-config.js';
-import {getSubscriberContext} from '../services/change-streamer/change-streamer-http.js';
-import {SyncDispatcher} from '../services/dispatcher/sync-dispatcher.js';
-import {installWebSocketHandoff} from '../services/dispatcher/websocket-handoff.js';
+import {must} from '../../../shared/src/must.ts';
+import {getZeroConfig} from '../config/zero-config.ts';
+import {getSubscriberContext} from '../services/change-streamer/change-streamer-http.ts';
+import {SyncDispatcher} from '../services/dispatcher/sync-dispatcher.ts';
+import {installWebSocketHandoff} from '../services/dispatcher/websocket-handoff.ts';
 import {
   exitAfter,
   ProcessManager,
   runUntilKilled,
   type WorkerType,
-} from '../services/life-cycle.js';
+} from '../services/life-cycle.ts';
 import {
   restoreReplica,
   startReplicaBackupProcess,
-} from '../services/litestream/commands.js';
-import type {Service} from '../services/service.js';
-import {initViewSyncerSchema} from '../services/view-syncer/schema/init.js';
-import {pgClient} from '../types/pg.js';
+} from '../services/litestream/commands.ts';
+import type {Service} from '../services/service.ts';
+import {initViewSyncerSchema} from '../services/view-syncer/schema/init.ts';
+import {pgClient} from '../types/pg.ts';
 import {
   childWorker,
   parentWorker,
   singleProcessMode,
   type Worker,
-} from '../types/processes.js';
-import {orTimeout} from '../types/timeout.js';
+} from '../types/processes.ts';
+import {orTimeout} from '../types/timeout.ts';
 import {
   createNotifierFrom,
   handleSubscriptionsFrom,
   type ReplicaFileMode,
   subscribeTo,
-} from '../workers/replicator.js';
-import {createLogContext} from './logging.js';
+} from '../workers/replicator.ts';
+import {createLogContext} from './logging.ts';
 
 export default async function runWorker(
   parent: Worker | null,
diff --git a/packages/zero-cache/src/server/multi/config.test.ts b/packages/zero-cache/src/server/multi/config.test.ts
index 12a0ab0169..57434683de 100644
--- a/packages/zero-cache/src/server/multi/config.test.ts
+++ b/packages/zero-cache/src/server/multi/config.test.ts
@@ -1,7 +1,7 @@
 import {stripVTControlCharacters as stripAnsi} from 'node:util';
 import {expect, test, vi} from 'vitest';
-import {parseOptions} from '../../../../shared/src/options.js';
-import {getMultiZeroConfig, multiConfigSchema} from './config.js';
+import {parseOptions} from '../../../../shared/src/options.ts';
+import {getMultiZeroConfig, multiConfigSchema} from './config.ts';
 
 test('parse options', () => {
   expect(
diff --git a/packages/zero-cache/src/server/multi/config.ts b/packages/zero-cache/src/server/multi/config.ts
index ccc08ce5ff..eb5f5f79e9 100644
--- a/packages/zero-cache/src/server/multi/config.ts
+++ b/packages/zero-cache/src/server/multi/config.ts
@@ -2,9 +2,9 @@ import {
   envSchema,
   parseOptionsAdvanced,
   type Config,
-} from '../../../../shared/src/options.js';
-import * as v from '../../../../shared/src/valita.js';
-import {zeroOptions} from '../../config/zero-config.js';
+} from '../../../../shared/src/options.ts';
+import * as v from '../../../../shared/src/valita.ts';
+import {zeroOptions} from '../../config/zero-config.ts';
 
 const ENV_VAR_PREFIX = 'ZERO_';
 
diff --git a/packages/zero-cache/src/server/multi/main.ts b/packages/zero-cache/src/server/multi/main.ts
index fe327bad3b..4137bc0768 100644
--- a/packages/zero-cache/src/server/multi/main.ts
+++ b/packages/zero-cache/src/server/multi/main.ts
@@ -1,22 +1,22 @@
 import 'dotenv/config'; // Imports ENV variables from .env
-import {assert} from '../../../../shared/src/asserts.js';
+import {assert} from '../../../../shared/src/asserts.ts';
 import {
   exitAfter,
   ProcessManager,
   runUntilKilled,
-} from '../../services/life-cycle.js';
-import type {Service} from '../../services/service.js';
+} from '../../services/life-cycle.ts';
+import type {Service} from '../../services/service.ts';
 import {
   childWorker,
   parentWorker,
   singleProcessMode,
   type Worker,
-} from '../../types/processes.js';
-import {orTimeout} from '../../types/timeout.js';
-import {createLogContext} from '../logging.js';
-import {getMultiZeroConfig} from './config.js';
-import {getTaskID} from './runtime.js';
-import {TenantDispatcher} from './tenant-dispatcher.js';
+} from '../../types/processes.ts';
+import {orTimeout} from '../../types/timeout.ts';
+import {createLogContext} from '../logging.ts';
+import {getMultiZeroConfig} from './config.ts';
+import {getTaskID} from './runtime.ts';
+import {TenantDispatcher} from './tenant-dispatcher.ts';
 
 export default async function runWorker(
   parent: Worker | null,
diff --git a/packages/zero-cache/src/server/multi/runtime.ts b/packages/zero-cache/src/server/multi/runtime.ts
index e094422676..63ffef563d 100644
--- a/packages/zero-cache/src/server/multi/runtime.ts
+++ b/packages/zero-cache/src/server/multi/runtime.ts
@@ -1,6 +1,6 @@
 import type {LogContext} from '@rocicorp/logger';
 import {nanoid} from 'nanoid';
-import * as v from '../../../../shared/src/valita.js';
+import * as v from '../../../../shared/src/valita.ts';
 
 // https://docs.aws.amazon.com/AmazonECS/latest/developerguide/task-metadata-endpoint-v4-response.html
 const containerMetadataSchema = v.object({['TaskARN']: v.string()});
diff --git a/packages/zero-cache/src/server/multi/tenant-dispatcher.ts b/packages/zero-cache/src/server/multi/tenant-dispatcher.ts
index a24b3db531..363b1a0701 100644
--- a/packages/zero-cache/src/server/multi/tenant-dispatcher.ts
+++ b/packages/zero-cache/src/server/multi/tenant-dispatcher.ts
@@ -1,8 +1,8 @@
 import type {LogContext} from '@rocicorp/logger';
-import {installWebSocketHandoff} from '../../services/dispatcher/websocket-handoff.js';
-import {HttpService, type Options} from '../../services/http-service.js';
-import type {IncomingMessageSubset} from '../../types/http.js';
-import type {Worker} from '../../types/processes.js';
+import {installWebSocketHandoff} from '../../services/dispatcher/websocket-handoff.ts';
+import {HttpService, type Options} from '../../services/http-service.ts';
+import type {IncomingMessageSubset} from '../../types/http.ts';
+import type {Worker} from '../../types/processes.ts';
 
 type Tenant = {
   id: string;
diff --git a/packages/zero-cache/src/server/replicator.ts b/packages/zero-cache/src/server/replicator.ts
index 5d56285ac6..f1ee2e41d1 100644
--- a/packages/zero-cache/src/server/replicator.ts
+++ b/packages/zero-cache/src/server/replicator.ts
@@ -1,25 +1,25 @@
 import {pid} from 'node:process';
-import {assert} from '../../../shared/src/asserts.js';
-import {must} from '../../../shared/src/must.js';
-import * as v from '../../../shared/src/valita.js';
-import {getZeroConfig} from '../config/zero-config.js';
-import {ChangeStreamerHttpClient} from '../services/change-streamer/change-streamer-http.js';
-import {exitAfter, runUntilKilled} from '../services/life-cycle.js';
+import {assert} from '../../../shared/src/asserts.ts';
+import {must} from '../../../shared/src/must.ts';
+import * as v from '../../../shared/src/valita.ts';
+import {getZeroConfig} from '../config/zero-config.ts';
+import {ChangeStreamerHttpClient} from '../services/change-streamer/change-streamer-http.ts';
+import {exitAfter, runUntilKilled} from '../services/life-cycle.ts';
 import {
   ReplicatorService,
   type ReplicatorMode,
-} from '../services/replicator/replicator.js';
+} from '../services/replicator/replicator.ts';
 import {
   parentWorker,
   singleProcessMode,
   type Worker,
-} from '../types/processes.js';
+} from '../types/processes.ts';
 import {
   replicaFileModeSchema,
   setUpMessageHandlers,
   setupReplica,
-} from '../workers/replicator.js';
-import {createLogContext} from './logging.js';
+} from '../workers/replicator.ts';
+import {createLogContext} from './logging.ts';
 
 export default async function runWorker(
   parent: Worker,
diff --git a/packages/zero-cache/src/server/syncer.ts b/packages/zero-cache/src/server/syncer.ts
index 699aaf8b1a..bcbdd9783d 100644
--- a/packages/zero-cache/src/server/syncer.ts
+++ b/packages/zero-cache/src/server/syncer.ts
@@ -8,32 +8,32 @@ import {
 import {tmpdir} from 'node:os';
 import path from 'node:path';
 import {pid} from 'node:process';
-import {NoopSpanExporter} from '../../../otel/src/noop-span-exporter.js';
-import {version} from '../../../otel/src/version.js';
-import {assert} from '../../../shared/src/asserts.js';
-import {must} from '../../../shared/src/must.js';
-import {randInt} from '../../../shared/src/rand.js';
-import * as v from '../../../shared/src/valita.js';
-import {getSchema} from '../auth/load-schema.js';
-import {getZeroConfig} from '../config/zero-config.js';
-import {exitAfter, runUntilKilled} from '../services/life-cycle.js';
-import {MutagenService} from '../services/mutagen/mutagen.js';
-import type {ReplicaState} from '../services/replicator/replicator.js';
-import {DatabaseStorage} from '../services/view-syncer/database-storage.js';
-import {DrainCoordinator} from '../services/view-syncer/drain-coordinator.js';
-import {PipelineDriver} from '../services/view-syncer/pipeline-driver.js';
-import {Snapshotter} from '../services/view-syncer/snapshotter.js';
-import {ViewSyncerService} from '../services/view-syncer/view-syncer.js';
-import {pgClient} from '../types/pg.js';
+import {NoopSpanExporter} from '../../../otel/src/noop-span-exporter.ts';
+import {version} from '../../../otel/src/version.ts';
+import {assert} from '../../../shared/src/asserts.ts';
+import {must} from '../../../shared/src/must.ts';
+import {randInt} from '../../../shared/src/rand.ts';
+import * as v from '../../../shared/src/valita.ts';
+import {getSchema} from '../auth/load-schema.ts';
+import {getZeroConfig} from '../config/zero-config.ts';
+import {exitAfter, runUntilKilled} from '../services/life-cycle.ts';
+import {MutagenService} from '../services/mutagen/mutagen.ts';
+import type {ReplicaState} from '../services/replicator/replicator.ts';
+import {DatabaseStorage} from '../services/view-syncer/database-storage.ts';
+import {DrainCoordinator} from '../services/view-syncer/drain-coordinator.ts';
+import {PipelineDriver} from '../services/view-syncer/pipeline-driver.ts';
+import {Snapshotter} from '../services/view-syncer/snapshotter.ts';
+import {ViewSyncerService} from '../services/view-syncer/view-syncer.ts';
+import {pgClient} from '../types/pg.ts';
 import {
   parentWorker,
   singleProcessMode,
   type Worker,
-} from '../types/processes.js';
-import {Subscription} from '../types/subscription.js';
-import {replicaFileModeSchema, replicaFileName} from '../workers/replicator.js';
-import {Syncer} from '../workers/syncer.js';
-import {createLogContext} from './logging.js';
+} from '../types/processes.ts';
+import {Subscription} from '../types/subscription.ts';
+import {replicaFileModeSchema, replicaFileName} from '../workers/replicator.ts';
+import {Syncer} from '../workers/syncer.ts';
+import {createLogContext} from './logging.ts';
 
 function randomID() {
   return randInt(1, Number.MAX_SAFE_INTEGER).toString(36);
diff --git a/packages/zero-cache/src/services/change-source/pg/change-source.end-to-mid.pg-test.ts b/packages/zero-cache/src/services/change-source/pg/change-source.end-to-mid.pg-test.ts
index 967e921a7e..32bd017851 100644
--- a/packages/zero-cache/src/services/change-source/pg/change-source.end-to-mid.pg-test.ts
+++ b/packages/zero-cache/src/services/change-source/pg/change-source.end-to-mid.pg-test.ts
@@ -1,20 +1,20 @@
 import {LogContext} from '@rocicorp/logger';
 import {afterAll, beforeAll, describe, expect, test} from 'vitest';
-import {createSilentLogContext} from '../../../../../shared/src/logging-test-utils.js';
-import {Queue} from '../../../../../shared/src/queue.js';
-import type {Database} from '../../../../../zqlite/src/db.js';
-import {listIndexes, listTables} from '../../../db/lite-tables.js';
-import type {LiteIndexSpec, LiteTableSpec} from '../../../db/specs.js';
-import {getConnectionURI, testDBs} from '../../../test/db.js';
-import {DbFile, expectMatchingObjectsInTables} from '../../../test/lite.js';
-import type {JSONValue} from '../../../types/bigint-json.js';
-import type {PostgresDB} from '../../../types/pg.js';
-import type {Source} from '../../../types/streams.js';
-import type {MessageProcessor} from '../../replicator/incremental-sync.js';
-import {createMessageProcessor} from '../../replicator/test-utils.js';
-import type {DataChange} from '../protocol/current/data.js';
-import type {ChangeStreamMessage} from '../protocol/current/downstream.js';
-import {initializeChangeSource} from './change-source.js';
+import {createSilentLogContext} from '../../../../../shared/src/logging-test-utils.ts';
+import {Queue} from '../../../../../shared/src/queue.ts';
+import type {Database} from '../../../../../zqlite/src/db.ts';
+import {listIndexes, listTables} from '../../../db/lite-tables.ts';
+import type {LiteIndexSpec, LiteTableSpec} from '../../../db/specs.ts';
+import {getConnectionURI, testDBs} from '../../../test/db.ts';
+import {DbFile, expectMatchingObjectsInTables} from '../../../test/lite.ts';
+import type {JSONValue} from '../../../types/bigint-json.ts';
+import type {PostgresDB} from '../../../types/pg.ts';
+import type {Source} from '../../../types/streams.ts';
+import type {MessageProcessor} from '../../replicator/incremental-sync.ts';
+import {createMessageProcessor} from '../../replicator/test-utils.ts';
+import type {DataChange} from '../protocol/current/data.ts';
+import type {ChangeStreamMessage} from '../protocol/current/downstream.ts';
+import {initializeChangeSource} from './change-source.ts';
 
 const SHARD_ID = 'change_source_end_to_mid_test_id';
 
diff --git a/packages/zero-cache/src/services/change-source/pg/change-source.pg-test.ts b/packages/zero-cache/src/services/change-source/pg/change-source.pg-test.ts
index 3c2f9525ef..80d8cec73b 100644
--- a/packages/zero-cache/src/services/change-source/pg/change-source.pg-test.ts
+++ b/packages/zero-cache/src/services/change-source/pg/change-source.pg-test.ts
@@ -2,36 +2,36 @@ import {PG_OBJECT_IN_USE} from '@drdgvhbh/postgres-error-codes';
 import {LogContext} from '@rocicorp/logger';
 import {DatabaseError} from 'pg-protocol';
 import {afterEach, beforeEach, describe, expect, test} from 'vitest';
-import {AbortError} from '../../../../../shared/src/abort-error.js';
-import {TestLogSink} from '../../../../../shared/src/logging-test-utils.js';
-import {Queue} from '../../../../../shared/src/queue.js';
-import {promiseVoid} from '../../../../../shared/src/resolved-promises.js';
-import {sleep} from '../../../../../shared/src/sleep.js';
-import {Default, Index} from '../../../db/postgres-replica-identity-enum.js';
-import {StatementRunner} from '../../../db/statements.js';
+import {AbortError} from '../../../../../shared/src/abort-error.ts';
+import {TestLogSink} from '../../../../../shared/src/logging-test-utils.ts';
+import {Queue} from '../../../../../shared/src/queue.ts';
+import {promiseVoid} from '../../../../../shared/src/resolved-promises.ts';
+import {sleep} from '../../../../../shared/src/sleep.ts';
+import {Default, Index} from '../../../db/postgres-replica-identity-enum.ts';
+import {StatementRunner} from '../../../db/statements.ts';
 import {
   dropReplicationSlots,
   getConnectionURI,
   testDBs,
-} from '../../../test/db.js';
-import {DbFile} from '../../../test/lite.js';
-import {versionFromLexi, versionToLexi} from '../../../types/lexi-version.js';
-import type {PostgresDB} from '../../../types/pg.js';
-import type {Source} from '../../../types/streams.js';
+} from '../../../test/db.ts';
+import {DbFile} from '../../../test/lite.ts';
+import {versionFromLexi, versionToLexi} from '../../../types/lexi-version.ts';
+import type {PostgresDB} from '../../../types/pg.ts';
+import type {Source} from '../../../types/streams.ts';
 import type {
   ChangeSource,
   ChangeStream,
-} from '../../change-streamer/change-streamer-service.js';
-import {getSubscriptionState} from '../../replicator/schema/replication-state.js';
+} from '../../change-streamer/change-streamer-service.ts';
+import {getSubscriptionState} from '../../replicator/schema/replication-state.ts';
 import type {
   Begin,
   ChangeStreamMessage,
   Commit,
-} from '../protocol/current/downstream.js';
-import {initializeChangeSource} from './change-source.js';
-import {replicationSlot} from './initial-sync.js';
-import {fromLexiVersion} from './lsn.js';
-import {dropEventTriggerStatements} from './schema/ddl-test-utils.js';
+} from '../protocol/current/downstream.ts';
+import {initializeChangeSource} from './change-source.ts';
+import {replicationSlot} from './initial-sync.ts';
+import {fromLexiVersion} from './lsn.ts';
+import {dropEventTriggerStatements} from './schema/ddl-test-utils.ts';
 
 const SHARD_ID = 'change_source_test_id';
 
diff --git a/packages/zero-cache/src/services/change-source/pg/change-source.test.ts b/packages/zero-cache/src/services/change-source/pg/change-source.test.ts
index 7f55f42d95..5d1f1607fe 100644
--- a/packages/zero-cache/src/services/change-source/pg/change-source.test.ts
+++ b/packages/zero-cache/src/services/change-source/pg/change-source.test.ts
@@ -1,6 +1,6 @@
 import type {LogicalReplicationService} from 'pg-logical-replication';
 import {afterEach, beforeEach, expect, test, vi} from 'vitest';
-import {Acker} from './change-source.js';
+import {Acker} from './change-source.ts';
 
 beforeEach(() => {
   vi.useFakeTimers();
diff --git a/packages/zero-cache/src/services/change-source/pg/change-source.ts b/packages/zero-cache/src/services/change-source/pg/change-source.ts
index cda61be726..a6381b5481 100644
--- a/packages/zero-cache/src/services/change-source/pg/change-source.ts
+++ b/packages/zero-cache/src/services/change-source/pg/change-source.ts
@@ -13,67 +13,67 @@ import {
 import type {
   MessageMessage,
   MessageRelation,
-} from 'pg-logical-replication/dist/output-plugins/pgoutput/pgoutput.types.js';
+} from 'pg-logical-replication/dist/output-plugins/pgoutput/pgoutput.types.ts';
 import {DatabaseError} from 'pg-protocol';
-import {AbortError} from '../../../../../shared/src/abort-error.js';
-import {assert} from '../../../../../shared/src/asserts.js';
-import {deepEqual} from '../../../../../shared/src/json.js';
-import {must} from '../../../../../shared/src/must.js';
+import {AbortError} from '../../../../../shared/src/abort-error.ts';
+import {assert} from '../../../../../shared/src/asserts.ts';
+import {deepEqual} from '../../../../../shared/src/json.ts';
+import {must} from '../../../../../shared/src/must.ts';
 import {
   intersection,
   symmetricDifferences,
-} from '../../../../../shared/src/set-utils.js';
-import {sleep} from '../../../../../shared/src/sleep.js';
-import * as v from '../../../../../shared/src/valita.js';
-import {Database} from '../../../../../zqlite/src/db.js';
-import {ShortLivedClient} from '../../../db/short-lived-client.js';
+} from '../../../../../shared/src/set-utils.ts';
+import {sleep} from '../../../../../shared/src/sleep.ts';
+import * as v from '../../../../../shared/src/valita.ts';
+import {Database} from '../../../../../zqlite/src/db.ts';
+import {ShortLivedClient} from '../../../db/short-lived-client.ts';
 import type {
   ColumnSpec,
   PublishedTableSpec,
   TableSpec,
-} from '../../../db/specs.js';
-import {StatementRunner} from '../../../db/statements.js';
-import {stringify} from '../../../types/bigint-json.js';
-import {oneAfter, type LexiVersion} from '../../../types/lexi-version.js';
+} from '../../../db/specs.ts';
+import {StatementRunner} from '../../../db/statements.ts';
+import {stringify} from '../../../types/bigint-json.ts';
+import {oneAfter, type LexiVersion} from '../../../types/lexi-version.ts';
 import {
   pgClient,
   registerPostgresTypeParsers,
   type PostgresDB,
-} from '../../../types/pg.js';
-import {Subscription} from '../../../types/subscription.js';
+} from '../../../types/pg.ts';
+import {Subscription} from '../../../types/subscription.ts';
 import type {
   ChangeSource,
   ChangeStream,
-} from '../../change-streamer/change-streamer-service.js';
+} from '../../change-streamer/change-streamer-service.ts';
 import {
   AutoResetSignal,
   type ReplicationConfig,
-} from '../../change-streamer/schema/tables.js';
-import {getSubscriptionState} from '../../replicator/schema/replication-state.js';
+} from '../../change-streamer/schema/tables.ts';
+import {getSubscriptionState} from '../../replicator/schema/replication-state.ts';
 import type {
   DataChange,
   Identifier,
   MessageDelete,
-} from '../protocol/current/data.js';
+} from '../protocol/current/data.ts';
 import type {
   ChangeStreamData,
   ChangeStreamMessage,
   Data,
-} from '../protocol/current/downstream.js';
-import {replicationSlot, type InitialSyncOptions} from './initial-sync.js';
-import {fromLexiVersion, toLexiVersion, type LSN} from './lsn.js';
-import {replicationEventSchema, type DdlUpdateEvent} from './schema/ddl.js';
-import {updateShardSchema} from './schema/init.js';
-import {getPublicationInfo, type PublishedSchema} from './schema/published.js';
+} from '../protocol/current/downstream.ts';
+import {replicationSlot, type InitialSyncOptions} from './initial-sync.ts';
+import {fromLexiVersion, toLexiVersion, type LSN} from './lsn.ts';
+import {replicationEventSchema, type DdlUpdateEvent} from './schema/ddl.ts';
+import {updateShardSchema} from './schema/init.ts';
+import {getPublicationInfo, type PublishedSchema} from './schema/published.ts';
 import {
   getInternalShardConfig,
   INTERNAL_PUBLICATION_PREFIX,
   replicaIdentitiesForTablesWithoutPrimaryKeys,
   type InternalShardConfig,
-} from './schema/shard.js';
-import {validate} from './schema/validation.js';
-import type {ShardConfig} from './shard-config.js';
-import {initSyncSchema} from './sync-schema.js';
+} from './schema/shard.ts';
+import {validate} from './schema/validation.ts';
+import type {ShardConfig} from './shard-config.ts';
+import {initSyncSchema} from './sync-schema.ts';
 
 // BigInt support from LogicalReplicationService.
 registerPostgresTypeParsers();
diff --git a/packages/zero-cache/src/services/change-source/pg/initial-sync.pg-test.ts b/packages/zero-cache/src/services/change-source/pg/initial-sync.pg-test.ts
index 55aa56cbe2..c3e75e14a6 100644
--- a/packages/zero-cache/src/services/change-source/pg/initial-sync.pg-test.ts
+++ b/packages/zero-cache/src/services/change-source/pg/initial-sync.pg-test.ts
@@ -1,25 +1,25 @@
 import {afterEach, beforeEach, describe, expect, test} from 'vitest';
-import {createSilentLogContext} from '../../../../../shared/src/logging-test-utils.js';
-import {Database} from '../../../../../zqlite/src/db.js';
-import {listIndexes, listTables} from '../../../db/lite-tables.js';
-import {mapPostgresToLiteIndex} from '../../../db/pg-to-lite.js';
+import {createSilentLogContext} from '../../../../../shared/src/logging-test-utils.ts';
+import {Database} from '../../../../../zqlite/src/db.ts';
+import {listIndexes, listTables} from '../../../db/lite-tables.ts';
+import {mapPostgresToLiteIndex} from '../../../db/pg-to-lite.ts';
 import type {
   IndexSpec,
   LiteTableSpec,
   PublishedTableSpec,
-} from '../../../db/specs.js';
-import {getConnectionURI, initDB, testDBs} from '../../../test/db.js';
+} from '../../../db/specs.ts';
+import {getConnectionURI, initDB, testDBs} from '../../../test/db.ts';
 import {
   expectMatchingObjectsInTables,
   expectTables,
   initDB as initLiteDB,
-} from '../../../test/lite.js';
-import type {PostgresDB} from '../../../types/pg.js';
-import {initialSync, replicationSlot} from './initial-sync.js';
-import {fromLexiVersion} from './lsn.js';
-import {initShardSchema} from './schema/init.js';
-import {getPublicationInfo} from './schema/published.js';
-import {UnsupportedTableSchemaError} from './schema/validation.js';
+} from '../../../test/lite.ts';
+import type {PostgresDB} from '../../../types/pg.ts';
+import {initialSync, replicationSlot} from './initial-sync.ts';
+import {fromLexiVersion} from './lsn.ts';
+import {initShardSchema} from './schema/init.ts';
+import {getPublicationInfo} from './schema/published.ts';
+import {UnsupportedTableSchemaError} from './schema/validation.ts';
 
 const SHARD_ID = 'initial_sync_test_id';
 
diff --git a/packages/zero-cache/src/services/change-source/pg/initial-sync.ts b/packages/zero-cache/src/services/change-source/pg/initial-sync.ts
index 4b4fd2e32c..72f2ba865c 100644
--- a/packages/zero-cache/src/services/change-source/pg/initial-sync.ts
+++ b/packages/zero-cache/src/services/change-source/pg/initial-sync.ts
@@ -1,37 +1,37 @@
 import {PG_INSUFFICIENT_PRIVILEGE} from '@drdgvhbh/postgres-error-codes';
 import type {LogContext} from '@rocicorp/logger';
 import postgres from 'postgres';
-import {Database} from '../../../../../zqlite/src/db.js';
+import {Database} from '../../../../../zqlite/src/db.ts';
 import {
   createIndexStatement,
   createTableStatement,
-} from '../../../db/create.js';
-import * as Mode from '../../../db/mode-enum.js';
+} from '../../../db/create.ts';
+import * as Mode from '../../../db/mode-enum.ts';
 import {
   mapPostgresToLite,
   mapPostgresToLiteIndex,
-} from '../../../db/pg-to-lite.js';
-import type {IndexSpec, PublishedTableSpec} from '../../../db/specs.js';
-import {importSnapshot, TransactionPool} from '../../../db/transaction-pool.js';
-import type {LexiVersion} from '../../../types/lexi-version.js';
-import {liteValues} from '../../../types/lite.js';
-import {liteTableName} from '../../../types/names.js';
-import {pgClient, type PostgresDB} from '../../../types/pg.js';
-import {id} from '../../../types/sql.js';
-import {initChangeLog} from '../../replicator/schema/change-log.js';
+} from '../../../db/pg-to-lite.ts';
+import type {IndexSpec, PublishedTableSpec} from '../../../db/specs.ts';
+import {importSnapshot, TransactionPool} from '../../../db/transaction-pool.ts';
+import type {LexiVersion} from '../../../types/lexi-version.ts';
+import {liteValues} from '../../../types/lite.ts';
+import {liteTableName} from '../../../types/names.ts';
+import {pgClient, type PostgresDB} from '../../../types/pg.ts';
+import {id} from '../../../types/sql.ts';
+import {initChangeLog} from '../../replicator/schema/change-log.ts';
 import {
   initReplicationState,
   ZERO_VERSION_COLUMN_NAME,
-} from '../../replicator/schema/replication-state.js';
-import {toLexiVersion} from './lsn.js';
-import {initShardSchema} from './schema/init.js';
-import {getPublicationInfo, type PublicationInfo} from './schema/published.js';
+} from '../../replicator/schema/replication-state.ts';
+import {toLexiVersion} from './lsn.ts';
+import {initShardSchema} from './schema/init.ts';
+import {getPublicationInfo, type PublicationInfo} from './schema/published.ts';
 import {
   getInternalShardConfig,
   setInitialSchema,
   validatePublications,
-} from './schema/shard.js';
-import type {ShardConfig} from './shard-config.js';
+} from './schema/shard.ts';
+import type {ShardConfig} from './shard-config.ts';
 
 export type InitialSyncOptions = {
   tableCopyWorkers: number;
diff --git a/packages/zero-cache/src/services/change-source/pg/lsn.test.ts b/packages/zero-cache/src/services/change-source/pg/lsn.test.ts
index 404c75807f..6737da5629 100644
--- a/packages/zero-cache/src/services/change-source/pg/lsn.test.ts
+++ b/packages/zero-cache/src/services/change-source/pg/lsn.test.ts
@@ -2,8 +2,8 @@ import {describe, expect, test} from 'vitest';
 import {
   versionFromLexi,
   type LexiVersion,
-} from '../../../types/lexi-version.js';
-import {fromLexiVersion, toLexiVersion, type LSN} from './lsn.js';
+} from '../../../types/lexi-version.ts';
+import {fromLexiVersion, toLexiVersion, type LSN} from './lsn.ts';
 
 describe('lsn to/from LexiVersion', () => {
   type Case = [LSN, LexiVersion, bigint];
diff --git a/packages/zero-cache/src/services/change-source/pg/lsn.ts b/packages/zero-cache/src/services/change-source/pg/lsn.ts
index f3c80dbde4..acd8e36fc5 100644
--- a/packages/zero-cache/src/services/change-source/pg/lsn.ts
+++ b/packages/zero-cache/src/services/change-source/pg/lsn.ts
@@ -1,10 +1,10 @@
-import {assert} from '../../../../../shared/src/asserts.js';
+import {assert} from '../../../../../shared/src/asserts.ts';
 import {
   versionFromLexi,
   versionToLexi,
   type LexiVersion,
-} from '../../../types/lexi-version.js';
-import type {Change} from '../protocol/current/data.js';
+} from '../../../types/lexi-version.ts';
+import type {Change} from '../protocol/current/data.ts';
 
 /**
  * Parsing and conversion utilities for the pg_lsn Type, which represents
diff --git a/packages/zero-cache/src/services/change-source/pg/schema/ddl-test-utils.ts b/packages/zero-cache/src/services/change-source/pg/schema/ddl-test-utils.ts
index 442e2f9caa..e20e6c7276 100644
--- a/packages/zero-cache/src/services/change-source/pg/schema/ddl-test-utils.ts
+++ b/packages/zero-cache/src/services/change-source/pg/schema/ddl-test-utils.ts
@@ -1,4 +1,4 @@
-import {append, TAGS} from './ddl.js';
+import {append, TAGS} from './ddl.ts';
 
 export function dropEventTriggerStatements(shardID: string) {
   const sharded = append(shardID);
diff --git a/packages/zero-cache/src/services/change-source/pg/schema/ddl.pg-test.ts b/packages/zero-cache/src/services/change-source/pg/schema/ddl.pg-test.ts
index e76553146a..8e6f2aa92c 100644
--- a/packages/zero-cache/src/services/change-source/pg/schema/ddl.pg-test.ts
+++ b/packages/zero-cache/src/services/change-source/pg/schema/ddl.pg-test.ts
@@ -5,14 +5,14 @@ import {
 } from 'pg-logical-replication';
 import type postgres from 'postgres';
 import {afterEach, beforeEach, describe, expect, test} from 'vitest';
-import {Queue} from '../../../../../../shared/src/queue.js';
-import {getConnectionURI, testDBs} from '../../../../test/db.js';
-import type {PostgresDB} from '../../../../types/pg.js';
+import {Queue} from '../../../../../../shared/src/queue.ts';
+import {getConnectionURI, testDBs} from '../../../../test/db.ts';
+import type {PostgresDB} from '../../../../types/pg.ts';
 import {
   createEventTriggerStatements,
   type DdlStartEvent,
   type DdlUpdateEvent,
-} from './ddl.js';
+} from './ddl.ts';
 
 const SLOT_NAME = 'ddl_test_slot';
 
diff --git a/packages/zero-cache/src/services/change-source/pg/schema/ddl.ts b/packages/zero-cache/src/services/change-source/pg/schema/ddl.ts
index e45c71b42c..fc4269f437 100644
--- a/packages/zero-cache/src/services/change-source/pg/schema/ddl.ts
+++ b/packages/zero-cache/src/services/change-source/pg/schema/ddl.ts
@@ -1,11 +1,11 @@
 import {literal as lit} from 'pg-format';
-import * as v from '../../../../../../shared/src/valita.js';
-import {id} from '../../../../types/sql.js';
+import * as v from '../../../../../../shared/src/valita.ts';
+import {id} from '../../../../types/sql.ts';
 import {
   indexDefinitionsQuery,
   publishedSchema,
   publishedTableQuery,
-} from './published.js';
+} from './published.ts';
 
 // Sent in the 'version' tag of "ddlStart" and "ddlUpdate" event messages.
 // This is used to ensure that the message constructed in the upstream
diff --git a/packages/zero-cache/src/services/change-source/pg/schema/init.pg-test.ts b/packages/zero-cache/src/services/change-source/pg/schema/init.pg-test.ts
index 1e40e935ec..09bb839581 100644
--- a/packages/zero-cache/src/services/change-source/pg/schema/init.pg-test.ts
+++ b/packages/zero-cache/src/services/change-source/pg/schema/init.pg-test.ts
@@ -1,13 +1,13 @@
 import {LogContext} from '@rocicorp/logger';
 import {afterEach, beforeEach, describe, test} from 'vitest';
-import {createSilentLogContext} from '../../../../../../shared/src/logging-test-utils.js';
+import {createSilentLogContext} from '../../../../../../shared/src/logging-test-utils.ts';
 import {
   createVersionHistoryTable,
   type VersionHistory,
-} from '../../../../db/migration.js';
-import {expectTablesToMatch, initDB, testDBs} from '../../../../test/db.js';
-import type {PostgresDB} from '../../../../types/pg.js';
-import {initShardSchema, updateShardSchema} from './init.js';
+} from '../../../../db/migration.ts';
+import {expectTablesToMatch, initDB, testDBs} from '../../../../test/db.ts';
+import type {PostgresDB} from '../../../../types/pg.ts';
+import {initShardSchema, updateShardSchema} from './init.ts';
 
 const SHARD_ID = 'shard_schema_test_id';
 
diff --git a/packages/zero-cache/src/services/change-source/pg/schema/init.ts b/packages/zero-cache/src/services/change-source/pg/schema/init.ts
index 8240149681..d7e05fd229 100644
--- a/packages/zero-cache/src/services/change-source/pg/schema/init.ts
+++ b/packages/zero-cache/src/services/change-source/pg/schema/init.ts
@@ -4,15 +4,15 @@ import {
   runSchemaMigrations,
   type IncrementalMigrationMap,
   type Migration,
-} from '../../../../db/migration.js';
-import type {PostgresDB} from '../../../../types/pg.js';
-import {AutoResetSignal} from '../../../change-streamer/schema/tables.js';
-import type {ShardConfig} from '../shard-config.js';
+} from '../../../../db/migration.ts';
+import type {PostgresDB} from '../../../../types/pg.ts';
+import {AutoResetSignal} from '../../../change-streamer/schema/tables.ts';
+import type {ShardConfig} from '../shard-config.ts';
 import {
   dropShard,
   setupTablesAndReplication,
   unescapedSchema,
-} from './shard.js';
+} from './shard.ts';
 
 /**
  * Initializes a shard for initial sync.
diff --git a/packages/zero-cache/src/services/change-source/pg/schema/published.pg-test.ts b/packages/zero-cache/src/services/change-source/pg/schema/published.pg-test.ts
index 051194885b..42f984f6f0 100644
--- a/packages/zero-cache/src/services/change-source/pg/schema/published.pg-test.ts
+++ b/packages/zero-cache/src/services/change-source/pg/schema/published.pg-test.ts
@@ -1,9 +1,9 @@
 import type postgres from 'postgres';
 import {afterEach, beforeEach, describe, expect, test} from 'vitest';
-import {assert} from '../../../../../../shared/src/asserts.js';
-import * as PostgresTypeClass from '../../../../db/postgres-type-class-enum.js';
-import {testDBs} from '../../../../test/db.js';
-import {type PublicationInfo, getPublicationInfo} from './published.js';
+import {assert} from '../../../../../../shared/src/asserts.ts';
+import * as PostgresTypeClass from '../../../../db/postgres-type-class-enum.ts';
+import {testDBs} from '../../../../test/db.ts';
+import {type PublicationInfo, getPublicationInfo} from './published.ts';
 
 describe('tables/published', () => {
   type Case = {
diff --git a/packages/zero-cache/src/services/change-source/pg/schema/published.ts b/packages/zero-cache/src/services/change-source/pg/schema/published.ts
index 5d13b876f2..37bd48a2e6 100644
--- a/packages/zero-cache/src/services/change-source/pg/schema/published.ts
+++ b/packages/zero-cache/src/services/change-source/pg/schema/published.ts
@@ -1,8 +1,8 @@
 import {literal} from 'pg-format';
 import type postgres from 'postgres';
-import {equals} from '../../../../../../shared/src/set-utils.js';
-import * as v from '../../../../../../shared/src/valita.js';
-import {publishedIndexSpec, publishedTableSpec} from '../../../../db/specs.js';
+import {equals} from '../../../../../../shared/src/set-utils.ts';
+import * as v from '../../../../../../shared/src/valita.ts';
+import {publishedIndexSpec, publishedTableSpec} from '../../../../db/specs.ts';
 
 export function publishedTableQuery(publications: string[]) {
   return `
diff --git a/packages/zero-cache/src/services/change-source/pg/schema/shard.pg-test.ts b/packages/zero-cache/src/services/change-source/pg/schema/shard.pg-test.ts
index d78cae2bea..bd9d0e1925 100644
--- a/packages/zero-cache/src/services/change-source/pg/schema/shard.pg-test.ts
+++ b/packages/zero-cache/src/services/change-source/pg/schema/shard.pg-test.ts
@@ -1,11 +1,11 @@
 import {LogContext} from '@rocicorp/logger';
 import {afterEach, beforeEach, describe, expect, test} from 'vitest';
-import {TestLogSink} from '../../../../../../shared/src/logging-test-utils.js';
-import {Index} from '../../../../db/postgres-replica-identity-enum.js';
-import {expectTables, initDB, testDBs} from '../../../../test/db.js';
-import type {PostgresDB} from '../../../../types/pg.js';
-import {getPublicationInfo} from './published.js';
-import {setupTablesAndReplication, validatePublications} from './shard.js';
+import {TestLogSink} from '../../../../../../shared/src/logging-test-utils.ts';
+import {Index} from '../../../../db/postgres-replica-identity-enum.ts';
+import {expectTables, initDB, testDBs} from '../../../../test/db.ts';
+import type {PostgresDB} from '../../../../types/pg.ts';
+import {getPublicationInfo} from './published.ts';
+import {setupTablesAndReplication, validatePublications} from './shard.ts';
 
 describe('change-source/pg', () => {
   let logSink: TestLogSink;
diff --git a/packages/zero-cache/src/services/change-source/pg/schema/shard.ts b/packages/zero-cache/src/services/change-source/pg/schema/shard.ts
index da66823bba..6d94f0d718 100644
--- a/packages/zero-cache/src/services/change-source/pg/schema/shard.ts
+++ b/packages/zero-cache/src/services/change-source/pg/schema/shard.ts
@@ -2,20 +2,20 @@ import {PG_INSUFFICIENT_PRIVILEGE} from '@drdgvhbh/postgres-error-codes';
 import type {LogContext} from '@rocicorp/logger';
 import {literal} from 'pg-format';
 import postgres from 'postgres';
-import {assert} from '../../../../../../shared/src/asserts.js';
-import * as v from '../../../../../../shared/src/valita.js';
-import {Default} from '../../../../db/postgres-replica-identity-enum.js';
-import type {PostgresDB, PostgresTransaction} from '../../../../types/pg.js';
-import {id} from '../../../../types/sql.js';
-import type {ShardConfig} from '../shard-config.js';
-import {createEventTriggerStatements} from './ddl.js';
+import {assert} from '../../../../../../shared/src/asserts.ts';
+import * as v from '../../../../../../shared/src/valita.ts';
+import {Default} from '../../../../db/postgres-replica-identity-enum.ts';
+import type {PostgresDB, PostgresTransaction} from '../../../../types/pg.ts';
+import {id} from '../../../../types/sql.ts';
+import type {ShardConfig} from '../shard-config.ts';
+import {createEventTriggerStatements} from './ddl.ts';
 import {
   getPublicationInfo,
   publishedSchema,
   type PublicationInfo,
   type PublishedSchema,
-} from './published.js';
-import {validate} from './validation.js';
+} from './published.ts';
+import {validate} from './validation.ts';
 
 // Creates a function that appends `_SHARD_ID` to the input.
 export function append(shardID: string) {
diff --git a/packages/zero-cache/src/services/change-source/pg/schema/validation.pg-test.ts b/packages/zero-cache/src/services/change-source/pg/schema/validation.pg-test.ts
index 05c17e873b..2331071501 100644
--- a/packages/zero-cache/src/services/change-source/pg/schema/validation.pg-test.ts
+++ b/packages/zero-cache/src/services/change-source/pg/schema/validation.pg-test.ts
@@ -1,9 +1,9 @@
 import {afterEach, beforeEach, describe, expect, test} from 'vitest';
-import {createSilentLogContext} from '../../../../../../shared/src/logging-test-utils.js';
-import {initDB, testDBs} from '../../../../test/db.js';
-import type {PostgresDB} from '../../../../types/pg.js';
-import {getPublicationInfo} from './published.js';
-import {UnsupportedTableSchemaError, validate} from './validation.js';
+import {createSilentLogContext} from '../../../../../../shared/src/logging-test-utils.ts';
+import {initDB, testDBs} from '../../../../test/db.ts';
+import type {PostgresDB} from '../../../../types/pg.ts';
+import {getPublicationInfo} from './published.ts';
+import {UnsupportedTableSchemaError, validate} from './validation.ts';
 
 describe('change-source/pg', () => {
   const lc = createSilentLogContext();
diff --git a/packages/zero-cache/src/services/change-source/pg/schema/validation.ts b/packages/zero-cache/src/services/change-source/pg/schema/validation.ts
index 7cb51503ff..ea30d84b60 100644
--- a/packages/zero-cache/src/services/change-source/pg/schema/validation.ts
+++ b/packages/zero-cache/src/services/change-source/pg/schema/validation.ts
@@ -2,11 +2,11 @@ import type {LogContext} from '@rocicorp/logger';
 import {
   mapPostgresToLite,
   warnIfDataTypeSupported,
-} from '../../../../db/pg-to-lite.js';
-import {Default} from '../../../../db/postgres-replica-identity-enum.js';
-import type {PublishedTableSpec} from '../../../../db/specs.js';
-import {ZERO_VERSION_COLUMN_NAME} from '../../../replicator/schema/replication-state.js';
-import {unescapedSchema} from './shard.js';
+} from '../../../../db/pg-to-lite.ts';
+import {Default} from '../../../../db/postgres-replica-identity-enum.ts';
+import type {PublishedTableSpec} from '../../../../db/specs.ts';
+import {ZERO_VERSION_COLUMN_NAME} from '../../../replicator/schema/replication-state.ts';
+import {unescapedSchema} from './shard.ts';
 
 const ALLOWED_IDENTIFIER_CHARS = /^[A-Za-z_]+[A-Za-z0-9_-]*$/;
 
diff --git a/packages/zero-cache/src/services/change-source/pg/sync-schema.pg-test.ts b/packages/zero-cache/src/services/change-source/pg/sync-schema.pg-test.ts
index 468646d5b6..e3cc7204f6 100644
--- a/packages/zero-cache/src/services/change-source/pg/sync-schema.pg-test.ts
+++ b/packages/zero-cache/src/services/change-source/pg/sync-schema.pg-test.ts
@@ -1,20 +1,20 @@
 import {afterEach, beforeEach, describe, expect, test} from 'vitest';
-import {createSilentLogContext} from '../../../../../shared/src/logging-test-utils.js';
+import {createSilentLogContext} from '../../../../../shared/src/logging-test-utils.ts';
 import {
   expectTables,
   getConnectionURI,
   initDB,
   testDBs,
-} from '../../../test/db.js';
+} from '../../../test/db.ts';
 import {
   DbFile,
   expectTables as expectLiteTables,
   expectMatchingObjectsInTables,
   initDB as initLiteDB,
-} from '../../../test/lite.js';
-import type {PostgresDB} from '../../../types/pg.js';
-import {replicationSlot} from './initial-sync.js';
-import {initSyncSchema} from './sync-schema.js';
+} from '../../../test/lite.ts';
+import type {PostgresDB} from '../../../types/pg.ts';
+import {replicationSlot} from './initial-sync.ts';
+import {initSyncSchema} from './sync-schema.ts';
 
 const SHARD_ID = 'sync_schema_test_id';
 
diff --git a/packages/zero-cache/src/services/change-source/pg/sync-schema.ts b/packages/zero-cache/src/services/change-source/pg/sync-schema.ts
index cc1c794aa6..a1f8f867b7 100644
--- a/packages/zero-cache/src/services/change-source/pg/sync-schema.ts
+++ b/packages/zero-cache/src/services/change-source/pg/sync-schema.ts
@@ -4,10 +4,10 @@ import {
   runSchemaMigrations,
   type IncrementalMigrationMap,
   type Migration,
-} from '../../../db/migration-lite.js';
-import {AutoResetSignal} from '../../change-streamer/schema/tables.js';
-import {initialSync, type InitialSyncOptions} from './initial-sync.js';
-import type {ShardConfig} from './shard-config.js';
+} from '../../../db/migration-lite.ts';
+import {AutoResetSignal} from '../../change-streamer/schema/tables.ts';
+import {initialSync, type InitialSyncOptions} from './initial-sync.ts';
+import type {ShardConfig} from './shard-config.ts';
 
 export async function initSyncSchema(
   log: LogContext,
diff --git a/packages/zero-cache/src/services/change-source/protocol/current/control.ts b/packages/zero-cache/src/services/change-source/protocol/current/control.ts
index d8a2717fb7..5815787ed5 100644
--- a/packages/zero-cache/src/services/change-source/protocol/current/control.ts
+++ b/packages/zero-cache/src/services/change-source/protocol/current/control.ts
@@ -3,7 +3,7 @@
  * ChangeSource and ChangeStreamer. These are not forwarded to subscribers
  * of the ChangeStreamer.
  */
-import * as v from '../../../../../../shared/src/valita.js';
+import * as v from '../../../../../../shared/src/valita.ts';
 
 /**
  * Indicates that replication cannot continue and that the replica must be resynced
diff --git a/packages/zero-cache/src/services/change-source/protocol/current/data.ts b/packages/zero-cache/src/services/change-source/protocol/current/data.ts
index ac05305993..8fcb24cd1e 100644
--- a/packages/zero-cache/src/services/change-source/protocol/current/data.ts
+++ b/packages/zero-cache/src/services/change-source/protocol/current/data.ts
@@ -4,13 +4,13 @@
  * stored in the Change DB for catchup of old subscribers.
  */
 
-import * as v from '../../../../../../shared/src/valita.js';
-import {columnSpec, indexSpec, tableSpec} from '../../../../db/specs.js';
+import * as v from '../../../../../../shared/src/valita.ts';
+import {columnSpec, indexSpec, tableSpec} from '../../../../db/specs.ts';
 import {
   jsonValueSchema,
   type JSONObject,
-} from '../../../../types/bigint-json.js';
-import type {Satisfies} from '../../../../types/satisfies.js';
+} from '../../../../types/bigint-json.ts';
+import type {Satisfies} from '../../../../types/satisfies.ts';
 
 export const beginSchema = v.object({
   tag: v.literal('begin'),
diff --git a/packages/zero-cache/src/services/change-source/protocol/current/downstream.ts b/packages/zero-cache/src/services/change-source/protocol/current/downstream.ts
index aca6cf2c9e..21d9219946 100644
--- a/packages/zero-cache/src/services/change-source/protocol/current/downstream.ts
+++ b/packages/zero-cache/src/services/change-source/protocol/current/downstream.ts
@@ -1,12 +1,12 @@
-import * as v from '../../../../../../shared/src/valita.js';
-import {resetRequiredSchema} from './control.js';
+import * as v from '../../../../../../shared/src/valita.ts';
+import {resetRequiredSchema} from './control.ts';
 import {
   beginSchema,
   commitSchema,
   dataChangeSchema,
   rollbackSchema,
-} from './data.js';
-import {statusMessageSchema} from './status.js';
+} from './data.ts';
+import {statusMessageSchema} from './status.ts';
 
 const begin = v.tuple([
   v.literal('begin'),
diff --git a/packages/zero-cache/src/services/change-source/protocol/current/mod.ts b/packages/zero-cache/src/services/change-source/protocol/current/mod.ts
index 9f7b01ffd9..4a9289a235 100644
--- a/packages/zero-cache/src/services/change-source/protocol/current/mod.ts
+++ b/packages/zero-cache/src/services/change-source/protocol/current/mod.ts
@@ -1,6 +1,6 @@
-export * from './control.js';
-export * from './data.js';
-export * from './downstream.js';
-export * from './path.js';
-export * from './status.js';
-export * from './upstream.js';
+export * from './control.ts';
+export * from './data.ts';
+export * from './downstream.ts';
+export * from './path.ts';
+export * from './status.ts';
+export * from './upstream.ts';
diff --git a/packages/zero-cache/src/services/change-source/protocol/current/status.ts b/packages/zero-cache/src/services/change-source/protocol/current/status.ts
index 3bbccbca54..58a4b85851 100644
--- a/packages/zero-cache/src/services/change-source/protocol/current/status.ts
+++ b/packages/zero-cache/src/services/change-source/protocol/current/status.ts
@@ -1,4 +1,4 @@
-import * as v from '../../../../../../shared/src/valita.js';
+import * as v from '../../../../../../shared/src/valita.ts';
 
 /**
  * The StatusMessage payload itself is unspecified. The `zero-cache` will
diff --git a/packages/zero-cache/src/services/change-source/protocol/current/upstream.ts b/packages/zero-cache/src/services/change-source/protocol/current/upstream.ts
index d495aac2fa..97296d603b 100644
--- a/packages/zero-cache/src/services/change-source/protocol/current/upstream.ts
+++ b/packages/zero-cache/src/services/change-source/protocol/current/upstream.ts
@@ -1,5 +1,5 @@
-import * as v from '../../../../../../shared/src/valita.js';
-import {statusMessageSchema} from './status.js';
+import * as v from '../../../../../../shared/src/valita.ts';
+import {statusMessageSchema} from './status.ts';
 
 /** At the moment, the only upstream messages are status messages.  */
 export const changeSourceUpstreamSchema = statusMessageSchema;
diff --git a/packages/zero-cache/src/services/change-source/protocol/mod.ts b/packages/zero-cache/src/services/change-source/protocol/mod.ts
index 4808455ed9..5e0f2e9790 100644
--- a/packages/zero-cache/src/services/change-source/protocol/mod.ts
+++ b/packages/zero-cache/src/services/change-source/protocol/mod.ts
@@ -1,4 +1,4 @@
 // Types are externally exported under stable versions. Code within
 // zero-cache, on the contrary, should reference the files in
 // current/* so that it is versioned with the latest version.
-export * as v0 from './current/mod.js';
+export * as v0 from './current/mod.ts';
diff --git a/packages/zero-cache/src/services/change-source/protocol/version.test.ts b/packages/zero-cache/src/services/change-source/protocol/version.test.ts
index 798eb46bd2..6fef0f01c9 100644
--- a/packages/zero-cache/src/services/change-source/protocol/version.test.ts
+++ b/packages/zero-cache/src/services/change-source/protocol/version.test.ts
@@ -1,9 +1,9 @@
 import {expect, test} from 'vitest';
-import {h64} from '../../../../../shared/src/hash.js';
-import {changeStreamMessageSchema} from './current/downstream.js';
-import {CHANGE_SOURCE_PATH} from './current/path.js';
-import {changeSourceUpstreamSchema} from './current/upstream.js';
-import {v0} from './mod.js';
+import {h64} from '../../../../../shared/src/hash.ts';
+import {changeStreamMessageSchema} from './current/downstream.ts';
+import {CHANGE_SOURCE_PATH} from './current/path.ts';
+import {changeSourceUpstreamSchema} from './current/upstream.ts';
+import {v0} from './mod.ts';
 
 function t(
   module: {
diff --git a/packages/zero-cache/src/services/change-streamer/change-streamer-http.test.ts b/packages/zero-cache/src/services/change-streamer/change-streamer-http.test.ts
index b88f86e994..41cc66748d 100644
--- a/packages/zero-cache/src/services/change-streamer/change-streamer-http.test.ts
+++ b/packages/zero-cache/src/services/change-streamer/change-streamer-http.test.ts
@@ -10,19 +10,19 @@ import {
   vi,
 } from 'vitest';
 import WebSocket from 'ws';
-import {createSilentLogContext} from '../../../../shared/src/logging-test-utils.js';
-import {inProcChannel} from '../../types/processes.js';
-import type {Source} from '../../types/streams.js';
-import {Subscription} from '../../types/subscription.js';
-import {installWebSocketHandoff} from '../dispatcher/websocket-handoff.js';
-import {HttpService} from '../http-service.js';
-import {ReplicationMessages} from '../replicator/test-utils.js';
+import {createSilentLogContext} from '../../../../shared/src/logging-test-utils.ts';
+import {inProcChannel} from '../../types/processes.ts';
+import type {Source} from '../../types/streams.ts';
+import {Subscription} from '../../types/subscription.ts';
+import {installWebSocketHandoff} from '../dispatcher/websocket-handoff.ts';
+import {HttpService} from '../http-service.ts';
+import {ReplicationMessages} from '../replicator/test-utils.ts';
 import {
   ChangeStreamerHttpClient,
   ChangeStreamerHttpServer,
   getSubscriberContext,
-} from './change-streamer-http.js';
-import type {Downstream, SubscriberContext} from './change-streamer.js';
+} from './change-streamer-http.ts';
+import type {Downstream, SubscriberContext} from './change-streamer.ts';
 
 describe('change-streamer/http', () => {
   let lc: LogContext;
diff --git a/packages/zero-cache/src/services/change-streamer/change-streamer-http.ts b/packages/zero-cache/src/services/change-streamer/change-streamer-http.ts
index 38a480dacd..baaff852b0 100644
--- a/packages/zero-cache/src/services/change-streamer/change-streamer-http.ts
+++ b/packages/zero-cache/src/services/change-streamer/change-streamer-http.ts
@@ -2,18 +2,18 @@ import websocket from '@fastify/websocket';
 import {LogContext} from '@rocicorp/logger';
 import {IncomingMessage} from 'node:http';
 import WebSocket from 'ws';
-import {type Worker} from '../../types/processes.js';
-import {streamIn, streamOut, type Source} from '../../types/streams.js';
-import {URLParams} from '../../types/url-params.js';
-import {closeWithProtocolError} from '../../types/ws.js';
-import {installWebSocketReceiver} from '../dispatcher/websocket-handoff.js';
-import {HttpService, type Options} from '../http-service.js';
+import {type Worker} from '../../types/processes.ts';
+import {streamIn, streamOut, type Source} from '../../types/streams.ts';
+import {URLParams} from '../../types/url-params.ts';
+import {closeWithProtocolError} from '../../types/ws.ts';
+import {installWebSocketReceiver} from '../dispatcher/websocket-handoff.ts';
+import {HttpService, type Options} from '../http-service.ts';
 import {
   downstreamSchema,
   type ChangeStreamer,
   type Downstream,
   type SubscriberContext,
-} from './change-streamer.js';
+} from './change-streamer.ts';
 
 const DIRECT_PATH_PATTERN = '/replication/:version/changes';
 const TENANT_PATH_PATTERN = '/:tenant' + DIRECT_PATH_PATTERN;
diff --git a/packages/zero-cache/src/services/change-streamer/change-streamer-service.pg-test.ts b/packages/zero-cache/src/services/change-streamer/change-streamer-service.pg-test.ts
index c3785aa37f..3bbc933956 100644
--- a/packages/zero-cache/src/services/change-streamer/change-streamer-service.pg-test.ts
+++ b/packages/zero-cache/src/services/change-streamer/change-streamer-service.pg-test.ts
@@ -9,35 +9,35 @@ import {
   vi,
   type Mock,
 } from 'vitest';
-import {AbortError} from '../../../../shared/src/abort-error.js';
-import {assert} from '../../../../shared/src/asserts.js';
-import {createSilentLogContext} from '../../../../shared/src/logging-test-utils.js';
-import {Queue} from '../../../../shared/src/queue.js';
-import {Database} from '../../../../zqlite/src/db.js';
-import {StatementRunner} from '../../db/statements.js';
-import {testDBs} from '../../test/db.js';
-import type {PostgresDB} from '../../types/pg.js';
-import type {Source} from '../../types/streams.js';
-import {Subscription} from '../../types/subscription.js';
-import {type ChangeStreamMessage} from '../change-source/protocol/current/downstream.js';
-import type {StatusMessage} from '../change-source/protocol/current/status.js';
+import {AbortError} from '../../../../shared/src/abort-error.ts';
+import {assert} from '../../../../shared/src/asserts.ts';
+import {createSilentLogContext} from '../../../../shared/src/logging-test-utils.ts';
+import {Queue} from '../../../../shared/src/queue.ts';
+import {Database} from '../../../../zqlite/src/db.ts';
+import {StatementRunner} from '../../db/statements.ts';
+import {testDBs} from '../../test/db.ts';
+import type {PostgresDB} from '../../types/pg.ts';
+import type {Source} from '../../types/streams.ts';
+import {Subscription} from '../../types/subscription.ts';
+import {type ChangeStreamMessage} from '../change-source/protocol/current/downstream.ts';
+import type {StatusMessage} from '../change-source/protocol/current/status.ts';
 import {
   getSubscriptionState,
   initReplicationState,
-} from '../replicator/schema/replication-state.js';
-import {ReplicationMessages} from '../replicator/test-utils.js';
-import {initializeStreamer} from './change-streamer-service.js';
+} from '../replicator/schema/replication-state.ts';
+import {ReplicationMessages} from '../replicator/test-utils.ts';
+import {initializeStreamer} from './change-streamer-service.ts';
 import {
   type ChangeStreamerService,
   type Downstream,
-} from './change-streamer.js';
-import * as ErrorType from './error-type-enum.js';
+} from './change-streamer.ts';
+import * as ErrorType from './error-type-enum.ts';
 import {
   AutoResetSignal,
   ensureReplicationConfig,
   type ChangeLogEntry,
   type ReplicationConfig,
-} from './schema/tables.js';
+} from './schema/tables.ts';
 
 describe('change-streamer/service', () => {
   let lc: LogContext;
diff --git a/packages/zero-cache/src/services/change-streamer/change-streamer-service.ts b/packages/zero-cache/src/services/change-streamer/change-streamer-service.ts
index 2e38e4ea4e..a9f8b95218 100644
--- a/packages/zero-cache/src/services/change-streamer/change-streamer-service.ts
+++ b/packages/zero-cache/src/services/change-streamer/change-streamer-service.ts
@@ -1,42 +1,42 @@
 import {LogContext} from '@rocicorp/logger';
 import {resolver} from '@rocicorp/resolver';
-import {unreachable} from '../../../../shared/src/asserts.js';
+import {unreachable} from '../../../../shared/src/asserts.ts';
 import {
   min,
   type AtLeastOne,
   type LexiVersion,
-} from '../../types/lexi-version.js';
-import type {PostgresDB} from '../../types/pg.js';
-import type {Sink, Source} from '../../types/streams.js';
-import {Subscription} from '../../types/subscription.js';
-import {orTimeout} from '../../types/timeout.js';
+} from '../../types/lexi-version.ts';
+import type {PostgresDB} from '../../types/pg.ts';
+import type {Sink, Source} from '../../types/streams.ts';
+import {Subscription} from '../../types/subscription.ts';
+import {orTimeout} from '../../types/timeout.ts';
 import {
   type ChangeStreamControl,
   type ChangeStreamData,
   type ChangeStreamMessage,
-} from '../change-source/protocol/current/downstream.js';
-import type {ChangeSourceUpstream} from '../change-source/protocol/current/upstream.js';
+} from '../change-source/protocol/current/downstream.ts';
+import type {ChangeSourceUpstream} from '../change-source/protocol/current/upstream.ts';
 import {
   DEFAULT_MAX_RETRY_DELAY_MS,
   RunningState,
   UnrecoverableError,
-} from '../running-state.js';
+} from '../running-state.ts';
 import {
   type ChangeStreamerService,
   type Downstream,
   type SubscriberContext,
-} from './change-streamer.js';
-import * as ErrorType from './error-type-enum.js';
-import {Forwarder} from './forwarder.js';
-import {initChangeStreamerSchema} from './schema/init.js';
+} from './change-streamer.ts';
+import * as ErrorType from './error-type-enum.ts';
+import {Forwarder} from './forwarder.ts';
+import {initChangeStreamerSchema} from './schema/init.ts';
 import {
   AutoResetSignal,
   ensureReplicationConfig,
   markResetRequired,
   type ReplicationConfig,
-} from './schema/tables.js';
-import {Storer} from './storer.js';
-import {Subscriber} from './subscriber.js';
+} from './schema/tables.ts';
+import {Storer} from './storer.ts';
+import {Subscriber} from './subscriber.ts';
 
 /**
  * Performs initialization and schema migrations to initialize a ChangeStreamerImpl.
diff --git a/packages/zero-cache/src/services/change-streamer/change-streamer.ts b/packages/zero-cache/src/services/change-streamer/change-streamer.ts
index fd8fa22419..729b2c5c4e 100644
--- a/packages/zero-cache/src/services/change-streamer/change-streamer.ts
+++ b/packages/zero-cache/src/services/change-streamer/change-streamer.ts
@@ -1,9 +1,9 @@
-import * as v from '../../../../shared/src/valita.js';
-import type {Source} from '../../types/streams.js';
-import {type Change} from '../change-source/protocol/current/data.js';
-import {changeStreamDataSchema} from '../change-source/protocol/current/downstream.js';
-import type {ReplicatorMode} from '../replicator/replicator.js';
-import type {Service} from '../service.js';
+import * as v from '../../../../shared/src/valita.ts';
+import type {Source} from '../../types/streams.ts';
+import {type Change} from '../change-source/protocol/current/data.ts';
+import {changeStreamDataSchema} from '../change-source/protocol/current/downstream.ts';
+import type {ReplicatorMode} from '../replicator/replicator.ts';
+import type {Service} from '../service.ts';
 
 /**
  * The ChangeStreamer is the component between replicators ("subscribers")
diff --git a/packages/zero-cache/src/services/change-streamer/forwarder.test.ts b/packages/zero-cache/src/services/change-streamer/forwarder.test.ts
index 794d8ae35f..3e488565f1 100644
--- a/packages/zero-cache/src/services/change-streamer/forwarder.test.ts
+++ b/packages/zero-cache/src/services/change-streamer/forwarder.test.ts
@@ -1,7 +1,7 @@
 import {describe, expect, test} from 'vitest';
-import {ReplicationMessages} from '../replicator/test-utils.js';
-import {Forwarder} from './forwarder.js';
-import {createSubscriber} from './test-utils.js';
+import {ReplicationMessages} from '../replicator/test-utils.ts';
+import {Forwarder} from './forwarder.ts';
+import {createSubscriber} from './test-utils.ts';
 
 describe('change-streamer/forwarder', () => {
   const messages = new ReplicationMessages({issues: 'id'});
diff --git a/packages/zero-cache/src/services/change-streamer/forwarder.ts b/packages/zero-cache/src/services/change-streamer/forwarder.ts
index 229715afcc..e44b1b18ed 100644
--- a/packages/zero-cache/src/services/change-streamer/forwarder.ts
+++ b/packages/zero-cache/src/services/change-streamer/forwarder.ts
@@ -1,6 +1,6 @@
-import {joinIterables, wrapIterable} from '../../../../shared/src/iterables.js';
-import type {WatermarkedChange} from './change-streamer-service.js';
-import {Subscriber} from './subscriber.js';
+import {joinIterables, wrapIterable} from '../../../../shared/src/iterables.ts';
+import type {WatermarkedChange} from './change-streamer-service.ts';
+import {Subscriber} from './subscriber.ts';
 
 export class Forwarder {
   readonly #active = new Set<Subscriber>();
diff --git a/packages/zero-cache/src/services/change-streamer/schema/init.ts b/packages/zero-cache/src/services/change-streamer/schema/init.ts
index 78119367db..cdb3814075 100644
--- a/packages/zero-cache/src/services/change-streamer/schema/init.ts
+++ b/packages/zero-cache/src/services/change-streamer/schema/init.ts
@@ -3,9 +3,9 @@ import {
   runSchemaMigrations,
   type IncrementalMigrationMap,
   type Migration,
-} from '../../../db/migration.js';
-import type {PostgresDB, PostgresTransaction} from '../../../types/pg.js';
-import {PG_SCHEMA, setupCDCTables} from './tables.js';
+} from '../../../db/migration.ts';
+import type {PostgresDB, PostgresTransaction} from '../../../types/pg.ts';
+import {PG_SCHEMA, setupCDCTables} from './tables.ts';
 
 const setupMigration: Migration = {
   migrateSchema: setupCDCTables,
diff --git a/packages/zero-cache/src/services/change-streamer/schema/tables.pg-test.ts b/packages/zero-cache/src/services/change-streamer/schema/tables.pg-test.ts
index 62ac1eff1d..cd207719c9 100644
--- a/packages/zero-cache/src/services/change-streamer/schema/tables.pg-test.ts
+++ b/packages/zero-cache/src/services/change-streamer/schema/tables.pg-test.ts
@@ -1,15 +1,15 @@
 import {afterEach, beforeEach, describe, expect, test} from 'vitest';
-import {createSilentLogContext} from '../../../../../shared/src/logging-test-utils.js';
-import {Database} from '../../../../../zqlite/src/db.js';
-import {expectTables, testDBs} from '../../../test/db.js';
-import type {PostgresDB} from '../../../types/pg.js';
-import {initReplicationState} from '../../replicator/schema/replication-state.js';
+import {createSilentLogContext} from '../../../../../shared/src/logging-test-utils.ts';
+import {Database} from '../../../../../zqlite/src/db.ts';
+import {expectTables, testDBs} from '../../../test/db.ts';
+import type {PostgresDB} from '../../../types/pg.ts';
+import {initReplicationState} from '../../replicator/schema/replication-state.ts';
 import {
   AutoResetSignal,
   ensureReplicationConfig,
   markResetRequired,
   setupCDCTables,
-} from './tables.js';
+} from './tables.ts';
 
 describe('change-streamer/schema/tables', () => {
   const lc = createSilentLogContext();
diff --git a/packages/zero-cache/src/services/change-streamer/schema/tables.ts b/packages/zero-cache/src/services/change-streamer/schema/tables.ts
index 14e4529f91..b102f96a72 100644
--- a/packages/zero-cache/src/services/change-streamer/schema/tables.ts
+++ b/packages/zero-cache/src/services/change-streamer/schema/tables.ts
@@ -1,9 +1,9 @@
 import {LogContext} from '@rocicorp/logger';
 import postgres from 'postgres';
-import {AbortError} from '../../../../../shared/src/abort-error.js';
-import {equals} from '../../../../../shared/src/set-utils.js';
-import type {PostgresDB} from '../../../types/pg.js';
-import type {Change} from '../../change-source/protocol/current/data.js';
+import {AbortError} from '../../../../../shared/src/abort-error.ts';
+import {equals} from '../../../../../shared/src/set-utils.ts';
+import type {PostgresDB} from '../../../types/pg.ts';
+import type {Change} from '../../change-source/protocol/current/data.ts';
 
 export const PG_SCHEMA = 'cdc';
 
diff --git a/packages/zero-cache/src/services/change-streamer/storer.pg-test.ts b/packages/zero-cache/src/services/change-streamer/storer.pg-test.ts
index 5ba013ce4b..31bfc1ebfb 100644
--- a/packages/zero-cache/src/services/change-streamer/storer.pg-test.ts
+++ b/packages/zero-cache/src/services/change-streamer/storer.pg-test.ts
@@ -1,18 +1,18 @@
 import {afterEach, beforeEach, describe, expect, test} from 'vitest';
-import {createSilentLogContext} from '../../../../shared/src/logging-test-utils.js';
-import {Queue} from '../../../../shared/src/queue.js';
-import {sleep} from '../../../../shared/src/sleep.js';
-import {testDBs} from '../../test/db.js';
-import type {PostgresDB} from '../../types/pg.js';
-import {Subscription} from '../../types/subscription.js';
-import {type Commit} from '../change-source/protocol/current/downstream.js';
-import type {StatusMessage} from '../change-source/protocol/current/status.js';
-import {ReplicationMessages} from '../replicator/test-utils.js';
-import {type Downstream} from './change-streamer.js';
-import * as ErrorType from './error-type-enum.js';
-import {setupCDCTables} from './schema/tables.js';
-import {Storer} from './storer.js';
-import {createSubscriber} from './test-utils.js';
+import {createSilentLogContext} from '../../../../shared/src/logging-test-utils.ts';
+import {Queue} from '../../../../shared/src/queue.ts';
+import {sleep} from '../../../../shared/src/sleep.ts';
+import {testDBs} from '../../test/db.ts';
+import type {PostgresDB} from '../../types/pg.ts';
+import {Subscription} from '../../types/subscription.ts';
+import {type Commit} from '../change-source/protocol/current/downstream.ts';
+import type {StatusMessage} from '../change-source/protocol/current/status.ts';
+import {ReplicationMessages} from '../replicator/test-utils.ts';
+import {type Downstream} from './change-streamer.ts';
+import * as ErrorType from './error-type-enum.ts';
+import {setupCDCTables} from './schema/tables.ts';
+import {Storer} from './storer.ts';
+import {createSubscriber} from './test-utils.ts';
 
 describe('change-streamer/storer', () => {
   const lc = createSilentLogContext();
diff --git a/packages/zero-cache/src/services/change-streamer/storer.ts b/packages/zero-cache/src/services/change-streamer/storer.ts
index 8c0e57048a..25533b9d68 100644
--- a/packages/zero-cache/src/services/change-streamer/storer.ts
+++ b/packages/zero-cache/src/services/change-streamer/storer.ts
@@ -1,19 +1,19 @@
 import {LogContext} from '@rocicorp/logger';
 import {resolver} from '@rocicorp/resolver';
-import {assert} from '../../../../shared/src/asserts.js';
-import {Queue} from '../../../../shared/src/queue.js';
-import {promiseVoid} from '../../../../shared/src/resolved-promises.js';
-import * as Mode from '../../db/mode-enum.js';
-import {TransactionPool} from '../../db/transaction-pool.js';
-import type {JSONValue} from '../../types/bigint-json.js';
-import type {PostgresDB} from '../../types/pg.js';
-import {type Commit} from '../change-source/protocol/current/downstream.js';
-import type {StatusMessage} from '../change-source/protocol/current/status.js';
-import type {Service} from '../service.js';
-import type {WatermarkedChange} from './change-streamer-service.js';
-import {type ChangeEntry} from './change-streamer.js';
-import * as ErrorType from './error-type-enum.js';
-import {Subscriber} from './subscriber.js';
+import {assert} from '../../../../shared/src/asserts.ts';
+import {Queue} from '../../../../shared/src/queue.ts';
+import {promiseVoid} from '../../../../shared/src/resolved-promises.ts';
+import * as Mode from '../../db/mode-enum.ts';
+import {TransactionPool} from '../../db/transaction-pool.ts';
+import type {JSONValue} from '../../types/bigint-json.ts';
+import type {PostgresDB} from '../../types/pg.ts';
+import {type Commit} from '../change-source/protocol/current/downstream.ts';
+import type {StatusMessage} from '../change-source/protocol/current/status.ts';
+import type {Service} from '../service.ts';
+import type {WatermarkedChange} from './change-streamer-service.ts';
+import {type ChangeEntry} from './change-streamer.ts';
+import * as ErrorType from './error-type-enum.ts';
+import {Subscriber} from './subscriber.ts';
 
 type QueueEntry =
   | ['change', WatermarkedChange]
diff --git a/packages/zero-cache/src/services/change-streamer/subscriber.test.ts b/packages/zero-cache/src/services/change-streamer/subscriber.test.ts
index a09916da08..ee687bb0b2 100644
--- a/packages/zero-cache/src/services/change-streamer/subscriber.test.ts
+++ b/packages/zero-cache/src/services/change-streamer/subscriber.test.ts
@@ -1,6 +1,6 @@
 import {describe, expect, test} from 'vitest';
-import {ReplicationMessages} from '../replicator/test-utils.js';
-import {createSubscriber} from './test-utils.js';
+import {ReplicationMessages} from '../replicator/test-utils.ts';
+import {createSubscriber} from './test-utils.ts';
 
 describe('change-streamer/subscriber', () => {
   const messages = new ReplicationMessages({issues: 'id'});
diff --git a/packages/zero-cache/src/services/change-streamer/subscriber.ts b/packages/zero-cache/src/services/change-streamer/subscriber.ts
index 8aefc132a4..0a5528debc 100644
--- a/packages/zero-cache/src/services/change-streamer/subscriber.ts
+++ b/packages/zero-cache/src/services/change-streamer/subscriber.ts
@@ -1,10 +1,10 @@
-import {assert} from '../../../../shared/src/asserts.js';
-import type {Enum} from '../../../../shared/src/enum.js';
-import {max} from '../../types/lexi-version.js';
-import {Subscription} from '../../types/subscription.js';
-import type {WatermarkedChange} from './change-streamer-service.js';
-import {type Downstream} from './change-streamer.js';
-import * as ErrorType from './error-type-enum.js';
+import {assert} from '../../../../shared/src/asserts.ts';
+import type {Enum} from '../../../../shared/src/enum.ts';
+import {max} from '../../types/lexi-version.ts';
+import {Subscription} from '../../types/subscription.ts';
+import type {WatermarkedChange} from './change-streamer-service.ts';
+import {type Downstream} from './change-streamer.ts';
+import * as ErrorType from './error-type-enum.ts';
 
 type ErrorType = Enum<typeof ErrorType>;
 
diff --git a/packages/zero-cache/src/services/change-streamer/test-utils.ts b/packages/zero-cache/src/services/change-streamer/test-utils.ts
index c5313bf640..ddd440f637 100644
--- a/packages/zero-cache/src/services/change-streamer/test-utils.ts
+++ b/packages/zero-cache/src/services/change-streamer/test-utils.ts
@@ -1,6 +1,6 @@
-import {Subscription} from '../../types/subscription.js';
-import type {Downstream} from './change-streamer.js';
-import {Subscriber} from './subscriber.js';
+import {Subscription} from '../../types/subscription.ts';
+import type {Downstream} from './change-streamer.ts';
+import {Subscriber} from './subscriber.ts';
 
 let nextID = 1;
 
diff --git a/packages/zero-cache/src/services/dispatcher/connect-params.ts b/packages/zero-cache/src/services/dispatcher/connect-params.ts
index fc037013ee..2a08f6d037 100644
--- a/packages/zero-cache/src/services/dispatcher/connect-params.ts
+++ b/packages/zero-cache/src/services/dispatcher/connect-params.ts
@@ -1,10 +1,10 @@
 import type {IncomingHttpHeaders} from 'node:http2';
-import {must} from '../../../../shared/src/must.js';
+import {must} from '../../../../shared/src/must.ts';
 import {
   decodeSecProtocols,
   type InitConnectionMessage,
-} from '../../../../zero-protocol/src/connect.js';
-import {URLParams} from '../../types/url-params.js';
+} from '../../../../zero-protocol/src/connect.ts';
+import {URLParams} from '../../types/url-params.ts';
 
 export type ConnectParams = {
   readonly protocolVersion: number;
diff --git a/packages/zero-cache/src/services/dispatcher/sync-dispatcher.test.ts b/packages/zero-cache/src/services/dispatcher/sync-dispatcher.test.ts
index 3b59a68293..f50dcb4ced 100644
--- a/packages/zero-cache/src/services/dispatcher/sync-dispatcher.test.ts
+++ b/packages/zero-cache/src/services/dispatcher/sync-dispatcher.test.ts
@@ -1,5 +1,5 @@
 import {expect, test} from 'vitest';
-import {parseSyncPath} from './sync-dispatcher.js';
+import {parseSyncPath} from './sync-dispatcher.ts';
 
 test.each([
   ['/sync/v1/connect', {version: '1'}],
diff --git a/packages/zero-cache/src/services/dispatcher/sync-dispatcher.ts b/packages/zero-cache/src/services/dispatcher/sync-dispatcher.ts
index 1cb189a602..bea8bf71e8 100644
--- a/packages/zero-cache/src/services/dispatcher/sync-dispatcher.ts
+++ b/packages/zero-cache/src/services/dispatcher/sync-dispatcher.ts
@@ -1,11 +1,11 @@
 import {LogContext} from '@rocicorp/logger';
 import UrlPattern from 'url-pattern';
-import {h32} from '../../../../shared/src/hash.js';
-import type {IncomingMessageSubset} from '../../types/http.js';
-import type {Worker} from '../../types/processes.js';
-import {HttpService, type Options} from '../http-service.js';
-import {getConnectParams} from './connect-params.js';
-import {installWebSocketHandoff} from './websocket-handoff.js';
+import {h32} from '../../../../shared/src/hash.ts';
+import type {IncomingMessageSubset} from '../../types/http.ts';
+import type {Worker} from '../../types/processes.ts';
+import {HttpService, type Options} from '../http-service.ts';
+import {getConnectParams} from './connect-params.ts';
+import {installWebSocketHandoff} from './websocket-handoff.ts';
 
 // The server allows the client to use any /:base/ path to facilitate
 // servicing requests on the same domain as the application.
diff --git a/packages/zero-cache/src/services/dispatcher/websocket-handoff.test.ts b/packages/zero-cache/src/services/dispatcher/websocket-handoff.test.ts
index 19be267a03..29eae28378 100644
--- a/packages/zero-cache/src/services/dispatcher/websocket-handoff.test.ts
+++ b/packages/zero-cache/src/services/dispatcher/websocket-handoff.test.ts
@@ -2,13 +2,13 @@ import {resolver} from '@rocicorp/resolver';
 import {Server} from 'node:http';
 import {afterAll, afterEach, beforeAll, describe, expect, test} from 'vitest';
 import {WebSocket, WebSocketServer, type RawData} from 'ws';
-import {createSilentLogContext} from '../../../../shared/src/logging-test-utils.js';
-import {randInt} from '../../../../shared/src/rand.js';
-import {inProcChannel} from '../../types/processes.js';
+import {createSilentLogContext} from '../../../../shared/src/logging-test-utils.ts';
+import {randInt} from '../../../../shared/src/rand.ts';
+import {inProcChannel} from '../../types/processes.ts';
 import {
   installWebSocketHandoff,
   installWebSocketReceiver,
-} from './websocket-handoff.js';
+} from './websocket-handoff.ts';
 
 describe('dispatcher/websocket-handoff', () => {
   let port: number;
diff --git a/packages/zero-cache/src/services/dispatcher/websocket-handoff.ts b/packages/zero-cache/src/services/dispatcher/websocket-handoff.ts
index ea41d4d07a..4ef62f5307 100644
--- a/packages/zero-cache/src/services/dispatcher/websocket-handoff.ts
+++ b/packages/zero-cache/src/services/dispatcher/websocket-handoff.ts
@@ -5,14 +5,14 @@ import {WebSocketServer, type WebSocket} from 'ws';
 import {
   serializableSubset,
   type IncomingMessageSubset,
-} from '../../types/http.js';
+} from '../../types/http.ts';
 import {
   MESSAGE_TYPES,
   type Receiver,
   type Sender,
   type Worker,
-} from '../../types/processes.js';
-import {closeWithProtocolError} from '../../types/ws.js';
+} from '../../types/processes.ts';
+import {closeWithProtocolError} from '../../types/ws.ts';
 
 export type WebSocketHandoff<P> = (message: IncomingMessageSubset) => {
   payload: P;
diff --git a/packages/zero-cache/src/services/http-service.ts b/packages/zero-cache/src/services/http-service.ts
index 57a71a7c43..5b6ba42adb 100644
--- a/packages/zero-cache/src/services/http-service.ts
+++ b/packages/zero-cache/src/services/http-service.ts
@@ -1,8 +1,8 @@
 import {LogContext} from '@rocicorp/logger';
 import Fastify, {type FastifyInstance} from 'fastify';
-import {HeartbeatMonitor} from './life-cycle.js';
-import {RunningState} from './running-state.js';
-import type {Service} from './service.js';
+import {HeartbeatMonitor} from './life-cycle.ts';
+import {RunningState} from './running-state.ts';
+import type {Service} from './service.ts';
 
 export type Options = {
   port: number;
diff --git a/packages/zero-cache/src/services/life-cycle.test.ts b/packages/zero-cache/src/services/life-cycle.test.ts
index 54da5a9954..283802c68b 100644
--- a/packages/zero-cache/src/services/life-cycle.test.ts
+++ b/packages/zero-cache/src/services/life-cycle.test.ts
@@ -1,15 +1,15 @@
 import {resolver} from '@rocicorp/resolver';
 import EventEmitter from 'node:events';
 import {beforeEach, describe, expect, test} from 'vitest';
-import {createSilentLogContext} from '../../../shared/src/logging-test-utils.js';
-import {promiseVoid} from '../../../shared/src/resolved-promises.js';
+import {createSilentLogContext} from '../../../shared/src/logging-test-utils.ts';
+import {promiseVoid} from '../../../shared/src/resolved-promises.ts';
 import {
   ProcessManager,
   runUntilKilled,
   type WorkerType,
-} from '../services/life-cycle.js';
-import type {SingletonService} from '../services/service.js';
-import {inProcChannel} from '../types/processes.js';
+} from '../services/life-cycle.ts';
+import type {SingletonService} from '../services/service.ts';
+import {inProcChannel} from '../types/processes.ts';
 
 describe('shutdown', () => {
   const lc = createSilentLogContext();
diff --git a/packages/zero-cache/src/services/life-cycle.ts b/packages/zero-cache/src/services/life-cycle.ts
index b9ef37fd59..084b861f75 100644
--- a/packages/zero-cache/src/services/life-cycle.ts
+++ b/packages/zero-cache/src/services/life-cycle.ts
@@ -6,9 +6,9 @@ import {
   singleProcessMode,
   type Subprocess,
   type Worker,
-} from '../types/processes.js';
-import {RunningState} from './running-state.js';
-import type {SingletonService} from './service.js';
+} from '../types/processes.ts';
+import {RunningState} from './running-state.ts';
+import type {SingletonService} from './service.ts';
 
 /**
  * * `user-facing` workers serve external requests and are the first to
diff --git a/packages/zero-cache/src/services/limiter/sliding-window-limiter.test.ts b/packages/zero-cache/src/services/limiter/sliding-window-limiter.test.ts
index b368f5b262..6a0a883578 100644
--- a/packages/zero-cache/src/services/limiter/sliding-window-limiter.test.ts
+++ b/packages/zero-cache/src/services/limiter/sliding-window-limiter.test.ts
@@ -1,5 +1,5 @@
 import {afterEach, beforeEach, expect, test, vi} from 'vitest';
-import {SlidingWindowLimiter} from './sliding-window-limiter.js';
+import {SlidingWindowLimiter} from './sliding-window-limiter.ts';
 
 beforeEach(() => {
   vi.useFakeTimers();
diff --git a/packages/zero-cache/src/services/limiter/sliding-window-limiter.ts b/packages/zero-cache/src/services/limiter/sliding-window-limiter.ts
index ae9b13ccbf..186ac77e4a 100644
--- a/packages/zero-cache/src/services/limiter/sliding-window-limiter.ts
+++ b/packages/zero-cache/src/services/limiter/sliding-window-limiter.ts
@@ -1,4 +1,4 @@
-import {assert} from '../../../../shared/src/asserts.js';
+import {assert} from '../../../../shared/src/asserts.ts';
 
 type Window = {
   start: number;
diff --git a/packages/zero-cache/src/services/litestream/commands.ts b/packages/zero-cache/src/services/litestream/commands.ts
index 70225666b6..922fe17381 100644
--- a/packages/zero-cache/src/services/litestream/commands.ts
+++ b/packages/zero-cache/src/services/litestream/commands.ts
@@ -2,9 +2,9 @@ import type {LogContext, LogLevel} from '@rocicorp/logger';
 import {resolver} from '@rocicorp/resolver';
 import {ChildProcess, spawn} from 'node:child_process';
 import {existsSync} from 'node:fs';
-import {must} from '../../../../shared/src/must.js';
-import {sleep} from '../../../../shared/src/sleep.js';
-import type {ZeroConfig} from '../../config/zero-config.js';
+import {must} from '../../../../shared/src/must.ts';
+import {sleep} from '../../../../shared/src/sleep.ts';
+import type {ZeroConfig} from '../../config/zero-config.ts';
 
 type ZeroLitestreamConfig = Pick<
   ZeroConfig,
diff --git a/packages/zero-cache/src/services/mutagen/mutagen.authz.pg-test.ts b/packages/zero-cache/src/services/mutagen/mutagen.authz.pg-test.ts
index 4f05ca40c6..3de63693a8 100644
--- a/packages/zero-cache/src/services/mutagen/mutagen.authz.pg-test.ts
+++ b/packages/zero-cache/src/services/mutagen/mutagen.authz.pg-test.ts
@@ -1,30 +1,30 @@
 import {afterEach, beforeEach, describe, expect, test} from 'vitest';
-import {createSilentLogContext} from '../../../../shared/src/logging-test-utils.js';
-import * as MutationType from '../../../../zero-protocol/src/mutation-type-enum.js';
-import {
-  ANYONE_CAN,
-  definePermissions,
-  NOBODY_CAN,
-} from '../../../../zero-schema/src/permissions.js';
-import {ExpressionBuilder} from '../../../../zql/src/query/expression.js';
-import type {Row} from '../../../../zql/src/query/query.js';
-import {Database} from '../../../../zqlite/src/db.js';
-import {WriteAuthorizerImpl} from '../../auth/write-authorizer.js';
-import {testDBs} from '../../test/db.js';
-import type {PostgresDB} from '../../types/pg.js';
-import {zeroSchema} from './mutagen-test-shared.js';
-import {processMutation} from './mutagen.js';
+import {createSilentLogContext} from '../../../../shared/src/logging-test-utils.ts';
+import * as MutationType from '../../../../zero-protocol/src/mutation-type-enum.ts';
 import {
   createSchema,
   type Schema as ZeroSchema,
-} from '../../../../zero-schema/src/builder/schema-builder.js';
+} from '../../../../zero-schema/src/builder/schema-builder.ts';
 import {
   boolean,
   json,
   number,
   string,
   table,
-} from '../../../../zero-schema/src/builder/table-builder.js';
+} from '../../../../zero-schema/src/builder/table-builder.ts';
+import {
+  ANYONE_CAN,
+  definePermissions,
+  NOBODY_CAN,
+} from '../../../../zero-schema/src/permissions.ts';
+import {ExpressionBuilder} from '../../../../zql/src/query/expression.ts';
+import type {Row} from '../../../../zql/src/query/query.ts';
+import {Database} from '../../../../zqlite/src/db.ts';
+import {WriteAuthorizerImpl} from '../../auth/write-authorizer.ts';
+import {testDBs} from '../../test/db.ts';
+import type {PostgresDB} from '../../types/pg.ts';
+import {zeroSchema} from './mutagen-test-shared.ts';
+import {processMutation} from './mutagen.ts';
 
 const SHARD_ID = '0';
 const CG_ID = 'abc';
diff --git a/packages/zero-cache/src/services/mutagen/mutagen.pg-test.ts b/packages/zero-cache/src/services/mutagen/mutagen.pg-test.ts
index dba84eecf4..d9caa571d4 100644
--- a/packages/zero-cache/src/services/mutagen/mutagen.pg-test.ts
+++ b/packages/zero-cache/src/services/mutagen/mutagen.pg-test.ts
@@ -1,20 +1,20 @@
 import {LogContext} from '@rocicorp/logger';
 import {resolver} from '@rocicorp/resolver';
 import {afterEach, beforeEach, describe, expect, test} from 'vitest';
-import {createSilentLogContext} from '../../../../shared/src/logging-test-utils.js';
-import * as ErrorKind from '../../../../zero-protocol/src/error-kind-enum.js';
+import {createSilentLogContext} from '../../../../shared/src/logging-test-utils.ts';
+import * as ErrorKind from '../../../../zero-protocol/src/error-kind-enum.ts';
 import {
   type CRUDMutation,
   type CRUDOp,
   type UpsertOp,
-} from '../../../../zero-protocol/src/mod.js';
-import * as MutationType from '../../../../zero-protocol/src/mutation-type-enum.js';
-import type {WriteAuthorizer} from '../../auth/write-authorizer.js';
-import * as Mode from '../../db/mode-enum.js';
-import {expectTables, testDBs} from '../../test/db.js';
-import type {PostgresDB} from '../../types/pg.js';
-import {zeroSchema} from './mutagen-test-shared.js';
-import {processMutation} from './mutagen.js';
+} from '../../../../zero-protocol/src/mod.ts';
+import * as MutationType from '../../../../zero-protocol/src/mutation-type-enum.ts';
+import type {WriteAuthorizer} from '../../auth/write-authorizer.ts';
+import * as Mode from '../../db/mode-enum.ts';
+import {expectTables, testDBs} from '../../test/db.ts';
+import type {PostgresDB} from '../../types/pg.ts';
+import {zeroSchema} from './mutagen-test-shared.ts';
+import {processMutation} from './mutagen.ts';
 
 const SHARD_ID = '0';
 
diff --git a/packages/zero-cache/src/services/mutagen/mutagen.ts b/packages/zero-cache/src/services/mutagen/mutagen.ts
index cd0bfa3747..007d97a1d0 100644
--- a/packages/zero-cache/src/services/mutagen/mutagen.ts
+++ b/packages/zero-cache/src/services/mutagen/mutagen.ts
@@ -3,14 +3,14 @@ import type {LogContext} from '@rocicorp/logger';
 import {resolver} from '@rocicorp/resolver';
 import type {JWTPayload} from 'jose';
 import postgres from 'postgres';
-import {assert, unreachable} from '../../../../shared/src/asserts.js';
-import * as v from '../../../../shared/src/valita.js';
-import * as ErrorKind from '../../../../zero-protocol/src/error-kind-enum.js';
-import * as MutationType from '../../../../zero-protocol/src/mutation-type-enum.js';
+import {assert, unreachable} from '../../../../shared/src/asserts.ts';
+import * as v from '../../../../shared/src/valita.ts';
+import * as ErrorKind from '../../../../zero-protocol/src/error-kind-enum.ts';
+import * as MutationType from '../../../../zero-protocol/src/mutation-type-enum.ts';
 import {
   primaryKeyValueSchema,
   type PrimaryKeyValue,
-} from '../../../../zero-protocol/src/primary-key.js';
+} from '../../../../zero-protocol/src/primary-key.ts';
 import {
   type CRUDMutation,
   type DeleteOp,
@@ -18,22 +18,22 @@ import {
   type Mutation,
   type UpdateOp,
   type UpsertOp,
-} from '../../../../zero-protocol/src/push.js';
-import type {PermissionsConfig} from '../../../../zero-schema/src/compiled-permissions.js';
-import type {Schema} from '../../../../zero-schema/src/builder/schema-builder.js';
-import {Database} from '../../../../zqlite/src/db.js';
+} from '../../../../zero-protocol/src/push.ts';
+import type {Schema} from '../../../../zero-schema/src/builder/schema-builder.ts';
+import type {PermissionsConfig} from '../../../../zero-schema/src/compiled-permissions.ts';
+import {Database} from '../../../../zqlite/src/db.ts';
 import {
   WriteAuthorizerImpl,
   type WriteAuthorizer,
-} from '../../auth/write-authorizer.js';
-import {type ZeroConfig} from '../../config/zero-config.js';
-import * as Mode from '../../db/mode-enum.js';
-import {ErrorForClient} from '../../types/error-for-client.js';
-import type {PostgresDB, PostgresTransaction} from '../../types/pg.js';
-import {throwErrorForClientIfSchemaVersionNotSupported} from '../../types/schema-versions.js';
-import {unescapedSchema as schema} from '../change-source/pg/schema/shard.js';
-import {SlidingWindowLimiter} from '../limiter/sliding-window-limiter.js';
-import type {Service} from '../service.js';
+} from '../../auth/write-authorizer.ts';
+import {type ZeroConfig} from '../../config/zero-config.ts';
+import * as Mode from '../../db/mode-enum.ts';
+import {ErrorForClient} from '../../types/error-for-client.ts';
+import type {PostgresDB, PostgresTransaction} from '../../types/pg.ts';
+import {throwErrorForClientIfSchemaVersionNotSupported} from '../../types/schema-versions.ts';
+import {unescapedSchema as schema} from '../change-source/pg/schema/shard.ts';
+import {SlidingWindowLimiter} from '../limiter/sliding-window-limiter.ts';
+import type {Service} from '../service.ts';
 
 // An error encountered processing a mutation.
 // Returned back to application for display to user.
diff --git a/packages/zero-cache/src/services/replicator/incremental-sync.message-processor.test.ts b/packages/zero-cache/src/services/replicator/incremental-sync.message-processor.test.ts
index 7561ba438d..5b8ea6382e 100644
--- a/packages/zero-cache/src/services/replicator/incremental-sync.message-processor.test.ts
+++ b/packages/zero-cache/src/services/replicator/incremental-sync.message-processor.test.ts
@@ -1,16 +1,16 @@
 import {LogContext} from '@rocicorp/logger';
 import {beforeEach, describe, expect, test} from 'vitest';
-import {createSilentLogContext} from '../../../../shared/src/logging-test-utils.js';
-import {Database} from '../../../../zqlite/src/db.js';
-import {StatementRunner} from '../../db/statements.js';
-import {expectTables} from '../../test/lite.js';
-import type {ChangeStreamData} from '../change-source/protocol/current/downstream.js';
-import {initChangeLog} from './schema/change-log.js';
+import {createSilentLogContext} from '../../../../shared/src/logging-test-utils.ts';
+import {Database} from '../../../../zqlite/src/db.ts';
+import {StatementRunner} from '../../db/statements.ts';
+import {expectTables} from '../../test/lite.ts';
+import type {ChangeStreamData} from '../change-source/protocol/current/downstream.ts';
+import {initChangeLog} from './schema/change-log.ts';
 import {
   getSubscriptionState,
   initReplicationState,
-} from './schema/replication-state.js';
-import {createMessageProcessor, ReplicationMessages} from './test-utils.js';
+} from './schema/replication-state.ts';
+import {createMessageProcessor, ReplicationMessages} from './test-utils.ts';
 
 describe('replicator/message-processor', () => {
   let lc: LogContext;
diff --git a/packages/zero-cache/src/services/replicator/incremental-sync.pg-test.ts b/packages/zero-cache/src/services/replicator/incremental-sync.pg-test.ts
index 123f861741..621f5ac8fd 100644
--- a/packages/zero-cache/src/services/replicator/incremental-sync.pg-test.ts
+++ b/packages/zero-cache/src/services/replicator/incremental-sync.pg-test.ts
@@ -9,23 +9,23 @@ import {
   test,
   vi,
 } from 'vitest';
-import {createSilentLogContext} from '../../../../shared/src/logging-test-utils.js';
-import {Database} from '../../../../zqlite/src/db.js';
-import {listIndexes, listTables} from '../../db/lite-tables.js';
-import type {LiteIndexSpec, LiteTableSpec} from '../../db/specs.js';
-import {testDBs} from '../../test/db.js';
-import {expectTables, initDB} from '../../test/lite.js';
-import type {JSONObject} from '../../types/bigint-json.js';
-import type {PostgresDB} from '../../types/pg.js';
-import {Subscription} from '../../types/subscription.js';
+import {createSilentLogContext} from '../../../../shared/src/logging-test-utils.ts';
+import {Database} from '../../../../zqlite/src/db.ts';
+import {listIndexes, listTables} from '../../db/lite-tables.ts';
+import type {LiteIndexSpec, LiteTableSpec} from '../../db/specs.ts';
+import {testDBs} from '../../test/db.ts';
+import {expectTables, initDB} from '../../test/lite.ts';
+import type {JSONObject} from '../../types/bigint-json.ts';
+import type {PostgresDB} from '../../types/pg.ts';
+import {Subscription} from '../../types/subscription.ts';
 import type {
   Downstream,
   SubscriberContext,
-} from '../change-streamer/change-streamer.js';
-import {IncrementalSyncer} from './incremental-sync.js';
-import {initChangeLog} from './schema/change-log.js';
-import {initReplicationState} from './schema/replication-state.js';
-import {ReplicationMessages} from './test-utils.js';
+} from '../change-streamer/change-streamer.ts';
+import {IncrementalSyncer} from './incremental-sync.ts';
+import {initChangeLog} from './schema/change-log.ts';
+import {initReplicationState} from './schema/replication-state.ts';
+import {ReplicationMessages} from './test-utils.ts';
 
 const REPLICA_ID = 'incremental_sync_test_id';
 
diff --git a/packages/zero-cache/src/services/replicator/incremental-sync.ts b/packages/zero-cache/src/services/replicator/incremental-sync.ts
index c4ba17f398..a4cbbc0d17 100644
--- a/packages/zero-cache/src/services/replicator/incremental-sync.ts
+++ b/packages/zero-cache/src/services/replicator/incremental-sync.ts
@@ -1,28 +1,28 @@
 import type {LogContext} from '@rocicorp/logger';
 import {SqliteError} from '@rocicorp/zero-sqlite3';
-import {AbortError} from '../../../../shared/src/abort-error.js';
-import {assert, unreachable} from '../../../../shared/src/asserts.js';
-import {must} from '../../../../shared/src/must.js';
-import {Database} from '../../../../zqlite/src/db.js';
+import {AbortError} from '../../../../shared/src/abort-error.ts';
+import {assert, unreachable} from '../../../../shared/src/asserts.ts';
+import {must} from '../../../../shared/src/must.ts';
+import {Database} from '../../../../zqlite/src/db.ts';
 import {
   columnDef,
   createIndexStatement,
   createTableStatement,
-} from '../../db/create.js';
-import {listIndexes, listTables} from '../../db/lite-tables.js';
+} from '../../db/create.ts';
+import {listIndexes, listTables} from '../../db/lite-tables.ts';
 import {
   mapPostgresToLite,
   mapPostgresToLiteColumn,
   mapPostgresToLiteIndex,
-} from '../../db/pg-to-lite.js';
-import type {LiteTableSpec} from '../../db/specs.js';
-import {StatementRunner} from '../../db/statements.js';
-import {stringify} from '../../types/bigint-json.js';
-import type {LexiVersion} from '../../types/lexi-version.js';
-import {liteRow} from '../../types/lite.js';
-import {liteTableName} from '../../types/names.js';
-import {id} from '../../types/sql.js';
-import type {Source} from '../../types/streams.js';
+} from '../../db/pg-to-lite.ts';
+import type {LiteTableSpec} from '../../db/specs.ts';
+import {StatementRunner} from '../../db/statements.ts';
+import {stringify} from '../../types/bigint-json.ts';
+import type {LexiVersion} from '../../types/lexi-version.ts';
+import {liteRow} from '../../types/lite.ts';
+import {liteTableName} from '../../types/names.ts';
+import {id} from '../../types/sql.ts';
+import type {Source} from '../../types/streams.ts';
 import type {
   Change,
   ColumnAdd,
@@ -38,26 +38,26 @@ import type {
   TableCreate,
   TableDrop,
   TableRename,
-} from '../change-source/protocol/current/data.js';
-import type {ChangeStreamData} from '../change-source/protocol/current/downstream.js';
+} from '../change-source/protocol/current/data.ts';
+import type {ChangeStreamData} from '../change-source/protocol/current/downstream.ts';
 import type {
   ChangeStreamer,
   Downstream,
-} from '../change-streamer/change-streamer.js';
-import {RunningState} from '../running-state.js';
-import {Notifier} from './notifier.js';
-import type {ReplicaState, ReplicatorMode} from './replicator.js';
+} from '../change-streamer/change-streamer.ts';
+import {RunningState} from '../running-state.ts';
+import {Notifier} from './notifier.ts';
+import type {ReplicaState, ReplicatorMode} from './replicator.ts';
 import {
   logDeleteOp,
   logResetOp,
   logSetOp,
   logTruncateOp,
-} from './schema/change-log.js';
+} from './schema/change-log.ts';
 import {
   ZERO_VERSION_COLUMN_NAME,
   getSubscriptionState,
   updateReplicationWatermark,
-} from './schema/replication-state.js';
+} from './schema/replication-state.ts';
 
 type TransactionMode = 'IMMEDIATE' | 'CONCURRENT';
 
diff --git a/packages/zero-cache/src/services/replicator/notifier.test.ts b/packages/zero-cache/src/services/replicator/notifier.test.ts
index eccd5f9c40..b1ce64014a 100644
--- a/packages/zero-cache/src/services/replicator/notifier.test.ts
+++ b/packages/zero-cache/src/services/replicator/notifier.test.ts
@@ -1,7 +1,7 @@
 import {beforeEach, describe, expect, test} from 'vitest';
-import type {Source} from '../../types/streams.js';
-import {Notifier} from './notifier.js';
-import type {ReplicaState} from './replicator.js';
+import type {Source} from '../../types/streams.ts';
+import {Notifier} from './notifier.ts';
+import type {ReplicaState} from './replicator.ts';
 
 describe('replicator/notifier', () => {
   let notifier: Notifier;
diff --git a/packages/zero-cache/src/services/replicator/notifier.ts b/packages/zero-cache/src/services/replicator/notifier.ts
index 8af2391339..4b9c858b3c 100644
--- a/packages/zero-cache/src/services/replicator/notifier.ts
+++ b/packages/zero-cache/src/services/replicator/notifier.ts
@@ -3,8 +3,8 @@ import {
   type PendingResult,
   type Result,
   Subscription,
-} from '../../types/subscription.js';
-import type {ReplicaState, ReplicaStateNotifier} from './replicator.js';
+} from '../../types/subscription.ts';
+import type {ReplicaState, ReplicaStateNotifier} from './replicator.ts';
 
 /**
  * Handles the semantics of {@link ReplicatorVersionNotifier.subscribe()}
diff --git a/packages/zero-cache/src/services/replicator/registry.ts b/packages/zero-cache/src/services/replicator/registry.ts
index c61d39c40c..b5ea78d7fc 100644
--- a/packages/zero-cache/src/services/replicator/registry.ts
+++ b/packages/zero-cache/src/services/replicator/registry.ts
@@ -1,4 +1,4 @@
-import type {Replicator} from './replicator.js';
+import type {Replicator} from './replicator.ts';
 
 export interface ReplicatorRegistry {
   /**
diff --git a/packages/zero-cache/src/services/replicator/replicator.ts b/packages/zero-cache/src/services/replicator/replicator.ts
index 024fe2c8d6..22754ce8a2 100644
--- a/packages/zero-cache/src/services/replicator/replicator.ts
+++ b/packages/zero-cache/src/services/replicator/replicator.ts
@@ -1,11 +1,11 @@
 import type {LogContext} from '@rocicorp/logger';
-import type {ReadonlyJSONObject} from '../../../../shared/src/json.js';
-import {promiseVoid} from '../../../../shared/src/resolved-promises.js';
-import {Database} from '../../../../zqlite/src/db.js';
-import type {Source} from '../../types/streams.js';
-import type {ChangeStreamer} from '../change-streamer/change-streamer.js';
-import type {Service} from '../service.js';
-import {IncrementalSyncer} from './incremental-sync.js';
+import type {ReadonlyJSONObject} from '../../../../shared/src/json.ts';
+import {promiseVoid} from '../../../../shared/src/resolved-promises.ts';
+import {Database} from '../../../../zqlite/src/db.ts';
+import type {Source} from '../../types/streams.ts';
+import type {ChangeStreamer} from '../change-streamer/change-streamer.ts';
+import type {Service} from '../service.ts';
+import {IncrementalSyncer} from './incremental-sync.ts';
 
 /** See {@link ReplicaStateNotifier.subscribe()}. */
 export type ReplicaState = {
diff --git a/packages/zero-cache/src/services/replicator/schema/change-log.test.ts b/packages/zero-cache/src/services/replicator/schema/change-log.test.ts
index 3d30d88df3..ab073b9f20 100644
--- a/packages/zero-cache/src/services/replicator/schema/change-log.test.ts
+++ b/packages/zero-cache/src/services/replicator/schema/change-log.test.ts
@@ -1,15 +1,15 @@
 import {beforeEach, describe, test} from 'vitest';
-import {createSilentLogContext} from '../../../../../shared/src/logging-test-utils.js';
-import {Database} from '../../../../../zqlite/src/db.js';
-import {StatementRunner} from '../../../db/statements.js';
-import {expectTables} from '../../../test/lite.js';
+import {createSilentLogContext} from '../../../../../shared/src/logging-test-utils.ts';
+import {Database} from '../../../../../zqlite/src/db.ts';
+import {StatementRunner} from '../../../db/statements.ts';
+import {expectTables} from '../../../test/lite.ts';
 import {
   initChangeLog,
   logDeleteOp,
   logResetOp,
   logSetOp,
   logTruncateOp,
-} from './change-log.js';
+} from './change-log.ts';
 
 describe('replicator/schema/change-log', () => {
   let db: StatementRunner;
diff --git a/packages/zero-cache/src/services/replicator/schema/change-log.ts b/packages/zero-cache/src/services/replicator/schema/change-log.ts
index ca6dfaf687..7aa3812f8d 100644
--- a/packages/zero-cache/src/services/replicator/schema/change-log.ts
+++ b/packages/zero-cache/src/services/replicator/schema/change-log.ts
@@ -1,14 +1,14 @@
-import * as v from '../../../../../shared/src/valita.js';
-import type {Database} from '../../../../../zqlite/src/db.js';
-import {StatementRunner} from '../../../db/statements.js';
+import * as v from '../../../../../shared/src/valita.ts';
+import type {Database} from '../../../../../zqlite/src/db.ts';
+import {StatementRunner} from '../../../db/statements.ts';
 import {
   jsonObjectSchema,
   parse,
   stringify,
-} from '../../../types/bigint-json.js';
-import type {LexiVersion} from '../../../types/lexi-version.js';
-import type {LiteRowKey} from '../../../types/lite.js';
-import {normalizedKeyOrder} from '../../../types/row-key.js';
+} from '../../../types/bigint-json.ts';
+import type {LexiVersion} from '../../../types/lexi-version.ts';
+import type {LiteRowKey} from '../../../types/lite.ts';
+import {normalizedKeyOrder} from '../../../types/row-key.ts';
 
 /**
  * The Change Log tracks the last operation (set or delete) for each row in the
diff --git a/packages/zero-cache/src/services/replicator/schema/replication-state.test.ts b/packages/zero-cache/src/services/replicator/schema/replication-state.test.ts
index eb527dadda..ff742d9a34 100644
--- a/packages/zero-cache/src/services/replicator/schema/replication-state.test.ts
+++ b/packages/zero-cache/src/services/replicator/schema/replication-state.test.ts
@@ -1,14 +1,14 @@
 import {beforeEach, describe, expect, test} from 'vitest';
-import {createSilentLogContext} from '../../../../../shared/src/logging-test-utils.js';
-import {Database} from '../../../../../zqlite/src/db.js';
-import {StatementRunner} from '../../../db/statements.js';
-import {expectTables} from '../../../test/lite.js';
+import {createSilentLogContext} from '../../../../../shared/src/logging-test-utils.ts';
+import {Database} from '../../../../../zqlite/src/db.ts';
+import {StatementRunner} from '../../../db/statements.ts';
+import {expectTables} from '../../../test/lite.ts';
 import {
   getReplicationState,
   getSubscriptionState,
   initReplicationState,
   updateReplicationWatermark,
-} from './replication-state.js';
+} from './replication-state.ts';
 
 describe('replicator/schema/replication-state', () => {
   let db: StatementRunner;
diff --git a/packages/zero-cache/src/services/replicator/schema/replication-state.ts b/packages/zero-cache/src/services/replicator/schema/replication-state.ts
index 2f6e06f0d5..33817a98e7 100644
--- a/packages/zero-cache/src/services/replicator/schema/replication-state.ts
+++ b/packages/zero-cache/src/services/replicator/schema/replication-state.ts
@@ -5,9 +5,9 @@
  * after the logical replication handoff when initial data synchronization has completed.
  */
 
-import * as v from '../../../../../shared/src/valita.js';
-import {Database} from '../../../../../zqlite/src/db.js';
-import {StatementRunner} from '../../../db/statements.js';
+import * as v from '../../../../../shared/src/valita.ts';
+import {Database} from '../../../../../zqlite/src/db.ts';
+import {StatementRunner} from '../../../db/statements.ts';
 
 export const ZERO_VERSION_COLUMN_NAME = '_0_version';
 
diff --git a/packages/zero-cache/src/services/replicator/test-utils.ts b/packages/zero-cache/src/services/replicator/test-utils.ts
index 41e2012c0a..73bd9e92ae 100644
--- a/packages/zero-cache/src/services/replicator/test-utils.ts
+++ b/packages/zero-cache/src/services/replicator/test-utils.ts
@@ -1,9 +1,9 @@
 import {LogContext} from '@rocicorp/logger';
-import {assert} from '../../../../shared/src/asserts.js';
-import {Database} from '../../../../zqlite/src/db.js';
-import type {ColumnSpec, IndexSpec, TableSpec} from '../../db/specs.js';
-import {StatementRunner} from '../../db/statements.js';
-import type {RowKey, RowValue} from '../../types/row-key.js';
+import {assert} from '../../../../shared/src/asserts.ts';
+import {Database} from '../../../../zqlite/src/db.ts';
+import type {ColumnSpec, IndexSpec, TableSpec} from '../../db/specs.ts';
+import {StatementRunner} from '../../db/statements.ts';
+import type {RowKey, RowValue} from '../../types/row-key.ts';
 import type {
   ColumnAdd,
   ColumnDrop,
@@ -22,8 +22,8 @@ import type {
   TableCreate,
   TableDrop,
   TableRename,
-} from '../change-source/protocol/current/data.js';
-import {MessageProcessor} from './incremental-sync.js';
+} from '../change-source/protocol/current/data.ts';
+import {MessageProcessor} from './incremental-sync.ts';
 
 export interface FakeReplicator {
   processTransaction(finalWatermark: string, ...msgs: DataChange[]): void;
diff --git a/packages/zero-cache/src/services/runner.test.ts b/packages/zero-cache/src/services/runner.test.ts
index b07fc266cb..cc7d2cacc6 100644
--- a/packages/zero-cache/src/services/runner.test.ts
+++ b/packages/zero-cache/src/services/runner.test.ts
@@ -1,9 +1,9 @@
 import {resolver} from '@rocicorp/resolver';
-import {createSilentLogContext} from '../../../shared/src/logging-test-utils.js';
-import {sleep} from '../../../shared/src/sleep.js';
 import {describe, expect, test} from 'vitest';
-import {ServiceRunner} from './runner.js';
-import type {Service} from './service.js';
+import {createSilentLogContext} from '../../../shared/src/logging-test-utils.ts';
+import {sleep} from '../../../shared/src/sleep.ts';
+import {ServiceRunner} from './runner.ts';
+import type {Service} from './service.ts';
 
 describe('services/runner', () => {
   class TestService implements Service {
diff --git a/packages/zero-cache/src/services/runner.ts b/packages/zero-cache/src/services/runner.ts
index e6a863e45d..95924ce85c 100644
--- a/packages/zero-cache/src/services/runner.ts
+++ b/packages/zero-cache/src/services/runner.ts
@@ -1,5 +1,5 @@
 import {LogContext} from '@rocicorp/logger';
-import type {Service} from './service.js';
+import type {Service} from './service.ts';
 
 /**
  * Manages the creation and lifecycle of objects that implement
diff --git a/packages/zero-cache/src/services/running-state.test.ts b/packages/zero-cache/src/services/running-state.test.ts
index a52d75c884..445ec954f9 100644
--- a/packages/zero-cache/src/services/running-state.test.ts
+++ b/packages/zero-cache/src/services/running-state.test.ts
@@ -1,7 +1,7 @@
 import {expect, test, vi} from 'vitest';
-import {AbortError} from '../../../shared/src/abort-error.js';
-import {createSilentLogContext} from '../../../shared/src/logging-test-utils.js';
-import {RunningState} from './running-state.js';
+import {AbortError} from '../../../shared/src/abort-error.ts';
+import {createSilentLogContext} from '../../../shared/src/logging-test-utils.ts';
+import {RunningState} from './running-state.ts';
 
 const lc = createSilentLogContext();
 
diff --git a/packages/zero-cache/src/services/running-state.ts b/packages/zero-cache/src/services/running-state.ts
index 5594d4e9dc..ab94287a1a 100644
--- a/packages/zero-cache/src/services/running-state.ts
+++ b/packages/zero-cache/src/services/running-state.ts
@@ -1,7 +1,7 @@
 import {LogContext} from '@rocicorp/logger';
 import {resolver} from '@rocicorp/resolver';
-import {AbortError} from '../../../shared/src/abort-error.js';
-import {sleepWithAbort} from '../../../shared/src/sleep.js';
+import {AbortError} from '../../../shared/src/abort-error.ts';
+import {sleepWithAbort} from '../../../shared/src/sleep.ts';
 
 const DEFAULT_INITIAL_RETRY_DELAY_MS = 100;
 export const DEFAULT_MAX_RETRY_DELAY_MS = 10000;
diff --git a/packages/zero-cache/src/services/view-syncer/client-handler.test.ts b/packages/zero-cache/src/services/view-syncer/client-handler.test.ts
index 9159f43995..ec4632d3d0 100644
--- a/packages/zero-cache/src/services/view-syncer/client-handler.test.ts
+++ b/packages/zero-cache/src/services/view-syncer/client-handler.test.ts
@@ -1,16 +1,16 @@
 import {describe, expect, test} from 'vitest';
-import {createSilentLogContext} from '../../../../shared/src/logging-test-utils.js';
-import * as ErrorKind from '../../../../zero-protocol/src/error-kind-enum.js';
+import {createSilentLogContext} from '../../../../shared/src/logging-test-utils.ts';
+import * as ErrorKind from '../../../../zero-protocol/src/error-kind-enum.ts';
 import {
   type Downstream,
   type PokeEndMessage,
   type PokePartMessage,
   type PokeStartMessage,
-} from '../../../../zero-protocol/src/mod.js';
-import type {JSONObject} from '../../types/bigint-json.js';
-import {ErrorForClient} from '../../types/error-for-client.js';
-import {Subscription} from '../../types/subscription.js';
-import {ClientHandler, ensureSafeJSON, type Patch} from './client-handler.js';
+} from '../../../../zero-protocol/src/mod.ts';
+import type {JSONObject} from '../../types/bigint-json.ts';
+import {ErrorForClient} from '../../types/error-for-client.ts';
+import {Subscription} from '../../types/subscription.ts';
+import {ClientHandler, ensureSafeJSON, type Patch} from './client-handler.ts';
 
 const SHARD_ID = 'xyz';
 
diff --git a/packages/zero-cache/src/services/view-syncer/client-handler.ts b/packages/zero-cache/src/services/view-syncer/client-handler.ts
index 759a420a7a..81b38a8143 100644
--- a/packages/zero-cache/src/services/view-syncer/client-handler.ts
+++ b/packages/zero-cache/src/services/view-syncer/client-handler.ts
@@ -1,27 +1,27 @@
 import type {LogContext} from '@rocicorp/logger';
-import {unreachable} from '../../../../shared/src/asserts.js';
+import {unreachable} from '../../../../shared/src/asserts.ts';
 import {
   assertJSONValue,
   type JSONObject as SafeJSONObject,
-} from '../../../../shared/src/json.js';
-import * as v from '../../../../shared/src/valita.js';
-import type {AST} from '../../../../zero-protocol/src/ast.js';
-import {rowSchema} from '../../../../zero-protocol/src/data.js';
+} from '../../../../shared/src/json.ts';
+import * as v from '../../../../shared/src/valita.ts';
+import type {AST} from '../../../../zero-protocol/src/ast.ts';
+import {rowSchema} from '../../../../zero-protocol/src/data.ts';
 import type {
   Downstream,
   PokePartBody,
   PokeStartBody,
   RowPatchOp,
-} from '../../../../zero-protocol/src/mod.js';
-import {primaryKeyValueRecordSchema} from '../../../../zero-protocol/src/primary-key.js';
-import type {JSONObject} from '../../types/bigint-json.js';
-import {getLogLevel} from '../../types/error-for-client.js';
+} from '../../../../zero-protocol/src/mod.ts';
+import {primaryKeyValueRecordSchema} from '../../../../zero-protocol/src/primary-key.ts';
+import type {JSONObject} from '../../types/bigint-json.ts';
+import {getLogLevel} from '../../types/error-for-client.ts';
 import {
   getErrorForClientIfSchemaVersionNotSupported,
   type SchemaVersions,
-} from '../../types/schema-versions.js';
-import type {Subscription} from '../../types/subscription.js';
-import {unescapedSchema as schema} from '../change-source/pg/schema/shard.js';
+} from '../../types/schema-versions.ts';
+import type {Subscription} from '../../types/subscription.ts';
+import {unescapedSchema as schema} from '../change-source/pg/schema/shard.ts';
 import {
   type ClientPatch,
   cmpVersions,
@@ -33,7 +33,7 @@ import {
   type RowID,
   versionToCookie,
   versionToNullableCookie,
-} from './schema/types.js';
+} from './schema/types.ts';
 
 export type PutRowPatch = {
   type: 'row';
diff --git a/packages/zero-cache/src/services/view-syncer/cvr-store.pg-test.ts b/packages/zero-cache/src/services/view-syncer/cvr-store.pg-test.ts
index bd2dbceed8..3721a76d48 100644
--- a/packages/zero-cache/src/services/view-syncer/cvr-store.pg-test.ts
+++ b/packages/zero-cache/src/services/view-syncer/cvr-store.pg-test.ts
@@ -7,21 +7,21 @@ import {
   vi,
   type Mock,
 } from 'vitest';
-import {CustomKeyMap} from '../../../../shared/src/custom-key-map.js';
-import {createSilentLogContext} from '../../../../shared/src/logging-test-utils.js';
-import {sleep} from '../../../../shared/src/sleep.js';
-import {testDBs} from '../../test/db.js';
-import {versionToLexi} from '../../types/lexi-version.js';
-import type {PostgresDB} from '../../types/pg.js';
-import {rowIDString, type RowID} from '../../types/row-key.js';
-import {CVRStore, OwnershipError} from './cvr-store.js';
+import {CustomKeyMap} from '../../../../shared/src/custom-key-map.ts';
+import {createSilentLogContext} from '../../../../shared/src/logging-test-utils.ts';
+import {sleep} from '../../../../shared/src/sleep.ts';
+import {testDBs} from '../../test/db.ts';
+import {versionToLexi} from '../../types/lexi-version.ts';
+import type {PostgresDB} from '../../types/pg.ts';
+import {rowIDString, type RowID} from '../../types/row-key.ts';
+import {CVRStore, OwnershipError} from './cvr-store.ts';
 import {
   CVRQueryDrivenUpdater,
   type CVRSnapshot,
   type RowUpdate,
-} from './cvr.js';
-import {setupCVRTables, type RowsRow} from './schema/cvr.js';
-import type {CVRVersion} from './schema/types.js';
+} from './cvr.ts';
+import {setupCVRTables, type RowsRow} from './schema/cvr.ts';
+import type {CVRVersion} from './schema/types.ts';
 
 describe('view-syncer/cvr-store', () => {
   const lc = createSilentLogContext();
diff --git a/packages/zero-cache/src/services/view-syncer/cvr-store.ts b/packages/zero-cache/src/services/view-syncer/cvr-store.ts
index 21fd158636..99b5f0ac7a 100644
--- a/packages/zero-cache/src/services/view-syncer/cvr-store.ts
+++ b/packages/zero-cache/src/services/view-syncer/cvr-store.ts
@@ -2,28 +2,28 @@ import {trace} from '@opentelemetry/api';
 import type {LogContext} from '@rocicorp/logger';
 import {resolver, type Resolver} from '@rocicorp/resolver';
 import type {MaybeRow, PendingQuery, Row} from 'postgres';
-import {startAsyncSpan} from '../../../../otel/src/span.js';
-import {version} from '../../../../otel/src/version.js';
-import {assert} from '../../../../shared/src/asserts.js';
-import {CustomKeyMap} from '../../../../shared/src/custom-key-map.js';
-import {CustomKeySet} from '../../../../shared/src/custom-key-set.js';
+import {startAsyncSpan} from '../../../../otel/src/span.ts';
+import {version} from '../../../../otel/src/version.ts';
+import {assert} from '../../../../shared/src/asserts.ts';
+import {CustomKeyMap} from '../../../../shared/src/custom-key-map.ts';
+import {CustomKeySet} from '../../../../shared/src/custom-key-set.ts';
 import {
   deepEqual,
   type ReadonlyJSONValue,
-} from '../../../../shared/src/json.js';
-import {must} from '../../../../shared/src/must.js';
-import {promiseVoid} from '../../../../shared/src/resolved-promises.js';
-import {sleep} from '../../../../shared/src/sleep.js';
-import {astSchema} from '../../../../zero-protocol/src/ast.js';
-import * as ErrorKind from '../../../../zero-protocol/src/error-kind-enum.js';
-import * as Mode from '../../db/mode-enum.js';
-import {TransactionPool} from '../../db/transaction-pool.js';
-import type {JSONValue} from '../../types/bigint-json.js';
-import {ErrorForClient, ErrorWithLevel} from '../../types/error-for-client.js';
-import type {PostgresDB, PostgresTransaction} from '../../types/pg.js';
-import {rowIDString} from '../../types/row-key.js';
-import type {Patch, PatchToVersion} from './client-handler.js';
-import type {CVR, CVRSnapshot} from './cvr.js';
+} from '../../../../shared/src/json.ts';
+import {must} from '../../../../shared/src/must.ts';
+import {promiseVoid} from '../../../../shared/src/resolved-promises.ts';
+import {sleep} from '../../../../shared/src/sleep.ts';
+import {astSchema} from '../../../../zero-protocol/src/ast.ts';
+import * as ErrorKind from '../../../../zero-protocol/src/error-kind-enum.ts';
+import * as Mode from '../../db/mode-enum.ts';
+import {TransactionPool} from '../../db/transaction-pool.ts';
+import type {JSONValue} from '../../types/bigint-json.ts';
+import {ErrorForClient, ErrorWithLevel} from '../../types/error-for-client.ts';
+import type {PostgresDB, PostgresTransaction} from '../../types/pg.ts';
+import {rowIDString} from '../../types/row-key.ts';
+import type {Patch, PatchToVersion} from './client-handler.ts';
+import type {CVR, CVRSnapshot} from './cvr.ts';
 import {
   type ClientsRow,
   type DesiresRow,
@@ -32,7 +32,7 @@ import {
   rowRecordToRowsRow,
   type RowsRow,
   rowsRowToRowRecord,
-} from './schema/cvr.js';
+} from './schema/cvr.ts';
 import {
   type ClientQueryRecord,
   type ClientRecord,
@@ -48,7 +48,7 @@ import {
   versionFromString,
   versionString,
   versionToNullableCookie,
-} from './schema/types.js';
+} from './schema/types.ts';
 
 type NotNull<T> = T extends null ? never : T;
 
diff --git a/packages/zero-cache/src/services/view-syncer/cvr.pg-test.ts b/packages/zero-cache/src/services/view-syncer/cvr.pg-test.ts
index 12e6f39518..72c1d340eb 100644
--- a/packages/zero-cache/src/services/view-syncer/cvr.pg-test.ts
+++ b/packages/zero-cache/src/services/view-syncer/cvr.pg-test.ts
@@ -1,20 +1,20 @@
 import {afterEach, beforeEach, describe, expect, test} from 'vitest';
-import {unreachable} from '../../../../shared/src/asserts.js';
-import {createSilentLogContext} from '../../../../shared/src/logging-test-utils.js';
-import {testDBs} from '../../test/db.js';
-import type {PostgresDB} from '../../types/pg.js';
-import type {PatchToVersion} from './client-handler.js';
+import {unreachable} from '../../../../shared/src/asserts.ts';
+import {createSilentLogContext} from '../../../../shared/src/logging-test-utils.ts';
+import {testDBs} from '../../test/db.ts';
+import type {PostgresDB} from '../../types/pg.ts';
+import type {PatchToVersion} from './client-handler.ts';
 import {
   ConcurrentModificationException,
   CVRStore,
   OwnershipError,
-} from './cvr-store.js';
+} from './cvr-store.ts';
 import {
   CVRConfigDrivenUpdater,
   CVRQueryDrivenUpdater,
   type CVRSnapshot,
   CVRUpdater,
-} from './cvr.js';
+} from './cvr.ts';
 import {
   type ClientsRow,
   compareClientsRows,
@@ -28,8 +28,8 @@ import {
   type RowsRow,
   type RowsVersionRow,
   setupCVRTables,
-} from './schema/cvr.js';
-import type {CVRVersion, RowID} from './schema/types.js';
+} from './schema/cvr.ts';
+import type {CVRVersion, RowID} from './schema/types.ts';
 
 const SHARD_ID = 'jkl';
 
diff --git a/packages/zero-cache/src/services/view-syncer/cvr.ts b/packages/zero-cache/src/services/view-syncer/cvr.ts
index 330d005979..46c5797181 100644
--- a/packages/zero-cache/src/services/view-syncer/cvr.ts
+++ b/packages/zero-cache/src/services/view-syncer/cvr.ts
@@ -1,20 +1,20 @@
 import type {LogContext} from '@rocicorp/logger';
 import {compareUTF8} from 'compare-utf8';
-import {assert} from '../../../../shared/src/asserts.js';
-import {CustomKeyMap} from '../../../../shared/src/custom-key-map.js';
+import {assert} from '../../../../shared/src/asserts.ts';
+import {CustomKeyMap} from '../../../../shared/src/custom-key-map.ts';
 import {
   difference,
   intersection,
   union,
-} from '../../../../shared/src/set-utils.js';
-import type {AST} from '../../../../zero-protocol/src/ast.js';
-import {stringify, type JSONObject} from '../../types/bigint-json.js';
-import type {LexiVersion} from '../../types/lexi-version.js';
-import {rowIDString} from '../../types/row-key.js';
-import {unescapedSchema as schema} from '../change-source/pg/schema/shard.js';
-import type {Patch, PatchToVersion} from './client-handler.js';
-import type {CVRFlushStats, CVRStore} from './cvr-store.js';
-import {KeyColumns} from './key-columns.js';
+} from '../../../../shared/src/set-utils.ts';
+import type {AST} from '../../../../zero-protocol/src/ast.ts';
+import {stringify, type JSONObject} from '../../types/bigint-json.ts';
+import type {LexiVersion} from '../../types/lexi-version.ts';
+import {rowIDString} from '../../types/row-key.ts';
+import {unescapedSchema as schema} from '../change-source/pg/schema/shard.ts';
+import type {Patch, PatchToVersion} from './client-handler.ts';
+import type {CVRFlushStats, CVRStore} from './cvr-store.ts';
+import {KeyColumns} from './key-columns.ts';
 import {
   cmpVersions,
   oneAfter,
@@ -26,7 +26,7 @@ import {
   type QueryRecord,
   type RowID,
   type RowRecord,
-} from './schema/types.js';
+} from './schema/types.ts';
 
 export type RowUpdate = {
   version?: string; // Undefined for an unref.
diff --git a/packages/zero-cache/src/services/view-syncer/database-storage.test.ts b/packages/zero-cache/src/services/view-syncer/database-storage.test.ts
index 00a33f6378..6adc43f19a 100644
--- a/packages/zero-cache/src/services/view-syncer/database-storage.test.ts
+++ b/packages/zero-cache/src/services/view-syncer/database-storage.test.ts
@@ -1,8 +1,8 @@
-import {Database} from '../../../../zqlite/src/db.js';
 import {afterEach} from 'node:test';
 import {beforeEach, describe, expect, test} from 'vitest';
-import {CREATE_STORAGE_TABLE, DatabaseStorage} from './database-storage.js';
-import {createSilentLogContext} from '../../../../shared/src/logging-test-utils.js';
+import {createSilentLogContext} from '../../../../shared/src/logging-test-utils.ts';
+import {Database} from '../../../../zqlite/src/db.ts';
+import {CREATE_STORAGE_TABLE, DatabaseStorage} from './database-storage.ts';
 
 describe('view-syncer/database-storage', () => {
   let db: Database;
diff --git a/packages/zero-cache/src/services/view-syncer/database-storage.ts b/packages/zero-cache/src/services/view-syncer/database-storage.ts
index c8c97fdcf2..6af4238733 100644
--- a/packages/zero-cache/src/services/view-syncer/database-storage.ts
+++ b/packages/zero-cache/src/services/view-syncer/database-storage.ts
@@ -1,8 +1,8 @@
 import {LogContext} from '@rocicorp/logger';
-import type {JSONValue} from '../../../../shared/src/json.js';
-import type {Storage} from '../../../../zql/src/ivm/operator.js';
-import type {Stream} from '../../../../zql/src/ivm/stream.js';
-import {Database, Statement} from '../../../../zqlite/src/db.js';
+import type {JSONValue} from '../../../../shared/src/json.ts';
+import type {Storage} from '../../../../zql/src/ivm/operator.ts';
+import type {Stream} from '../../../../zql/src/ivm/stream.ts';
+import {Database, Statement} from '../../../../zqlite/src/db.ts';
 
 export interface ClientGroupStorage {
   /** Creates a {@link Storage} instance for a single operator. */
diff --git a/packages/zero-cache/src/services/view-syncer/drain-coordinator.ts b/packages/zero-cache/src/services/view-syncer/drain-coordinator.ts
index 90da2fd4b0..50c76e5153 100644
--- a/packages/zero-cache/src/services/view-syncer/drain-coordinator.ts
+++ b/packages/zero-cache/src/services/view-syncer/drain-coordinator.ts
@@ -1,5 +1,5 @@
 import {resolver} from '@rocicorp/resolver';
-import {assert} from '../../../../shared/src/asserts.js';
+import {assert} from '../../../../shared/src/asserts.ts';
 
 // The target (additional) utilization to impose on the server
 // that receives the drained connections.
diff --git a/packages/zero-cache/src/services/view-syncer/key-columns.test.ts b/packages/zero-cache/src/services/view-syncer/key-columns.test.ts
index 84a2fef499..f16295c1bc 100644
--- a/packages/zero-cache/src/services/view-syncer/key-columns.test.ts
+++ b/packages/zero-cache/src/services/view-syncer/key-columns.test.ts
@@ -1,6 +1,6 @@
 import {describe, expect, test} from 'vitest';
-import {KeyColumns} from './key-columns.js';
-import type {RowID, RowRecord} from './schema/types.js';
+import {KeyColumns} from './key-columns.ts';
+import type {RowID, RowRecord} from './schema/types.ts';
 
 describe('key columns', () => {
   function rowRecord(rowID: RowID): RowRecord {
diff --git a/packages/zero-cache/src/services/view-syncer/key-columns.ts b/packages/zero-cache/src/services/view-syncer/key-columns.ts
index edc3dbf4c6..5222e41767 100644
--- a/packages/zero-cache/src/services/view-syncer/key-columns.ts
+++ b/packages/zero-cache/src/services/view-syncer/key-columns.ts
@@ -1,8 +1,8 @@
-import {deepEqual} from '../../../../shared/src/json.js';
-import * as ErrorKind from '../../../../zero-protocol/src/error-kind-enum.js';
-import type {JSONObject} from '../../types/bigint-json.js';
-import {ErrorForClient} from '../../types/error-for-client.js';
-import type {RowID, RowRecord} from './schema/types.js';
+import {deepEqual} from '../../../../shared/src/json.ts';
+import * as ErrorKind from '../../../../zero-protocol/src/error-kind-enum.ts';
+import type {JSONObject} from '../../types/bigint-json.ts';
+import {ErrorForClient} from '../../types/error-for-client.ts';
+import type {RowID, RowRecord} from './schema/types.ts';
 
 /**
  * KeyColumns track the key columns used to reference rows in the CVR.
diff --git a/packages/zero-cache/src/services/view-syncer/pipeline-driver.test.ts b/packages/zero-cache/src/services/view-syncer/pipeline-driver.test.ts
index 3a92948cbb..1152457c74 100644
--- a/packages/zero-cache/src/services/view-syncer/pipeline-driver.test.ts
+++ b/packages/zero-cache/src/services/view-syncer/pipeline-driver.test.ts
@@ -1,20 +1,20 @@
 import {LogContext} from '@rocicorp/logger';
 import {afterEach, beforeEach, describe, expect, test} from 'vitest';
-import {createSilentLogContext} from '../../../../shared/src/logging-test-utils.js';
-import type {AST} from '../../../../zero-protocol/src/ast.js';
-import type {Database as DB} from '../../../../zqlite/src/db.js';
-import {Database} from '../../../../zqlite/src/db.js';
-import {DbFile} from '../../test/lite.js';
-import {initChangeLog} from '../replicator/schema/change-log.js';
-import {initReplicationState} from '../replicator/schema/replication-state.js';
+import {createSilentLogContext} from '../../../../shared/src/logging-test-utils.ts';
+import type {AST} from '../../../../zero-protocol/src/ast.ts';
+import type {Database as DB} from '../../../../zqlite/src/db.ts';
+import {Database} from '../../../../zqlite/src/db.ts';
+import {DbFile} from '../../test/lite.ts';
+import {initChangeLog} from '../replicator/schema/change-log.ts';
+import {initReplicationState} from '../replicator/schema/replication-state.ts';
 import {
   fakeReplicator,
   ReplicationMessages,
   type FakeReplicator,
-} from '../replicator/test-utils.js';
-import {CREATE_STORAGE_TABLE, DatabaseStorage} from './database-storage.js';
-import {PipelineDriver} from './pipeline-driver.js';
-import {ResetPipelinesSignal, Snapshotter} from './snapshotter.js';
+} from '../replicator/test-utils.ts';
+import {CREATE_STORAGE_TABLE, DatabaseStorage} from './database-storage.ts';
+import {PipelineDriver} from './pipeline-driver.ts';
+import {ResetPipelinesSignal, Snapshotter} from './snapshotter.ts';
 
 describe('view-syncer/pipeline-driver', () => {
   let dbFile: DbFile;
diff --git a/packages/zero-cache/src/services/view-syncer/pipeline-driver.ts b/packages/zero-cache/src/services/view-syncer/pipeline-driver.ts
index 075130de66..1d62e09e24 100644
--- a/packages/zero-cache/src/services/view-syncer/pipeline-driver.ts
+++ b/packages/zero-cache/src/services/view-syncer/pipeline-driver.ts
@@ -1,26 +1,26 @@
 import {LogContext} from '@rocicorp/logger';
-import {assert, unreachable} from '../../../../shared/src/asserts.js';
-import {must} from '../../../../shared/src/must.js';
-import type {AST} from '../../../../zero-protocol/src/ast.js';
-import type {Row} from '../../../../zero-protocol/src/data.js';
-import {buildPipeline} from '../../../../zql/src/builder/builder.js';
-import type {Change} from '../../../../zql/src/ivm/change.js';
-import type {Node} from '../../../../zql/src/ivm/data.js';
-import type {Input, Storage} from '../../../../zql/src/ivm/operator.js';
-import type {SourceSchema} from '../../../../zql/src/ivm/schema.js';
-import type {Source, SourceChange} from '../../../../zql/src/ivm/source.js';
+import {assert, unreachable} from '../../../../shared/src/asserts.ts';
+import {must} from '../../../../shared/src/must.ts';
+import type {AST} from '../../../../zero-protocol/src/ast.ts';
+import type {Row} from '../../../../zero-protocol/src/data.ts';
+import {buildPipeline} from '../../../../zql/src/builder/builder.ts';
+import type {Change} from '../../../../zql/src/ivm/change.ts';
+import type {Node} from '../../../../zql/src/ivm/data.ts';
+import type {Input, Storage} from '../../../../zql/src/ivm/operator.ts';
+import type {SourceSchema} from '../../../../zql/src/ivm/schema.ts';
+import type {Source, SourceChange} from '../../../../zql/src/ivm/source.ts';
 import {
   runtimeDebugFlags,
   runtimeDebugStats,
-} from '../../../../zqlite/src/runtime-debug.js';
-import {TableSource} from '../../../../zqlite/src/table-source.js';
-import {computeZqlSpecs} from '../../db/lite-tables.js';
-import type {LiteAndZqlSpec} from '../../db/specs.js';
-import type {RowKey} from '../../types/row-key.js';
-import type {SchemaVersions} from '../../types/schema-versions.js';
-import {getSubscriptionState} from '../replicator/schema/replication-state.js';
-import type {ClientGroupStorage} from './database-storage.js';
-import {type SnapshotDiff, Snapshotter} from './snapshotter.js';
+} from '../../../../zqlite/src/runtime-debug.ts';
+import {TableSource} from '../../../../zqlite/src/table-source.ts';
+import {computeZqlSpecs} from '../../db/lite-tables.ts';
+import type {LiteAndZqlSpec} from '../../db/specs.ts';
+import type {RowKey} from '../../types/row-key.ts';
+import type {SchemaVersions} from '../../types/schema-versions.ts';
+import {getSubscriptionState} from '../replicator/schema/replication-state.ts';
+import type {ClientGroupStorage} from './database-storage.ts';
+import {type SnapshotDiff, Snapshotter} from './snapshotter.ts';
 
 export type RowAdd = {
   readonly type: 'add';
diff --git a/packages/zero-cache/src/services/view-syncer/schema/cvr.ts b/packages/zero-cache/src/services/view-syncer/schema/cvr.ts
index 9e57991deb..9c3f68262c 100644
--- a/packages/zero-cache/src/services/view-syncer/schema/cvr.ts
+++ b/packages/zero-cache/src/services/view-syncer/schema/cvr.ts
@@ -1,18 +1,18 @@
 import type {LogContext} from '@rocicorp/logger';
 import type postgres from 'postgres';
-import {stringCompare} from '../../../../../shared/src/string-compare.js';
+import {stringCompare} from '../../../../../shared/src/string-compare.ts';
 import {
   type JSONObject,
   type JSONValue,
   stringify,
-} from '../../../types/bigint-json.js';
-import {normalizedKeyOrder, type RowKey} from '../../../types/row-key.js';
+} from '../../../types/bigint-json.ts';
+import {normalizedKeyOrder, type RowKey} from '../../../types/row-key.ts';
 import {
   type RowID,
   type RowRecord,
   versionFromString,
   versionString,
-} from './types.js';
+} from './types.ts';
 
 export const PG_SCHEMA = 'cvr';
 
diff --git a/packages/zero-cache/src/services/view-syncer/schema/init.ts b/packages/zero-cache/src/services/view-syncer/schema/init.ts
index 57523298df..c94f996e7b 100644
--- a/packages/zero-cache/src/services/view-syncer/schema/init.ts
+++ b/packages/zero-cache/src/services/view-syncer/schema/init.ts
@@ -4,13 +4,13 @@ import {
   runSchemaMigrations,
   type IncrementalMigrationMap,
   type Migration,
-} from '../../../db/migration.js';
-import type {PostgresDB} from '../../../types/pg.js';
+} from '../../../db/migration.ts';
+import type {PostgresDB} from '../../../types/pg.ts';
 import {
   CREATE_CVR_ROWS_VERSION_TABLE,
   PG_SCHEMA,
   setupCVRTables,
-} from './cvr.js';
+} from './cvr.ts';
 
 const setupMigration: Migration = {
   migrateSchema: setupCVRTables,
diff --git a/packages/zero-cache/src/services/view-syncer/schema/types.test.ts b/packages/zero-cache/src/services/view-syncer/schema/types.test.ts
index 1498e231c6..04a3ecc10a 100644
--- a/packages/zero-cache/src/services/view-syncer/schema/types.test.ts
+++ b/packages/zero-cache/src/services/view-syncer/schema/types.test.ts
@@ -5,7 +5,7 @@ import {
   cookieToVersion,
   oneAfter,
   versionToNullableCookie,
-} from './types.js';
+} from './types.ts';
 
 describe('view-syncer/schema/types', () => {
   test('version comparison', () => {
diff --git a/packages/zero-cache/src/services/view-syncer/schema/types.ts b/packages/zero-cache/src/services/view-syncer/schema/types.ts
index 7307ffb074..87599191d1 100644
--- a/packages/zero-cache/src/services/view-syncer/schema/types.ts
+++ b/packages/zero-cache/src/services/view-syncer/schema/types.ts
@@ -1,7 +1,7 @@
-import * as v from '../../../../../shared/src/valita.js';
-import {astSchema} from '../../../../../zero-protocol/src/ast.js';
-import {jsonValueSchema} from '../../../types/bigint-json.js';
-import {versionFromLexi, versionToLexi} from '../../../types/lexi-version.js';
+import * as v from '../../../../../shared/src/valita.ts';
+import {astSchema} from '../../../../../zero-protocol/src/ast.ts';
+import {jsonValueSchema} from '../../../types/bigint-json.ts';
+import {versionFromLexi, versionToLexi} from '../../../types/lexi-version.ts';
 
 export const cvrVersionSchema = v.object({
   /**
diff --git a/packages/zero-cache/src/services/view-syncer/snapshotter.test.ts b/packages/zero-cache/src/services/view-syncer/snapshotter.test.ts
index c385d681d9..60f6ab6dd8 100644
--- a/packages/zero-cache/src/services/view-syncer/snapshotter.test.ts
+++ b/packages/zero-cache/src/services/view-syncer/snapshotter.test.ts
@@ -1,21 +1,21 @@
 import {LogContext} from '@rocicorp/logger';
 import {afterEach, beforeEach, describe, expect, test} from 'vitest';
-import {createSilentLogContext} from '../../../../shared/src/logging-test-utils.js';
-import {computeZqlSpecs} from '../../db/lite-tables.js';
-import type {LiteAndZqlSpec} from '../../db/specs.js';
-import {DbFile, expectTables} from '../../test/lite.js';
-import {initChangeLog} from '../replicator/schema/change-log.js';
-import {initReplicationState} from '../replicator/schema/replication-state.js';
+import {createSilentLogContext} from '../../../../shared/src/logging-test-utils.ts';
+import {computeZqlSpecs} from '../../db/lite-tables.ts';
+import type {LiteAndZqlSpec} from '../../db/specs.ts';
+import {DbFile, expectTables} from '../../test/lite.ts';
+import {initChangeLog} from '../replicator/schema/change-log.ts';
+import {initReplicationState} from '../replicator/schema/replication-state.ts';
 import {
   fakeReplicator,
   ReplicationMessages,
   type FakeReplicator,
-} from '../replicator/test-utils.js';
+} from '../replicator/test-utils.ts';
 import {
   InvalidDiffError,
   ResetPipelinesSignal,
   Snapshotter,
-} from './snapshotter.js';
+} from './snapshotter.ts';
 
 describe('view-syncer/snapshotter', () => {
   let lc: LogContext;
diff --git a/packages/zero-cache/src/services/view-syncer/snapshotter.ts b/packages/zero-cache/src/services/view-syncer/snapshotter.ts
index 9cabea5076..0d946ecca2 100644
--- a/packages/zero-cache/src/services/view-syncer/snapshotter.ts
+++ b/packages/zero-cache/src/services/view-syncer/snapshotter.ts
@@ -1,29 +1,29 @@
 import {LogContext} from '@rocicorp/logger';
-import {assert} from '../../../../shared/src/asserts.js';
-import {must} from '../../../../shared/src/must.js';
-import * as v from '../../../../shared/src/valita.js';
-import {Database} from '../../../../zqlite/src/db.js';
-import {fromSQLiteTypes} from '../../../../zqlite/src/table-source.js';
-import type {LiteAndZqlSpec, LiteTableSpecWithKeys} from '../../db/specs.js';
-import {StatementRunner} from '../../db/statements.js';
-import {type JSONValue} from '../../types/bigint-json.js';
+import {assert} from '../../../../shared/src/asserts.ts';
+import {must} from '../../../../shared/src/must.ts';
+import * as v from '../../../../shared/src/valita.ts';
+import {Database} from '../../../../zqlite/src/db.ts';
+import {fromSQLiteTypes} from '../../../../zqlite/src/table-source.ts';
+import type {LiteAndZqlSpec, LiteTableSpecWithKeys} from '../../db/specs.ts';
+import {StatementRunner} from '../../db/statements.ts';
+import {type JSONValue} from '../../types/bigint-json.ts';
 import {
   normalizedKeyOrder,
   type RowKey,
   type RowValue,
-} from '../../types/row-key.js';
-import {type SchemaVersions} from '../../types/schema-versions.js';
-import {id} from '../../types/sql.js';
+} from '../../types/row-key.ts';
+import {type SchemaVersions} from '../../types/schema-versions.ts';
+import {id} from '../../types/sql.ts';
 import {
   RESET_OP,
   changeLogEntrySchema as schema,
   SET_OP,
   TRUNCATE_OP,
-} from '../replicator/schema/change-log.js';
+} from '../replicator/schema/change-log.ts';
 import {
   getReplicationState,
   ZERO_VERSION_COLUMN_NAME as ROW_VERSION,
-} from '../replicator/schema/replication-state.js';
+} from '../replicator/schema/replication-state.ts';
 
 /**
  * A `Snapshotter` manages the progression of database snapshots for a
diff --git a/packages/zero-cache/src/services/view-syncer/view-syncer.pg-test.ts b/packages/zero-cache/src/services/view-syncer/view-syncer.pg-test.ts
index 4a503d051c..4d8d7bf172 100644
--- a/packages/zero-cache/src/services/view-syncer/view-syncer.pg-test.ts
+++ b/packages/zero-cache/src/services/view-syncer/view-syncer.pg-test.ts
@@ -1,57 +1,57 @@
 import {afterEach, beforeEach, describe, expect, test} from 'vitest';
-import {createSilentLogContext} from '../../../../shared/src/logging-test-utils.js';
-import {Queue} from '../../../../shared/src/queue.js';
-import {sleep} from '../../../../shared/src/sleep.js';
-import type {AST} from '../../../../zero-protocol/src/ast.js';
-import * as ErrorKind from '../../../../zero-protocol/src/error-kind-enum.js';
+import {createSilentLogContext} from '../../../../shared/src/logging-test-utils.ts';
+import {Queue} from '../../../../shared/src/queue.ts';
+import {sleep} from '../../../../shared/src/sleep.ts';
+import type {AST} from '../../../../zero-protocol/src/ast.ts';
+import * as ErrorKind from '../../../../zero-protocol/src/error-kind-enum.ts';
 import {
   type Downstream,
   type ErrorBody,
   type PokePartBody,
   type PokeStartBody,
   type QueriesPatch,
-} from '../../../../zero-protocol/src/mod.js';
-import type {PermissionsConfig} from '../../../../zero-schema/src/compiled-permissions.js';
-import {definePermissions} from '../../../../zero-schema/src/permissions.js';
-import type {ExpressionBuilder} from '../../../../zql/src/query/expression.js';
-import {Database} from '../../../../zqlite/src/db.js';
-import {StatementRunner} from '../../db/statements.js';
-import {testDBs} from '../../test/db.js';
-import {DbFile} from '../../test/lite.js';
-import {ErrorForClient} from '../../types/error-for-client.js';
-import type {PostgresDB} from '../../types/pg.js';
-import {Subscription} from '../../types/subscription.js';
-import type {ReplicaState} from '../replicator/replicator.js';
-import {initChangeLog} from '../replicator/schema/change-log.js';
+} from '../../../../zero-protocol/src/mod.ts';
+import {relationships} from '../../../../zero-schema/src/builder/relationship-builder.ts';
+import {createSchema} from '../../../../zero-schema/src/builder/schema-builder.ts';
+import {
+  json,
+  number,
+  string,
+  table,
+} from '../../../../zero-schema/src/builder/table-builder.ts';
+import type {PermissionsConfig} from '../../../../zero-schema/src/compiled-permissions.ts';
+import {definePermissions} from '../../../../zero-schema/src/permissions.ts';
+import type {ExpressionBuilder} from '../../../../zql/src/query/expression.ts';
+import {Database} from '../../../../zqlite/src/db.ts';
+import {StatementRunner} from '../../db/statements.ts';
+import {testDBs} from '../../test/db.ts';
+import {DbFile} from '../../test/lite.ts';
+import {ErrorForClient} from '../../types/error-for-client.ts';
+import type {PostgresDB} from '../../types/pg.ts';
+import {Subscription} from '../../types/subscription.ts';
+import type {ReplicaState} from '../replicator/replicator.ts';
+import {initChangeLog} from '../replicator/schema/change-log.ts';
 import {
   initReplicationState,
   updateReplicationWatermark,
-} from '../replicator/schema/replication-state.js';
+} from '../replicator/schema/replication-state.ts';
 import {
   fakeReplicator,
   type FakeReplicator,
   ReplicationMessages,
-} from '../replicator/test-utils.js';
-import {CVRStore} from './cvr-store.js';
-import {CVRQueryDrivenUpdater} from './cvr.js';
+} from '../replicator/test-utils.ts';
+import {CVRStore} from './cvr-store.ts';
+import {CVRQueryDrivenUpdater} from './cvr.ts';
 import {
   type ClientGroupStorage,
   CREATE_STORAGE_TABLE,
   DatabaseStorage,
-} from './database-storage.js';
-import {DrainCoordinator} from './drain-coordinator.js';
-import {PipelineDriver} from './pipeline-driver.js';
-import {initViewSyncerSchema} from './schema/init.js';
-import {Snapshotter} from './snapshotter.js';
-import {pickToken, type SyncContext, ViewSyncerService} from './view-syncer.js';
-import {createSchema} from '../../../../zero-schema/src/builder/schema-builder.js';
-import {
-  json,
-  number,
-  string,
-  table,
-} from '../../../../zero-schema/src/builder/table-builder.js';
-import {relationships} from '../../../../zero-schema/src/builder/relationship-builder.js';
+} from './database-storage.ts';
+import {DrainCoordinator} from './drain-coordinator.ts';
+import {PipelineDriver} from './pipeline-driver.ts';
+import {initViewSyncerSchema} from './schema/init.ts';
+import {Snapshotter} from './snapshotter.ts';
+import {pickToken, type SyncContext, ViewSyncerService} from './view-syncer.ts';
 
 const SHARD_ID = 'ABC';
 
diff --git a/packages/zero-cache/src/services/view-syncer/view-syncer.ts b/packages/zero-cache/src/services/view-syncer/view-syncer.ts
index 344299bdfa..2f0fd58011 100644
--- a/packages/zero-cache/src/services/view-syncer/view-syncer.ts
+++ b/packages/zero-cache/src/services/view-syncer/view-syncer.ts
@@ -8,46 +8,46 @@ import {
   manualSpan,
   startAsyncSpan,
   startSpan,
-} from '../../../../otel/src/span.js';
-import {version} from '../../../../otel/src/version.js';
-import {assert, unreachable} from '../../../../shared/src/asserts.js';
-import {CustomKeyMap} from '../../../../shared/src/custom-key-map.js';
-import {must} from '../../../../shared/src/must.js';
-import {randInt} from '../../../../shared/src/rand.js';
-import type {AST} from '../../../../zero-protocol/src/ast.js';
-import * as ErrorKind from '../../../../zero-protocol/src/error-kind-enum.js';
+} from '../../../../otel/src/span.ts';
+import {version} from '../../../../otel/src/version.ts';
+import {assert, unreachable} from '../../../../shared/src/asserts.ts';
+import {CustomKeyMap} from '../../../../shared/src/custom-key-map.ts';
+import {must} from '../../../../shared/src/must.ts';
+import {randInt} from '../../../../shared/src/rand.ts';
+import type {AST} from '../../../../zero-protocol/src/ast.ts';
+import * as ErrorKind from '../../../../zero-protocol/src/error-kind-enum.ts';
 import {
   type ChangeDesiredQueriesBody,
   type ChangeDesiredQueriesMessage,
   type Downstream,
   type InitConnectionMessage,
-} from '../../../../zero-protocol/src/mod.js';
-import type {PermissionsConfig} from '../../../../zero-schema/src/compiled-permissions.js';
-import {transformAndHashQuery} from '../../auth/read-authorizer.js';
-import {stringify} from '../../types/bigint-json.js';
-import {ErrorForClient, getLogLevel} from '../../types/error-for-client.js';
-import type {PostgresDB} from '../../types/pg.js';
-import {rowIDString, type RowKey} from '../../types/row-key.js';
-import type {Source} from '../../types/streams.js';
-import {Subscription} from '../../types/subscription.js';
-import type {ReplicaState} from '../replicator/replicator.js';
-import {ZERO_VERSION_COLUMN_NAME} from '../replicator/schema/replication-state.js';
-import type {ActivityBasedService} from '../service.js';
+} from '../../../../zero-protocol/src/mod.ts';
+import type {PermissionsConfig} from '../../../../zero-schema/src/compiled-permissions.ts';
+import {transformAndHashQuery} from '../../auth/read-authorizer.ts';
+import {stringify} from '../../types/bigint-json.ts';
+import {ErrorForClient, getLogLevel} from '../../types/error-for-client.ts';
+import type {PostgresDB} from '../../types/pg.ts';
+import {rowIDString, type RowKey} from '../../types/row-key.ts';
+import type {Source} from '../../types/streams.ts';
+import {Subscription} from '../../types/subscription.ts';
+import type {ReplicaState} from '../replicator/replicator.ts';
+import {ZERO_VERSION_COLUMN_NAME} from '../replicator/schema/replication-state.ts';
+import type {ActivityBasedService} from '../service.ts';
 import {
   ClientHandler,
   type PatchToVersion,
   type PokeHandler,
   type RowPatch,
-} from './client-handler.js';
-import {CVRStore} from './cvr-store.js';
+} from './client-handler.ts';
+import {CVRStore} from './cvr-store.ts';
 import {
   CVRConfigDrivenUpdater,
   CVRQueryDrivenUpdater,
   type CVRSnapshot,
   type RowUpdate,
-} from './cvr.js';
-import type {DrainCoordinator} from './drain-coordinator.js';
-import {PipelineDriver, type RowChange} from './pipeline-driver.js';
+} from './cvr.ts';
+import type {DrainCoordinator} from './drain-coordinator.ts';
+import {PipelineDriver, type RowChange} from './pipeline-driver.ts';
 import {
   cmpVersions,
   EMPTY_CVR_VERSION,
@@ -57,8 +57,8 @@ import {
   type CVRVersion,
   type NullableCVRVersion,
   type RowID,
-} from './schema/types.js';
-import {ResetPipelinesSignal} from './snapshotter.js';
+} from './schema/types.ts';
+import {ResetPipelinesSignal} from './snapshotter.ts';
 
 export type TokenData = {
   readonly raw: string;
diff --git a/packages/zero-cache/src/test/db.ts b/packages/zero-cache/src/test/db.ts
index a415c3bf54..2a65181968 100644
--- a/packages/zero-cache/src/test/db.ts
+++ b/packages/zero-cache/src/test/db.ts
@@ -1,9 +1,9 @@
 /* eslint-disable no-console */
 import postgres from 'postgres';
 import {afterAll, expect, inject} from 'vitest';
-import {assert} from '../../../shared/src/asserts.js';
-import {sleep} from '../../../shared/src/sleep.js';
-import {type PostgresDB, postgresTypeConfig} from '../types/pg.js';
+import {assert} from '../../../shared/src/asserts.ts';
+import {sleep} from '../../../shared/src/sleep.ts';
+import {type PostgresDB, postgresTypeConfig} from '../types/pg.ts';
 
 declare module 'vitest' {
   export interface ProvidedContext {
diff --git a/packages/zero-cache/src/test/lite.ts b/packages/zero-cache/src/test/lite.ts
index ebbfb1bc13..b99b59a1a6 100644
--- a/packages/zero-cache/src/test/lite.ts
+++ b/packages/zero-cache/src/test/lite.ts
@@ -1,10 +1,10 @@
 import {LogContext} from '@rocicorp/logger';
 import {tmpdir} from 'node:os';
 import {expect} from 'vitest';
-import {randInt} from '../../../shared/src/rand.js';
-import {Database} from '../../../zqlite/src/db.js';
-import {deleteLiteDB} from '../db/delete-lite-db.js';
-import {id} from '../types/sql.js';
+import {randInt} from '../../../shared/src/rand.ts';
+import {Database} from '../../../zqlite/src/db.ts';
+import {deleteLiteDB} from '../db/delete-lite-db.ts';
+import {id} from '../types/sql.ts';
 
 export class DbFile {
   readonly path;
diff --git a/packages/zero-cache/src/types/big-time.test.ts b/packages/zero-cache/src/types/big-time.test.ts
index 56873e3739..9b982b93ea 100644
--- a/packages/zero-cache/src/types/big-time.test.ts
+++ b/packages/zero-cache/src/types/big-time.test.ts
@@ -1,5 +1,5 @@
 import {describe, expect, test} from 'vitest';
-import {epochMicrosToTimestampTz} from './big-time.js';
+import {epochMicrosToTimestampTz} from './big-time.ts';
 
 describe('types/bigtime', () => {
   type Case = {
diff --git a/packages/zero-cache/src/types/bigint-json.test.ts b/packages/zero-cache/src/types/bigint-json.test.ts
index 720ea044da..3ba5a9e1e5 100644
--- a/packages/zero-cache/src/types/bigint-json.test.ts
+++ b/packages/zero-cache/src/types/bigint-json.test.ts
@@ -1,5 +1,5 @@
 import {describe, expect, test} from 'vitest';
-import {parse, stringify} from './bigint-json.js';
+import {parse, stringify} from './bigint-json.ts';
 
 describe('types/json', () => {
   type Case = {
diff --git a/packages/zero-cache/src/types/bigint-json.ts b/packages/zero-cache/src/types/bigint-json.ts
index d816022d36..2e6a140301 100644
--- a/packages/zero-cache/src/types/bigint-json.ts
+++ b/packages/zero-cache/src/types/bigint-json.ts
@@ -7,7 +7,7 @@ import {
   parse as customParse,
   stringify as customStringify,
 } from 'json-custom-numbers';
-import * as v from '../../../shared/src/valita.js';
+import * as v from '../../../shared/src/valita.ts';
 
 function numberParser(_: unknown, v: string) {
   const n = +v;
diff --git a/packages/zero-cache/src/types/error-for-client.ts b/packages/zero-cache/src/types/error-for-client.ts
index 623858f617..b17215be22 100644
--- a/packages/zero-cache/src/types/error-for-client.ts
+++ b/packages/zero-cache/src/types/error-for-client.ts
@@ -1,5 +1,5 @@
 import type {LogLevel} from '@rocicorp/logger';
-import type {ErrorBody} from '../../../zero-protocol/src/error.js';
+import type {ErrorBody} from '../../../zero-protocol/src/error.ts';
 
 export class ErrorWithLevel extends Error {
   readonly logLevel: LogLevel;
diff --git a/packages/zero-cache/src/types/lexi-version.test.ts b/packages/zero-cache/src/types/lexi-version.test.ts
index 83ad29be02..6fb7365e3c 100644
--- a/packages/zero-cache/src/types/lexi-version.test.ts
+++ b/packages/zero-cache/src/types/lexi-version.test.ts
@@ -7,7 +7,7 @@ import {
   versionToLexi,
   type AtLeastOne,
   type LexiVersion,
-} from './lexi-version.js';
+} from './lexi-version.ts';
 
 test('LexiVersion encoding', () => {
   type Case = [number | bigint, string];
diff --git a/packages/zero-cache/src/types/lexi-version.ts b/packages/zero-cache/src/types/lexi-version.ts
index f28e90f7f2..552c759b67 100644
--- a/packages/zero-cache/src/types/lexi-version.ts
+++ b/packages/zero-cache/src/types/lexi-version.ts
@@ -1,5 +1,5 @@
-import {assert} from '../../../shared/src/asserts.js';
-import {parseBigInt} from '../../../shared/src/parse-big-int.js';
+import {assert} from '../../../shared/src/asserts.ts';
+import {parseBigInt} from '../../../shared/src/parse-big-int.ts';
 
 /**
  * A LexiVersion is a lexicographically sortable representation of
diff --git a/packages/zero-cache/src/types/lite.test.ts b/packages/zero-cache/src/types/lite.test.ts
index db271c68e9..1e7f92983c 100644
--- a/packages/zero-cache/src/types/lite.test.ts
+++ b/packages/zero-cache/src/types/lite.test.ts
@@ -1,5 +1,5 @@
 import {describe, expect, test} from 'vitest';
-import {liteRow, liteValue, liteValues} from './lite.js';
+import {liteRow, liteValue, liteValues} from './lite.ts';
 
 describe('types/lite', () => {
   test.each([
diff --git a/packages/zero-cache/src/types/lite.ts b/packages/zero-cache/src/types/lite.ts
index faee14ba44..12de81bfcd 100644
--- a/packages/zero-cache/src/types/lite.ts
+++ b/packages/zero-cache/src/types/lite.ts
@@ -1,12 +1,12 @@
-import {assert} from '../../../shared/src/asserts.js';
+import {assert} from '../../../shared/src/asserts.ts';
 import type {
   SchemaValue,
   ValueType,
-} from '../../../zero-schema/src/table-schema.js';
-import type {LiteTableSpec} from '../db/specs.js';
-import {stringify, type JSONValue} from './bigint-json.js';
-import type {PostgresValueType} from './pg.js';
-import type {RowValue} from './row-key.js';
+} from '../../../zero-schema/src/table-schema.ts';
+import type {LiteTableSpec} from '../db/specs.ts';
+import {stringify, type JSONValue} from './bigint-json.ts';
+import type {PostgresValueType} from './pg.ts';
+import type {RowValue} from './row-key.ts';
 
 /** Javascript value types supported by better-sqlite3. */
 export type LiteValueType = number | bigint | string | null | Uint8Array;
diff --git a/packages/zero-cache/src/types/names.test.ts b/packages/zero-cache/src/types/names.test.ts
index 4e60810d0d..50028712b0 100644
--- a/packages/zero-cache/src/types/names.test.ts
+++ b/packages/zero-cache/src/types/names.test.ts
@@ -1,5 +1,5 @@
 import {describe, expect, test} from 'vitest';
-import {liteTableName} from './names.js';
+import {liteTableName} from './names.ts';
 
 describe('tables/names', () => {
   (
diff --git a/packages/zero-cache/src/types/pg.pg-test.ts b/packages/zero-cache/src/types/pg.pg-test.ts
index f458674dec..14246edfdd 100644
--- a/packages/zero-cache/src/types/pg.pg-test.ts
+++ b/packages/zero-cache/src/types/pg.pg-test.ts
@@ -1,8 +1,8 @@
 import pg from 'pg';
 import type postgres from 'postgres';
 import {afterEach, beforeEach, describe, expect, test} from 'vitest';
-import {testDBs} from '../test/db.js';
-import {timestampToFpMillis, typeNameByOID} from './pg.js';
+import {testDBs} from '../test/db.ts';
+import {timestampToFpMillis, typeNameByOID} from './pg.ts';
 
 describe('types/pg-types', () => {
   test('typeNameByIOD', () => {
diff --git a/packages/zero-cache/src/types/pg.ts b/packages/zero-cache/src/types/pg.ts
index f234707494..c9360283f1 100644
--- a/packages/zero-cache/src/types/pg.ts
+++ b/packages/zero-cache/src/types/pg.ts
@@ -4,8 +4,8 @@ import {LogContext} from '@rocicorp/logger';
 import pg from 'pg';
 import postgres, {type Notice, type PostgresType} from 'postgres';
 import array from 'postgres-array';
-import {randInt} from '../../../shared/src/rand.js';
-import {BigIntJSON, type JSONValue} from './bigint-json.js';
+import {randInt} from '../../../shared/src/rand.ts';
+import {BigIntJSON, type JSONValue} from './bigint-json.ts';
 
 const {
   types: {builtins, setTypeParser},
diff --git a/packages/zero-cache/src/types/processes.test.ts b/packages/zero-cache/src/types/processes.test.ts
index 39c4ad0ff5..03a26f11d5 100644
--- a/packages/zero-cache/src/types/processes.test.ts
+++ b/packages/zero-cache/src/types/processes.test.ts
@@ -1,6 +1,6 @@
 import type {SendHandle} from 'child_process';
 import {describe, expect, test, vi} from 'vitest';
-import {inProcChannel} from './processes.js';
+import {inProcChannel} from './processes.ts';
 
 describe('types/processes', () => {
   test('in-proc channel', () => {
diff --git a/packages/zero-cache/src/types/row-key.test.ts b/packages/zero-cache/src/types/row-key.test.ts
index e0c8924181..0a8d8d7b73 100644
--- a/packages/zero-cache/src/types/row-key.test.ts
+++ b/packages/zero-cache/src/types/row-key.test.ts
@@ -5,7 +5,7 @@ import {
   rowIDHash,
   rowIDString,
   rowKeyString,
-} from './row-key.js';
+} from './row-key.ts';
 
 describe('types/row-key', () => {
   type Case = {
diff --git a/packages/zero-cache/src/types/row-key.ts b/packages/zero-cache/src/types/row-key.ts
index 68cf19d0df..a40d30d2de 100644
--- a/packages/zero-cache/src/types/row-key.ts
+++ b/packages/zero-cache/src/types/row-key.ts
@@ -1,6 +1,6 @@
-import {assert} from '../../../shared/src/asserts.js';
-import {h128} from '../../../shared/src/hash.js';
-import {stringify, type JSONValue} from './bigint-json.js';
+import {assert} from '../../../shared/src/asserts.ts';
+import {h128} from '../../../shared/src/hash.ts';
+import {stringify, type JSONValue} from './bigint-json.ts';
 
 export type ColumnType = {readonly typeOid: number};
 export type RowKeyType = Readonly<Record<string, ColumnType>>;
diff --git a/packages/zero-cache/src/types/schema-versions.ts b/packages/zero-cache/src/types/schema-versions.ts
index d760350630..345238626e 100644
--- a/packages/zero-cache/src/types/schema-versions.ts
+++ b/packages/zero-cache/src/types/schema-versions.ts
@@ -1,5 +1,5 @@
-import * as ErrorKind from '../../../zero-protocol/src/error-kind-enum.js';
-import {ErrorForClient} from './error-for-client.js';
+import * as ErrorKind from '../../../zero-protocol/src/error-kind-enum.ts';
+import {ErrorForClient} from './error-for-client.ts';
 
 export type SchemaVersions = {
   readonly minSupportedVersion: number;
diff --git a/packages/zero-cache/src/types/sql.test.ts b/packages/zero-cache/src/types/sql.test.ts
index 54088cf2dd..a05d2578e3 100644
--- a/packages/zero-cache/src/types/sql.test.ts
+++ b/packages/zero-cache/src/types/sql.test.ts
@@ -1,5 +1,5 @@
 import {describe, expect, test} from 'vitest';
-import {id, idList} from './sql.js';
+import {id, idList} from './sql.ts';
 
 describe('types/sql', () => {
   type Case = {
diff --git a/packages/zero-cache/src/types/streams.test.ts b/packages/zero-cache/src/types/streams.test.ts
index 8641731cb8..57f7cb66d2 100644
--- a/packages/zero-cache/src/types/streams.test.ts
+++ b/packages/zero-cache/src/types/streams.test.ts
@@ -4,13 +4,13 @@ import {resolver} from '@rocicorp/resolver';
 import Fastify, {type FastifyInstance} from 'fastify';
 import {afterEach, beforeEach, describe, expect, test} from 'vitest';
 import WebSocket from 'ws';
-import {createSilentLogContext} from '../../../shared/src/logging-test-utils.js';
-import {Queue} from '../../../shared/src/queue.js';
-import {randInt} from '../../../shared/src/rand.js';
-import {sleep} from '../../../shared/src/sleep.js';
-import * as v from '../../../shared/src/valita.js';
-import {type Source, streamIn, streamOut} from './streams.js';
-import {Subscription} from './subscription.js';
+import {createSilentLogContext} from '../../../shared/src/logging-test-utils.ts';
+import {Queue} from '../../../shared/src/queue.ts';
+import {randInt} from '../../../shared/src/rand.ts';
+import {sleep} from '../../../shared/src/sleep.ts';
+import * as v from '../../../shared/src/valita.ts';
+import {type Source, streamIn, streamOut} from './streams.ts';
+import {Subscription} from './subscription.ts';
 
 const messageSchema = v.object({
   from: v.number(),
diff --git a/packages/zero-cache/src/types/streams.ts b/packages/zero-cache/src/types/streams.ts
index 19522ae508..1cb87e263f 100644
--- a/packages/zero-cache/src/types/streams.ts
+++ b/packages/zero-cache/src/types/streams.ts
@@ -1,10 +1,10 @@
 import type {LogContext} from '@rocicorp/logger';
 import {resolver} from '@rocicorp/resolver';
 import type {CloseEvent, ErrorEvent, MessageEvent, WebSocket} from 'ws';
-import {Queue} from '../../../shared/src/queue.js';
-import * as v from '../../../shared/src/valita.js';
-import {BigIntJSON, type JSONValue} from './bigint-json.js';
-import {Subscription} from './subscription.js';
+import {Queue} from '../../../shared/src/queue.ts';
+import * as v from '../../../shared/src/valita.ts';
+import {BigIntJSON, type JSONValue} from './bigint-json.ts';
+import {Subscription} from './subscription.ts';
 
 export type Source<T> = AsyncIterable<T> & {
   /**
diff --git a/packages/zero-cache/src/types/subscription.test.ts b/packages/zero-cache/src/types/subscription.test.ts
index 8452428088..6e7ac83f71 100644
--- a/packages/zero-cache/src/types/subscription.test.ts
+++ b/packages/zero-cache/src/types/subscription.test.ts
@@ -1,7 +1,7 @@
-import {assert} from '../../../shared/src/asserts.js';
-import {sleep} from '../../../shared/src/sleep.js';
 import {describe, expect, test, vi} from 'vitest';
-import {type Result, Subscription} from './subscription.js';
+import {assert} from '../../../shared/src/asserts.ts';
+import {sleep} from '../../../shared/src/sleep.ts';
+import {type Result, Subscription} from './subscription.ts';
 
 describe('types/subscription', () => {
   test('cancel', async () => {
diff --git a/packages/zero-cache/src/types/subscription.ts b/packages/zero-cache/src/types/subscription.ts
index c37ef48e3f..664b351808 100644
--- a/packages/zero-cache/src/types/subscription.ts
+++ b/packages/zero-cache/src/types/subscription.ts
@@ -1,5 +1,5 @@
 import {resolver, type Resolver} from '@rocicorp/resolver';
-import type {Sink, Source} from './streams.js';
+import type {Sink, Source} from './streams.ts';
 
 /**
  * A Subscription abstracts a continuous, logically infinite stream of messages intended
diff --git a/packages/zero-cache/src/types/timeout.test.ts b/packages/zero-cache/src/types/timeout.test.ts
index 8639de539d..fa616ad53d 100644
--- a/packages/zero-cache/src/types/timeout.test.ts
+++ b/packages/zero-cache/src/types/timeout.test.ts
@@ -1,6 +1,6 @@
 import {resolver} from '@rocicorp/resolver';
 import {describe, expect, test} from 'vitest';
-import {orTimeout, orTimeoutWith} from './timeout.js';
+import {orTimeout, orTimeoutWith} from './timeout.ts';
 
 describe('timeout', () => {
   test('resolved', async () => {
diff --git a/packages/zero-cache/src/types/timeout.ts b/packages/zero-cache/src/types/timeout.ts
index 477bd6c707..05ea57a1a0 100644
--- a/packages/zero-cache/src/types/timeout.ts
+++ b/packages/zero-cache/src/types/timeout.ts
@@ -1,4 +1,4 @@
-import {sleepWithAbort} from '../../../shared/src/sleep.js';
+import {sleepWithAbort} from '../../../shared/src/sleep.ts';
 
 /**
  * Resolves to the the string `"timed-out"` if `timeoutMs` elapses before
diff --git a/packages/zero-cache/src/types/ws.test.ts b/packages/zero-cache/src/types/ws.test.ts
index 26a16fa38a..07773ddc40 100644
--- a/packages/zero-cache/src/types/ws.test.ts
+++ b/packages/zero-cache/src/types/ws.test.ts
@@ -1,9 +1,9 @@
 import {resolver} from '@rocicorp/resolver';
 import {afterAll, beforeAll, describe, expect, test} from 'vitest';
 import WebSocket, {WebSocketServer} from 'ws';
-import {createSilentLogContext} from '../../../shared/src/logging-test-utils.js';
-import {randInt} from '../../../shared/src/rand.js';
-import {closeWithProtocolError} from './ws.js';
+import {createSilentLogContext} from '../../../shared/src/logging-test-utils.ts';
+import {randInt} from '../../../shared/src/rand.ts';
+import {closeWithProtocolError} from './ws.ts';
 
 describe('types/ws', () => {
   let port: number;
diff --git a/packages/zero-cache/src/workers/connection.ts b/packages/zero-cache/src/workers/connection.ts
index b2ccce9842..0f5aa9b1a8 100644
--- a/packages/zero-cache/src/workers/connection.ts
+++ b/packages/zero-cache/src/workers/connection.ts
@@ -4,31 +4,31 @@ import type {LogContext} from '@rocicorp/logger';
 import type {JWTPayload} from 'jose';
 import type {CloseEvent, Data, ErrorEvent} from 'ws';
 import WebSocket from 'ws';
-import {startAsyncSpan, startSpan} from '../../../otel/src/span.js';
-import {version} from '../../../otel/src/version.js';
-import {unreachable} from '../../../shared/src/asserts.js';
-import * as valita from '../../../shared/src/valita.js';
-import * as ErrorKind from '../../../zero-protocol/src/error-kind-enum.js';
-import {type ErrorBody} from '../../../zero-protocol/src/error.js';
+import {startAsyncSpan, startSpan} from '../../../otel/src/span.ts';
+import {version} from '../../../otel/src/version.ts';
+import {unreachable} from '../../../shared/src/asserts.ts';
+import * as valita from '../../../shared/src/valita.ts';
+import * as ErrorKind from '../../../zero-protocol/src/error-kind-enum.ts';
+import {type ErrorBody} from '../../../zero-protocol/src/error.ts';
 import {
   type ConnectedMessage,
   type Downstream,
   type PongMessage,
   upstreamSchema,
-} from '../../../zero-protocol/src/mod.js';
+} from '../../../zero-protocol/src/mod.ts';
 import {
   MIN_SERVER_SUPPORTED_PROTOCOL_VERSION,
   PROTOCOL_VERSION,
-} from '../../../zero-protocol/src/protocol-version.js';
-import type {ConnectParams} from '../services/dispatcher/connect-params.js';
-import type {Mutagen} from '../services/mutagen/mutagen.js';
+} from '../../../zero-protocol/src/protocol-version.ts';
+import type {ConnectParams} from '../services/dispatcher/connect-params.ts';
+import type {Mutagen} from '../services/mutagen/mutagen.ts';
 import type {
   SyncContext,
   TokenData,
   ViewSyncer,
-} from '../services/view-syncer/view-syncer.js';
-import {findErrorForClient, getLogLevel} from '../types/error-for-client.js';
-import type {Source} from '../types/streams.js';
+} from '../services/view-syncer/view-syncer.ts';
+import {findErrorForClient, getLogLevel} from '../types/error-for-client.ts';
+import type {Source} from '../types/streams.ts';
 
 const tracer = trace.getTracer('syncer-ws-server', version);
 
diff --git a/packages/zero-cache/src/workers/replicator.test.ts b/packages/zero-cache/src/workers/replicator.test.ts
index e535e076a1..8317e47146 100644
--- a/packages/zero-cache/src/workers/replicator.test.ts
+++ b/packages/zero-cache/src/workers/replicator.test.ts
@@ -1,13 +1,13 @@
-import {createSilentLogContext} from '../../../shared/src/logging-test-utils.js';
 import {describe, expect, test, vi} from 'vitest';
-import type {ReplicaState} from '../services/replicator/replicator.js';
-import {Subscription} from '../types/subscription.js';
-import {inProcChannel} from '../types/processes.js';
+import {createSilentLogContext} from '../../../shared/src/logging-test-utils.ts';
+import type {ReplicaState} from '../services/replicator/replicator.ts';
+import {inProcChannel} from '../types/processes.ts';
+import {Subscription} from '../types/subscription.ts';
 import {
   createNotifierFrom,
   setUpMessageHandlers,
   subscribeTo,
-} from './replicator.js';
+} from './replicator.ts';
 
 const lc = createSilentLogContext();
 
diff --git a/packages/zero-cache/src/workers/replicator.ts b/packages/zero-cache/src/workers/replicator.ts
index f208385744..a98eeb7f39 100644
--- a/packages/zero-cache/src/workers/replicator.ts
+++ b/packages/zero-cache/src/workers/replicator.ts
@@ -1,14 +1,14 @@
 import {LogContext} from '@rocicorp/logger';
-import * as v from '../../../shared/src/valita.js';
-import {Database} from '../../../zqlite/src/db.js';
-import {deleteLiteDB} from '../db/delete-lite-db.js';
-import {Notifier} from '../services/replicator/notifier.js';
+import * as v from '../../../shared/src/valita.ts';
+import {Database} from '../../../zqlite/src/db.ts';
+import {deleteLiteDB} from '../db/delete-lite-db.ts';
+import {Notifier} from '../services/replicator/notifier.ts';
 import type {
   ReplicaState,
   ReplicaStateNotifier,
   Replicator,
-} from '../services/replicator/replicator.js';
-import type {Worker} from '../types/processes.js';
+} from '../services/replicator/replicator.ts';
+import type {Worker} from '../types/processes.ts';
 
 export const replicaFileModeSchema = v.union(
   v.literal('serving'),
diff --git a/packages/zero-cache/src/workers/syncer.ts b/packages/zero-cache/src/workers/syncer.ts
index fa79c72fa6..ba06575901 100644
--- a/packages/zero-cache/src/workers/syncer.ts
+++ b/packages/zero-cache/src/workers/syncer.ts
@@ -4,26 +4,26 @@ import {type JWTPayload} from 'jose';
 import {pid} from 'process';
 import {MessagePort} from 'worker_threads';
 import {WebSocketServer, type WebSocket} from 'ws';
-import {promiseVoid} from '../../../shared/src/resolved-promises.js';
-import * as ErrorKind from '../../../zero-protocol/src/error-kind-enum.js';
-import {verifyToken} from '../auth/jwt.js';
-import {type AuthConfig, type ZeroConfig} from '../config/zero-config.js';
-import type {ConnectParams} from '../services/dispatcher/connect-params.js';
-import {installWebSocketReceiver} from '../services/dispatcher/websocket-handoff.js';
-import type {Mutagen} from '../services/mutagen/mutagen.js';
-import type {ReplicaState} from '../services/replicator/replicator.js';
-import {ServiceRunner} from '../services/runner.js';
+import {promiseVoid} from '../../../shared/src/resolved-promises.ts';
+import * as ErrorKind from '../../../zero-protocol/src/error-kind-enum.ts';
+import {verifyToken} from '../auth/jwt.ts';
+import {type AuthConfig, type ZeroConfig} from '../config/zero-config.ts';
+import type {ConnectParams} from '../services/dispatcher/connect-params.ts';
+import {installWebSocketReceiver} from '../services/dispatcher/websocket-handoff.ts';
+import type {Mutagen} from '../services/mutagen/mutagen.ts';
+import type {ReplicaState} from '../services/replicator/replicator.ts';
+import {ServiceRunner} from '../services/runner.ts';
 import type {
   ActivityBasedService,
   Service,
   SingletonService,
-} from '../services/service.js';
-import {DrainCoordinator} from '../services/view-syncer/drain-coordinator.js';
-import type {ViewSyncer} from '../services/view-syncer/view-syncer.js';
-import type {Worker} from '../types/processes.js';
-import {Subscription} from '../types/subscription.js';
-import {Connection, sendError} from './connection.js';
-import {createNotifierFrom, subscribeTo} from './replicator.js';
+} from '../services/service.ts';
+import {DrainCoordinator} from '../services/view-syncer/drain-coordinator.ts';
+import type {ViewSyncer} from '../services/view-syncer/view-syncer.ts';
+import type {Worker} from '../types/processes.ts';
+import {Subscription} from '../types/subscription.ts';
+import {Connection, sendError} from './connection.ts';
+import {createNotifierFrom, subscribeTo} from './replicator.ts';
 
 export type SyncerWorkerData = {
   replicatorPort: MessagePort;
diff --git a/packages/zero-cache/tool/replace-node-util.test.ts b/packages/zero-cache/tool/replace-node-util.test.ts
index 813f28a7df..f4ea84990c 100644
--- a/packages/zero-cache/tool/replace-node-util.test.ts
+++ b/packages/zero-cache/tool/replace-node-util.test.ts
@@ -1,6 +1,6 @@
 import * as esbuild from 'esbuild';
 import {expect, test} from 'vitest';
-import {replaceNodeUtil} from './replace-node-util.js';
+import {replaceNodeUtil} from './replace-node-util.ts';
 
 async function compile(contents: string) {
   const res = await esbuild.build({
diff --git a/packages/zero-cache/vitest.config.ts b/packages/zero-cache/vitest.config.ts
index 3775ccb727..b36167aac0 100644
--- a/packages/zero-cache/vitest.config.ts
+++ b/packages/zero-cache/vitest.config.ts
@@ -1,5 +1,5 @@
 import {defineConfig} from 'vitest/config';
-import config from '../shared/src/tool/vitest-config.js';
+import config from '../shared/src/tool/vitest-config.ts';
 
 const {define, esbuild} = config;
 
diff --git a/packages/zero-client/src/client/connect-checks.ts b/packages/zero-client/src/client/connect-checks.ts
index 462d5f71a1..5f6497baf2 100644
--- a/packages/zero-client/src/client/connect-checks.ts
+++ b/packages/zero-client/src/client/connect-checks.ts
@@ -1,9 +1,9 @@
 import type {LogContext} from '@rocicorp/logger';
 import {resolver} from '@rocicorp/resolver';
-import {navigator} from '../../../shared/src/navigator.js';
-import {sleep} from '../../../shared/src/sleep.js';
-import {PROTOCOL_VERSION} from '../../../zero-protocol/src/protocol-version.js';
-import {nanoid} from '../util/nanoid.js';
+import {navigator} from '../../../shared/src/navigator.ts';
+import {sleep} from '../../../shared/src/sleep.ts';
+import {PROTOCOL_VERSION} from '../../../zero-protocol/src/protocol-version.ts';
+import {nanoid} from '../util/nanoid.ts';
 import {
   type HTTPString,
   type WSString,
@@ -11,7 +11,7 @@ import {
   assertHTTPString,
   assertWSString,
   toWSString,
-} from './http-string.js';
+} from './http-string.ts';
 
 type CheckResult = {success: boolean; detail: string};
 type Check = (l: LogContext) => Promise<CheckResult>;
diff --git a/packages/zero-client/src/client/context.test.ts b/packages/zero-client/src/client/context.test.ts
index e92c42d786..79d6ad6fb5 100644
--- a/packages/zero-client/src/client/context.test.ts
+++ b/packages/zero-client/src/client/context.test.ts
@@ -1,14 +1,14 @@
 import {expect, test} from 'vitest';
-import type {ExperimentalNoIndexDiff} from '../../../replicache/src/mod.js';
-import {assert} from '../../../shared/src/asserts.js';
-import {Catch} from '../../../zql/src/ivm/catch.js';
-import {Join} from '../../../zql/src/ivm/join.js';
-import {MemorySource} from '../../../zql/src/ivm/memory-source.js';
-import {MemoryStorage} from '../../../zql/src/ivm/memory-storage.js';
-import {type AddQuery, ZeroContext} from './context.js';
-import {ENTITIES_KEY_PREFIX} from './keys.js';
-import {createSchema} from '../../../zero-schema/src/builder/schema-builder.js';
-import {string, table} from '../../../zero-schema/src/builder/table-builder.js';
+import type {ExperimentalNoIndexDiff} from '../../../replicache/src/mod.ts';
+import {assert} from '../../../shared/src/asserts.ts';
+import {createSchema} from '../../../zero-schema/src/builder/schema-builder.ts';
+import {string, table} from '../../../zero-schema/src/builder/table-builder.ts';
+import {Catch} from '../../../zql/src/ivm/catch.ts';
+import {Join} from '../../../zql/src/ivm/join.ts';
+import {MemorySource} from '../../../zql/src/ivm/memory-source.ts';
+import {MemoryStorage} from '../../../zql/src/ivm/memory-storage.ts';
+import {type AddQuery, ZeroContext} from './context.ts';
+import {ENTITIES_KEY_PREFIX} from './keys.ts';
 
 const testBatchViewUpdates = (applyViewUpdates: () => void) =>
   applyViewUpdates();
diff --git a/packages/zero-client/src/client/context.ts b/packages/zero-client/src/client/context.ts
index 20dd6bd6d5..dbe56993d2 100644
--- a/packages/zero-client/src/client/context.ts
+++ b/packages/zero-client/src/client/context.ts
@@ -1,18 +1,18 @@
-import type {ExperimentalNoIndexDiff} from '../../../replicache/src/mod.js';
-import {assert, unreachable} from '../../../shared/src/asserts.js';
-import type {AST} from '../../../zero-protocol/src/ast.js';
-import type {Row} from '../../../zero-protocol/src/data.js';
-import type {TableSchema} from '../../../zero-schema/src/table-schema.js';
-import {MemorySource} from '../../../zql/src/ivm/memory-source.js';
-import {MemoryStorage} from '../../../zql/src/ivm/memory-storage.js';
-import type {Storage} from '../../../zql/src/ivm/operator.js';
-import type {Source} from '../../../zql/src/ivm/source.js';
+import type {ExperimentalNoIndexDiff} from '../../../replicache/src/mod.ts';
+import {assert, unreachable} from '../../../shared/src/asserts.ts';
+import type {AST} from '../../../zero-protocol/src/ast.ts';
+import type {Row} from '../../../zero-protocol/src/data.ts';
+import type {TableSchema} from '../../../zero-schema/src/table-schema.ts';
+import {MemorySource} from '../../../zql/src/ivm/memory-source.ts';
+import {MemoryStorage} from '../../../zql/src/ivm/memory-storage.ts';
+import type {Storage} from '../../../zql/src/ivm/operator.ts';
+import type {Source} from '../../../zql/src/ivm/source.ts';
 import type {
   CommitListener,
   GotCallback,
   QueryDelegate,
-} from '../../../zql/src/query/query-impl.js';
-import {ENTITIES_KEY_PREFIX} from './keys.js';
+} from '../../../zql/src/query/query-impl.ts';
+import {ENTITIES_KEY_PREFIX} from './keys.ts';
 
 export type AddQuery = (
   ast: AST,
diff --git a/packages/zero-client/src/client/crud.ts b/packages/zero-client/src/client/crud.ts
index 24663dfbb2..1f5afcf4d2 100644
--- a/packages/zero-client/src/client/crud.ts
+++ b/packages/zero-client/src/client/crud.ts
@@ -1,24 +1,24 @@
-import {promiseVoid} from '../../../shared/src/resolved-promises.js';
-import type {MaybePromise} from '../../../shared/src/types.js';
-import type {Expand} from '../../../shared/src/expand.js';
+import type {Expand} from '../../../shared/src/expand.ts';
+import {promiseVoid} from '../../../shared/src/resolved-promises.ts';
+import type {MaybePromise} from '../../../shared/src/types.ts';
 import {
   CRUD_MUTATION_NAME,
-  type InsertOp,
   type CRUDMutationArg,
   type CRUDOp,
   type CRUDOpKind,
   type DeleteOp,
-  type UpsertOp,
+  type InsertOp,
   type UpdateOp,
-} from '../../../zero-protocol/src/push.js';
+  type UpsertOp,
+} from '../../../zero-protocol/src/push.ts';
+import type {Schema} from '../../../zero-schema/src/mod.ts';
 import type {
   SchemaValueToTSType,
   TableSchema,
-} from '../../../zero-schema/src/table-schema.js';
-import {toPrimaryKeyString} from './keys.js';
-import type {MutatorDefs, WriteTransaction} from './replicache-types.js';
-import type {Schema} from '../../../zero-schema/src/mod.js';
-import type {ReadonlyJSONObject} from '../mod.js';
+} from '../../../zero-schema/src/table-schema.ts';
+import type {ReadonlyJSONObject} from '../mod.ts';
+import {toPrimaryKeyString} from './keys.ts';
+import type {MutatorDefs, WriteTransaction} from './replicache-types.ts';
 
 export type InsertValue<S extends TableSchema> = Expand<
   PrimaryKeyFields<S> & {
diff --git a/packages/zero-client/src/client/enable-analytics.test.ts b/packages/zero-client/src/client/enable-analytics.test.ts
index 4eef7006c6..5ded4d55a4 100644
--- a/packages/zero-client/src/client/enable-analytics.test.ts
+++ b/packages/zero-client/src/client/enable-analytics.test.ts
@@ -1,5 +1,5 @@
 import {expect, suite, test} from 'vitest';
-import {shouldEnableAnalytics} from './enable-analytics.js';
+import {shouldEnableAnalytics} from './enable-analytics.ts';
 
 suite('when server indicates testing or local dev', () => {
   const cases: (string | null)[] = [
diff --git a/packages/zero-client/src/client/http-string.test.ts b/packages/zero-client/src/client/http-string.test.ts
index f801f906cd..8d6fdf97af 100644
--- a/packages/zero-client/src/client/http-string.test.ts
+++ b/packages/zero-client/src/client/http-string.test.ts
@@ -5,7 +5,7 @@ import {
   assertWSString,
   toHTTPString,
   toWSString,
-} from './http-string.js';
+} from './http-string.ts';
 
 test('toWSString', () => {
   expect(toWSString('http://example.com')).equal('ws://example.com');
diff --git a/packages/zero-client/src/client/http-string.ts b/packages/zero-client/src/client/http-string.ts
index 4312e450f2..c6972546b7 100644
--- a/packages/zero-client/src/client/http-string.ts
+++ b/packages/zero-client/src/client/http-string.ts
@@ -1,4 +1,4 @@
-import {assert} from '../../../shared/src/asserts.js';
+import {assert} from '../../../shared/src/asserts.ts';
 
 export type HTTPString = `http${'' | 's'}://${string}`;
 
diff --git a/packages/zero-client/src/client/keys.test.ts b/packages/zero-client/src/client/keys.test.ts
index 497d7da2c6..9f3cf3a46b 100644
--- a/packages/zero-client/src/client/keys.test.ts
+++ b/packages/zero-client/src/client/keys.test.ts
@@ -3,8 +3,8 @@ import {expect, test} from 'vitest';
 import type {
   PrimaryKey,
   PrimaryKeyValueRecord,
-} from '../../../zero-protocol/src/primary-key.js';
-import {toPrimaryKeyString as toPrimaryKeyStringImpl} from './keys.js';
+} from '../../../zero-protocol/src/primary-key.ts';
+import {toPrimaryKeyString as toPrimaryKeyStringImpl} from './keys.ts';
 
 test('toPrimaryKeyString', () => {
   function toPrimaryKeyString(
diff --git a/packages/zero-client/src/client/keys.ts b/packages/zero-client/src/client/keys.ts
index dd1c6a74b2..436cd5459d 100644
--- a/packages/zero-client/src/client/keys.ts
+++ b/packages/zero-client/src/client/keys.ts
@@ -1,8 +1,8 @@
-import {h128} from '../../../shared/src/hash.js';
-import * as v from '../../../shared/src/valita.js';
-import type {CompoundKey} from '../../../zero-protocol/src/ast.js';
-import type {Row} from '../../../zero-protocol/src/data.js';
-import {primaryKeyValueSchema} from '../../../zero-protocol/src/primary-key.js';
+import {h128} from '../../../shared/src/hash.ts';
+import * as v from '../../../shared/src/valita.ts';
+import type {CompoundKey} from '../../../zero-protocol/src/ast.ts';
+import type {Row} from '../../../zero-protocol/src/data.ts';
+import {primaryKeyValueSchema} from '../../../zero-protocol/src/primary-key.ts';
 
 export const CLIENTS_KEY_PREFIX = 'c/';
 export const DESIRED_QUERIES_KEY_PREFIX = 'd/';
diff --git a/packages/zero-client/src/client/log-options.test.ts b/packages/zero-client/src/client/log-options.test.ts
index 75803a6caf..cf25827ef5 100644
--- a/packages/zero-client/src/client/log-options.test.ts
+++ b/packages/zero-client/src/client/log-options.test.ts
@@ -1,10 +1,10 @@
 import {consoleLogSink, type LogSink} from '@rocicorp/logger';
-import type {DatadogLogSinkOptions} from '../../../datadog/src/mod.js';
-import {TestLogSink} from '../../../shared/src/logging-test-utils.js';
 import * as sinon from 'sinon';
 import {afterEach, beforeEach, expect, suite, test} from 'vitest';
-import {createLogOptions} from './log-options.js';
-import type {HTTPString} from './http-string.js';
+import type {DatadogLogSinkOptions} from '../../../datadog/src/mod.ts';
+import {TestLogSink} from '../../../shared/src/logging-test-utils.ts';
+import type {HTTPString} from './http-string.ts';
+import {createLogOptions} from './log-options.ts';
 
 let consoleLogSinkSpy: sinon.SinonSpiedInstance<LogSink>;
 let datadogLogSinkSpy: sinon.SinonSpiedInstance<LogSink>;
diff --git a/packages/zero-client/src/client/log-options.ts b/packages/zero-client/src/client/log-options.ts
index c7aaff380d..54668da583 100644
--- a/packages/zero-client/src/client/log-options.ts
+++ b/packages/zero-client/src/client/log-options.ts
@@ -8,9 +8,9 @@ import {
 import {
   DatadogLogSink,
   type DatadogLogSinkOptions,
-} from '../../../datadog/src/mod.js';
-import {version} from './version.js';
-import {appendPath, type HTTPString} from './http-string.js';
+} from '../../../datadog/src/mod.ts';
+import {appendPath, type HTTPString} from './http-string.ts';
+import {version} from './version.ts';
 
 class LevelFilterLogSink implements LogSink {
   readonly #wrappedLogSink: LogSink;
diff --git a/packages/zero-client/src/client/metrics.test.ts b/packages/zero-client/src/client/metrics.test.ts
index b5aa8ae64d..60ebf3cfe7 100644
--- a/packages/zero-client/src/client/metrics.test.ts
+++ b/packages/zero-client/src/client/metrics.test.ts
@@ -1,7 +1,7 @@
 import {LogContext} from '@rocicorp/logger';
 import sinon from 'sinon';
 import {afterEach, expect, test} from 'vitest';
-import * as ErrorKind from '../../../zero-protocol/src/error-kind-enum.js';
+import * as ErrorKind from '../../../zero-protocol/src/error-kind-enum.ts';
 import {
   DID_NOT_CONNECT_VALUE,
   type DisconnectReason,
@@ -11,7 +11,7 @@ import {
   REPORT_INTERVAL_MS,
   type Series,
   State,
-} from './metrics.js';
+} from './metrics.ts';
 
 afterEach(() => {
   sinon.restore();
diff --git a/packages/zero-client/src/client/metrics.ts b/packages/zero-client/src/client/metrics.ts
index ac48fc8b80..7dbcf099b6 100644
--- a/packages/zero-client/src/client/metrics.ts
+++ b/packages/zero-client/src/client/metrics.ts
@@ -1,7 +1,7 @@
 import type {LogContext} from '@rocicorp/logger';
-import type {MaybePromise} from '../../../shared/src/types.js';
-import * as ServerErrorKind from '../../../zero-protocol/src/error-kind-enum.js';
-import * as MetricName from './metric-name-enum.js';
+import type {MaybePromise} from '../../../shared/src/types.ts';
+import * as ServerErrorKind from '../../../zero-protocol/src/error-kind-enum.ts';
+import * as MetricName from './metric-name-enum.ts';
 
 type ServerErrorKind = (typeof ServerErrorKind)[keyof typeof ServerErrorKind];
 
diff --git a/packages/zero-client/src/client/options.ts b/packages/zero-client/src/client/options.ts
index 18bfd6a4bf..49323d2c26 100644
--- a/packages/zero-client/src/client/options.ts
+++ b/packages/zero-client/src/client/options.ts
@@ -1,7 +1,7 @@
 import type {LogLevel} from '@rocicorp/logger';
-import type {KVStoreProvider} from '../../../replicache/src/mod.js';
-import type {MaybePromise} from '../../../shared/src/types.js';
-import type {Schema} from '../../../zero-schema/src/mod.js';
+import type {KVStoreProvider} from '../../../replicache/src/mod.ts';
+import type {MaybePromise} from '../../../shared/src/types.ts';
+import type {Schema} from '../../../zero-schema/src/mod.ts';
 
 /**
  * Configuration for [[Zero]].
diff --git a/packages/zero-client/src/client/query-manager.test.ts b/packages/zero-client/src/client/query-manager.test.ts
index 584e0e4b04..1eb24de386 100644
--- a/packages/zero-client/src/client/query-manager.test.ts
+++ b/packages/zero-client/src/client/query-manager.test.ts
@@ -9,11 +9,11 @@ import {
   type ScanNoIndexOptions,
   type ScanOptions,
   type ScanResult,
-} from '../../../replicache/src/mod.js';
-import type {AST} from '../../../zero-protocol/src/ast.js';
-import type {ChangeDesiredQueriesMessage} from '../../../zero-protocol/src/mod.js';
-import {toGotQueriesKey} from './keys.js';
-import {QueryManager} from './query-manager.js';
+} from '../../../replicache/src/mod.ts';
+import type {AST} from '../../../zero-protocol/src/ast.ts';
+import type {ChangeDesiredQueriesMessage} from '../../../zero-protocol/src/mod.ts';
+import {toGotQueriesKey} from './keys.ts';
+import {QueryManager} from './query-manager.ts';
 
 function createExperimentalWatchMock() {
   return vi.fn();
diff --git a/packages/zero-client/src/client/query-manager.ts b/packages/zero-client/src/client/query-manager.ts
index 09fa29f399..21a2908f18 100644
--- a/packages/zero-client/src/client/query-manager.ts
+++ b/packages/zero-client/src/client/query-manager.ts
@@ -1,16 +1,16 @@
-import type {ClientID} from '../../../replicache/src/mod.js';
-import type {ReplicacheImpl} from '../../../replicache/src/replicache-impl.js';
-import {assert} from '../../../shared/src/asserts.js';
-import {must} from '../../../shared/src/must.js';
-import {hashOfAST} from '../../../zero-protocol/src/ast-hash.js';
-import {normalizeAST, type AST} from '../../../zero-protocol/src/ast.js';
+import type {ClientID} from '../../../replicache/src/mod.ts';
+import type {ReplicacheImpl} from '../../../replicache/src/replicache-impl.ts';
+import {assert} from '../../../shared/src/asserts.ts';
+import {must} from '../../../shared/src/must.ts';
+import {hashOfAST} from '../../../zero-protocol/src/ast-hash.ts';
+import {normalizeAST, type AST} from '../../../zero-protocol/src/ast.ts';
 import type {
   ChangeDesiredQueriesMessage,
   QueriesPatchOp,
-} from '../../../zero-protocol/src/mod.js';
-import type {GotCallback} from '../../../zql/src/query/query-impl.js';
-import type {ReadTransaction} from '../mod.js';
-import {desiredQueriesPrefixForClient, GOT_QUERIES_KEY_PREFIX} from './keys.js';
+} from '../../../zero-protocol/src/mod.ts';
+import type {GotCallback} from '../../../zql/src/query/query-impl.ts';
+import type {ReadTransaction} from '../mod.ts';
+import {desiredQueriesPrefixForClient, GOT_QUERIES_KEY_PREFIX} from './keys.ts';
 
 type QueryHash = string;
 
diff --git a/packages/zero-client/src/client/reload-error-handler.test.ts b/packages/zero-client/src/client/reload-error-handler.test.ts
index 3fc29e6a6e..a5cd6f4cc2 100644
--- a/packages/zero-client/src/client/reload-error-handler.test.ts
+++ b/packages/zero-client/src/client/reload-error-handler.test.ts
@@ -1,7 +1,7 @@
 import {LogContext} from '@rocicorp/logger';
 import sinon from 'sinon';
 import {afterEach, beforeEach, describe, expect, test, vi} from 'vitest';
-import {TestLogSink} from '../../../shared/src/logging-test-utils.js';
+import {TestLogSink} from '../../../shared/src/logging-test-utils.ts';
 import {
   FALLBACK_RELOAD_INTERVAL_MS,
   MAX_RELOAD_INTERVAL_MS,
@@ -11,8 +11,8 @@ import {
   reportReloadReason,
   resetBackoff,
   type BackoffState,
-} from './reload-error-handler.js';
-import {storageMock} from './test-utils.js';
+} from './reload-error-handler.ts';
+import {storageMock} from './test-utils.ts';
 
 describe('reloadWithReason', () => {
   let sessionStorageDescriptor: PropertyDescriptor;
diff --git a/packages/zero-client/src/client/reload-error-handler.ts b/packages/zero-client/src/client/reload-error-handler.ts
index 43f1e58dc6..3b64176747 100644
--- a/packages/zero-client/src/client/reload-error-handler.ts
+++ b/packages/zero-client/src/client/reload-error-handler.ts
@@ -1,5 +1,5 @@
 import {LogContext} from '@rocicorp/logger';
-import * as v from '../../../shared/src/valita.js';
+import * as v from '../../../shared/src/valita.ts';
 
 export const RELOAD_REASON_STORAGE_KEY = '_zeroReloadReason';
 export const RELOAD_BACKOFF_STATE_KEY = '_zeroReloadBackoffState';
diff --git a/packages/zero-client/src/client/replicache-types.ts b/packages/zero-client/src/client/replicache-types.ts
index 17cd1be6eb..7b934559aa 100644
--- a/packages/zero-client/src/client/replicache-types.ts
+++ b/packages/zero-client/src/client/replicache-types.ts
@@ -3,7 +3,7 @@ import type {
   ReadonlyJSONObject,
   ReadTransaction as ReplicacheReadTransaction,
   WriteTransaction as ReplicacheWriteTransaction,
-} from '../../../replicache/src/mod.js';
+} from '../../../replicache/src/mod.ts';
 
 /**
  * `AuthData` must include a `userID` which is unique stable identifier
diff --git a/packages/zero-client/src/client/server-error.ts b/packages/zero-client/src/client/server-error.ts
index a567826b8b..825e972bd6 100644
--- a/packages/zero-client/src/client/server-error.ts
+++ b/packages/zero-client/src/client/server-error.ts
@@ -1,8 +1,8 @@
-import * as ErrorKind from '../../../zero-protocol/src/error-kind-enum.js';
+import * as ErrorKind from '../../../zero-protocol/src/error-kind-enum.ts';
 import {
   type BackoffBody,
   type ErrorBody,
-} from '../../../zero-protocol/src/error.js';
+} from '../../../zero-protocol/src/error.ts';
 
 type ErrorKind = (typeof ErrorKind)[keyof typeof ErrorKind];
 
diff --git a/packages/zero-client/src/client/server-option.test.ts b/packages/zero-client/src/client/server-option.test.ts
index 40dfcb7efd..c8a2cedb28 100644
--- a/packages/zero-client/src/client/server-option.test.ts
+++ b/packages/zero-client/src/client/server-option.test.ts
@@ -1,5 +1,5 @@
 import {expect, test} from 'vitest';
-import {getServer} from './server-option.js';
+import {getServer} from './server-option.ts';
 
 test('getServer', () => {
   expect(getServer(null)).equal(null);
diff --git a/packages/zero-client/src/client/server-option.ts b/packages/zero-client/src/client/server-option.ts
index bc2ef90b8f..00fe63d105 100644
--- a/packages/zero-client/src/client/server-option.ts
+++ b/packages/zero-client/src/client/server-option.ts
@@ -1,5 +1,5 @@
-import {getBrowserGlobal} from '../../../shared/src/browser-env.js';
-import type {HTTPString} from './http-string.js';
+import {getBrowserGlobal} from '../../../shared/src/browser-env.ts';
+import type {HTTPString} from './http-string.ts';
 
 function validateServerParam(paramName: string, server: string): HTTPString {
   const expectedProtocol = 'http';
diff --git a/packages/zero-client/src/client/test-utils.ts b/packages/zero-client/src/client/test-utils.ts
index ab48bd11f7..b8ab79a0cb 100644
--- a/packages/zero-client/src/client/test-utils.ts
+++ b/packages/zero-client/src/client/test-utils.ts
@@ -1,10 +1,10 @@
 import type {LogLevel} from '@rocicorp/logger';
 import {resolver} from '@rocicorp/resolver';
 import type {SinonFakeTimers} from 'sinon';
-import {assert} from '../../../shared/src/asserts.js';
-import type {Enum} from '../../../shared/src/enum.js';
-import {TestLogSink} from '../../../shared/src/logging-test-utils.js';
-import * as ErrorKind from '../../../zero-protocol/src/error-kind-enum.js';
+import {assert} from '../../../shared/src/asserts.ts';
+import type {Enum} from '../../../shared/src/enum.ts';
+import {TestLogSink} from '../../../shared/src/logging-test-utils.ts';
+import * as ErrorKind from '../../../zero-protocol/src/error-kind-enum.ts';
 import {
   type ConnectedMessage,
   type Downstream,
@@ -19,18 +19,18 @@ import {
   type PullResponseBody,
   type PullResponseMessage,
   upstreamSchema,
-} from '../../../zero-protocol/src/mod.js';
-import type {Schema} from '../../../zero-schema/src/mod.js';
-import * as ConnectionState from './connection-state-enum.js';
-import type {LogOptions} from './log-options.js';
-import type {ZeroOptions} from './options.js';
+} from '../../../zero-protocol/src/mod.ts';
+import type {Schema} from '../../../zero-schema/src/mod.ts';
+import * as ConnectionState from './connection-state-enum.ts';
+import type {LogOptions} from './log-options.ts';
+import type {ZeroOptions} from './options.ts';
 import {
   type TestingContext,
   Zero,
   createLogOptionsSymbol,
   exposedToTestingSymbol,
   onSetConnectionStateSymbol,
-} from './zero.js';
+} from './zero.ts';
 
 type ConnectionState = Enum<typeof ConnectionState>;
 type ErrorKind = Enum<typeof ErrorKind>;
diff --git a/packages/zero-client/src/client/version.test.ts b/packages/zero-client/src/client/version.test.ts
index dcab5e29a9..7ee34a06c6 100644
--- a/packages/zero-client/src/client/version.test.ts
+++ b/packages/zero-client/src/client/version.test.ts
@@ -1,5 +1,5 @@
 import {expect, test} from 'vitest';
-import {version} from './version.js';
+import {version} from './version.ts';
 
 test('version basics', () => {
   expect(version).to.match(/^\d+\.\d+\.\d+(\+[a-f0-9]+)?$/);
diff --git a/packages/zero-client/src/client/worker-test.ts b/packages/zero-client/src/client/worker-test.ts
index 62d3799a45..842319a468 100644
--- a/packages/zero-client/src/client/worker-test.ts
+++ b/packages/zero-client/src/client/worker-test.ts
@@ -1,16 +1,16 @@
 // This test file is loaded by worker.test.ts
 
 import sinon from 'sinon';
-import {assert} from '../../../shared/src/asserts.js';
-import {deepEqual} from '../../../shared/src/json.js';
-import {sleep} from '../../../shared/src/sleep.js';
-import {MockSocket, zeroForTest} from './test-utils.js';
-import {createSchema} from '../../../zero-schema/src/builder/schema-builder.js';
+import {assert} from '../../../shared/src/asserts.ts';
+import {deepEqual} from '../../../shared/src/json.ts';
+import {sleep} from '../../../shared/src/sleep.ts';
+import {createSchema} from '../../../zero-schema/src/builder/schema-builder.ts';
 import {
+  number,
   string,
   table,
-  number,
-} from '../../../zero-schema/src/builder/table-builder.js';
+} from '../../../zero-schema/src/builder/table-builder.ts';
+import {MockSocket, zeroForTest} from './test-utils.ts';
 
 onmessage = async (e: MessageEvent) => {
   const {userID} = e.data;
diff --git a/packages/zero-client/src/client/worker.test.ts b/packages/zero-client/src/client/worker.test.ts
index a416d78c6f..39da3a5ba3 100644
--- a/packages/zero-client/src/client/worker.test.ts
+++ b/packages/zero-client/src/client/worker.test.ts
@@ -1,5 +1,5 @@
-import {sleep} from '../../../shared/src/sleep.js';
 import {expect, test} from 'vitest';
+import {sleep} from '../../../shared/src/sleep.ts';
 
 test('worker test', async () => {
   const url = new URL('./worker-test.ts', import.meta.url);
diff --git a/packages/zero-client/src/client/zero-poke-handler.test.ts b/packages/zero-client/src/client/zero-poke-handler.test.ts
index df83294799..e295c4a167 100644
--- a/packages/zero-client/src/client/zero-poke-handler.test.ts
+++ b/packages/zero-client/src/client/zero-poke-handler.test.ts
@@ -9,10 +9,10 @@ import {
   test,
   vi,
 } from 'vitest';
-import type {AST} from '../../../zero-protocol/src/ast.js';
-import {PokeHandler, mergePokes} from './zero-poke-handler.js';
-import {createSchema} from '../../../zero-schema/src/builder/schema-builder.js';
-import {string, table} from '../../../zero-schema/src/builder/table-builder.js';
+import type {AST} from '../../../zero-protocol/src/ast.ts';
+import {createSchema} from '../../../zero-schema/src/builder/schema-builder.ts';
+import {string, table} from '../../../zero-schema/src/builder/table-builder.ts';
+import {PokeHandler, mergePokes} from './zero-poke-handler.ts';
 
 let rafStub: MockInstance<(cb: FrameRequestCallback) => number>;
 // The FrameRequestCallback in PokeHandler does not use
diff --git a/packages/zero-client/src/client/zero-poke-handler.ts b/packages/zero-client/src/client/zero-poke-handler.ts
index c54dd7c329..2ca5c10b93 100644
--- a/packages/zero-client/src/client/zero-poke-handler.ts
+++ b/packages/zero-client/src/client/zero-poke-handler.ts
@@ -3,9 +3,9 @@ import type {LogContext} from '@rocicorp/logger';
 import type {
   PatchOperationInternal,
   PokeInternal,
-} from '../../../replicache/src/impl.js';
-import type {ClientID, PatchOperation} from '../../../replicache/src/mod.js';
-import {getBrowserGlobalMethod} from '../../../shared/src/browser-env.js';
+} from '../../../replicache/src/impl.ts';
+import type {ClientID, PatchOperation} from '../../../replicache/src/mod.ts';
+import {getBrowserGlobalMethod} from '../../../shared/src/browser-env.ts';
 import type {
   ClientsPatchOp,
   PokeEndBody,
@@ -13,14 +13,14 @@ import type {
   PokeStartBody,
   QueriesPatchOp,
   RowPatchOp,
-} from '../../../zero-protocol/src/mod.js';
+} from '../../../zero-protocol/src/mod.ts';
+import type {Schema} from '../../../zero-schema/src/builder/schema-builder.ts';
 import {
   toClientsKey,
   toDesiredQueriesKey,
   toGotQueriesKey,
   toPrimaryKeyString,
-} from './keys.js';
-import type {Schema} from '../../../zero-schema/src/builder/schema-builder.js';
+} from './keys.ts';
 
 type PokeAccumulator = {
   readonly pokeStart: PokeStartBody;
diff --git a/packages/zero-client/src/client/zero-rate.test.ts b/packages/zero-client/src/client/zero-rate.test.ts
index 208b10875a..cfa0bebfb9 100644
--- a/packages/zero-client/src/client/zero-rate.test.ts
+++ b/packages/zero-client/src/client/zero-rate.test.ts
@@ -1,11 +1,11 @@
 import * as sinon from 'sinon';
 import {afterEach, beforeEach, expect, test} from 'vitest';
-import type {PushRequest} from '../../../replicache/src/sync/push.js';
-import * as ErrorKind from '../../../zero-protocol/src/error-kind-enum.js';
-import type {Mutation} from '../../../zero-protocol/src/push.js';
-import {createSchema, number, string, table} from '../mod.js';
-import * as ConnectionState from './connection-state-enum.js';
-import {MockSocket, tickAFewTimes, zeroForTest} from './test-utils.js';
+import type {PushRequest} from '../../../replicache/src/sync/push.ts';
+import * as ErrorKind from '../../../zero-protocol/src/error-kind-enum.ts';
+import type {Mutation} from '../../../zero-protocol/src/push.ts';
+import {createSchema, number, string, table} from '../mod.ts';
+import * as ConnectionState from './connection-state-enum.ts';
+import {MockSocket, tickAFewTimes, zeroForTest} from './test-utils.ts';
 
 let clock: sinon.SinonFakeTimers;
 const startTime = 1678829450000;
diff --git a/packages/zero-client/src/client/zero.bench.ts b/packages/zero-client/src/client/zero.bench.ts
index ab3baf200d..f7f91f68c8 100644
--- a/packages/zero-client/src/client/zero.bench.ts
+++ b/packages/zero-client/src/client/zero.bench.ts
@@ -1,7 +1,7 @@
 import {resolver} from '@rocicorp/resolver';
 import {bench, describe, expect} from 'vitest';
-import type {Row} from '../../../zql/src/query/query.js';
-import {getInternalReplicacheImplForTesting, Zero} from './zero.js';
+import type {Row} from '../../../zql/src/query/query.ts';
+import {getInternalReplicacheImplForTesting, Zero} from './zero.ts';
 
 const user = {
   name: 'user',
diff --git a/packages/zero-client/src/client/zero.json.test.ts b/packages/zero-client/src/client/zero.json.test.ts
index c437cb6e61..6b7c1c88f7 100644
--- a/packages/zero-client/src/client/zero.json.test.ts
+++ b/packages/zero-client/src/client/zero.json.test.ts
@@ -1,6 +1,6 @@
 import {expect, test} from 'vitest';
-import {zeroForTest} from './test-utils.js';
-import {createSchema, json, string, table} from '../mod.js';
+import {createSchema, json, string, table} from '../mod.ts';
+import {zeroForTest} from './test-utils.ts';
 
 test('we can create rows with json columns and query those rows', async () => {
   const z = zeroForTest({
diff --git a/packages/zero-client/src/client/zero.test.ts b/packages/zero-client/src/client/zero.test.ts
index 6ee90a402d..e5e8764bdd 100644
--- a/packages/zero-client/src/client/zero.test.ts
+++ b/packages/zero-client/src/client/zero.test.ts
@@ -2,36 +2,36 @@ import {LogContext} from '@rocicorp/logger';
 import {resolver} from '@rocicorp/resolver';
 import * as sinon from 'sinon';
 import {afterEach, beforeEach, expect, suite, test} from 'vitest';
-import type {ReplicacheImpl} from '../../../replicache/src/replicache-impl.js';
-import type {PullRequest} from '../../../replicache/src/sync/pull.js';
-import type {PushRequest} from '../../../replicache/src/sync/push.js';
-import {assert} from '../../../shared/src/asserts.js';
-import {TestLogSink} from '../../../shared/src/logging-test-utils.js';
-import * as valita from '../../../shared/src/valita.js';
-import type {AST} from '../../../zero-protocol/src/ast.js';
-import * as ErrorKind from '../../../zero-protocol/src/error-kind-enum.js';
+import type {ReplicacheImpl} from '../../../replicache/src/replicache-impl.ts';
+import type {PullRequest} from '../../../replicache/src/sync/pull.ts';
+import type {PushRequest} from '../../../replicache/src/sync/push.ts';
+import {assert} from '../../../shared/src/asserts.ts';
+import {TestLogSink} from '../../../shared/src/logging-test-utils.ts';
+import * as valita from '../../../shared/src/valita.ts';
+import type {AST} from '../../../zero-protocol/src/ast.ts';
+import * as ErrorKind from '../../../zero-protocol/src/error-kind-enum.ts';
 import {
   changeDesiredQueriesMessageSchema,
   decodeSecProtocols,
   encodeSecProtocols,
   initConnectionMessageSchema,
   type QueriesPatchOp,
-} from '../../../zero-protocol/src/mod.js';
-import * as MutationType from '../../../zero-protocol/src/mutation-type-enum.js';
-import {PROTOCOL_VERSION} from '../../../zero-protocol/src/protocol-version.js';
+} from '../../../zero-protocol/src/mod.ts';
+import * as MutationType from '../../../zero-protocol/src/mutation-type-enum.ts';
+import {PROTOCOL_VERSION} from '../../../zero-protocol/src/protocol-version.ts';
 import {
   type Mutation,
   pushMessageSchema,
-} from '../../../zero-protocol/src/push.js';
-import type {NullableVersion} from '../../../zero-protocol/src/version.js';
-import {createSchema, type Schema} from '../../../zero-schema/src/mod.js';
-import {number, string, table} from '../mod.js';
-import * as ConnectionState from './connection-state-enum.js';
-import type {WSString} from './http-string.js';
-import type {UpdateNeededReason, ZeroOptions} from './options.js';
-import type {QueryManager} from './query-manager.js';
-import {RELOAD_REASON_STORAGE_KEY} from './reload-error-handler.js';
-import {ServerError} from './server-error.js';
+} from '../../../zero-protocol/src/push.ts';
+import type {NullableVersion} from '../../../zero-protocol/src/version.ts';
+import {createSchema, type Schema} from '../../../zero-schema/src/mod.ts';
+import {number, string, table} from '../mod.ts';
+import * as ConnectionState from './connection-state-enum.ts';
+import type {WSString} from './http-string.ts';
+import type {UpdateNeededReason, ZeroOptions} from './options.ts';
+import type {QueryManager} from './query-manager.ts';
+import {RELOAD_REASON_STORAGE_KEY} from './reload-error-handler.ts';
+import {ServerError} from './server-error.ts';
 import {
   MockSocket,
   storageMock,
@@ -39,7 +39,7 @@ import {
   tickAFewTimes,
   waitForUpstreamMessage,
   zeroForTest,
-} from './test-utils.js'; // Why use fakes when we can use the real thing!
+} from './test-utils.ts'; // Why use fakes when we can use the real thing!
 import {
   CONNECT_TIMEOUT_MS,
   createSocket,
@@ -48,7 +48,7 @@ import {
   PING_TIMEOUT_MS,
   PULL_TIMEOUT_MS,
   RUN_LOOP_INTERVAL_MS,
-} from './zero.js';
+} from './zero.ts';
 
 let realSetTimeout: typeof setTimeout;
 let clock: sinon.SinonFakeTimers;
diff --git a/packages/zero-client/src/client/zero.ts b/packages/zero-client/src/client/zero.ts
index 3841108161..30fb6b7d24 100644
--- a/packages/zero-client/src/client/zero.ts
+++ b/packages/zero-client/src/client/zero.ts
@@ -3,7 +3,7 @@ import {type Resolver, resolver} from '@rocicorp/resolver';
 import {
   ReplicacheImpl,
   type ReplicacheImplOptions,
-} from '../../../replicache/src/impl.js';
+} from '../../../replicache/src/impl.ts';
 import {
   type ClientGroupID,
   type ClientID,
@@ -18,20 +18,20 @@ import {
   type ReplicacheOptions,
   type UpdateNeededReason as ReplicacheUpdateNeededReason,
   dropDatabase,
-} from '../../../replicache/src/mod.js';
-import {assert, unreachable} from '../../../shared/src/asserts.js';
+} from '../../../replicache/src/mod.ts';
+import {assert, unreachable} from '../../../shared/src/asserts.ts';
 import {
   getBrowserGlobal,
   mustGetBrowserGlobal,
-} from '../../../shared/src/browser-env.js';
-import {getDocumentVisibilityWatcher} from '../../../shared/src/document-visible.js';
-import type {Enum} from '../../../shared/src/enum.js';
-import {must} from '../../../shared/src/must.js';
-import {navigator} from '../../../shared/src/navigator.js';
-import {sleep, sleepWithAbort} from '../../../shared/src/sleep.js';
-import * as valita from '../../../shared/src/valita.js';
-import type {ChangeDesiredQueriesMessage} from '../../../zero-protocol/src/change-desired-queries.js';
-import * as ErrorKind from '../../../zero-protocol/src/error-kind-enum.js';
+} from '../../../shared/src/browser-env.ts';
+import {getDocumentVisibilityWatcher} from '../../../shared/src/document-visible.ts';
+import type {Enum} from '../../../shared/src/enum.ts';
+import {must} from '../../../shared/src/must.ts';
+import {navigator} from '../../../shared/src/navigator.ts';
+import {sleep, sleepWithAbort} from '../../../shared/src/sleep.ts';
+import * as valita from '../../../shared/src/valita.ts';
+import type {ChangeDesiredQueriesMessage} from '../../../zero-protocol/src/change-desired-queries.ts';
+import * as ErrorKind from '../../../zero-protocol/src/error-kind-enum.ts';
 import {
   type CRUDMutation,
   type CRUDMutationArg,
@@ -50,37 +50,37 @@ import {
   downstreamSchema,
   encodeSecProtocols,
   nullableVersionSchema,
-} from '../../../zero-protocol/src/mod.js';
-import * as MutationType from '../../../zero-protocol/src/mutation-type-enum.js';
-import {PROTOCOL_VERSION} from '../../../zero-protocol/src/protocol-version.js';
+} from '../../../zero-protocol/src/mod.ts';
+import * as MutationType from '../../../zero-protocol/src/mutation-type-enum.ts';
+import {PROTOCOL_VERSION} from '../../../zero-protocol/src/protocol-version.ts';
 import type {
   PullRequestMessage,
   PullResponseBody,
   PullResponseMessage,
-} from '../../../zero-protocol/src/pull.js';
-import type {Schema} from '../../../zero-schema/src/mod.js';
-import {newQuery} from '../../../zql/src/query/query-impl.js';
-import type {Query} from '../../../zql/src/query/query.js';
-import {nanoid} from '../util/nanoid.js';
-import {send} from '../util/socket.js';
-import * as ConnectionState from './connection-state-enum.js';
-import {ZeroContext} from './context.js';
+} from '../../../zero-protocol/src/pull.ts';
+import type {Schema} from '../../../zero-schema/src/mod.ts';
+import {newQuery} from '../../../zql/src/query/query-impl.ts';
+import type {Query} from '../../../zql/src/query/query.ts';
+import {nanoid} from '../util/nanoid.ts';
+import {send} from '../util/socket.ts';
+import * as ConnectionState from './connection-state-enum.ts';
+import {ZeroContext} from './context.ts';
 import {
   type BatchMutator,
   type DBMutator,
   type WithCRUD,
   makeCRUDMutate,
   makeCRUDMutator,
-} from './crud.js';
-import {shouldEnableAnalytics} from './enable-analytics.js';
+} from './crud.ts';
+import {shouldEnableAnalytics} from './enable-analytics.ts';
 import {
   type HTTPString,
   type WSString,
   appendPath,
   toWSString,
-} from './http-string.js';
-import {ENTITIES_KEY_PREFIX} from './keys.js';
-import {type LogOptions, createLogOptions} from './log-options.js';
+} from './http-string.ts';
+import {ENTITIES_KEY_PREFIX} from './keys.ts';
+import {type LogOptions, createLogOptions} from './log-options.ts';
 import {
   DID_NOT_CONNECT_VALUE,
   type DisconnectReason,
@@ -88,29 +88,29 @@ import {
   REPORT_INTERVAL_MS,
   type Series,
   getLastConnectErrorValue,
-} from './metrics.js';
+} from './metrics.ts';
 import type {
   UpdateNeededReason,
   ZeroAdvancedOptions,
   ZeroOptions,
-} from './options.js';
-import * as PingResult from './ping-result-enum.js';
-import {QueryManager} from './query-manager.js';
+} from './options.ts';
+import * as PingResult from './ping-result-enum.ts';
+import {QueryManager} from './query-manager.ts';
 import {
   reloadScheduled,
   reloadWithReason,
   reportReloadReason,
   resetBackoff,
-} from './reload-error-handler.js';
+} from './reload-error-handler.ts';
 import {
   ServerError,
   isAuthError,
   isBackoffError,
   isServerError,
-} from './server-error.js';
-import {getServer} from './server-option.js';
-import {version} from './version.js';
-import {PokeHandler} from './zero-poke-handler.js';
+} from './server-error.ts';
+import {getServer} from './server-option.ts';
+import {version} from './version.ts';
+import {PokeHandler} from './zero-poke-handler.ts';
 
 type ConnectionState = Enum<typeof ConnectionState>;
 type PingResult = Enum<typeof PingResult>;
diff --git a/packages/zero-client/src/mod.ts b/packages/zero-client/src/mod.ts
index 5128f84bbb..0568a6f143 100644
--- a/packages/zero-client/src/mod.ts
+++ b/packages/zero-client/src/mod.ts
@@ -5,7 +5,7 @@ export {
   IDBNotFoundError,
   makeIDBName,
   TransactionClosedError,
-} from '../../replicache/src/mod.js';
+} from '../../replicache/src/mod.ts';
 export type {
   AsyncIterableIteratorToArray,
   ClientGroupID,
@@ -56,7 +56,7 @@ export type {
   UpdateNeededReason,
   VersionNotSupportedResponse,
   WriteTransaction,
-} from '../../replicache/src/mod.js';
+} from '../../replicache/src/mod.ts';
 export type {
   AST,
   Bound,
@@ -80,12 +80,12 @@ export type {
   SimpleCondition,
   SimpleOperator,
   ValuePosition,
-} from '../../zero-protocol/src/ast.js';
-export {relationships} from '../../zero-schema/src/builder/relationship-builder.js';
+} from '../../zero-protocol/src/ast.ts';
+export {relationships} from '../../zero-schema/src/builder/relationship-builder.ts';
 export {
   createSchema,
   type Schema,
-} from '../../zero-schema/src/builder/schema-builder.js';
+} from '../../zero-schema/src/builder/schema-builder.ts';
 export {
   boolean,
   enumeration,
@@ -93,38 +93,38 @@ export {
   number,
   string,
   table,
-  type TableBuilderWithColumns,
   type ColumnBuilder,
-} from '../../zero-schema/src/builder/table-builder.js';
+  type TableBuilderWithColumns,
+} from '../../zero-schema/src/builder/table-builder.ts';
 export type {
   AssetPermissions as CompiledAssetPermissions,
   PermissionsConfig as CompiledPermissionsConfig,
   Policy as CompiledPermissionsPolicy,
   Rule as CompiledPermissionsRule,
-} from '../../zero-schema/src/compiled-permissions.js';
+} from '../../zero-schema/src/compiled-permissions.ts';
 export {
   ANYONE_CAN,
   definePermissions,
   NOBODY_CAN,
-} from '../../zero-schema/src/permissions.js';
+} from '../../zero-schema/src/permissions.ts';
 export type {
   AssetPermissions,
   PermissionRule,
   PermissionsConfig,
-} from '../../zero-schema/src/permissions.js';
-export {type TableSchema} from '../../zero-schema/src/table-schema.js';
+} from '../../zero-schema/src/permissions.ts';
+export {type TableSchema} from '../../zero-schema/src/table-schema.ts';
 export type {
   EnumSchemaValue,
   SchemaValue,
   SchemaValueWithCustomType,
   ValueType,
-} from '../../zero-schema/src/table-schema.js';
-export {escapeLike} from '../../zql/src/query/escape-like.js';
+} from '../../zero-schema/src/table-schema.ts';
+export {escapeLike} from '../../zql/src/query/escape-like.ts';
 export type {
   ExpressionBuilder,
   ExpressionFactory,
-} from '../../zql/src/query/expression.js';
-export type {Query, Row} from '../../zql/src/query/query.js';
-export type {TypedView, ResultType} from '../../zql/src/query/typed-view.js';
-export type {ZeroOptions} from './client/options.js';
-export {Zero} from './client/zero.js';
+} from '../../zql/src/query/expression.ts';
+export type {Query, Row} from '../../zql/src/query/query.ts';
+export type {ResultType, TypedView} from '../../zql/src/query/typed-view.ts';
+export type {ZeroOptions} from './client/options.ts';
+export {Zero} from './client/zero.ts';
diff --git a/packages/zero-client/src/types/client-mutation.ts b/packages/zero-client/src/types/client-mutation.ts
index 30187b58bb..5accc7559e 100644
--- a/packages/zero-client/src/types/client-mutation.ts
+++ b/packages/zero-client/src/types/client-mutation.ts
@@ -1,5 +1,5 @@
-import type {Mutation} from '../../../zero-protocol/src/mod.js';
-import type {ClientID} from './client-state.js';
+import type {Mutation} from '../../../zero-protocol/src/mod.ts';
+import type {ClientID} from './client-state.ts';
 
 export type ClientMutation = Mutation & {
   clientID: ClientID;
diff --git a/packages/zero-client/src/types/client-state.ts b/packages/zero-client/src/types/client-state.ts
index dfe23c3100..7c71d457e0 100644
--- a/packages/zero-client/src/types/client-state.ts
+++ b/packages/zero-client/src/types/client-state.ts
@@ -1,4 +1,4 @@
-import type {Mutation} from '../../../zero-protocol/src/mod.js';
+import type {Mutation} from '../../../zero-protocol/src/mod.ts';
 
 export type ClientID = string;
 
diff --git a/packages/zero-client/src/util/nanoid.ts b/packages/zero-client/src/util/nanoid.ts
index a9e9da4edc..13e544c27c 100644
--- a/packages/zero-client/src/util/nanoid.ts
+++ b/packages/zero-client/src/util/nanoid.ts
@@ -4,7 +4,7 @@
 // Also we changed the random number generator to use Math.random() for compat
 // with React Native.
 
-import {getNonCryptoRandomValues} from '../../../shared/src/random-values.js';
+import {getNonCryptoRandomValues} from '../../../shared/src/random-values.ts';
 
 export function nanoid(size = 21): string {
   // Use our custom getRandomValues function to fill a Uint8Array with random values.
diff --git a/packages/zero-client/src/util/peek-iterator.test.ts b/packages/zero-client/src/util/peek-iterator.test.ts
index 7928fd4c2a..9d9ac85352 100644
--- a/packages/zero-client/src/util/peek-iterator.test.ts
+++ b/packages/zero-client/src/util/peek-iterator.test.ts
@@ -1,5 +1,5 @@
 import {expect, test} from 'vitest';
-import {PeekIterator} from '../util/peek-iterator.js';
+import {PeekIterator} from '../util/peek-iterator.ts';
 
 test('PeekIterator', () => {
   const c = new PeekIterator('abc'[Symbol.iterator]());
diff --git a/packages/zero-client/src/util/socket.ts b/packages/zero-client/src/util/socket.ts
index e4fc57843d..9854892f14 100644
--- a/packages/zero-client/src/util/socket.ts
+++ b/packages/zero-client/src/util/socket.ts
@@ -1,4 +1,4 @@
-import type {Upstream} from '../../../zero-protocol/src/up.js';
+import type {Upstream} from '../../../zero-protocol/src/up.ts';
 
 export function send(ws: WebSocket, data: Upstream) {
   ws.send(JSON.stringify(data));
diff --git a/packages/zero-client/vitest.config.ts b/packages/zero-client/vitest.config.ts
index 960efc6d6b..12508b30d0 100644
--- a/packages/zero-client/vitest.config.ts
+++ b/packages/zero-client/vitest.config.ts
@@ -1 +1 @@
-export {default} from '../shared/src/tool/vitest-config.js';
+export {default} from '../shared/src/tool/vitest-config.ts';
diff --git a/packages/zero-protocol/src/ast-hash.ts b/packages/zero-protocol/src/ast-hash.ts
index 3bd3485457..5ceb01b7b1 100644
--- a/packages/zero-protocol/src/ast-hash.ts
+++ b/packages/zero-protocol/src/ast-hash.ts
@@ -1,5 +1,5 @@
-import {h64} from '../../shared/src/hash.js';
-import {normalizeAST, type AST} from './ast.js';
+import {h64} from '../../shared/src/hash.ts';
+import {normalizeAST, type AST} from './ast.ts';
 
 const hashCache = new WeakMap<AST, string>();
 
diff --git a/packages/zero-protocol/src/ast-type-test.ts b/packages/zero-protocol/src/ast-type-test.ts
index 60c473504c..2d1eef5da1 100644
--- a/packages/zero-protocol/src/ast-type-test.ts
+++ b/packages/zero-protocol/src/ast-type-test.ts
@@ -1,4 +1,4 @@
-import type * as v from '../../shared/src/valita.js';
+import type * as v from '../../shared/src/valita.ts';
 import type {
   AST,
   Condition,
@@ -21,7 +21,7 @@ import type {
   orderOpsSchema,
   orderingSchema,
   simpleOperatorSchema,
-} from './ast.js';
+} from './ast.ts';
 
 type MakeAllFieldsRequired<T> = {
   [K in keyof T]-?: MakeAllFieldsRequired<T[K]>;
diff --git a/packages/zero-protocol/src/ast.test.ts b/packages/zero-protocol/src/ast.test.ts
index 15945dc3bb..a97430d871 100644
--- a/packages/zero-protocol/src/ast.test.ts
+++ b/packages/zero-protocol/src/ast.test.ts
@@ -1,8 +1,8 @@
 import {expect, test} from 'vitest';
-import {h64} from '../../shared/src/hash.js';
-import type {AST} from './ast.js';
-import {astSchema, normalizeAST} from './ast.js';
-import {PROTOCOL_VERSION} from './protocol-version.js';
+import {h64} from '../../shared/src/hash.ts';
+import type {AST} from './ast.ts';
+import {astSchema, normalizeAST} from './ast.ts';
+import {PROTOCOL_VERSION} from './protocol-version.ts';
 
 test('fields are placed into correct positions', () => {
   function normalizeAndStringify(ast: AST) {
diff --git a/packages/zero-protocol/src/ast.ts b/packages/zero-protocol/src/ast.ts
index b702492f40..58a22e859c 100644
--- a/packages/zero-protocol/src/ast.ts
+++ b/packages/zero-protocol/src/ast.ts
@@ -7,11 +7,11 @@
  */
 
 import {compareUTF8} from 'compare-utf8';
-import {defined} from '../../shared/src/arrays.js';
-import {assert} from '../../shared/src/asserts.js';
-import {must} from '../../shared/src/must.js';
-import * as v from '../../shared/src/valita.js';
-import {rowSchema, type Row} from './data.js';
+import {defined} from '../../shared/src/arrays.ts';
+import {assert} from '../../shared/src/asserts.ts';
+import {must} from '../../shared/src/must.ts';
+import * as v from '../../shared/src/valita.ts';
+import {rowSchema, type Row} from './data.ts';
 
 export const selectorSchema = v.string();
 export const toStaticParam = Symbol();
diff --git a/packages/zero-protocol/src/change-desired-queries.ts b/packages/zero-protocol/src/change-desired-queries.ts
index 481bc1b4ca..95cfae18f9 100644
--- a/packages/zero-protocol/src/change-desired-queries.ts
+++ b/packages/zero-protocol/src/change-desired-queries.ts
@@ -1,5 +1,5 @@
-import * as v from '../../shared/src/valita.js';
-import {queriesPatchSchema} from './queries-patch.js';
+import * as v from '../../shared/src/valita.ts';
+import {queriesPatchSchema} from './queries-patch.ts';
 
 const changeDesiredQueriesBodySchema = v.object({
   desiredQueriesPatch: queriesPatchSchema,
diff --git a/packages/zero-protocol/src/clients-patch.ts b/packages/zero-protocol/src/clients-patch.ts
index e9b3943814..3cc379aeb0 100644
--- a/packages/zero-protocol/src/clients-patch.ts
+++ b/packages/zero-protocol/src/clients-patch.ts
@@ -1,4 +1,4 @@
-import * as v from '../../shared/src/valita.js';
+import * as v from '../../shared/src/valita.ts';
 
 const putOpSchema = v.object({
   op: v.literal('put'),
diff --git a/packages/zero-protocol/src/connect.test.ts b/packages/zero-protocol/src/connect.test.ts
index c345ad2bd2..ab1a016b11 100644
--- a/packages/zero-protocol/src/connect.test.ts
+++ b/packages/zero-protocol/src/connect.test.ts
@@ -1,6 +1,6 @@
-import {expect, test} from 'vitest';
 import fc from 'fast-check';
-import {decodeSecProtocols, encodeSecProtocols} from './connect.js';
+import {expect, test} from 'vitest';
+import {decodeSecProtocols, encodeSecProtocols} from './connect.ts';
 
 test('encode/decodeSecProtocols round-trip', () => {
   fc.assert(
diff --git a/packages/zero-protocol/src/connect.ts b/packages/zero-protocol/src/connect.ts
index c9e0e21d39..30ba66fd65 100644
--- a/packages/zero-protocol/src/connect.ts
+++ b/packages/zero-protocol/src/connect.ts
@@ -1,5 +1,5 @@
-import * as v from '../../shared/src/valita.js';
-import {queriesPatchSchema} from './queries-patch.js';
+import * as v from '../../shared/src/valita.ts';
+import {queriesPatchSchema} from './queries-patch.ts';
 
 /**
  * After opening a websocket the client waits for a `connected` message
diff --git a/packages/zero-protocol/src/data.ts b/packages/zero-protocol/src/data.ts
index 2201f7e86a..b6990c1c4e 100644
--- a/packages/zero-protocol/src/data.ts
+++ b/packages/zero-protocol/src/data.ts
@@ -1,5 +1,5 @@
-import {jsonSchema} from '../../shared/src/json-schema.js';
-import * as v from '../../shared/src/valita.js';
+import {jsonSchema} from '../../shared/src/json-schema.ts';
+import * as v from '../../shared/src/valita.ts';
 
 export const valueSchema = v.union(jsonSchema, v.undefined());
 
diff --git a/packages/zero-protocol/src/delete-clients.ts b/packages/zero-protocol/src/delete-clients.ts
index 0292c9fe1a..778a2a473b 100644
--- a/packages/zero-protocol/src/delete-clients.ts
+++ b/packages/zero-protocol/src/delete-clients.ts
@@ -1,4 +1,4 @@
-import * as v from '../../shared/src/valita.js';
+import * as v from '../../shared/src/valita.ts';
 
 const deleteClientsBodySchema = v.object({
   clientIDs: v.array(v.string()),
diff --git a/packages/zero-protocol/src/down.ts b/packages/zero-protocol/src/down.ts
index d9e3ebe7b9..d87d0c4551 100644
--- a/packages/zero-protocol/src/down.ts
+++ b/packages/zero-protocol/src/down.ts
@@ -1,14 +1,14 @@
-import * as v from '../../shared/src/valita.js';
-import {connectedMessageSchema} from './connect.js';
-import {errorMessageSchema} from './error.js';
+import * as v from '../../shared/src/valita.ts';
+import {connectedMessageSchema} from './connect.ts';
+import {errorMessageSchema} from './error.ts';
 import {
   pokeEndMessageSchema,
   pokePartMessageSchema,
   pokeStartMessageSchema,
-} from './poke.js';
-import {pongMessageSchema} from './pong.js';
-import {pullResponseMessageSchema} from './pull.js';
-import {warmMessageSchema} from './warm.js';
+} from './poke.ts';
+import {pongMessageSchema} from './pong.ts';
+import {pullResponseMessageSchema} from './pull.ts';
+import {warmMessageSchema} from './warm.ts';
 
 export const downstreamSchema = v.union(
   connectedMessageSchema,
diff --git a/packages/zero-protocol/src/error-type-test.ts b/packages/zero-protocol/src/error-type-test.ts
index 1901683895..059884e9f6 100644
--- a/packages/zero-protocol/src/error-type-test.ts
+++ b/packages/zero-protocol/src/error-type-test.ts
@@ -1,7 +1,7 @@
-import type {Enum} from '../../shared/src/enum.js';
-import type * as v from '../../shared/src/valita.js';
-import * as ErrorKind from './error-kind-enum.js';
-import type {errorBodySchema} from './error.js';
+import type {Enum} from '../../shared/src/enum.ts';
+import type * as v from '../../shared/src/valita.ts';
+import * as ErrorKind from './error-kind-enum.ts';
+import type {errorBodySchema} from './error.ts';
 
 type ErrorKind = Enum<typeof ErrorKind>;
 
diff --git a/packages/zero-protocol/src/error.ts b/packages/zero-protocol/src/error.ts
index 4dca36b132..0d7769e43b 100644
--- a/packages/zero-protocol/src/error.ts
+++ b/packages/zero-protocol/src/error.ts
@@ -1,5 +1,5 @@
-import * as v from '../../shared/src/valita.js';
-import * as ErrorKind from './error-kind-enum.js';
+import * as v from '../../shared/src/valita.ts';
+import * as ErrorKind from './error-kind-enum.ts';
 
 const basicErrorKindSchema = v.union(
   v.literal(ErrorKind.AuthInvalidated),
diff --git a/packages/zero-protocol/src/mod.ts b/packages/zero-protocol/src/mod.ts
index 7abda1f285..33040bd3a6 100644
--- a/packages/zero-protocol/src/mod.ts
+++ b/packages/zero-protocol/src/mod.ts
@@ -1,15 +1,15 @@
 // TODO: Remove this file
-export * from './change-desired-queries.js';
-export * from './clients-patch.js';
-export * from './connect.js';
-export * from './down.js';
-export * from './error.js';
-export * from './ping.js';
-export * from './poke.js';
-export * from './pong.js';
-export * from './pull.js';
-export * from './push.js';
-export * from './queries-patch.js';
-export * from './row-patch.js';
-export * from './up.js';
-export * from './version.js';
+export * from './change-desired-queries.ts';
+export * from './clients-patch.ts';
+export * from './connect.ts';
+export * from './down.ts';
+export * from './error.ts';
+export * from './ping.ts';
+export * from './poke.ts';
+export * from './pong.ts';
+export * from './pull.ts';
+export * from './push.ts';
+export * from './queries-patch.ts';
+export * from './row-patch.ts';
+export * from './up.ts';
+export * from './version.ts';
diff --git a/packages/zero-protocol/src/ping.ts b/packages/zero-protocol/src/ping.ts
index c5dfe9ac47..c40dc6a3a6 100644
--- a/packages/zero-protocol/src/ping.ts
+++ b/packages/zero-protocol/src/ping.ts
@@ -1,4 +1,4 @@
-import * as v from '../../shared/src/valita.js';
+import * as v from '../../shared/src/valita.ts';
 
 export const pingBodySchema = v.object({});
 export const pingMessageSchema = v.tuple([v.literal('ping'), pingBodySchema]);
diff --git a/packages/zero-protocol/src/poke.ts b/packages/zero-protocol/src/poke.ts
index 92f79c33ae..3916bb66c9 100644
--- a/packages/zero-protocol/src/poke.ts
+++ b/packages/zero-protocol/src/poke.ts
@@ -1,8 +1,8 @@
-import * as v from '../../shared/src/valita.js';
-import {clientsPatchSchema} from './clients-patch.js';
-import {queriesPatchSchema} from './queries-patch.js';
-import {rowsPatchSchema} from './row-patch.js';
-import {nullableVersionSchema, versionSchema} from './version.js';
+import * as v from '../../shared/src/valita.ts';
+import {clientsPatchSchema} from './clients-patch.ts';
+import {queriesPatchSchema} from './queries-patch.ts';
+import {rowsPatchSchema} from './row-patch.ts';
+import {nullableVersionSchema, versionSchema} from './version.ts';
 
 /**
  * Pokes use a multi-part format. Pokes send entity data to the client and can
diff --git a/packages/zero-protocol/src/pong.ts b/packages/zero-protocol/src/pong.ts
index 1ab0b27d18..796a828556 100644
--- a/packages/zero-protocol/src/pong.ts
+++ b/packages/zero-protocol/src/pong.ts
@@ -1,4 +1,4 @@
-import * as v from '../../shared/src/valita.js';
+import * as v from '../../shared/src/valita.ts';
 
 export const pongBodySchema = v.object({});
 export const pongMessageSchema = v.tuple([v.literal('pong'), pongBodySchema]);
diff --git a/packages/zero-protocol/src/primary-key.ts b/packages/zero-protocol/src/primary-key.ts
index 34b4ccb7ba..45aaa19abf 100644
--- a/packages/zero-protocol/src/primary-key.ts
+++ b/packages/zero-protocol/src/primary-key.ts
@@ -1,4 +1,4 @@
-import * as v from '../../shared/src/valita.js';
+import * as v from '../../shared/src/valita.ts';
 
 export const primaryKeySchema = v.readonly(
   v.tuple([v.string()]).concat(v.array(v.string())),
diff --git a/packages/zero-protocol/src/protocol-version.ts b/packages/zero-protocol/src/protocol-version.ts
index 13d1461a5e..82e7f556f5 100644
--- a/packages/zero-protocol/src/protocol-version.ts
+++ b/packages/zero-protocol/src/protocol-version.ts
@@ -1,4 +1,4 @@
-import {assert} from '../../shared/src/asserts.js';
+import {assert} from '../../shared/src/asserts.ts';
 
 /**
  * The current `PROTOCOL_VERSION` of the code.
diff --git a/packages/zero-protocol/src/pull.ts b/packages/zero-protocol/src/pull.ts
index 67f2633b2f..f5f23c01bb 100644
--- a/packages/zero-protocol/src/pull.ts
+++ b/packages/zero-protocol/src/pull.ts
@@ -1,5 +1,5 @@
-import * as v from '../../shared/src/valita.js';
-import {nullableVersionSchema, versionSchema} from './version.js';
+import * as v from '../../shared/src/valita.ts';
+import {nullableVersionSchema, versionSchema} from './version.ts';
 
 export const pullRequestBodySchema = v.object({
   clientGroupID: v.string(),
diff --git a/packages/zero-protocol/src/push.ts b/packages/zero-protocol/src/push.ts
index 636651b048..2f8b1f1cba 100644
--- a/packages/zero-protocol/src/push.ts
+++ b/packages/zero-protocol/src/push.ts
@@ -1,8 +1,8 @@
-import {jsonSchema} from '../../shared/src/json-schema.js';
-import * as v from '../../shared/src/valita.js';
-import {rowSchema} from './data.js';
-import * as MutationType from './mutation-type-enum.js';
-import {primaryKeySchema, primaryKeyValueRecordSchema} from './primary-key.js';
+import {jsonSchema} from '../../shared/src/json-schema.ts';
+import * as v from '../../shared/src/valita.ts';
+import {rowSchema} from './data.ts';
+import * as MutationType from './mutation-type-enum.ts';
+import {primaryKeySchema, primaryKeyValueRecordSchema} from './primary-key.ts';
 
 export const CRUD_MUTATION_NAME = '_zero_crud';
 
diff --git a/packages/zero-protocol/src/queries-patch.ts b/packages/zero-protocol/src/queries-patch.ts
index 9641afb1df..ba3d20f372 100644
--- a/packages/zero-protocol/src/queries-patch.ts
+++ b/packages/zero-protocol/src/queries-patch.ts
@@ -1,5 +1,5 @@
-import * as v from '../../shared/src/valita.js';
-import {astSchema} from './ast.js';
+import * as v from '../../shared/src/valita.ts';
+import {astSchema} from './ast.ts';
 
 const putOpSchema = v.object({
   op: v.literal('put'),
diff --git a/packages/zero-protocol/src/row-patch.ts b/packages/zero-protocol/src/row-patch.ts
index f85cb5d1a4..f6c91ea1d8 100644
--- a/packages/zero-protocol/src/row-patch.ts
+++ b/packages/zero-protocol/src/row-patch.ts
@@ -1,7 +1,7 @@
-import {jsonObjectSchema} from '../../shared/src/json-schema.js';
-import * as v from '../../shared/src/valita.js';
-import {rowSchema} from './data.js';
-import {primaryKeyValueRecordSchema} from './primary-key.js';
+import {jsonObjectSchema} from '../../shared/src/json-schema.ts';
+import * as v from '../../shared/src/valita.ts';
+import {rowSchema} from './data.ts';
+import {primaryKeyValueRecordSchema} from './primary-key.ts';
 
 const putOpSchema = v.object({
   op: v.literal('put'),
diff --git a/packages/zero-protocol/src/up.ts b/packages/zero-protocol/src/up.ts
index 492a63e4e7..7f692846b5 100644
--- a/packages/zero-protocol/src/up.ts
+++ b/packages/zero-protocol/src/up.ts
@@ -1,10 +1,10 @@
-import * as v from '../../shared/src/valita.js';
-import {pingMessageSchema} from './ping.js';
-import {deleteClientsMessageSchema} from './delete-clients.js';
-import {initConnectionMessageSchema} from './connect.js';
-import {pullRequestMessageSchema} from './pull.js';
-import {pushMessageSchema} from './push.js';
-import {changeDesiredQueriesMessageSchema} from './change-desired-queries.js';
+import * as v from '../../shared/src/valita.ts';
+import {changeDesiredQueriesMessageSchema} from './change-desired-queries.ts';
+import {initConnectionMessageSchema} from './connect.ts';
+import {deleteClientsMessageSchema} from './delete-clients.ts';
+import {pingMessageSchema} from './ping.ts';
+import {pullRequestMessageSchema} from './pull.ts';
+import {pushMessageSchema} from './push.ts';
 
 export const upstreamSchema = v.union(
   initConnectionMessageSchema,
diff --git a/packages/zero-protocol/src/version.ts b/packages/zero-protocol/src/version.ts
index 87c5198c6d..cd0167f317 100644
--- a/packages/zero-protocol/src/version.ts
+++ b/packages/zero-protocol/src/version.ts
@@ -1,4 +1,4 @@
-import * as v from '../../shared/src/valita.js';
+import * as v from '../../shared/src/valita.ts';
 
 export const versionSchema = v.string();
 export const nullableVersionSchema = v.union(versionSchema, v.null());
diff --git a/packages/zero-protocol/src/warm.ts b/packages/zero-protocol/src/warm.ts
index 291ef2a053..0565fb49b3 100644
--- a/packages/zero-protocol/src/warm.ts
+++ b/packages/zero-protocol/src/warm.ts
@@ -1,4 +1,4 @@
-import * as v from '../../shared/src/valita.js';
+import * as v from '../../shared/src/valita.ts';
 
 export const warmBodySchema = v.object({
   payload: v.string(),
diff --git a/packages/zero-react/src/mod.ts b/packages/zero-react/src/mod.ts
index 9488a311c8..ae47a5512f 100644
--- a/packages/zero-react/src/mod.ts
+++ b/packages/zero-react/src/mod.ts
@@ -1,16 +1,16 @@
-export type {Expand} from '../../shared/src/expand.js';
-export type {PrimaryKey} from '../../zero-protocol/src/primary-key.js';
-export type {Schema} from '../../zero-schema/src/builder/schema-builder.js';
+export type {Expand} from '../../shared/src/expand.ts';
+export type {PrimaryKey} from '../../zero-protocol/src/primary-key.ts';
+export type {Schema} from '../../zero-schema/src/builder/schema-builder.ts';
 export type {
   RelationshipsSchema,
   SchemaValue,
   TableSchema,
-} from '../../zero-schema/src/table-schema.js';
-export type {HumanReadable} from '../../zql/src/query/query.js';
-export type {ResultType} from '../../zql/src/query/typed-view.js';
+} from '../../zero-schema/src/table-schema.ts';
+export type {HumanReadable} from '../../zql/src/query/query.ts';
+export type {ResultType} from '../../zql/src/query/typed-view.ts';
 export {
   useQuery,
   type QueryResult,
   type QueryResultDetails,
-} from './use-query.jsx';
-export {createUseZero, useZero, ZeroProvider} from './use-zero.jsx';
+} from './use-query.tsx';
+export {createUseZero, useZero, ZeroProvider} from './use-zero.tsx';
diff --git a/packages/zero-react/src/use-query.test.ts b/packages/zero-react/src/use-query.test.ts
index fcc51888cb..8e6d40fdfc 100644
--- a/packages/zero-react/src/use-query.test.ts
+++ b/packages/zero-react/src/use-query.test.ts
@@ -1,8 +1,8 @@
 import {beforeEach, describe, expect, test, vi} from 'vitest';
-import type {Schema} from '../../zero-schema/src/mod.js';
-import type {AdvancedQuery} from '../../zql/src/query/query-internal.js';
-import type {ResultType} from '../../zql/src/query/typed-view.js';
-import {getAllViewsSizeForTesting, ViewStore} from './use-query.js';
+import type {Schema} from '../../zero-schema/src/mod.ts';
+import type {AdvancedQuery} from '../../zql/src/query/query-internal.ts';
+import type {ResultType} from '../../zql/src/query/typed-view.ts';
+import {getAllViewsSizeForTesting, ViewStore} from './use-query.tsx';
 
 function newMockQuery(
   query: string,
diff --git a/packages/zero-react/src/use-query.tsx b/packages/zero-react/src/use-query.tsx
index 642fb5e644..14cf2cd72b 100644
--- a/packages/zero-react/src/use-query.tsx
+++ b/packages/zero-react/src/use-query.tsx
@@ -1,16 +1,16 @@
 import {useSyncExternalStore} from 'react';
-import {deepClone} from '../../shared/src/deep-clone.js';
-import type {Immutable} from '../../shared/src/immutable.js';
+import {deepClone} from '../../shared/src/deep-clone.ts';
+import type {Immutable} from '../../shared/src/immutable.ts';
 import type {
   Query,
   ReadonlyJSONValue,
   Schema,
   TypedView,
-} from '../../zero-client/src/mod.js';
-import type {AdvancedQuery} from '../../zql/src/query/query-internal.js';
-import type {HumanReadable} from '../../zql/src/query/query.js';
-import type {ResultType} from '../../zql/src/query/typed-view.js';
-import {useZero} from './use-zero.js';
+} from '../../zero-client/src/mod.ts';
+import type {AdvancedQuery} from '../../zql/src/query/query-internal.ts';
+import type {HumanReadable} from '../../zql/src/query/query.ts';
+import type {ResultType} from '../../zql/src/query/typed-view.ts';
+import {useZero} from './use-zero.tsx';
 
 export type QueryResultDetails = Readonly<{
   type: ResultType;
diff --git a/packages/zero-react/src/use-zero.tsx b/packages/zero-react/src/use-zero.tsx
index 6758614029..6e03916daa 100644
--- a/packages/zero-react/src/use-zero.tsx
+++ b/packages/zero-react/src/use-zero.tsx
@@ -1,6 +1,6 @@
 import {createContext, useContext} from 'react';
-import type {Zero} from '../../zero-client/src/mod.js';
-import type {Schema} from '../../zero-schema/src/mod.js';
+import type {Zero} from '../../zero-client/src/mod.ts';
+import type {Schema} from '../../zero-schema/src/mod.ts';
 
 // eslint-disable-next-line @typescript-eslint/naming-convention
 const ZeroContext = createContext<unknown | undefined>(undefined);
diff --git a/packages/zero-react/vitest.config.ts b/packages/zero-react/vitest.config.ts
index 960efc6d6b..12508b30d0 100644
--- a/packages/zero-react/vitest.config.ts
+++ b/packages/zero-react/vitest.config.ts
@@ -1 +1 @@
-export {default} from '../shared/src/tool/vitest-config.js';
+export {default} from '../shared/src/tool/vitest-config.ts';
diff --git a/packages/zero-schema/src/build-schema-options.ts b/packages/zero-schema/src/build-schema-options.ts
index 785fbdbcb1..b5688bff48 100644
--- a/packages/zero-schema/src/build-schema-options.ts
+++ b/packages/zero-schema/src/build-schema-options.ts
@@ -1,4 +1,4 @@
-import * as v from '../../shared/src/valita.js';
+import * as v from '../../shared/src/valita.ts';
 
 export const ZERO_BUILD_SCHEMA_ENV_VAR_PREFIX = 'ZERO_';
 
diff --git a/packages/zero-schema/src/build-schema.ts b/packages/zero-schema/src/build-schema.ts
index 495c7964cf..ecc11178f6 100644
--- a/packages/zero-schema/src/build-schema.ts
+++ b/packages/zero-schema/src/build-schema.ts
@@ -1,13 +1,13 @@
+import {writeFile} from 'node:fs/promises';
 import path from 'node:path';
 import {fileURLToPath} from 'node:url';
 import {tsImport} from 'tsx/esm/api';
-import {writeFile} from 'node:fs/promises';
-import {parseOptions} from '../../shared/src/options.js';
-import {stringifySchema} from './schema-config.js';
+import {parseOptions} from '../../shared/src/options.ts';
 import {
   buildSchemaOptions,
   ZERO_BUILD_SCHEMA_ENV_VAR_PREFIX,
-} from './build-schema-options.js';
+} from './build-schema-options.ts';
+import {stringifySchema} from './schema-config.ts';
 
 async function main() {
   const config = parseOptions(
@@ -25,7 +25,7 @@ async function main() {
 
   // tsImport doesn't expect to receive slashes in the Windows format when running
   // on Windows. They need to be converted to *nix format.
-  relativePath = relativePath.replace(/\\/g, "/");
+  relativePath = relativePath.replace(/\\/g, '/');
 
   try {
     const module = await tsImport(relativePath, import.meta.url);
diff --git a/packages/zero-schema/src/builder/relationship-builder.ts b/packages/zero-schema/src/builder/relationship-builder.ts
index 155620def9..08f75e2f4d 100644
--- a/packages/zero-schema/src/builder/relationship-builder.ts
+++ b/packages/zero-schema/src/builder/relationship-builder.ts
@@ -1,6 +1,6 @@
 /* eslint-disable @typescript-eslint/no-explicit-any */
-import type {Relationship, TableSchema} from '../table-schema.js';
-import type {TableBuilderWithColumns} from './table-builder.js';
+import type {Relationship, TableSchema} from '../table-schema.ts';
+import type {TableBuilderWithColumns} from './table-builder.ts';
 
 type ConnectArg<TSourceField, TDestField, TDest extends TableSchema> = {
   readonly sourceField: TSourceField;
diff --git a/packages/zero-schema/src/builder/schema-builder.test.ts b/packages/zero-schema/src/builder/schema-builder.test.ts
index 0fa9d628ed..036bbea68a 100644
--- a/packages/zero-schema/src/builder/schema-builder.test.ts
+++ b/packages/zero-schema/src/builder/schema-builder.test.ts
@@ -1,8 +1,8 @@
 import {expectTypeOf, test} from 'vitest';
-import type {Query} from '../../../zql/src/query/query.js';
-import {relationships} from './relationship-builder.js';
-import {createSchema} from './schema-builder.js';
-import {number, string, table} from './table-builder.js';
+import type {Query} from '../../../zql/src/query/query.ts';
+import {relationships} from './relationship-builder.ts';
+import {createSchema} from './schema-builder.ts';
+import {number, string, table} from './table-builder.ts';
 
 const mockQuery = {
   select() {
diff --git a/packages/zero-schema/src/builder/schema-builder.ts b/packages/zero-schema/src/builder/schema-builder.ts
index 3939c85603..2a21802006 100644
--- a/packages/zero-schema/src/builder/schema-builder.ts
+++ b/packages/zero-schema/src/builder/schema-builder.ts
@@ -3,9 +3,9 @@ import type {
   Relationship,
   RelationshipsSchema,
   TableSchema,
-} from '../table-schema.js';
-import type {Relationships} from './relationship-builder.js';
-import {type TableBuilderWithColumns} from './table-builder.js';
+} from '../table-schema.ts';
+import type {Relationships} from './relationship-builder.ts';
+import {type TableBuilderWithColumns} from './table-builder.ts';
 
 export type Schema = {
   readonly version: number;
diff --git a/packages/zero-schema/src/builder/table-builder.ts b/packages/zero-schema/src/builder/table-builder.ts
index 780ddd189b..9d9d6b5d44 100644
--- a/packages/zero-schema/src/builder/table-builder.ts
+++ b/packages/zero-schema/src/builder/table-builder.ts
@@ -1,6 +1,6 @@
-import type {ReadonlyJSONValue} from '../../../shared/src/json.js';
-import type {PrimaryKey} from '../../../zero-protocol/src/primary-key.js';
-import type {SchemaValue, TableSchema} from '../table-schema.js';
+import type {ReadonlyJSONValue} from '../../../shared/src/json.ts';
+import type {PrimaryKey} from '../../../zero-protocol/src/primary-key.ts';
+import type {SchemaValue, TableSchema} from '../table-schema.ts';
 
 /* eslint-disable @typescript-eslint/no-explicit-any */
 export function table<TName extends string>(name: TName) {
diff --git a/packages/zero-schema/src/compiled-permissions.ts b/packages/zero-schema/src/compiled-permissions.ts
index e4eca57b45..9ef747b26f 100644
--- a/packages/zero-schema/src/compiled-permissions.ts
+++ b/packages/zero-schema/src/compiled-permissions.ts
@@ -1,5 +1,5 @@
-import * as v from '../../shared/src/valita.js';
-import {conditionSchema} from '../../zero-protocol/src/ast.js';
+import * as v from '../../shared/src/valita.ts';
+import {conditionSchema} from '../../zero-protocol/src/ast.ts';
 
 const ruleSchema = v.tuple([v.literal('allow'), conditionSchema]);
 export type Rule = v.Infer<typeof ruleSchema>;
diff --git a/packages/zero-schema/src/mod.ts b/packages/zero-schema/src/mod.ts
index d1d1891157..dc6391599c 100644
--- a/packages/zero-schema/src/mod.ts
+++ b/packages/zero-schema/src/mod.ts
@@ -1,4 +1,4 @@
-export {authQuery} from '../../zql/src/query/auth-query.js';
-export {type TableSchema} from './table-schema.js';
-export {createSchema, type Schema} from './builder/schema-builder.js';
-export {definePermissions} from './permissions.js';
+export {authQuery} from '../../zql/src/query/auth-query.ts';
+export {createSchema, type Schema} from './builder/schema-builder.ts';
+export {definePermissions} from './permissions.ts';
+export {type TableSchema} from './table-schema.ts';
diff --git a/packages/zero-schema/src/permissions.test.ts b/packages/zero-schema/src/permissions.test.ts
index 118540f594..cb9a175633 100644
--- a/packages/zero-schema/src/permissions.test.ts
+++ b/packages/zero-schema/src/permissions.test.ts
@@ -1,9 +1,9 @@
 import {expect, test} from 'vitest';
-import {createSchema} from './builder/schema-builder.js';
-import {definePermissions} from './permissions.js';
-import type {ExpressionBuilder} from '../../zql/src/query/expression.js';
-import {table, column} from './builder/table-builder.js';
-import type {Schema as ZeroSchema} from './builder/schema-builder.js';
+import type {ExpressionBuilder} from '../../zql/src/query/expression.ts';
+import type {Schema as ZeroSchema} from './builder/schema-builder.ts';
+import {createSchema} from './builder/schema-builder.ts';
+import {column, table} from './builder/table-builder.ts';
+import {definePermissions} from './permissions.ts';
 
 const {string} = column;
 
diff --git a/packages/zero-schema/src/permissions.ts b/packages/zero-schema/src/permissions.ts
index c02face9f1..09cd0728e6 100644
--- a/packages/zero-schema/src/permissions.ts
+++ b/packages/zero-schema/src/permissions.ts
@@ -1,18 +1,18 @@
-import {assert} from '../../shared/src/asserts.js';
+import {assert} from '../../shared/src/asserts.ts';
 import {
   toStaticParam,
   type Condition,
   type Parameter,
-} from '../../zero-protocol/src/ast.js';
-import {AuthQuery} from '../../zql/src/query/auth-query.js';
-import type {ExpressionBuilder} from '../../zql/src/query/expression.js';
-import {staticParam} from '../../zql/src/query/query-impl.js';
-import type {Query} from '../../zql/src/query/query.js';
+} from '../../zero-protocol/src/ast.ts';
+import {AuthQuery} from '../../zql/src/query/auth-query.ts';
+import type {ExpressionBuilder} from '../../zql/src/query/expression.ts';
+import {staticParam} from '../../zql/src/query/query-impl.ts';
+import type {Query} from '../../zql/src/query/query.ts';
 import type {
   AssetPermissions as CompiledAssetPermissions,
   PermissionsConfig as CompiledPermissionsConfig,
-} from './compiled-permissions.js';
-import type {Schema} from './mod.js';
+} from './compiled-permissions.ts';
+import type {Schema} from './mod.ts';
 
 export const ANYONE_CAN = undefined;
 export const NOBODY_CAN = [];
diff --git a/packages/zero-schema/src/schema-config.test.ts b/packages/zero-schema/src/schema-config.test.ts
index f9b1d7894e..a430117456 100644
--- a/packages/zero-schema/src/schema-config.test.ts
+++ b/packages/zero-schema/src/schema-config.test.ts
@@ -1,9 +1,9 @@
 import {expect, test} from 'vitest';
-import {createSchema} from './builder/schema-builder.js';
-import {parseSchema, stringifySchema} from './schema-config.js';
-import {definePermissions} from './permissions.js';
-import {string, table} from './builder/table-builder.js';
-import {relationships} from './builder/relationship-builder.js';
+import {relationships} from './builder/relationship-builder.ts';
+import {createSchema} from './builder/schema-builder.ts';
+import {string, table} from './builder/table-builder.ts';
+import {definePermissions} from './permissions.ts';
+import {parseSchema, stringifySchema} from './schema-config.ts';
 
 test('round trip', async () => {
   const circular = table('circular')
diff --git a/packages/zero-schema/src/schema-config.ts b/packages/zero-schema/src/schema-config.ts
index 7dccbe5802..912eb01eeb 100644
--- a/packages/zero-schema/src/schema-config.ts
+++ b/packages/zero-schema/src/schema-config.ts
@@ -1,12 +1,12 @@
-import * as v from '../../shared/src/valita.js';
-import {compoundKeySchema} from '../../zero-protocol/src/ast.js';
-import {primaryKeySchema} from '../../zero-protocol/src/primary-key.js';
+import * as v from '../../shared/src/valita.ts';
+import {compoundKeySchema} from '../../zero-protocol/src/ast.ts';
+import {primaryKeySchema} from '../../zero-protocol/src/primary-key.ts';
+import type {Schema} from './builder/schema-builder.ts';
 import {
   permissionsConfigSchema,
   type PermissionsConfig,
-} from './compiled-permissions.js';
-import type {Schema} from './builder/schema-builder.js';
-import type {Relationship, TableSchema, ValueType} from './table-schema.js';
+} from './compiled-permissions.ts';
+import type {Relationship, TableSchema, ValueType} from './table-schema.ts';
 
 export type SchemaConfig = {
   schema: Schema;
diff --git a/packages/zero-schema/src/schema-type-test.ts b/packages/zero-schema/src/schema-type-test.ts
index d607ea964f..9c27a30994 100644
--- a/packages/zero-schema/src/schema-type-test.ts
+++ b/packages/zero-schema/src/schema-type-test.ts
@@ -1,11 +1,11 @@
-import type * as v from '../../shared/src/valita.js';
+import type * as v from '../../shared/src/valita.ts';
+import type {Schema} from './builder/schema-builder.ts';
 import type {
   relationshipSchema,
   schemaSchema,
   schemaValueSchema,
-} from './schema-config.js';
-import type {Schema} from './builder/schema-builder.js';
-import type {Relationship, SchemaValue} from './table-schema.js';
+} from './schema-config.ts';
+import type {Relationship, SchemaValue} from './table-schema.ts';
 
 type MakeAllFieldsRequired<T> = {
   [K in keyof T]-?: MakeAllFieldsRequired<T[K]>;
diff --git a/packages/zero-schema/src/schema.test.ts b/packages/zero-schema/src/schema.test.ts
index bb9cdb89cd..8ac469eaf3 100644
--- a/packages/zero-schema/src/schema.test.ts
+++ b/packages/zero-schema/src/schema.test.ts
@@ -1,7 +1,7 @@
 import {expect, expectTypeOf, test} from 'vitest';
-import {createSchema} from './mod.js';
-import {number, string, table} from './builder/table-builder.js';
-import {relationships} from './builder/relationship-builder.js';
+import {relationships} from './builder/relationship-builder.ts';
+import {number, string, table} from './builder/table-builder.ts';
+import {createSchema} from './mod.ts';
 
 test('Key name does not matter', () => {
   const schema = createSchema(1, {
diff --git a/packages/zero-schema/src/table-schema.test.ts b/packages/zero-schema/src/table-schema.test.ts
index 2a39d4839b..8e09ec9823 100644
--- a/packages/zero-schema/src/table-schema.test.ts
+++ b/packages/zero-schema/src/table-schema.test.ts
@@ -1,10 +1,10 @@
 /* eslint-disable @typescript-eslint/no-explicit-any */
 /* eslint-disable @typescript-eslint/ban-types */
 import {expectTypeOf, test} from 'vitest';
-import type {Relationship, TableSchema} from './table-schema.js';
-import {number, string, table} from './builder/table-builder.js';
-import {relationships} from './builder/relationship-builder.js';
-import {createSchema} from './mod.js';
+import {relationships} from './builder/relationship-builder.ts';
+import {number, string, table} from './builder/table-builder.ts';
+import {createSchema} from './mod.ts';
+import type {Relationship, TableSchema} from './table-schema.ts';
 
 test('relationship schema types', () => {
   const issueLabel = table('issueLabel')
diff --git a/packages/zero-schema/src/table-schema.ts b/packages/zero-schema/src/table-schema.ts
index d7503a3956..413e38b897 100644
--- a/packages/zero-schema/src/table-schema.ts
+++ b/packages/zero-schema/src/table-schema.ts
@@ -1,4 +1,4 @@
-import type {PrimaryKey} from '../../zero-protocol/src/primary-key.js';
+import type {PrimaryKey} from '../../zero-protocol/src/primary-key.ts';
 
 export type ValueType = 'string' | 'number' | 'boolean' | 'null' | 'json';
 
diff --git a/packages/zero-solid/src/create-zero.ts b/packages/zero-solid/src/create-zero.ts
index 531890cf59..dbdd6275ef 100644
--- a/packages/zero-solid/src/create-zero.ts
+++ b/packages/zero-solid/src/create-zero.ts
@@ -1,7 +1,7 @@
 import {batch} from 'solid-js';
-import {Zero, type ZeroOptions} from '../../zero-client/src/mod.js';
-import type {ZeroAdvancedOptions} from '../../zero-advanced/src/mod.js';
-import type {Schema} from '../../zero-schema/src/mod.js';
+import type {ZeroAdvancedOptions} from '../../zero-advanced/src/mod.ts';
+import {Zero, type ZeroOptions} from '../../zero-client/src/mod.ts';
+import type {Schema} from '../../zero-schema/src/mod.ts';
 
 export function createZero<S extends Schema>(options: ZeroOptions<S>): Zero<S> {
   const opts: ZeroAdvancedOptions<S> = {
diff --git a/packages/zero-solid/src/mod.ts b/packages/zero-solid/src/mod.ts
index bc494b3d20..1466d19193 100644
--- a/packages/zero-solid/src/mod.ts
+++ b/packages/zero-solid/src/mod.ts
@@ -1,2 +1,2 @@
-export {createZero} from './create-zero.js';
-export {useQuery} from './use-query.js';
+export {createZero} from './create-zero.ts';
+export {useQuery} from './use-query.ts';
diff --git a/packages/zero-solid/src/solid-view.test.ts b/packages/zero-solid/src/solid-view.test.ts
index f1ce4409dd..35e48f3b95 100644
--- a/packages/zero-solid/src/solid-view.test.ts
+++ b/packages/zero-solid/src/solid-view.test.ts
@@ -1,10 +1,10 @@
 import {resolver} from '@rocicorp/resolver';
 import {expect, test, vi} from 'vitest';
-import {number, string, table} from '../../zero-client/src/mod.js';
-import {createSchema} from '../../zero-schema/src/mod.js';
-import {MemorySource} from '../../zql/src/ivm/memory-source.js';
-import type {HumanReadable, Query} from '../../zql/src/query/query.js';
-import {SolidView, solidViewFactory} from './solid-view.js';
+import {number, string, table} from '../../zero-client/src/mod.ts';
+import {createSchema} from '../../zero-schema/src/mod.ts';
+import {MemorySource} from '../../zql/src/ivm/memory-source.ts';
+import type {HumanReadable, Query} from '../../zql/src/query/query.ts';
+import {SolidView, solidViewFactory} from './solid-view.ts';
 
 test('basics', () => {
   const ms = new MemorySource(
diff --git a/packages/zero-solid/src/solid-view.ts b/packages/zero-solid/src/solid-view.ts
index e156b1f9f2..5fa26a0ff7 100644
--- a/packages/zero-solid/src/solid-view.ts
+++ b/packages/zero-solid/src/solid-view.ts
@@ -14,9 +14,9 @@ import {
   type Output,
   type Query,
   type ViewFactory,
-} from '../../zero-advanced/src/mod.js';
-import type {Schema} from '../../zero-schema/src/mod.js';
-import type {ResultType} from '../../zql/src/query/typed-view.js';
+} from '../../zero-advanced/src/mod.ts';
+import type {Schema} from '../../zero-schema/src/mod.ts';
+import type {ResultType} from '../../zql/src/query/typed-view.ts';
 
 export type QueryResultDetails = {
   readonly type: ResultType;
diff --git a/packages/zero-solid/src/use-query.test.ts b/packages/zero-solid/src/use-query.test.ts
index 627760dcd1..b81431bdb7 100644
--- a/packages/zero-solid/src/use-query.test.ts
+++ b/packages/zero-solid/src/use-query.test.ts
@@ -1,13 +1,13 @@
 import {testEffect} from '@solidjs/testing-library';
 import {createEffect, createSignal} from 'solid-js';
 import {expect, test} from 'vitest';
-import {must} from '../../shared/src/must.js';
-import {number, string, table} from '../../zero-client/src/mod.js';
-import {createSchema} from '../../zero-schema/src/mod.js';
-import {MemorySource} from '../../zql/src/ivm/memory-source.js';
-import {newQuery} from '../../zql/src/query/query-impl.js';
-import {QueryDelegateImpl} from '../../zql/src/query/test/query-delegate.js';
-import {useQuery} from './use-query.js';
+import {must} from '../../shared/src/must.ts';
+import {number, string, table} from '../../zero-client/src/mod.ts';
+import {createSchema} from '../../zero-schema/src/mod.ts';
+import {MemorySource} from '../../zql/src/ivm/memory-source.ts';
+import {newQuery} from '../../zql/src/query/query-impl.ts';
+import {QueryDelegateImpl} from '../../zql/src/query/test/query-delegate.ts';
+import {useQuery} from './use-query.ts';
 
 function setupTestEnvironment() {
   const schema = createSchema(1, {
diff --git a/packages/zero-solid/src/use-query.ts b/packages/zero-solid/src/use-query.ts
index 495d1fa370..3fc1a28177 100644
--- a/packages/zero-solid/src/use-query.ts
+++ b/packages/zero-solid/src/use-query.ts
@@ -3,9 +3,9 @@ import type {
   AdvancedQuery,
   HumanReadable,
   Query,
-} from '../../zero-advanced/src/mod.js';
-import {solidViewFactory, type QueryResultDetails} from './solid-view.js';
-import type {Schema} from '../../zero-schema/src/mod.js';
+} from '../../zero-advanced/src/mod.ts';
+import type {Schema} from '../../zero-schema/src/mod.ts';
+import {solidViewFactory, type QueryResultDetails} from './solid-view.ts';
 
 export type QueryResult<TReturn> = readonly [
   Accessor<HumanReadable<TReturn>>,
diff --git a/packages/zero-solid/vitest.config.ts b/packages/zero-solid/vitest.config.ts
index 960efc6d6b..12508b30d0 100644
--- a/packages/zero-solid/vitest.config.ts
+++ b/packages/zero-solid/vitest.config.ts
@@ -1 +1 @@
-export {default} from '../shared/src/tool/vitest-config.js';
+export {default} from '../shared/src/tool/vitest-config.ts';
diff --git a/packages/zero/src/advanced.ts b/packages/zero/src/advanced.ts
index 7e1f36a439..3a492e63bf 100644
--- a/packages/zero/src/advanced.ts
+++ b/packages/zero/src/advanced.ts
@@ -1 +1 @@
-export * from '../../zero-advanced/src/mod.js';
+export * from '../../zero-advanced/src/mod.ts';
diff --git a/packages/zero/src/build-schema.ts b/packages/zero/src/build-schema.ts
index 2a42a4a6f5..3c1ef046fe 100644
--- a/packages/zero/src/build-schema.ts
+++ b/packages/zero/src/build-schema.ts
@@ -1,2 +1,2 @@
 #!/usr/bin/env node
-import '../../zero-schema/src/build-schema.js';
+import '../../zero-schema/src/build-schema.ts';
diff --git a/packages/zero/src/change-protocol.ts b/packages/zero/src/change-protocol.ts
index 9915fa2f35..a088caa81c 100644
--- a/packages/zero/src/change-protocol.ts
+++ b/packages/zero/src/change-protocol.ts
@@ -1 +1 @@
-export * from '../../zero-cache/src/services/change-source/protocol/mod.js';
+export * from '../../zero-cache/src/services/change-source/protocol/mod.ts';
diff --git a/packages/zero/src/cli.ts b/packages/zero/src/cli.ts
index e42bc41239..ae4397edf9 100755
--- a/packages/zero/src/cli.ts
+++ b/packages/zero/src/cli.ts
@@ -1,3 +1,3 @@
 #!/usr/bin/env node
 
-import './server/multi/main.js';
+import './server/multi/main.ts';
diff --git a/packages/zero/src/react.ts b/packages/zero/src/react.ts
index d979b9968a..c35575f846 100644
--- a/packages/zero/src/react.ts
+++ b/packages/zero/src/react.ts
@@ -1 +1 @@
-export * from '../../zero-react/src/mod.js';
+export * from '../../zero-react/src/mod.ts';
diff --git a/packages/zero/src/server/change-streamer.ts b/packages/zero/src/server/change-streamer.ts
index 986e103251..e8d0c92d24 100644
--- a/packages/zero/src/server/change-streamer.ts
+++ b/packages/zero/src/server/change-streamer.ts
@@ -1 +1 @@
-import '../../../zero-cache/src/server/change-streamer.js';
+import '../../../zero-cache/src/server/change-streamer.ts';
diff --git a/packages/zero/src/server/main.ts b/packages/zero/src/server/main.ts
index 1e4620ba1d..ee1db1f038 100644
--- a/packages/zero/src/server/main.ts
+++ b/packages/zero/src/server/main.ts
@@ -1 +1 @@
-import '../../../zero-cache/src/server/main.js';
+import '../../../zero-cache/src/server/main.ts';
diff --git a/packages/zero/src/server/multi/main.ts b/packages/zero/src/server/multi/main.ts
index 7f9990ff55..71dba4836d 100644
--- a/packages/zero/src/server/multi/main.ts
+++ b/packages/zero/src/server/multi/main.ts
@@ -1 +1 @@
-import '../../../../zero-cache/src/server/multi/main.js';
+import '../../../../zero-cache/src/server/multi/main.ts';
diff --git a/packages/zero/src/server/replicator.ts b/packages/zero/src/server/replicator.ts
index 04547bbf5b..00df30080e 100644
--- a/packages/zero/src/server/replicator.ts
+++ b/packages/zero/src/server/replicator.ts
@@ -1 +1 @@
-import '../../../zero-cache/src/server/replicator.js';
+import '../../../zero-cache/src/server/replicator.ts';
diff --git a/packages/zero/src/server/syncer.ts b/packages/zero/src/server/syncer.ts
index 8379310903..34f4704e66 100644
--- a/packages/zero/src/server/syncer.ts
+++ b/packages/zero/src/server/syncer.ts
@@ -1 +1 @@
-import '../../../zero-cache/src/server/syncer.js';
+import '../../../zero-cache/src/server/syncer.ts';
diff --git a/packages/zero/src/solid.ts b/packages/zero/src/solid.ts
index a187daae62..a636606d14 100644
--- a/packages/zero/src/solid.ts
+++ b/packages/zero/src/solid.ts
@@ -1 +1 @@
-export * from '../../zero-solid/src/mod.js';
+export * from '../../zero-solid/src/mod.ts';
diff --git a/packages/zero/src/zero-cache-dev.test.ts b/packages/zero/src/zero-cache-dev.test.ts
index 0e603fe340..f222a7dd90 100644
--- a/packages/zero/src/zero-cache-dev.test.ts
+++ b/packages/zero/src/zero-cache-dev.test.ts
@@ -1,13 +1,13 @@
 import {expect, test} from 'vitest';
-import {
-  buildSchemaOptions,
-  ZERO_BUILD_SCHEMA_ENV_VAR_PREFIX,
-} from '../../zero-schema/src/build-schema-options.js';
+import type {Group} from '../../shared/src/options.ts';
 import {
   ZERO_ENV_VAR_PREFIX,
   zeroOptions,
-} from '../../zero-cache/src/config/zero-config.js';
-import type {Group} from '../../shared/src/options.js';
+} from '../../zero-cache/src/config/zero-config.ts';
+import {
+  buildSchemaOptions,
+  ZERO_BUILD_SCHEMA_ENV_VAR_PREFIX,
+} from '../../zero-schema/src/build-schema-options.ts';
 test('zeroOptions and buildSchemaOptions are compatible', () => {
   expect(ZERO_BUILD_SCHEMA_ENV_VAR_PREFIX).toEqual(ZERO_ENV_VAR_PREFIX);
 
diff --git a/packages/zero/src/zero-cache-dev.ts b/packages/zero/src/zero-cache-dev.ts
index 05986694fe..5a4c79cf0b 100644
--- a/packages/zero/src/zero-cache-dev.ts
+++ b/packages/zero/src/zero-cache-dev.ts
@@ -6,12 +6,12 @@ import chalk from 'chalk';
 import {watch} from 'chokidar';
 import 'dotenv/config';
 import {spawn, type ChildProcess} from 'node:child_process';
-import {parseOptionsAdvanced} from '../../shared/src/options.js';
+import {parseOptionsAdvanced} from '../../shared/src/options.ts';
 import {
   ZERO_ENV_VAR_PREFIX,
   zeroOptions,
-} from '../../zero-cache/src/config/zero-config.js';
-import {buildSchemaOptions} from '../../zero-schema/src/build-schema-options.js';
+} from '../../zero-cache/src/config/zero-config.ts';
+import {buildSchemaOptions} from '../../zero-schema/src/build-schema-options.ts';
 
 const buildSchemaScript = 'zero-build-schema';
 const zeroCacheScript = 'zero-cache';
diff --git a/packages/zero/src/zero.ts b/packages/zero/src/zero.ts
index c88724b5ba..346a273d29 100644
--- a/packages/zero/src/zero.ts
+++ b/packages/zero/src/zero.ts
@@ -1 +1 @@
-export * from '../../zero-client/src/mod.js';
+export * from '../../zero-client/src/mod.ts';
diff --git a/packages/zql/src/builder/builder.test.ts b/packages/zql/src/builder/builder.test.ts
index ff383b05d5..c50ccd393c 100644
--- a/packages/zql/src/builder/builder.test.ts
+++ b/packages/zql/src/builder/builder.test.ts
@@ -1,14 +1,14 @@
 import {expect, test} from 'vitest';
-import type {AST, Disjunction} from '../../../zero-protocol/src/ast.js';
-import {Catch} from '../ivm/catch.js';
-import {MemoryStorage} from '../ivm/memory-storage.js';
-import type {Source} from '../ivm/source.js';
-import {createSource} from '../ivm/test/source-factory.js';
+import type {AST, Disjunction} from '../../../zero-protocol/src/ast.ts';
+import {Catch} from '../ivm/catch.ts';
+import {MemoryStorage} from '../ivm/memory-storage.ts';
+import type {Source} from '../ivm/source.ts';
+import {createSource} from '../ivm/test/source-factory.ts';
 import {
   bindStaticParameters,
   buildPipeline,
   groupSubqueryConditions,
-} from './builder.js';
+} from './builder.ts';
 
 export function testSources() {
   const users = createSource(
diff --git a/packages/zql/src/builder/builder.ts b/packages/zql/src/builder/builder.ts
index 82f70f5280..fb3df51f53 100644
--- a/packages/zql/src/builder/builder.ts
+++ b/packages/zql/src/builder/builder.ts
@@ -1,6 +1,6 @@
-import {assert} from '../../../shared/src/asserts.js';
-import type {JSONValue} from '../../../shared/src/json.js';
-import {must} from '../../../shared/src/must.js';
+import {assert} from '../../../shared/src/asserts.ts';
+import type {JSONValue} from '../../../shared/src/json.ts';
+import {must} from '../../../shared/src/must.ts';
 import type {
   AST,
   ColumnReference,
@@ -15,19 +15,19 @@ import type {
   Parameter,
   SimpleCondition,
   ValuePosition,
-} from '../../../zero-protocol/src/ast.js';
-import type {Row} from '../../../zero-protocol/src/data.js';
-import type {PrimaryKey} from '../../../zero-protocol/src/primary-key.js';
-import {Exists} from '../ivm/exists.js';
-import {FanIn} from '../ivm/fan-in.js';
-import {FanOut} from '../ivm/fan-out.js';
-import {Filter} from '../ivm/filter.js';
-import {Join} from '../ivm/join.js';
-import type {Input, Storage} from '../ivm/operator.js';
-import {Skip} from '../ivm/skip.js';
-import type {Source} from '../ivm/source.js';
-import {Take} from '../ivm/take.js';
-import {createPredicate, type NoSubqueryCondition} from './filter.js';
+} from '../../../zero-protocol/src/ast.ts';
+import type {Row} from '../../../zero-protocol/src/data.ts';
+import type {PrimaryKey} from '../../../zero-protocol/src/primary-key.ts';
+import {Exists} from '../ivm/exists.ts';
+import {FanIn} from '../ivm/fan-in.ts';
+import {FanOut} from '../ivm/fan-out.ts';
+import {Filter} from '../ivm/filter.ts';
+import {Join} from '../ivm/join.ts';
+import type {Input, Storage} from '../ivm/operator.ts';
+import {Skip} from '../ivm/skip.ts';
+import type {Source} from '../ivm/source.ts';
+import {Take} from '../ivm/take.ts';
+import {createPredicate, type NoSubqueryCondition} from './filter.ts';
 
 export type StaticQueryParameters = {
   authData: Record<string, JSONValue>;
diff --git a/packages/zql/src/builder/filter.test.ts b/packages/zql/src/builder/filter.test.ts
index e463f545b8..3dd8883e45 100644
--- a/packages/zql/src/builder/filter.test.ts
+++ b/packages/zql/src/builder/filter.test.ts
@@ -3,9 +3,9 @@ import {expect, test} from 'vitest';
 import type {
   SimpleCondition,
   SimpleOperator,
-} from '../../../zero-protocol/src/ast.js';
-import {createPredicate} from './filter.js';
-import {cases} from './like.test.js';
+} from '../../../zero-protocol/src/ast.ts';
+import {createPredicate} from './filter.ts';
+import {cases} from './like.test.ts';
 
 test('basics', () => {
   // nulls and undefined are false in all conditions except IS NULL and IS NOT NULL
diff --git a/packages/zql/src/builder/filter.ts b/packages/zql/src/builder/filter.ts
index dd20d0348c..bcfbbcb14c 100644
--- a/packages/zql/src/builder/filter.ts
+++ b/packages/zql/src/builder/filter.ts
@@ -1,11 +1,11 @@
-import {assert, unreachable} from '../../../shared/src/asserts.js';
+import {assert, unreachable} from '../../../shared/src/asserts.ts';
 import type {
   Condition,
   SimpleCondition,
   SimpleOperator,
-} from '../../../zero-protocol/src/ast.js';
-import type {Row, Value} from '../../../zero-protocol/src/data.js';
-import {getLikePredicate} from './like.js';
+} from '../../../zero-protocol/src/ast.ts';
+import type {Row, Value} from '../../../zero-protocol/src/data.ts';
+import {getLikePredicate} from './like.ts';
 
 export type NonNullValue = Exclude<Value, null | undefined>;
 export type SimplePredicate = (rhs: Value) => boolean;
diff --git a/packages/zql/src/builder/like.test.ts b/packages/zql/src/builder/like.test.ts
index acb23301f7..5265adef63 100644
--- a/packages/zql/src/builder/like.test.ts
+++ b/packages/zql/src/builder/like.test.ts
@@ -1,5 +1,5 @@
 import {expect, test} from 'vitest';
-import {getLikePredicate} from './like.js';
+import {getLikePredicate} from './like.ts';
 
 export const cases: {
   pattern: string;
diff --git a/packages/zql/src/builder/like.ts b/packages/zql/src/builder/like.ts
index 1d9008408b..4ee5d4ce57 100644
--- a/packages/zql/src/builder/like.ts
+++ b/packages/zql/src/builder/like.ts
@@ -1,5 +1,5 @@
-import {assertString} from '../../../shared/src/asserts.js';
-import type {NonNullValue, SimplePredicateNoNull} from './filter.js';
+import {assertString} from '../../../shared/src/asserts.ts';
+import type {NonNullValue, SimplePredicateNoNull} from './filter.ts';
 
 export function getLikePredicate(
   pattern: NonNullValue,
diff --git a/packages/zql/src/ivm/array-view.test.ts b/packages/zql/src/ivm/array-view.test.ts
index 0e7bf95636..8e426cf972 100644
--- a/packages/zql/src/ivm/array-view.test.ts
+++ b/packages/zql/src/ivm/array-view.test.ts
@@ -1,15 +1,15 @@
 import {expect, test} from 'vitest';
-import {assertArray, unreachable} from '../../../shared/src/asserts.js';
-import type {ReadonlyJSONValue} from '../../../shared/src/json.js';
-import {stringCompare} from '../../../shared/src/string-compare.js';
-import {ArrayView} from './array-view.js';
-import type {Change} from './change.js';
-import {Join} from './join.js';
-import {MemoryStorage} from './memory-storage.js';
-import type {Input} from './operator.js';
-import type {SourceSchema} from './schema.js';
-import {Take} from './take.js';
-import {createSource} from './test/source-factory.js';
+import {assertArray, unreachable} from '../../../shared/src/asserts.ts';
+import type {ReadonlyJSONValue} from '../../../shared/src/json.ts';
+import {stringCompare} from '../../../shared/src/string-compare.ts';
+import {ArrayView} from './array-view.ts';
+import type {Change} from './change.ts';
+import {Join} from './join.ts';
+import {MemoryStorage} from './memory-storage.ts';
+import type {Input} from './operator.ts';
+import type {SourceSchema} from './schema.ts';
+import {Take} from './take.ts';
+import {createSource} from './test/source-factory.ts';
 
 test('basics', () => {
   const ms = createSource('table', {a: {type: 'number'}, b: {type: 'string'}}, [
diff --git a/packages/zql/src/ivm/array-view.ts b/packages/zql/src/ivm/array-view.ts
index 8f9163a39d..a6da0c5775 100644
--- a/packages/zql/src/ivm/array-view.ts
+++ b/packages/zql/src/ivm/array-view.ts
@@ -1,11 +1,11 @@
-import {assert} from '../../../shared/src/asserts.js';
-import type {Immutable} from '../../../shared/src/immutable.js';
-import type {Listener, TypedView} from '../query/typed-view.js';
-import type {Change} from './change.js';
-import type {Input, Output} from './operator.js';
-import type {SourceSchema} from './schema.js';
-import {applyChange} from './view-apply-change.js';
-import type {Entry, Format, View} from './view.js';
+import {assert} from '../../../shared/src/asserts.ts';
+import type {Immutable} from '../../../shared/src/immutable.ts';
+import type {Listener, TypedView} from '../query/typed-view.ts';
+import type {Change} from './change.ts';
+import type {Input, Output} from './operator.ts';
+import type {SourceSchema} from './schema.ts';
+import {applyChange} from './view-apply-change.ts';
+import type {Entry, Format, View} from './view.ts';
 
 /**
  * Implements a materialized view of the output of an operator.
diff --git a/packages/zql/src/ivm/catch.ts b/packages/zql/src/ivm/catch.ts
index bde6a2b6b3..c8b7424199 100644
--- a/packages/zql/src/ivm/catch.ts
+++ b/packages/zql/src/ivm/catch.ts
@@ -1,8 +1,8 @@
-import {unreachable} from '../../../shared/src/asserts.js';
-import type {Row} from '../../../zero-protocol/src/data.js';
-import type {AddChange, Change, RemoveChange} from './change.js';
-import type {Node} from './data.js';
-import type {FetchRequest, Input, Output} from './operator.js';
+import {unreachable} from '../../../shared/src/asserts.ts';
+import type {Row} from '../../../zero-protocol/src/data.ts';
+import type {AddChange, Change, RemoveChange} from './change.ts';
+import type {Node} from './data.ts';
+import type {FetchRequest, Input, Output} from './operator.ts';
 
 export type CaughtChildChange = {
   type: 'child';
diff --git a/packages/zql/src/ivm/change.ts b/packages/zql/src/ivm/change.ts
index 4e75b02792..8f450cbc5f 100644
--- a/packages/zql/src/ivm/change.ts
+++ b/packages/zql/src/ivm/change.ts
@@ -1,5 +1,5 @@
-import type {Row} from '../../../zero-protocol/src/data.js';
-import type {Node} from './data.js';
+import type {Row} from '../../../zero-protocol/src/data.ts';
+import type {Node} from './data.ts';
 
 export type Change = AddChange | RemoveChange | ChildChange | EditChange;
 export type ChangeType = Change['type'];
diff --git a/packages/zql/src/ivm/constraint.ts b/packages/zql/src/ivm/constraint.ts
index 52bf171df9..0130084a99 100644
--- a/packages/zql/src/ivm/constraint.ts
+++ b/packages/zql/src/ivm/constraint.ts
@@ -1,8 +1,8 @@
-import {assert} from '../../../shared/src/asserts.js';
-import {stringCompare} from '../../../shared/src/string-compare.js';
-import type {Row, Value} from '../../../zero-protocol/src/data.js';
-import type {PrimaryKey} from '../../../zero-protocol/src/primary-key.js';
-import {valuesEqual} from './data.js';
+import {assert} from '../../../shared/src/asserts.ts';
+import {stringCompare} from '../../../shared/src/string-compare.ts';
+import type {Row, Value} from '../../../zero-protocol/src/data.ts';
+import type {PrimaryKey} from '../../../zero-protocol/src/primary-key.ts';
+import {valuesEqual} from './data.ts';
 
 export type Constraint = {
   readonly [key: string]: Value;
diff --git a/packages/zql/src/ivm/data.test.ts b/packages/zql/src/ivm/data.test.ts
index 1a0a6f438b..638655bc85 100644
--- a/packages/zql/src/ivm/data.test.ts
+++ b/packages/zql/src/ivm/data.test.ts
@@ -1,14 +1,14 @@
 import {compareUTF8} from 'compare-utf8';
 import fc from 'fast-check';
 import {expect, test} from 'vitest';
-import type {Ordering} from '../../../zero-protocol/src/ast.js';
-import type {Row} from '../../../zero-protocol/src/data.js';
+import type {Ordering} from '../../../zero-protocol/src/ast.ts';
+import type {Row} from '../../../zero-protocol/src/data.ts';
 import {
   compareValues,
   makeComparator,
   normalizeUndefined,
   valuesEqual,
-} from './data.js';
+} from './data.ts';
 
 test('normalizeUndefined', () => {
   fc.assert(
diff --git a/packages/zql/src/ivm/data.ts b/packages/zql/src/ivm/data.ts
index 66ff7fee68..e1fb0233a4 100644
--- a/packages/zql/src/ivm/data.ts
+++ b/packages/zql/src/ivm/data.ts
@@ -3,10 +3,10 @@ import {
   assertBoolean,
   assertNumber,
   assertString,
-} from '../../../shared/src/asserts.js';
-import type {Ordering} from '../../../zero-protocol/src/ast.js';
-import type {Row, Value} from '../../../zero-protocol/src/data.js';
-import type {Stream} from './stream.js';
+} from '../../../shared/src/asserts.ts';
+import type {Ordering} from '../../../zero-protocol/src/ast.ts';
+import type {Row, Value} from '../../../zero-protocol/src/data.ts';
+import type {Stream} from './stream.ts';
 
 /**
  * A row flowing through the pipeline, plus its relationships.
diff --git a/packages/zql/src/ivm/destroy.test.ts b/packages/zql/src/ivm/destroy.test.ts
index 7d5c86cb56..d9b5b7130b 100644
--- a/packages/zql/src/ivm/destroy.test.ts
+++ b/packages/zql/src/ivm/destroy.test.ts
@@ -1,10 +1,10 @@
 import {expect, test} from 'vitest';
-import {Snitch} from './snitch.js';
-import {Filter} from './filter.js';
-import {FanOut} from './fan-out.js';
-import {FanIn} from './fan-in.js';
-import {Catch} from './catch.js';
-import {createSource} from './test/source-factory.js';
+import {Catch} from './catch.ts';
+import {FanIn} from './fan-in.ts';
+import {FanOut} from './fan-out.ts';
+import {Filter} from './filter.ts';
+import {Snitch} from './snitch.ts';
+import {createSource} from './test/source-factory.ts';
 
 test('destroy source connections', () => {
   const ms = createSource('table', {a: {type: 'string'}, b: {type: 'string'}}, [
diff --git a/packages/zql/src/ivm/exists.fetch.test.ts b/packages/zql/src/ivm/exists.fetch.test.ts
index 05885a00f5..961ae2e7bc 100644
--- a/packages/zql/src/ivm/exists.fetch.test.ts
+++ b/packages/zql/src/ivm/exists.fetch.test.ts
@@ -1,17 +1,17 @@
 import {expect, suite, test} from 'vitest';
-import {unreachable} from '../../../shared/src/asserts.js';
-import type {JSONValue} from '../../../shared/src/json.js';
-import type {CompoundKey, Ordering} from '../../../zero-protocol/src/ast.js';
-import type {Row} from '../../../zero-protocol/src/data.js';
-import type {PrimaryKey} from '../../../zero-protocol/src/primary-key.js';
-import type {SchemaValue} from '../../../zero-schema/src/table-schema.js';
-import {Catch} from './catch.js';
-import type {Node} from './data.js';
-import {Exists} from './exists.js';
-import {Join} from './join.js';
-import {MemoryStorage} from './memory-storage.js';
-import {Snitch, type SnitchMessage} from './snitch.js';
-import {createSource} from './test/source-factory.js';
+import {unreachable} from '../../../shared/src/asserts.ts';
+import type {JSONValue} from '../../../shared/src/json.ts';
+import type {CompoundKey, Ordering} from '../../../zero-protocol/src/ast.ts';
+import type {Row} from '../../../zero-protocol/src/data.ts';
+import type {PrimaryKey} from '../../../zero-protocol/src/primary-key.ts';
+import type {SchemaValue} from '../../../zero-schema/src/table-schema.ts';
+import {Catch} from './catch.ts';
+import type {Node} from './data.ts';
+import {Exists} from './exists.ts';
+import {Join} from './join.ts';
+import {MemoryStorage} from './memory-storage.ts';
+import {Snitch, type SnitchMessage} from './snitch.ts';
+import {createSource} from './test/source-factory.ts';
 
 const base = {
   columns: [
diff --git a/packages/zql/src/ivm/exists.push.test.ts b/packages/zql/src/ivm/exists.push.test.ts
index b6ad13a6f7..f14adc5593 100644
--- a/packages/zql/src/ivm/exists.push.test.ts
+++ b/packages/zql/src/ivm/exists.push.test.ts
@@ -1,14 +1,14 @@
 import {expect, suite, test} from 'vitest';
-import {Exists} from './exists.js';
-import type {Input, Storage} from './operator.js';
+import {Exists} from './exists.ts';
+import type {Input, Storage} from './operator.ts';
+import {Take} from './take.ts';
 import {
   runJoinTest,
   type Joins,
   type SourceContents,
   type Sources,
-} from './test/join-push-tests.js';
-import type {Format} from './view.js';
-import {Take} from './take.js';
+} from './test/join-push-tests.ts';
+import type {Format} from './view.ts';
 
 const sources: Sources = {
   issue: {
diff --git a/packages/zql/src/ivm/exists.ts b/packages/zql/src/ivm/exists.ts
index 144e725710..fbaaf1b844 100644
--- a/packages/zql/src/ivm/exists.ts
+++ b/packages/zql/src/ivm/exists.ts
@@ -1,10 +1,10 @@
-import {areEqual} from '../../../shared/src/arrays.js';
-import {assert, unreachable} from '../../../shared/src/asserts.js';
-import {must} from '../../../shared/src/must.js';
-import type {CompoundKey} from '../../../zero-protocol/src/ast.js';
-import type {Row} from '../../../zero-protocol/src/data.js';
-import {rowForChange, type Change} from './change.js';
-import {normalizeUndefined, type NormalizedValue} from './data.js';
+import {areEqual} from '../../../shared/src/arrays.ts';
+import {assert, unreachable} from '../../../shared/src/asserts.ts';
+import {must} from '../../../shared/src/must.ts';
+import type {CompoundKey} from '../../../zero-protocol/src/ast.ts';
+import type {Row} from '../../../zero-protocol/src/data.ts';
+import {rowForChange, type Change} from './change.ts';
+import {normalizeUndefined, type NormalizedValue} from './data.ts';
 import {
   throwOutput,
   type FetchRequest,
@@ -12,9 +12,9 @@ import {
   type Operator,
   type Output,
   type Storage,
-} from './operator.js';
-import type {SourceSchema} from './schema.js';
-import {first} from './stream.js';
+} from './operator.ts';
+import type {SourceSchema} from './schema.ts';
+import {first} from './stream.ts';
 
 type SizeStorageKey = `row/${string}/${string}`;
 type CacheStorageKey = `row/${string}`;
diff --git a/packages/zql/src/ivm/fan-in.ts b/packages/zql/src/ivm/fan-in.ts
index 9fe0eff7f6..7d0bc9833a 100644
--- a/packages/zql/src/ivm/fan-in.ts
+++ b/packages/zql/src/ivm/fan-in.ts
@@ -1,18 +1,18 @@
-import {assert} from '../../../shared/src/asserts.js';
-import {mergeIterables} from '../../../shared/src/iterables.js';
-import {must} from '../../../shared/src/must.js';
-import type {Change} from './change.js';
-import type {Node} from './data.js';
-import type {FanOut} from './fan-out.js';
+import {assert} from '../../../shared/src/asserts.ts';
+import {mergeIterables} from '../../../shared/src/iterables.ts';
+import {must} from '../../../shared/src/must.ts';
+import type {Change} from './change.ts';
+import type {Node} from './data.ts';
+import type {FanOut} from './fan-out.ts';
 import {
   throwOutput,
   type FetchRequest,
   type Input,
   type Operator,
   type Output,
-} from './operator.js';
-import type {SourceSchema} from './schema.js';
-import type {Stream} from './stream.js';
+} from './operator.ts';
+import type {SourceSchema} from './schema.ts';
+import type {Stream} from './stream.ts';
 
 /**
  * The FanIn operator merges multiple streams into one.
diff --git a/packages/zql/src/ivm/fan-out-fan-in.test.ts b/packages/zql/src/ivm/fan-out-fan-in.test.ts
index 9052bbd9d4..cab213022d 100644
--- a/packages/zql/src/ivm/fan-out-fan-in.test.ts
+++ b/packages/zql/src/ivm/fan-out-fan-in.test.ts
@@ -1,9 +1,9 @@
 import {expect, test, vi} from 'vitest';
-import {FanOut} from './fan-out.js';
-import {Catch} from './catch.js';
-import {Filter} from './filter.js';
-import {FanIn} from './fan-in.js';
-import {createSource} from './test/source-factory.js';
+import {Catch} from './catch.ts';
+import {FanIn} from './fan-in.ts';
+import {FanOut} from './fan-out.ts';
+import {Filter} from './filter.ts';
+import {createSource} from './test/source-factory.ts';
 
 test('fan-out pushes along all paths', () => {
   const s = createSource('table', {a: {type: 'number'}, b: {type: 'string'}}, [
diff --git a/packages/zql/src/ivm/fan-out.ts b/packages/zql/src/ivm/fan-out.ts
index fb48dd2ad3..ef1152a30c 100644
--- a/packages/zql/src/ivm/fan-out.ts
+++ b/packages/zql/src/ivm/fan-out.ts
@@ -1,5 +1,5 @@
-import type {Change} from './change.js';
-import type {FetchRequest, Input, Operator, Output} from './operator.js';
+import type {Change} from './change.ts';
+import type {FetchRequest, Input, Operator, Output} from './operator.ts';
 
 /**
  * Forks a stream into multiple streams.
diff --git a/packages/zql/src/ivm/filter-push.ts b/packages/zql/src/ivm/filter-push.ts
index 44ff032063..7b6b164b82 100644
--- a/packages/zql/src/ivm/filter-push.ts
+++ b/packages/zql/src/ivm/filter-push.ts
@@ -1,8 +1,8 @@
-import {unreachable} from '../../../shared/src/asserts.js';
-import type {Change} from './change.js';
-import {maybeSplitAndPushEditChange} from './maybe-split-and-push-edit-change.js';
-import type {Output} from './operator.js';
-import type {Row} from '../../../zero-protocol/src/data.js';
+import {unreachable} from '../../../shared/src/asserts.ts';
+import type {Row} from '../../../zero-protocol/src/data.ts';
+import type {Change} from './change.ts';
+import {maybeSplitAndPushEditChange} from './maybe-split-and-push-edit-change.ts';
+import type {Output} from './operator.ts';
 
 export function filterPush(
   change: Change,
diff --git a/packages/zql/src/ivm/filter.test.ts b/packages/zql/src/ivm/filter.test.ts
index 51dbd47c0e..420152883f 100644
--- a/packages/zql/src/ivm/filter.test.ts
+++ b/packages/zql/src/ivm/filter.test.ts
@@ -1,7 +1,7 @@
 import {expect, test} from 'vitest';
-import {Catch} from './catch.js';
-import {Filter} from './filter.js';
-import {createSource} from './test/source-factory.js';
+import {Catch} from './catch.ts';
+import {Filter} from './filter.ts';
+import {createSource} from './test/source-factory.ts';
 
 test('basics', () => {
   const ms = createSource('table', {a: {type: 'number'}, b: {type: 'string'}}, [
diff --git a/packages/zql/src/ivm/filter.ts b/packages/zql/src/ivm/filter.ts
index a5b76af877..755fb38397 100644
--- a/packages/zql/src/ivm/filter.ts
+++ b/packages/zql/src/ivm/filter.ts
@@ -1,16 +1,16 @@
-import type {Row} from '../../../zero-protocol/src/data.js';
-import type {Change} from './change.js';
-import type {Node} from './data.js';
-import {filterPush} from './filter-push.js';
+import type {Row} from '../../../zero-protocol/src/data.ts';
+import type {Change} from './change.ts';
+import type {Node} from './data.ts';
+import {filterPush} from './filter-push.ts';
 import {
   throwOutput,
   type FetchRequest,
   type Input,
   type Operator,
   type Output,
-} from './operator.js';
-import type {SourceSchema} from './schema.js';
-import type {Stream} from './stream.js';
+} from './operator.ts';
+import type {SourceSchema} from './schema.ts';
+import type {Stream} from './stream.ts';
 
 /**
  * The Filter operator filters data through a predicate. It is stateless.
diff --git a/packages/zql/src/ivm/join.fetch.test.ts b/packages/zql/src/ivm/join.fetch.test.ts
index aee96941be..36ba67ce3d 100644
--- a/packages/zql/src/ivm/join.fetch.test.ts
+++ b/packages/zql/src/ivm/join.fetch.test.ts
@@ -1,18 +1,18 @@
 import {expect, suite, test} from 'vitest';
-import {assert} from '../../../shared/src/asserts.js';
-import type {JSONValue} from '../../../shared/src/json.js';
-import type {CompoundKey, Ordering} from '../../../zero-protocol/src/ast.js';
-import type {Row} from '../../../zero-protocol/src/data.js';
-import type {PrimaryKey} from '../../../zero-protocol/src/primary-key.js';
-import type {SchemaValue} from '../../../zero-schema/src/table-schema.js';
-import {Catch} from './catch.js';
-import {SetOfConstraint} from './constraint.js';
-import type {Node} from './data.js';
-import {Join, makeStorageKey, makeStorageKeyPrefix} from './join.js';
-import {MemoryStorage} from './memory-storage.js';
-import type {SourceSchema} from './schema.js';
-import {Snitch, type SnitchMessage} from './snitch.js';
-import {createSource} from './test/source-factory.js';
+import {assert} from '../../../shared/src/asserts.ts';
+import type {JSONValue} from '../../../shared/src/json.ts';
+import type {CompoundKey, Ordering} from '../../../zero-protocol/src/ast.ts';
+import type {Row} from '../../../zero-protocol/src/data.ts';
+import type {PrimaryKey} from '../../../zero-protocol/src/primary-key.ts';
+import type {SchemaValue} from '../../../zero-schema/src/table-schema.ts';
+import {Catch} from './catch.ts';
+import {SetOfConstraint} from './constraint.ts';
+import type {Node} from './data.ts';
+import {Join, makeStorageKey, makeStorageKeyPrefix} from './join.ts';
+import {MemoryStorage} from './memory-storage.ts';
+import type {SourceSchema} from './schema.ts';
+import {Snitch, type SnitchMessage} from './snitch.ts';
+import {createSource} from './test/source-factory.ts';
 
 suite('fetch one:many', () => {
   const base = {
diff --git a/packages/zql/src/ivm/join.push.test.ts b/packages/zql/src/ivm/join.push.test.ts
index c8478a6540..3266805c5d 100644
--- a/packages/zql/src/ivm/join.push.test.ts
+++ b/packages/zql/src/ivm/join.push.test.ts
@@ -4,8 +4,8 @@ import {
   type Joins,
   type SourceContents,
   type Sources,
-} from './test/join-push-tests.js';
-import type {Format} from './view.js';
+} from './test/join-push-tests.ts';
+import type {Format} from './view.ts';
 
 suite('push one:many', () => {
   const sources: Sources = {
diff --git a/packages/zql/src/ivm/join.sibling.test.ts b/packages/zql/src/ivm/join.sibling.test.ts
index ddf2028f65..2fa9455228 100644
--- a/packages/zql/src/ivm/join.sibling.test.ts
+++ b/packages/zql/src/ivm/join.sibling.test.ts
@@ -1,17 +1,17 @@
 import {expect, suite, test} from 'vitest';
-import {assert} from '../../../shared/src/asserts.js';
-import type {JSONValue} from '../../../shared/src/json.js';
-import type {CompoundKey, Ordering} from '../../../zero-protocol/src/ast.js';
-import type {Row} from '../../../zero-protocol/src/data.js';
-import type {PrimaryKey} from '../../../zero-protocol/src/primary-key.js';
-import type {SchemaValue} from '../../../zero-schema/src/table-schema.js';
-import {Catch, type CaughtChange} from './catch.js';
-import {Join} from './join.js';
-import {MemoryStorage} from './memory-storage.js';
-import type {Input} from './operator.js';
-import {Snitch, type SnitchMessage} from './snitch.js';
-import type {SourceChange} from './source.js';
-import {createSource} from './test/source-factory.js';
+import {assert} from '../../../shared/src/asserts.ts';
+import type {JSONValue} from '../../../shared/src/json.ts';
+import type {CompoundKey, Ordering} from '../../../zero-protocol/src/ast.ts';
+import type {Row} from '../../../zero-protocol/src/data.ts';
+import type {PrimaryKey} from '../../../zero-protocol/src/primary-key.ts';
+import type {SchemaValue} from '../../../zero-schema/src/table-schema.ts';
+import {Catch, type CaughtChange} from './catch.ts';
+import {Join} from './join.ts';
+import {MemoryStorage} from './memory-storage.ts';
+import type {Input} from './operator.ts';
+import {Snitch, type SnitchMessage} from './snitch.ts';
+import type {SourceChange} from './source.ts';
+import {createSource} from './test/source-factory.ts';
 
 suite('sibling relationships tests with issues, comments, and owners', () => {
   const base = {
diff --git a/packages/zql/src/ivm/join.ts b/packages/zql/src/ivm/join.ts
index f92107b2c1..49a92d1da8 100644
--- a/packages/zql/src/ivm/join.ts
+++ b/packages/zql/src/ivm/join.ts
@@ -1,18 +1,18 @@
-import {assert, unreachable} from '../../../shared/src/asserts.js';
-import type {CompoundKey, System} from '../../../zero-protocol/src/ast.js';
-import type {Row, Value} from '../../../zero-protocol/src/data.js';
-import type {PrimaryKey} from '../../../zero-protocol/src/primary-key.js';
-import type {Change, ChildChange} from './change.js';
-import {valuesEqual, type Node} from './data.js';
+import {assert, unreachable} from '../../../shared/src/asserts.ts';
+import type {CompoundKey, System} from '../../../zero-protocol/src/ast.ts';
+import type {Row, Value} from '../../../zero-protocol/src/data.ts';
+import type {PrimaryKey} from '../../../zero-protocol/src/primary-key.ts';
+import type {Change, ChildChange} from './change.ts';
+import {valuesEqual, type Node} from './data.ts';
 import {
   throwOutput,
   type FetchRequest,
   type Input,
   type Output,
   type Storage,
-} from './operator.js';
-import type {SourceSchema} from './schema.js';
-import {take, type Stream} from './stream.js';
+} from './operator.ts';
+import type {SourceSchema} from './schema.ts';
+import {take, type Stream} from './stream.ts';
 
 type Args = {
   parent: Input;
diff --git a/packages/zql/src/ivm/maybe-split-and-push-edit-change.ts b/packages/zql/src/ivm/maybe-split-and-push-edit-change.ts
index be7bd43e34..20a93f84b1 100644
--- a/packages/zql/src/ivm/maybe-split-and-push-edit-change.ts
+++ b/packages/zql/src/ivm/maybe-split-and-push-edit-change.ts
@@ -1,6 +1,6 @@
-import type {Row} from '../../../zero-protocol/src/data.js';
-import type {EditChange} from './change.js';
-import type {Output} from './operator.js';
+import type {Row} from '../../../zero-protocol/src/data.ts';
+import type {EditChange} from './change.ts';
+import type {Output} from './operator.ts';
 
 /**
  * This takes an {@linkcode EditChange} and a predicate that determines if a row
diff --git a/packages/zql/src/ivm/memory-source.test.ts b/packages/zql/src/ivm/memory-source.test.ts
index ea44cd1e3b..44b3b16821 100644
--- a/packages/zql/src/ivm/memory-source.test.ts
+++ b/packages/zql/src/ivm/memory-source.test.ts
@@ -1,16 +1,16 @@
 import {describe, expect, test} from 'vitest';
-import type {Ordering} from '../../../zero-protocol/src/ast.js';
-import type {Row} from '../../../zero-protocol/src/data.js';
-import {Catch} from './catch.js';
-import type {Change} from './change.js';
-import {compareRowsTest} from './data.test.js';
+import type {Ordering} from '../../../zero-protocol/src/ast.ts';
+import type {Row} from '../../../zero-protocol/src/data.ts';
+import {Catch} from './catch.ts';
+import type {Change} from './change.ts';
+import {compareRowsTest} from './data.test.ts';
 import {
   generateWithOverlayInner,
   MemorySource,
   overlaysForConstraintForTest,
   overlaysForStartAtForTest,
-} from './memory-source.js';
-import {createSource} from './test/source-factory.js';
+} from './memory-source.ts';
+import {createSource} from './test/source-factory.ts';
 
 test('schema', () => {
   compareRowsTest((order: Ordering) => {
diff --git a/packages/zql/src/ivm/memory-source.ts b/packages/zql/src/ivm/memory-source.ts
index b8d896b38d..6ff5ac84a4 100644
--- a/packages/zql/src/ivm/memory-source.ts
+++ b/packages/zql/src/ivm/memory-source.ts
@@ -1,41 +1,41 @@
-import {assert, unreachable} from '../../../shared/src/asserts.js';
-import {BTreeSet} from '../../../shared/src/btree-set.js';
-import {hasOwn} from '../../../shared/src/has-own.js';
+import {assert, unreachable} from '../../../shared/src/asserts.ts';
+import {BTreeSet} from '../../../shared/src/btree-set.ts';
+import {hasOwn} from '../../../shared/src/has-own.ts';
 import type {
   Condition,
   Ordering,
   OrderPart,
-} from '../../../zero-protocol/src/ast.js';
-import type {Row, Value} from '../../../zero-protocol/src/data.js';
-import type {PrimaryKey} from '../../../zero-protocol/src/primary-key.js';
-import type {SchemaValue} from '../../../zero-schema/src/table-schema.js';
-import {assertOrderingIncludesPK} from '../builder/builder.js';
+} from '../../../zero-protocol/src/ast.ts';
+import type {Row, Value} from '../../../zero-protocol/src/data.ts';
+import type {PrimaryKey} from '../../../zero-protocol/src/primary-key.ts';
+import type {SchemaValue} from '../../../zero-schema/src/table-schema.ts';
+import {assertOrderingIncludesPK} from '../builder/builder.ts';
 import {
   createPredicate,
   transformFilters,
   type NoSubqueryCondition,
-} from '../builder/filter.js';
+} from '../builder/filter.ts';
 import {
   constraintMatchesPrimaryKey,
   constraintMatchesRow,
   type Constraint,
-} from './constraint.js';
+} from './constraint.ts';
 import {
   compareValues,
   makeComparator,
   type Comparator,
   type Node,
-} from './data.js';
-import {filterPush} from './filter-push.js';
+} from './data.ts';
+import {filterPush} from './filter-push.ts';
 import {
   type FetchRequest,
   type Input,
   type Output,
   type Start,
-} from './operator.js';
-import type {SourceSchema} from './schema.js';
-import type {Source, SourceChange, SourceInput} from './source.js';
-import type {Stream} from './stream.js';
+} from './operator.ts';
+import type {SourceSchema} from './schema.ts';
+import type {Source, SourceChange, SourceInput} from './source.ts';
+import type {Stream} from './stream.ts';
 
 export type Overlay = {
   outputIndex: number;
diff --git a/packages/zql/src/ivm/memory-storage.test.ts b/packages/zql/src/ivm/memory-storage.test.ts
index 56776c00ec..7b40701a0c 100644
--- a/packages/zql/src/ivm/memory-storage.test.ts
+++ b/packages/zql/src/ivm/memory-storage.test.ts
@@ -1,5 +1,5 @@
 import {expect, test} from 'vitest';
-import {MemoryStorage} from './memory-storage.js';
+import {MemoryStorage} from './memory-storage.ts';
 
 test('basics', () => {
   const ms = new MemoryStorage();
diff --git a/packages/zql/src/ivm/memory-storage.ts b/packages/zql/src/ivm/memory-storage.ts
index 83c47a0a1d..353ad4ea11 100644
--- a/packages/zql/src/ivm/memory-storage.ts
+++ b/packages/zql/src/ivm/memory-storage.ts
@@ -1,8 +1,8 @@
 import {compareUTF8} from 'compare-utf8';
-import {BTreeSet} from '../../../shared/src/btree-set.js';
-import type {JSONValue} from '../../../shared/src/json.js';
-import type {Storage} from './operator.js';
-import type {Stream} from './stream.js';
+import {BTreeSet} from '../../../shared/src/btree-set.ts';
+import type {JSONValue} from '../../../shared/src/json.ts';
+import type {Storage} from './operator.ts';
+import type {Stream} from './stream.ts';
 
 type Entry = [key: string, value: JSONValue];
 
diff --git a/packages/zql/src/ivm/operator.ts b/packages/zql/src/ivm/operator.ts
index d4d9d569d0..3e23e6b58a 100644
--- a/packages/zql/src/ivm/operator.ts
+++ b/packages/zql/src/ivm/operator.ts
@@ -1,10 +1,10 @@
-import type {JSONValue} from '../../../shared/src/json.js';
-import type {Row} from '../../../zero-protocol/src/data.js';
-import type {Change} from './change.js';
-import type {Constraint} from './constraint.js';
-import {type Node} from './data.js';
-import type {SourceSchema} from './schema.js';
-import type {Stream} from './stream.js';
+import type {JSONValue} from '../../../shared/src/json.ts';
+import type {Row} from '../../../zero-protocol/src/data.ts';
+import type {Change} from './change.ts';
+import type {Constraint} from './constraint.ts';
+import {type Node} from './data.ts';
+import type {SourceSchema} from './schema.ts';
+import type {Stream} from './stream.ts';
 
 /**
  * Input to an operator.
diff --git a/packages/zql/src/ivm/schema.ts b/packages/zql/src/ivm/schema.ts
index f0dff2a694..bde3cb031f 100644
--- a/packages/zql/src/ivm/schema.ts
+++ b/packages/zql/src/ivm/schema.ts
@@ -1,7 +1,7 @@
-import type {Ordering, System} from '../../../zero-protocol/src/ast.js';
-import type {Row} from '../../../zero-protocol/src/data.js';
-import type {PrimaryKey} from '../../../zero-protocol/src/primary-key.js';
-import type {SchemaValue} from '../../../zero-schema/src/table-schema.js';
+import type {Ordering, System} from '../../../zero-protocol/src/ast.ts';
+import type {Row} from '../../../zero-protocol/src/data.ts';
+import type {PrimaryKey} from '../../../zero-protocol/src/primary-key.ts';
+import type {SchemaValue} from '../../../zero-schema/src/table-schema.ts';
 
 /**
  * Information about the nodes output by an operator.
diff --git a/packages/zql/src/ivm/skip.test.ts b/packages/zql/src/ivm/skip.test.ts
index 8171b9881d..dc5213f095 100644
--- a/packages/zql/src/ivm/skip.test.ts
+++ b/packages/zql/src/ivm/skip.test.ts
@@ -1,9 +1,9 @@
 import {expect, suite, test} from 'vitest';
-import {Catch} from './catch.js';
-import {type Bound, Skip} from './skip.js';
-import type {SourceChange} from './source.js';
-import {createSource} from './test/source-factory.js';
-import type {FetchRequest} from './operator.js';
+import {Catch} from './catch.ts';
+import type {FetchRequest} from './operator.ts';
+import {type Bound, Skip} from './skip.ts';
+import type {SourceChange} from './source.ts';
+import {createSource} from './test/source-factory.ts';
 
 suite('fetch', () => {
   function t(c: {skipBound: Bound; fetchRequest: FetchRequest}) {
diff --git a/packages/zql/src/ivm/skip.ts b/packages/zql/src/ivm/skip.ts
index 304efc502d..65f15c4127 100644
--- a/packages/zql/src/ivm/skip.ts
+++ b/packages/zql/src/ivm/skip.ts
@@ -1,7 +1,7 @@
-import type {Row} from '../../../zero-protocol/src/data.js';
-import type {AddChange, Change, ChildChange, RemoveChange} from './change.js';
-import type {Comparator, Node} from './data.js';
-import {maybeSplitAndPushEditChange} from './maybe-split-and-push-edit-change.js';
+import type {Row} from '../../../zero-protocol/src/data.ts';
+import type {AddChange, Change, ChildChange, RemoveChange} from './change.ts';
+import type {Comparator, Node} from './data.ts';
+import {maybeSplitAndPushEditChange} from './maybe-split-and-push-edit-change.ts';
 import {
   throwOutput,
   type FetchRequest,
@@ -9,9 +9,9 @@ import {
   type Operator,
   type Output,
   type Start,
-} from './operator.js';
-import type {SourceSchema} from './schema.js';
-import type {Stream} from './stream.js';
+} from './operator.ts';
+import type {SourceSchema} from './schema.ts';
+import type {Stream} from './stream.ts';
 
 export type Bound = {
   row: Row;
diff --git a/packages/zql/src/ivm/snitch.ts b/packages/zql/src/ivm/snitch.ts
index dcdbeee640..c6644788a2 100644
--- a/packages/zql/src/ivm/snitch.ts
+++ b/packages/zql/src/ivm/snitch.ts
@@ -1,15 +1,15 @@
-import {unreachable} from '../../../shared/src/asserts.js';
-import type {Row} from '../../../zero-protocol/src/data.js';
-import type {Change} from './change.js';
-import type {Node} from './data.js';
+import {unreachable} from '../../../shared/src/asserts.ts';
+import type {Row} from '../../../zero-protocol/src/data.ts';
+import type {Change} from './change.ts';
+import type {Node} from './data.ts';
 import {
   type FetchRequest,
   type Input,
   type Operator,
   type Output,
-} from './operator.js';
-import type {SourceSchema} from './schema.js';
-import type {Stream} from './stream.js';
+} from './operator.ts';
+import type {SourceSchema} from './schema.ts';
+import type {Stream} from './stream.ts';
 
 /**
  * Snitch is an Operator that records all messages it receives. Useful for
diff --git a/packages/zql/src/ivm/source.test.ts b/packages/zql/src/ivm/source.test.ts
index 3fabd00101..15b687c597 100644
--- a/packages/zql/src/ivm/source.test.ts
+++ b/packages/zql/src/ivm/source.test.ts
@@ -2,15 +2,15 @@ import {expect, suite, test} from 'vitest';
 import type {
   Condition,
   SimpleOperator,
-} from '../../../zero-protocol/src/ast.js';
-import type {Row} from '../../../zero-protocol/src/data.js';
-import type {SchemaValue} from '../../../zero-schema/src/table-schema.js';
-import {Catch, expandNode} from './catch.js';
-import type {Constraint} from './constraint.js';
-import type {Node} from './data.js';
-import type {FetchRequest, Input, Output, Start} from './operator.js';
-import type {SourceChange} from './source.js';
-import {createSource} from './test/source-factory.js';
+} from '../../../zero-protocol/src/ast.ts';
+import type {Row} from '../../../zero-protocol/src/data.ts';
+import type {SchemaValue} from '../../../zero-schema/src/table-schema.ts';
+import {Catch, expandNode} from './catch.ts';
+import type {Constraint} from './constraint.ts';
+import type {Node} from './data.ts';
+import type {FetchRequest, Input, Output, Start} from './operator.ts';
+import type {SourceChange} from './source.ts';
+import {createSource} from './test/source-factory.ts';
 
 function asNodes(rows: Row[]) {
   return rows.map(row => ({
diff --git a/packages/zql/src/ivm/source.ts b/packages/zql/src/ivm/source.ts
index 471d8f62d0..689caef385 100644
--- a/packages/zql/src/ivm/source.ts
+++ b/packages/zql/src/ivm/source.ts
@@ -1,6 +1,6 @@
-import type {Condition, Ordering} from '../../../zero-protocol/src/ast.js';
-import type {Row} from '../../../zero-protocol/src/data.js';
-import type {Input} from './operator.js';
+import type {Condition, Ordering} from '../../../zero-protocol/src/ast.ts';
+import type {Row} from '../../../zero-protocol/src/data.ts';
+import type {Input} from './operator.ts';
 
 export type SourceChangeAdd = {
   type: 'add';
diff --git a/packages/zql/src/ivm/stream.test.ts b/packages/zql/src/ivm/stream.test.ts
index 370370584d..08dff124b5 100644
--- a/packages/zql/src/ivm/stream.test.ts
+++ b/packages/zql/src/ivm/stream.test.ts
@@ -1,5 +1,5 @@
 import {describe, expect, test} from 'vitest';
-import {first, type Stream, take} from './stream.js';
+import {first, type Stream, take} from './stream.ts';
 
 describe('take', () => {
   test('take the first n elements from the stream', () => {
diff --git a/packages/zql/src/ivm/take.fetch.test.ts b/packages/zql/src/ivm/take.fetch.test.ts
index e588fd19cd..c1e05c1e25 100644
--- a/packages/zql/src/ivm/take.fetch.test.ts
+++ b/packages/zql/src/ivm/take.fetch.test.ts
@@ -1,18 +1,18 @@
 import {expect, suite, test} from 'vitest';
-import {assert} from '../../../shared/src/asserts.js';
-import type {JSONValue} from '../../../shared/src/json.js';
-import type {Ordering} from '../../../zero-protocol/src/ast.js';
-import type {Row, Value} from '../../../zero-protocol/src/data.js';
-import type {PrimaryKey} from '../../../zero-protocol/src/primary-key.js';
-import type {SchemaValue} from '../../../zero-schema/src/table-schema.js';
-import {Catch} from './catch.js';
-import type {Node} from './data.js';
-import {MemoryStorage} from './memory-storage.js';
-import {Snitch, type SnitchMessage} from './snitch.js';
-import {Take, type PartitionKey} from './take.js';
-import {createSource} from './test/source-factory.js';
-import type {FetchRequest} from './operator.js';
-import type {Stream} from './stream.js';
+import {assert} from '../../../shared/src/asserts.ts';
+import type {JSONValue} from '../../../shared/src/json.ts';
+import type {Ordering} from '../../../zero-protocol/src/ast.ts';
+import type {Row, Value} from '../../../zero-protocol/src/data.ts';
+import type {PrimaryKey} from '../../../zero-protocol/src/primary-key.ts';
+import type {SchemaValue} from '../../../zero-schema/src/table-schema.ts';
+import {Catch} from './catch.ts';
+import type {Node} from './data.ts';
+import {MemoryStorage} from './memory-storage.ts';
+import type {FetchRequest} from './operator.ts';
+import {Snitch, type SnitchMessage} from './snitch.ts';
+import type {Stream} from './stream.ts';
+import {Take, type PartitionKey} from './take.ts';
+import {createSource} from './test/source-factory.ts';
 
 suite('take with no partition', () => {
   const base = {
diff --git a/packages/zql/src/ivm/take.push-child.test.ts b/packages/zql/src/ivm/take.push-child.test.ts
index df964b71c3..8bfc2995b1 100644
--- a/packages/zql/src/ivm/take.push-child.test.ts
+++ b/packages/zql/src/ivm/take.push-child.test.ts
@@ -1,13 +1,13 @@
 import {expect, test} from 'vitest';
-import type {Input, Storage} from './operator.js';
-import {Take} from './take.js';
+import type {Input, Storage} from './operator.ts';
+import {Take} from './take.ts';
 import {
   runJoinTest,
   type Joins,
   type SourceContents,
   type Sources,
-} from './test/join-push-tests.js';
-import type {Format} from './view.js';
+} from './test/join-push-tests.ts';
+import type {Format} from './view.ts';
 
 const sources: Sources = {
   issue: {
diff --git a/packages/zql/src/ivm/take.push.test.ts b/packages/zql/src/ivm/take.push.test.ts
index 6e503285fd..cb2207c595 100644
--- a/packages/zql/src/ivm/take.push.test.ts
+++ b/packages/zql/src/ivm/take.push.test.ts
@@ -1,16 +1,16 @@
 import {describe, expect, suite, test} from 'vitest';
-import {assert} from '../../../shared/src/asserts.js';
-import type {JSONValue} from '../../../shared/src/json.js';
-import type {Ordering} from '../../../zero-protocol/src/ast.js';
-import type {Row, Value} from '../../../zero-protocol/src/data.js';
-import type {PrimaryKey} from '../../../zero-protocol/src/primary-key.js';
-import type {SchemaValue} from '../../../zero-schema/src/table-schema.js';
-import {Catch, type CaughtChange} from './catch.js';
-import {MemoryStorage} from './memory-storage.js';
-import {Snitch, type SnitchMessage} from './snitch.js';
-import type {SourceChange} from './source.js';
-import {Take, type PartitionKey} from './take.js';
-import {createSource} from './test/source-factory.js';
+import {assert} from '../../../shared/src/asserts.ts';
+import type {JSONValue} from '../../../shared/src/json.ts';
+import type {Ordering} from '../../../zero-protocol/src/ast.ts';
+import type {Row, Value} from '../../../zero-protocol/src/data.ts';
+import type {PrimaryKey} from '../../../zero-protocol/src/primary-key.ts';
+import type {SchemaValue} from '../../../zero-schema/src/table-schema.ts';
+import {Catch, type CaughtChange} from './catch.ts';
+import {MemoryStorage} from './memory-storage.ts';
+import {Snitch, type SnitchMessage} from './snitch.ts';
+import type {SourceChange} from './source.ts';
+import {Take, type PartitionKey} from './take.ts';
+import {createSource} from './test/source-factory.ts';
 
 suite('take with no partition', () => {
   const base = {
diff --git a/packages/zql/src/ivm/take.ts b/packages/zql/src/ivm/take.ts
index d83604baf5..87d27cbe87 100644
--- a/packages/zql/src/ivm/take.ts
+++ b/packages/zql/src/ivm/take.ts
@@ -1,17 +1,17 @@
-import {assert, unreachable} from '../../../shared/src/asserts.js';
-import {hasOwn} from '../../../shared/src/has-own.js';
-import {must} from '../../../shared/src/must.js';
-import type {Row, Value} from '../../../zero-protocol/src/data.js';
-import type {PrimaryKey} from '../../../zero-protocol/src/primary-key.js';
-import {assertOrderingIncludesPK} from '../builder/builder.js';
+import {assert, unreachable} from '../../../shared/src/asserts.ts';
+import {hasOwn} from '../../../shared/src/has-own.ts';
+import {must} from '../../../shared/src/must.ts';
+import type {Row, Value} from '../../../zero-protocol/src/data.ts';
+import type {PrimaryKey} from '../../../zero-protocol/src/primary-key.ts';
+import {assertOrderingIncludesPK} from '../builder/builder.ts';
 import {
   rowForChange,
   type Change,
   type EditChange,
   type RemoveChange,
-} from './change.js';
-import type {Constraint} from './constraint.js';
-import {compareValues, type Comparator, type Node} from './data.js';
+} from './change.ts';
+import type {Constraint} from './constraint.ts';
+import {compareValues, type Comparator, type Node} from './data.ts';
 import {
   throwOutput,
   type FetchRequest,
@@ -19,9 +19,9 @@ import {
   type Operator,
   type Output,
   type Storage,
-} from './operator.js';
-import type {SourceSchema} from './schema.js';
-import {first, take, type Stream} from './stream.js';
+} from './operator.ts';
+import type {SourceSchema} from './schema.ts';
+import {first, take, type Stream} from './stream.ts';
 
 const MAX_BOUND_KEY = 'maxBound';
 
diff --git a/packages/zql/src/ivm/test/join-push-tests.ts b/packages/zql/src/ivm/test/join-push-tests.ts
index aa71b30b2b..f00741818f 100644
--- a/packages/zql/src/ivm/test/join-push-tests.ts
+++ b/packages/zql/src/ivm/test/join-push-tests.ts
@@ -1,19 +1,19 @@
 import {expect} from 'vitest';
-import type {JSONObject} from '../../../../shared/src/json.js';
-import {must} from '../../../../shared/src/must.js';
-import type {CompoundKey, Ordering} from '../../../../zero-protocol/src/ast.js';
-import type {Row} from '../../../../zero-protocol/src/data.js';
-import type {PrimaryKey} from '../../../../zero-protocol/src/primary-key.js';
-import type {SchemaValue} from '../../../../zero-schema/src/table-schema.js';
-import {ArrayView} from '../array-view.js';
-import {Catch} from '../catch.js';
-import {Join} from '../join.js';
-import {MemoryStorage} from '../memory-storage.js';
-import type {Input, Operator, Storage} from '../operator.js';
-import {Snitch, type SnitchMessage} from '../snitch.js';
-import type {Source, SourceChange} from '../source.js';
-import type {Format} from '../view.js';
-import {createSource} from './source-factory.js';
+import type {JSONObject} from '../../../../shared/src/json.ts';
+import {must} from '../../../../shared/src/must.ts';
+import type {CompoundKey, Ordering} from '../../../../zero-protocol/src/ast.ts';
+import type {Row} from '../../../../zero-protocol/src/data.ts';
+import type {PrimaryKey} from '../../../../zero-protocol/src/primary-key.ts';
+import type {SchemaValue} from '../../../../zero-schema/src/table-schema.ts';
+import {ArrayView} from '../array-view.ts';
+import {Catch} from '../catch.ts';
+import {Join} from '../join.ts';
+import {MemoryStorage} from '../memory-storage.ts';
+import type {Input, Operator, Storage} from '../operator.ts';
+import {Snitch, type SnitchMessage} from '../snitch.ts';
+import type {Source, SourceChange} from '../source.ts';
+import type {Format} from '../view.ts';
+import {createSource} from './source-factory.ts';
 
 function makeSource(
   rows: readonly Row[],
diff --git a/packages/zql/src/ivm/test/source-factory.ts b/packages/zql/src/ivm/test/source-factory.ts
index 290f5c00f8..edafa20ab0 100644
--- a/packages/zql/src/ivm/test/source-factory.ts
+++ b/packages/zql/src/ivm/test/source-factory.ts
@@ -1,7 +1,7 @@
-import type {PrimaryKey} from '../../../../zero-protocol/src/primary-key.js';
-import type {SchemaValue} from '../../../../zero-schema/src/table-schema.js';
-import {MemorySource} from '../memory-source.js';
-import type {Source} from '../source.js';
+import type {PrimaryKey} from '../../../../zero-protocol/src/primary-key.ts';
+import type {SchemaValue} from '../../../../zero-schema/src/table-schema.ts';
+import {MemorySource} from '../memory-source.ts';
+import type {Source} from '../source.ts';
 
 export type SourceFactory = (
   tableName: string,
diff --git a/packages/zql/src/ivm/view-apply-change.ts b/packages/zql/src/ivm/view-apply-change.ts
index dfcab72371..1ac0657b67 100644
--- a/packages/zql/src/ivm/view-apply-change.ts
+++ b/packages/zql/src/ivm/view-apply-change.ts
@@ -4,13 +4,13 @@ import {
   assertObject,
   assertUndefined,
   unreachable,
-} from '../../../shared/src/asserts.js';
-import {must} from '../../../shared/src/must.js';
-import type {Row} from '../../../zero-protocol/src/data.js';
-import type {Change} from './change.js';
-import type {Comparator, Node} from './data.js';
-import type {SourceSchema} from './schema.js';
-import type {Entry, EntryList, Format} from './view.js';
+} from '../../../shared/src/asserts.ts';
+import {must} from '../../../shared/src/must.ts';
+import type {Row} from '../../../zero-protocol/src/data.ts';
+import type {Change} from './change.ts';
+import type {Comparator, Node} from './data.ts';
+import type {SourceSchema} from './schema.ts';
+import type {Entry, EntryList, Format} from './view.ts';
 
 export function applyChange(
   parentEntry: Entry,
diff --git a/packages/zql/src/ivm/view.ts b/packages/zql/src/ivm/view.ts
index 62b5581dd7..af43263f55 100644
--- a/packages/zql/src/ivm/view.ts
+++ b/packages/zql/src/ivm/view.ts
@@ -1,7 +1,7 @@
-import type {Value} from '../../../zero-protocol/src/data.js';
-import type {Schema} from '../../../zero-schema/src/builder/schema-builder.js';
-import type {Query} from '../query/query.js';
-import type {Input} from './operator.js';
+import type {Value} from '../../../zero-protocol/src/data.ts';
+import type {Schema} from '../../../zero-schema/src/builder/schema-builder.ts';
+import type {Query} from '../query/query.ts';
+import type {Input} from './operator.ts';
 
 export type View = EntryList | Entry | undefined;
 export type EntryList = readonly Entry[];
diff --git a/packages/zql/src/query/auth-query.ts b/packages/zql/src/query/auth-query.ts
index 26fb19240f..16bfc170d5 100644
--- a/packages/zql/src/query/auth-query.ts
+++ b/packages/zql/src/query/auth-query.ts
@@ -1,10 +1,10 @@
-import type {AST} from '../../../zero-protocol/src/ast.js';
-import type {Schema} from '../../../zero-schema/src/builder/schema-builder.js';
-import type {Format} from '../ivm/view.js';
-import {ExpressionBuilder} from './expression.js';
-import {AbstractQuery} from './query-impl.js';
-import type {HumanReadable, PullRow, Query} from './query.js';
-import type {TypedView} from './typed-view.js';
+import type {AST} from '../../../zero-protocol/src/ast.ts';
+import type {Schema} from '../../../zero-schema/src/builder/schema-builder.ts';
+import type {Format} from '../ivm/view.ts';
+import {ExpressionBuilder} from './expression.ts';
+import {AbstractQuery} from './query-impl.ts';
+import type {HumanReadable, PullRow, Query} from './query.ts';
+import type {TypedView} from './typed-view.ts';
 
 export function authQuery<
   TSchema extends Schema,
diff --git a/packages/zql/src/query/dnf.test.ts b/packages/zql/src/query/dnf.test.ts
index 24e9c39018..8d153fe558 100644
--- a/packages/zql/src/query/dnf.test.ts
+++ b/packages/zql/src/query/dnf.test.ts
@@ -3,9 +3,9 @@ import {
   type Condition,
   type Conjunction,
   type Disjunction,
-} from '../../../zero-protocol/src/ast.js';
-import {dnf, unwrap} from './dnf.js';
-import {parse, stringify} from './expression-test-util.js';
+} from '../../../zero-protocol/src/ast.ts';
+import {dnf, unwrap} from './dnf.ts';
+import {parse, stringify} from './expression-test-util.ts';
 
 function simple(value: number | string): Condition {
   return {
diff --git a/packages/zql/src/query/dnf.ts b/packages/zql/src/query/dnf.ts
index 6999d5aacd..b44caa65b7 100644
--- a/packages/zql/src/query/dnf.ts
+++ b/packages/zql/src/query/dnf.ts
@@ -1,6 +1,6 @@
-import {unreachable} from '../../../shared/src/asserts.js';
-import type {Condition, Disjunction} from '../../../zero-protocol/src/ast.js';
-import {flatten, TRUE} from './expression.js';
+import {unreachable} from '../../../shared/src/asserts.ts';
+import type {Condition, Disjunction} from '../../../zero-protocol/src/ast.ts';
+import {flatten, TRUE} from './expression.ts';
 
 /**
  * DNF (Disjunctive Normal Form) is a way to represent a boolean expression as a
diff --git a/packages/zql/src/query/escape-like.test.ts b/packages/zql/src/query/escape-like.test.ts
index 9dacb91e09..bfe0abad1d 100644
--- a/packages/zql/src/query/escape-like.test.ts
+++ b/packages/zql/src/query/escape-like.test.ts
@@ -1,5 +1,5 @@
 import {expect, test} from 'vitest';
-import {escapeLike} from './escape-like.js';
+import {escapeLike} from './escape-like.ts';
 
 test('basics', () => {
   const cases: {
diff --git a/packages/zql/src/query/expression-parser.test.ts b/packages/zql/src/query/expression-parser.test.ts
index d4766c59b3..9d2122a41b 100644
--- a/packages/zql/src/query/expression-parser.test.ts
+++ b/packages/zql/src/query/expression-parser.test.ts
@@ -1,5 +1,5 @@
 import {expect, test} from 'vitest';
-import {parse, stringify} from './expression-test-util.js';
+import {parse, stringify} from './expression-test-util.ts';
 
 test('parse', () => {
   expect(parse('A & B')).toMatchInlineSnapshot(`
diff --git a/packages/zql/src/query/expression-test-util.ts b/packages/zql/src/query/expression-test-util.ts
index 6b49a4bd92..fb71d58a21 100644
--- a/packages/zql/src/query/expression-test-util.ts
+++ b/packages/zql/src/query/expression-test-util.ts
@@ -3,7 +3,7 @@ import type {
   CorrelatedSubquery,
   SimpleOperator,
   ValuePosition,
-} from '../../../zero-protocol/src/ast.js';
+} from '../../../zero-protocol/src/ast.ts';
 
 // This was written by ChatGPT with some improvements. It is only used for tests
 
diff --git a/packages/zql/src/query/expression.test.ts b/packages/zql/src/query/expression.test.ts
index bb8bc1ceea..3d44c47e3d 100644
--- a/packages/zql/src/query/expression.test.ts
+++ b/packages/zql/src/query/expression.test.ts
@@ -1,13 +1,13 @@
 import fc from 'fast-check';
 import {describe, expect, test} from 'vitest';
-import {assert} from '../../../shared/src/asserts.js';
+import {assert} from '../../../shared/src/asserts.ts';
 import {
   type Condition,
   type SimpleCondition,
-} from '../../../zero-protocol/src/ast.js';
-import {dnf} from './dnf.js';
-import {parse, stringify} from './expression-test-util.js';
-import {and, not, or} from './expression.js';
+} from '../../../zero-protocol/src/ast.ts';
+import {dnf} from './dnf.ts';
+import {parse, stringify} from './expression-test-util.ts';
+import {and, not, or} from './expression.ts';
 
 type TestCondition =
   | {
diff --git a/packages/zql/src/query/expression.ts b/packages/zql/src/query/expression.ts
index b01a2469a0..ba73ac30e4 100644
--- a/packages/zql/src/query/expression.ts
+++ b/packages/zql/src/query/expression.ts
@@ -1,21 +1,21 @@
 /* eslint-disable @typescript-eslint/no-explicit-any */
-import {must} from '../../../shared/src/must.js';
+import {must} from '../../../shared/src/must.ts';
 import {
   toStaticParam,
   type Condition,
   type LiteralValue,
   type Parameter,
-} from '../../../zero-protocol/src/ast.js';
-import type {Schema} from '../../../zero-schema/src/builder/schema-builder.js';
-import type {Operator} from './query.js';
+} from '../../../zero-protocol/src/ast.ts';
+import type {Schema} from '../../../zero-schema/src/builder/schema-builder.ts';
 import type {
   AvailableRelationships,
   DestTableName,
   GetFilterType,
   NoJsonSelector,
+  Operator,
   PullTableSchema,
   Query,
-} from './query.js';
+} from './query.ts';
 
 export type ParameterReference = {
   [toStaticParam](): Parameter;
diff --git a/packages/zql/src/query/query-impl.ast.test.ts b/packages/zql/src/query/query-impl.ast.test.ts
index effa786d96..9a5a3cafa3 100644
--- a/packages/zql/src/query/query-impl.ast.test.ts
+++ b/packages/zql/src/query/query-impl.ast.test.ts
@@ -1,14 +1,14 @@
 import {describe, expect, test} from 'vitest';
-import type {ExpressionFactory} from './expression.js';
+import type {Schema} from '../../../zero-schema/src/builder/schema-builder.ts';
+import type {ExpressionFactory} from './expression.ts';
 import {
   astForTestingSymbol,
   newQuery,
   QueryImpl,
   type QueryDelegate,
-} from './query-impl.js';
-import type {Query} from './query.js';
-import {schema} from './test/test-schemas.js';
-import type {Schema} from '../../../zero-schema/src/builder/schema-builder.js';
+} from './query-impl.ts';
+import type {Query} from './query.ts';
+import {schema} from './test/test-schemas.ts';
 
 const mockDelegate = {} as QueryDelegate;
 
diff --git a/packages/zql/src/query/query-impl.query-kitchen-sink.test.ts b/packages/zql/src/query/query-impl.query-kitchen-sink.test.ts
index 2ee87f3a8c..8e0f64f0ce 100644
--- a/packages/zql/src/query/query-impl.query-kitchen-sink.test.ts
+++ b/packages/zql/src/query/query-impl.query-kitchen-sink.test.ts
@@ -1,8 +1,8 @@
 import {describe, expect, test} from 'vitest';
-import {must} from '../../../shared/src/must.js';
-import {newQuery, type QueryDelegate} from './query-impl.js';
-import {QueryDelegateImpl} from './test/query-delegate.js';
-import {schema} from './test/test-schemas.js';
+import {must} from '../../../shared/src/must.ts';
+import {newQuery, type QueryDelegate} from './query-impl.ts';
+import {QueryDelegateImpl} from './test/query-delegate.ts';
+import {schema} from './test/test-schemas.ts';
 
 function addData(queryDelegate: QueryDelegate) {
   const userSource = must(queryDelegate.getSource('user'));
diff --git a/packages/zql/src/query/query-impl.query.test.ts b/packages/zql/src/query/query-impl.query.test.ts
index c8fb4a6d3e..5381851a03 100644
--- a/packages/zql/src/query/query-impl.query.test.ts
+++ b/packages/zql/src/query/query-impl.query.test.ts
@@ -1,17 +1,17 @@
 import {describe, expect, test} from 'vitest';
-import {deepClone} from '../../../shared/src/deep-clone.js';
-import {must} from '../../../shared/src/must.js';
-import {newQuery, type QueryDelegate, QueryImpl} from './query-impl.js';
-import type {AdvancedQuery} from './query-internal.js';
-import {QueryDelegateImpl} from './test/query-delegate.js';
-import {schema} from './test/test-schemas.js';
-import {number, table} from '../../../zero-schema/src/builder/table-builder.js';
-import {relationships} from '../../../zero-schema/src/builder/relationship-builder.js';
+import {deepClone} from '../../../shared/src/deep-clone.ts';
+import {must} from '../../../shared/src/must.ts';
+import {relationships} from '../../../zero-schema/src/builder/relationship-builder.ts';
 import {
   createSchema,
   type Schema,
-} from '../../../zero-schema/src/builder/schema-builder.js';
-import {createSource} from '../ivm/test/source-factory.js';
+} from '../../../zero-schema/src/builder/schema-builder.ts';
+import {number, table} from '../../../zero-schema/src/builder/table-builder.ts';
+import {createSource} from '../ivm/test/source-factory.ts';
+import {newQuery, type QueryDelegate, QueryImpl} from './query-impl.ts';
+import type {AdvancedQuery} from './query-internal.ts';
+import {QueryDelegateImpl} from './test/query-delegate.ts';
+import {schema} from './test/test-schemas.ts';
 
 /**
  * Some basic manual tests to get us started.
diff --git a/packages/zql/src/query/query-impl.ts b/packages/zql/src/query/query-impl.ts
index ec8f80520b..361390f32b 100644
--- a/packages/zql/src/query/query-impl.ts
+++ b/packages/zql/src/query/query-impl.ts
@@ -1,9 +1,9 @@
 /* eslint-disable @typescript-eslint/naming-convention */
 /* eslint-disable @typescript-eslint/no-explicit-any */
 import {resolver} from '@rocicorp/resolver';
-import {assert} from '../../../shared/src/asserts.js';
-import type {Writable} from '../../../shared/src/writable.js';
-import {hashOfAST} from '../../../zero-protocol/src/ast-hash.js';
+import {assert} from '../../../shared/src/asserts.ts';
+import type {Writable} from '../../../shared/src/writable.ts';
+import {hashOfAST} from '../../../zero-protocol/src/ast-hash.ts';
 import type {
   AST,
   CompoundKey,
@@ -11,34 +11,34 @@ import type {
   Ordering,
   Parameter,
   System,
-} from '../../../zero-protocol/src/ast.js';
-import type {Row as IVMRow} from '../../../zero-protocol/src/data.js';
+} from '../../../zero-protocol/src/ast.ts';
+import type {Row as IVMRow} from '../../../zero-protocol/src/data.ts';
+import type {Schema} from '../../../zero-schema/src/builder/schema-builder.ts';
 import {
   isOneHop,
   isTwoHop,
   type TableSchema,
-} from '../../../zero-schema/src/table-schema.js';
-import {buildPipeline, type BuilderDelegate} from '../builder/builder.js';
-import {ArrayView} from '../ivm/array-view.js';
-import type {Input} from '../ivm/operator.js';
-import type {Format, ViewFactory} from '../ivm/view.js';
-import {dnf} from './dnf.js';
+} from '../../../zero-schema/src/table-schema.ts';
+import {buildPipeline, type BuilderDelegate} from '../builder/builder.ts';
+import {ArrayView} from '../ivm/array-view.ts';
+import type {Input} from '../ivm/operator.ts';
+import type {Format, ViewFactory} from '../ivm/view.ts';
+import {dnf} from './dnf.ts';
 import {
   and,
   cmp,
   ExpressionBuilder,
   type ExpressionFactory,
-} from './expression.js';
-import type {AdvancedQuery} from './query-internal.js';
+} from './expression.ts';
+import type {AdvancedQuery} from './query-internal.ts';
 import type {
   GetFilterType,
   HumanReadable,
   Operator,
   PullRow,
   Query,
-} from './query.js';
-import type {TypedView} from './typed-view.js';
-import type {Schema} from '../../../zero-schema/src/builder/schema-builder.js';
+} from './query.ts';
+import type {TypedView} from './typed-view.ts';
 
 type AnyQuery = Query<Schema, string, any>;
 
diff --git a/packages/zql/src/query/query-internal.ts b/packages/zql/src/query/query-internal.ts
index 2088cb54d3..f8d78c0847 100644
--- a/packages/zql/src/query/query-internal.ts
+++ b/packages/zql/src/query/query-internal.ts
@@ -1,7 +1,7 @@
-import type {Schema} from '../../../zero-schema/src/builder/schema-builder.js';
-import type {Format, ViewFactory} from '../ivm/view.js';
-import type {HumanReadable, PullRow, Query} from './query.js';
-import type {TypedView} from './typed-view.js';
+import type {Schema} from '../../../zero-schema/src/builder/schema-builder.ts';
+import type {Format, ViewFactory} from '../ivm/view.ts';
+import type {HumanReadable, PullRow, Query} from './query.ts';
+import type {TypedView} from './typed-view.ts';
 
 export interface AdvancedQuery<
   TSchema extends Schema,
diff --git a/packages/zql/src/query/query.test.ts b/packages/zql/src/query/query.test.ts
index d04662cb1e..6375d20a7f 100644
--- a/packages/zql/src/query/query.test.ts
+++ b/packages/zql/src/query/query.test.ts
@@ -1,15 +1,10 @@
 /* eslint-disable @typescript-eslint/ban-types */
 import {describe, expectTypeOf, test} from 'vitest';
-import type {ReadonlyJSONValue} from '../../../shared/src/json.js';
-import {
-  type Opaque,
-  type TableSchema,
-} from '../../../zero-schema/src/table-schema.js';
-import type {ExpressionFactory} from './expression.js';
-import {staticParam} from './query-impl.js';
-import type {AdvancedQuery} from './query-internal.js';
-import {type Query, type Row} from './query.js';
-import {toStaticParam} from '../../../zero-protocol/src/ast.js';
+import type {ReadonlyJSONValue} from '../../../shared/src/json.ts';
+import {toStaticParam} from '../../../zero-protocol/src/ast.ts';
+import {relationships} from '../../../zero-schema/src/builder/relationship-builder.ts';
+import type {Schema as ZeroSchema} from '../../../zero-schema/src/builder/schema-builder.ts';
+import {createSchema} from '../../../zero-schema/src/builder/schema-builder.ts';
 import {
   boolean,
   enumeration,
@@ -17,10 +12,15 @@ import {
   number,
   string,
   table,
-} from '../../../zero-schema/src/builder/table-builder.js';
-import {relationships} from '../../../zero-schema/src/builder/relationship-builder.js';
-import {createSchema} from '../../../zero-schema/src/builder/schema-builder.js';
-import type {Schema as ZeroSchema} from '../../../zero-schema/src/builder/schema-builder.js';
+} from '../../../zero-schema/src/builder/table-builder.ts';
+import {
+  type Opaque,
+  type TableSchema,
+} from '../../../zero-schema/src/table-schema.ts';
+import type {ExpressionFactory} from './expression.ts';
+import {staticParam} from './query-impl.ts';
+import type {AdvancedQuery} from './query-internal.ts';
+import {type Query, type Row} from './query.ts';
 
 const mockQuery = {
   select() {
diff --git a/packages/zql/src/query/query.ts b/packages/zql/src/query/query.ts
index 2e05c1fc34..f820ae0937 100644
--- a/packages/zql/src/query/query.ts
+++ b/packages/zql/src/query/query.ts
@@ -1,13 +1,13 @@
 /* eslint-disable @typescript-eslint/no-explicit-any */
-import type {Expand, ExpandRecursive} from '../../../shared/src/expand.js';
-import type {Schema as ZeroSchema} from '../../../zero-schema/src/builder/schema-builder.js';
+import type {Expand, ExpandRecursive} from '../../../shared/src/expand.ts';
+import type {Schema as ZeroSchema} from '../../../zero-schema/src/builder/schema-builder.ts';
 import type {
   LastInTuple,
   SchemaValueToTSType,
   TableSchema,
-} from '../../../zero-schema/src/table-schema.js';
-import type {ExpressionFactory, ParameterReference} from './expression.js';
-import type {TypedView} from './typed-view.js';
+} from '../../../zero-schema/src/table-schema.ts';
+import type {ExpressionFactory, ParameterReference} from './expression.ts';
+import type {TypedView} from './typed-view.ts';
 
 type Selector<E extends TableSchema> = keyof E['columns'];
 export type NoJsonSelector<T extends TableSchema> = Exclude<
diff --git a/packages/zql/src/query/test/query-delegate.ts b/packages/zql/src/query/test/query-delegate.ts
index dc8a1b4d9b..6f74f0457d 100644
--- a/packages/zql/src/query/test/query-delegate.ts
+++ b/packages/zql/src/query/test/query-delegate.ts
@@ -1,12 +1,12 @@
-import type {AST} from '../../../../zero-protocol/src/ast.js';
-import {MemoryStorage} from '../../ivm/memory-storage.js';
-import {createSource} from '../../ivm/test/source-factory.js';
-import type {Source} from '../../ivm/source.js';
+import type {AST} from '../../../../zero-protocol/src/ast.ts';
+import {MemoryStorage} from '../../ivm/memory-storage.ts';
+import type {Source} from '../../ivm/source.ts';
+import {createSource} from '../../ivm/test/source-factory.ts';
 import type {
   CommitListener,
   GotCallback,
   QueryDelegate,
-} from '../query-impl.js';
+} from '../query-impl.ts';
 import {
   commentSchema,
   issueLabelSchema,
@@ -14,7 +14,7 @@ import {
   labelSchema,
   revisionSchema,
   userSchema,
-} from './test-schemas.js';
+} from './test-schemas.ts';
 
 export class QueryDelegateImpl implements QueryDelegate {
   readonly #sources: Record<string, Source> = makeSources();
diff --git a/packages/zql/src/query/test/test-schemas.ts b/packages/zql/src/query/test/test-schemas.ts
index 4fc1d7d921..b592dff4d6 100644
--- a/packages/zql/src/query/test/test-schemas.ts
+++ b/packages/zql/src/query/test/test-schemas.ts
@@ -1,12 +1,12 @@
+import {relationships} from '../../../../zero-schema/src/builder/relationship-builder.ts';
+import {createSchema} from '../../../../zero-schema/src/builder/schema-builder.ts';
 import {
   boolean,
   json,
   number,
   string,
   table,
-} from '../../../../zero-schema/src/builder/table-builder.js';
-import {relationships} from '../../../../zero-schema/src/builder/relationship-builder.js';
-import {createSchema} from '../../../../zero-schema/src/builder/schema-builder.js';
+} from '../../../../zero-schema/src/builder/table-builder.ts';
 
 const issue = table('issue')
   .columns({
diff --git a/packages/zql/src/query/typed-view.ts b/packages/zql/src/query/typed-view.ts
index 331c81d9cd..9b6bd439fe 100644
--- a/packages/zql/src/query/typed-view.ts
+++ b/packages/zql/src/query/typed-view.ts
@@ -1,4 +1,4 @@
-import type {Immutable} from '../../../shared/src/immutable.js';
+import type {Immutable} from '../../../shared/src/immutable.ts';
 
 export type ResultType = 'unknown' | 'complete';
 
diff --git a/packages/zql/tool/build.js b/packages/zql/tool/build.js
index 98decafa58..a45cd04073 100644
--- a/packages/zql/tool/build.js
+++ b/packages/zql/tool/build.js
@@ -4,8 +4,8 @@ import * as esbuild from 'esbuild';
 import * as fs from 'node:fs';
 import * as path from 'node:path';
 import {fileURLToPath} from 'node:url';
-import {makeDefine, sharedOptions} from '../../shared/src/build.js';
-import {getExternalFromPackageJSON} from '../../shared/src/tool/get-external-from-package-json.js';
+import {makeDefine, sharedOptions} from '../../shared/src/build.ts';
+import {getExternalFromPackageJSON} from '../../shared/src/tool/get-external-from-package-json.ts';
 
 /** @param {string[]} parts */
 function basePath(...parts) {
diff --git a/packages/zql/vitest.config.ts b/packages/zql/vitest.config.ts
index e6fbbb7abe..88d28f5fca 100644
--- a/packages/zql/vitest.config.ts
+++ b/packages/zql/vitest.config.ts
@@ -1,5 +1,5 @@
 import {defineConfig, mergeConfig} from 'vitest/config';
-import config from '../shared/src/tool/vitest-config.js';
+import config from '../shared/src/tool/vitest-config.ts';
 
 export default mergeConfig(
   config,
diff --git a/packages/zqlite-zql-test/src/setup.ts b/packages/zqlite-zql-test/src/setup.ts
index d29ae69d76..b11538c7ae 100644
--- a/packages/zqlite-zql-test/src/setup.ts
+++ b/packages/zqlite-zql-test/src/setup.ts
@@ -1,5 +1,5 @@
 import {afterAll, beforeAll} from 'vitest';
-import {createSource} from '../../zqlite/src/test/source-factory.js';
+import {createSource} from '../../zqlite/src/test/source-factory.ts';
 
 beforeAll(() => {
   // eslint-disable-next-line @typescript-eslint/no-explicit-any
diff --git a/packages/zqlite-zql-test/vitest.config.ts b/packages/zqlite-zql-test/vitest.config.ts
index 3460bcae61..ee01e983e9 100644
--- a/packages/zqlite-zql-test/vitest.config.ts
+++ b/packages/zqlite-zql-test/vitest.config.ts
@@ -1,5 +1,5 @@
 import {defineConfig} from 'vitest/config';
-import config from '../shared/src/tool/vitest-config.js';
+import config from '../shared/src/tool/vitest-config.ts';
 
 const {define, esbuild} = config;
 
diff --git a/packages/zqlite/src/db.test.ts b/packages/zqlite/src/db.test.ts
index 2e4e922455..d632a548ec 100644
--- a/packages/zqlite/src/db.test.ts
+++ b/packages/zqlite/src/db.test.ts
@@ -1,7 +1,7 @@
 import {LogContext} from '@rocicorp/logger';
 import {expect, test, vi} from 'vitest';
-import {TestLogSink} from '../../shared/src/logging-test-utils.js';
-import {Database} from './db.js';
+import {TestLogSink} from '../../shared/src/logging-test-utils.ts';
+import {Database} from './db.ts';
 
 test('slow queries are logged', () => {
   vi.useFakeTimers();
diff --git a/packages/zqlite/src/db.ts b/packages/zqlite/src/db.ts
index 0f3556b0b2..e1cbb3d588 100644
--- a/packages/zqlite/src/db.ts
+++ b/packages/zqlite/src/db.ts
@@ -5,8 +5,8 @@ import SQLite3Database, {
   type RunResult,
   type Statement as SQLite3Statement,
 } from '@rocicorp/zero-sqlite3';
-import {manualSpan} from '../../otel/src/span.js';
-import {version} from '../../otel/src/version.js';
+import {manualSpan} from '../../otel/src/span.ts';
+import {version} from '../../otel/src/version.ts';
 
 const tracer = trace.getTracer('view-syncer', version);
 
diff --git a/packages/zqlite/src/internal/sql.test.ts b/packages/zqlite/src/internal/sql.test.ts
index 929f5ffa4c..cf7be52528 100644
--- a/packages/zqlite/src/internal/sql.test.ts
+++ b/packages/zqlite/src/internal/sql.test.ts
@@ -1,5 +1,5 @@
 import {expect, test} from 'vitest';
-import {compile, sql} from './sql.js';
+import {compile, sql} from './sql.ts';
 
 test('can do empty slots', () => {
   const str = compile(sql`INSERT INTO foo (id, name) VALUES (?, ?)`);
diff --git a/packages/zqlite/src/internal/statement-cache.test.ts b/packages/zqlite/src/internal/statement-cache.test.ts
index 3a7711c316..e3bad367ea 100644
--- a/packages/zqlite/src/internal/statement-cache.test.ts
+++ b/packages/zqlite/src/internal/statement-cache.test.ts
@@ -1,7 +1,7 @@
-import {createSilentLogContext} from '../../../shared/src/logging-test-utils.js';
 import {expect, test} from 'vitest';
-import {Database} from '../db.js';
-import {type CachedStatement, StatementCache} from './statement-cache.js';
+import {createSilentLogContext} from '../../../shared/src/logging-test-utils.ts';
+import {Database} from '../db.ts';
+import {type CachedStatement, StatementCache} from './statement-cache.ts';
 
 test('Same sql results in same statement instance. The same instance is not outstanding twice.', () => {
   const db = new Database(createSilentLogContext(), ':memory:');
diff --git a/packages/zqlite/src/internal/statement-cache.ts b/packages/zqlite/src/internal/statement-cache.ts
index 890e302921..2ac2131466 100644
--- a/packages/zqlite/src/internal/statement-cache.ts
+++ b/packages/zqlite/src/internal/statement-cache.ts
@@ -1,5 +1,5 @@
-import type {Database, Statement} from '../db.js';
-import {assert} from '../../../shared/src/asserts.js';
+import {assert} from '../../../shared/src/asserts.ts';
+import type {Database, Statement} from '../db.ts';
 
 export type CachedStatementMap = Map<string, Statement[]>;
 export type CachedStatement = {
diff --git a/packages/zqlite/src/options.ts b/packages/zqlite/src/options.ts
index 9a0398083f..a7cf07993b 100644
--- a/packages/zqlite/src/options.ts
+++ b/packages/zqlite/src/options.ts
@@ -1,5 +1,5 @@
-import type {Schema} from '../../zero-schema/src/mod.js';
-import type {Database} from './db.js';
+import type {Schema} from '../../zero-schema/src/mod.ts';
+import type {Database} from './db.ts';
 
 /**
  * Configuration for [[ZqlLiteZero]].
diff --git a/packages/zqlite/src/query.test.ts b/packages/zqlite/src/query.test.ts
index c1a8669b60..ba0e0c9f6a 100644
--- a/packages/zqlite/src/query.test.ts
+++ b/packages/zqlite/src/query.test.ts
@@ -1,12 +1,12 @@
 import {beforeEach, expect, expectTypeOf, test} from 'vitest';
-import {createSilentLogContext} from '../../shared/src/logging-test-utils.js';
-import {must} from '../../shared/src/must.js';
-import {MemoryStorage} from '../../zql/src/ivm/memory-storage.js';
-import type {Source} from '../../zql/src/ivm/source.js';
-import {newQuery, type QueryDelegate} from '../../zql/src/query/query-impl.js';
-import {schema} from '../../zql/src/query/test/test-schemas.js';
-import {Database} from './db.js';
-import {TableSource, toSQLiteTypeName} from './table-source.js';
+import {createSilentLogContext} from '../../shared/src/logging-test-utils.ts';
+import {must} from '../../shared/src/must.ts';
+import {MemoryStorage} from '../../zql/src/ivm/memory-storage.ts';
+import type {Source} from '../../zql/src/ivm/source.ts';
+import {newQuery, type QueryDelegate} from '../../zql/src/query/query-impl.ts';
+import {schema} from '../../zql/src/query/test/test-schemas.ts';
+import {Database} from './db.ts';
+import {TableSource, toSQLiteTypeName} from './table-source.ts';
 
 let queryDelegate: QueryDelegate;
 beforeEach(() => {
diff --git a/packages/zqlite/src/table-source.test.ts b/packages/zqlite/src/table-source.test.ts
index df4567c841..be70b6f502 100644
--- a/packages/zqlite/src/table-source.test.ts
+++ b/packages/zqlite/src/table-source.test.ts
@@ -1,19 +1,19 @@
 import {describe, expect, test} from 'vitest';
-import type {JSONValue} from '../../shared/src/json.js';
-import {createSilentLogContext} from '../../shared/src/logging-test-utils.js';
-import type {Ordering} from '../../zero-protocol/src/ast.js';
-import type {Row, Value} from '../../zero-protocol/src/data.js';
-import type {PrimaryKey} from '../../zero-protocol/src/primary-key.js';
-import {Catch} from '../../zql/src/ivm/catch.js';
-import type {Change} from '../../zql/src/ivm/change.js';
-import {makeComparator} from '../../zql/src/ivm/data.js';
-import {Database} from './db.js';
-import {format} from './internal/sql.js';
+import type {JSONValue} from '../../shared/src/json.ts';
+import {createSilentLogContext} from '../../shared/src/logging-test-utils.ts';
+import type {Ordering} from '../../zero-protocol/src/ast.ts';
+import type {Row, Value} from '../../zero-protocol/src/data.ts';
+import type {PrimaryKey} from '../../zero-protocol/src/primary-key.ts';
+import {Catch} from '../../zql/src/ivm/catch.ts';
+import type {Change} from '../../zql/src/ivm/change.ts';
+import {makeComparator} from '../../zql/src/ivm/data.ts';
+import {Database} from './db.ts';
+import {format} from './internal/sql.ts';
 import {
   filtersToSQL,
   TableSource,
   UnsupportedValueError,
-} from './table-source.js';
+} from './table-source.ts';
 
 const columns = {
   id: {type: 'string'},
diff --git a/packages/zqlite/src/table-source.ts b/packages/zqlite/src/table-source.ts
index 0f43ba8274..2b8dfef758 100644
--- a/packages/zqlite/src/table-source.ts
+++ b/packages/zqlite/src/table-source.ts
@@ -1,54 +1,54 @@
 import type {SQLQuery} from '@databases/sql';
-import {assert, unreachable} from '../../shared/src/asserts.js';
-import {must} from '../../shared/src/must.js';
-import {difference} from '../../shared/src/set-utils.js';
-import type {Writable} from '../../shared/src/writable.js';
+import {assert, unreachable} from '../../shared/src/asserts.ts';
+import {must} from '../../shared/src/must.ts';
+import {difference} from '../../shared/src/set-utils.ts';
+import type {Writable} from '../../shared/src/writable.ts';
 import type {
   Condition,
   Ordering,
   SimpleCondition,
   ValuePosition,
-} from '../../zero-protocol/src/ast.js';
-import type {Row, Value} from '../../zero-protocol/src/data.js';
-import type {PrimaryKey} from '../../zero-protocol/src/primary-key.js';
+} from '../../zero-protocol/src/ast.ts';
+import type {Row, Value} from '../../zero-protocol/src/data.ts';
+import type {PrimaryKey} from '../../zero-protocol/src/primary-key.ts';
 import type {
   SchemaValue,
   ValueType,
-} from '../../zero-schema/src/table-schema.js';
+} from '../../zero-schema/src/table-schema.ts';
 import {
   createPredicate,
   transformFilters,
   type NoSubqueryCondition,
-} from '../../zql/src/builder/filter.js';
-import type {Change} from '../../zql/src/ivm/change.js';
+} from '../../zql/src/builder/filter.ts';
+import type {Change} from '../../zql/src/ivm/change.ts';
 import {
   makeComparator,
   type Comparator,
   type Node,
-} from '../../zql/src/ivm/data.js';
-import {filterPush} from '../../zql/src/ivm/filter-push.js';
+} from '../../zql/src/ivm/data.ts';
+import {filterPush} from '../../zql/src/ivm/filter-push.ts';
 import {
   generateWithOverlay,
   generateWithStart,
   type Overlay,
-} from '../../zql/src/ivm/memory-source.js';
+} from '../../zql/src/ivm/memory-source.ts';
 import type {
   FetchRequest,
   Input,
   Output,
   Start,
-} from '../../zql/src/ivm/operator.js';
-import type {SourceSchema} from '../../zql/src/ivm/schema.js';
+} from '../../zql/src/ivm/operator.ts';
+import type {SourceSchema} from '../../zql/src/ivm/schema.ts';
 import type {
   Source,
   SourceChange,
   SourceInput,
-} from '../../zql/src/ivm/source.js';
-import type {Stream} from '../../zql/src/ivm/stream.js';
-import {Database, Statement} from './db.js';
-import {compile, format, sql} from './internal/sql.js';
-import {StatementCache} from './internal/statement-cache.js';
-import {runtimeDebugFlags, runtimeDebugStats} from './runtime-debug.js';
+} from '../../zql/src/ivm/source.ts';
+import type {Stream} from '../../zql/src/ivm/stream.ts';
+import {Database, Statement} from './db.ts';
+import {compile, format, sql} from './internal/sql.ts';
+import {StatementCache} from './internal/statement-cache.ts';
+import {runtimeDebugFlags, runtimeDebugStats} from './runtime-debug.ts';
 
 type Connection = {
   input: Input;
diff --git a/packages/zqlite/src/test/source-factory.ts b/packages/zqlite/src/test/source-factory.ts
index 201ba6700d..f27d310b20 100644
--- a/packages/zqlite/src/test/source-factory.ts
+++ b/packages/zqlite/src/test/source-factory.ts
@@ -1,11 +1,11 @@
-import {Database} from '../db.js';
-import type {SchemaValue} from '../../../zero-schema/src/table-schema.js';
-import type {Source} from '../../../zql/src/ivm/source.js';
-import type {SourceFactory} from '../../../zql/src/ivm/test/source-factory.js';
-import {createSilentLogContext} from '../../../shared/src/logging-test-utils.js';
-import {compile, sql} from '../internal/sql.js';
-import {TableSource} from '../table-source.js';
-import type {PrimaryKey} from '../../../zero-protocol/src/primary-key.js';
+import {createSilentLogContext} from '../../../shared/src/logging-test-utils.ts';
+import type {PrimaryKey} from '../../../zero-protocol/src/primary-key.ts';
+import type {SchemaValue} from '../../../zero-schema/src/table-schema.ts';
+import type {Source} from '../../../zql/src/ivm/source.ts';
+import type {SourceFactory} from '../../../zql/src/ivm/test/source-factory.ts';
+import {Database} from '../db.ts';
+import {compile, sql} from '../internal/sql.ts';
+import {TableSource} from '../table-source.ts';
 
 export const createSource: SourceFactory = (
   tableName: string,
diff --git a/packages/zqlite/vitest.config.ts b/packages/zqlite/vitest.config.ts
index 0cafc06390..5d3d470876 100644
--- a/packages/zqlite/vitest.config.ts
+++ b/packages/zqlite/vitest.config.ts
@@ -1,5 +1,5 @@
 import {configDefaults, defineConfig} from 'vitest/config';
-import config from '../shared/src/tool/vitest-config.js';
+import config from '../shared/src/tool/vitest-config.ts';
 
 const {define, esbuild} = config;