diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 89020056e3..496eec87fd 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -15,8 +15,6 @@ on:
 
 jobs:
   lint:
-    name: lint
-
     # begin macro
 
     runs-on: ubuntu-latest
@@ -28,7 +26,8 @@ jobs:
         uses: actions/checkout@v4
 
       # without this, setup-node errors on mismatched yarn versions
-      - run: corepack enable
+      - name: Enable corepack
+        run: corepack enable
 
       - name: Use Node.js
         uses: actions/setup-node@v3
@@ -47,6 +46,35 @@ jobs:
       - name: Run yarn lint
         run: yarn lint
 
+  docs:
+    # begin macro
+
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      # without this, setup-node errors on mismatched yarn versions
+      - name: Enable corepack
+        run: corepack enable
+
+      - name: Use Node.js
+        uses: actions/setup-node@v3
+        with:
+          node-version: 20.x
+          cache: yarn
+
+      - name: Install dependencies
+        run: yarn install --immutable
+
+      # end macro
+
+      - name: Run yarn build
+        run: yarn build
+
       # build the API docs to verify it works
       - name: build API docs
         run: yarn docs
@@ -56,8 +84,6 @@ jobs:
         run: yarn docs:markdown-for-agoric-documentation-repo
 
   test:
-    name: test
-
     # begin macro
 
     runs-on: ${{ matrix.platform }}
@@ -98,8 +124,6 @@ jobs:
         run: yarn test
 
   test-async-hooks:
-    name: test-async-hooks
-
     runs-on: ${{ matrix.platform }}
     strategy:
       fail-fast: false
@@ -145,8 +169,6 @@ jobs:
         run: yarn test
 
   cover:
-    name: cover
-
     # begin macro
 
     runs-on: ${{ matrix.platform }}
@@ -181,8 +203,6 @@ jobs:
         run: yarn cover
 
   test262:
-    name: test262
-
     # begin macro
 
     runs-on: ${{ matrix.platform }}
@@ -217,8 +237,6 @@ jobs:
         run: exit 0 # TODO remove test262 from required tests for CI
 
   test-hermes:
-    name: test-hermes
-
     # begin macro
 
     runs-on: ${{ matrix.platform }}
@@ -252,8 +270,6 @@ jobs:
         run: yarn test:hermes
 
   viable-release:
-    name: viable-release
-
     # begin macro
 
     runs-on: ${{ matrix.platform }}
@@ -296,8 +312,6 @@ jobs:
         run: yarn lerna run --reject-cycles --concurrency 1 prepack
 
   test-xs:
-    name: test-xs
-
     # begin macro
 
     runs-on: ${{ matrix.platform }}
@@ -384,3 +398,76 @@ jobs:
         run: |
           PATH=$PATH:$GITHUB_WORKSPACE/bin
           yarn test:xs
+
+  linear-history:
+    runs-on: ubuntu-latest
+    if: >-
+      github.event_name == 'pull_request' &&
+      github.event.pull_request.draft == false &&
+      github.event.pull_request.base.ref == 'master' &&
+      !contains(github.event.pull_request.labels.*.name, 'bypass:linear-history')
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+      - shell: bash
+        env:
+          HEAD_SHA: ${{ github.event.pull_request.head.sha }}
+          HEAD_LABEL: ${{ github.event.pull_request.head.label }}
+          BASE_SHA: ${{ github.event.pull_request.base.sha }}
+          BASE_LABEL: ${{ github.event.pull_request.base.label }}
+        run: |
+          merge_commits=$(git rev-list --merges "$BASE_SHA".."$HEAD_SHA")
+
+          if [ -n "$merge_commits" ]; then
+            echo "Error: merge commits found in $BASE_LABEL..$HEAD_LABEL"
+
+            for merge_commit in $merge_commits; do
+              echo "$merge_commit"
+            done
+
+            exit 1
+          fi
+
+          fixup_commits=
+          for commit in $(git rev-list $BASE_SHA..$HEAD_SHA); do
+            case $(git show --pretty=format:%s -s $commit) in fixup\!*|squash\!*|amend\!*)
+              fixup_commits="$fixup_commits\n$commit"
+              ;;
+            esac
+          done
+
+          if [ -n "$fixup_commits" ]; then
+            echo "Error: fixup/squash/amend commits found in $BASE_LABEL..$HEAD_LABEL"
+            echo -e "$fixup_commits"
+            exit 1
+          fi
+
+  no-fixup-commits:
+    runs-on: ubuntu-latest
+    if: >-
+      github.event_name == 'pull_request' &&
+      github.event.pull_request.draft == false &&
+      github.event.pull_request.base.ref == 'master' &&
+      !contains(github.event.pull_request.labels.*.name, 'bypass:linear-history')
+
+    env:
+      HEAD_SHA: ${{ github.event.pull_request.head.sha }}
+      BASE_SHA: ${{ github.event.pull_request.base.sha }}
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+      - name: Check for fixup commits
+        id: fixup-commits
+        run: |
+          if ! git merge-base --is-ancestor "$BASE_SHA" "$HEAD_SHA"; then
+             echo "PR is not up to date with target branch, skipping fixup commit check"
+          elif [[ $(git rev-list "$BASE_SHA".."$HEAD_SHA" --grep="^\(fixup\|amend\|squash\)! " | wc -l) -eq 0 ]]; then
+            echo "No fixup/amend/squash commits found in commit history"
+          else
+            echo "fixup/amend/squash commits found in commit history"
+            exit 1
+          fi