fix: properly hydrate already-resolved async blocks

We were missing a "skip nodes to the end" invocation

Fixes #17261

Author: dummdidumm

.changeset/sixty-garlics-drive.md

@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: properly hydrate already-resolved async blocks

packages/svelte/src/internal/client/dom/blocks/async.js

@@ -27,6 +27,10 @@ export function async(node, blockers = [], expressions = [], fn) {
 
 	if (expressions.length === 0 && blockers.every((b) => b.settled)) {
 		fn(node);
+		if (was_hydrating) {
+			skip_nodes(false);
+			hydrate_next();
+		}
 		return;
 	}
 

packages/svelte/tests/runtime-runes/samples/async-each-item-duplication/Component.svelte

@@ -0,0 +1,5 @@
+<script>
+	let { message, another } = $props()
+</script>
+
+<p>{message}</p>

packages/svelte/tests/runtime-runes/samples/async-each-item-duplication/_config.js

@@ -0,0 +1,14 @@
+import { tick } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+	mode: ['hydrate'],
+
+	ssrHtml: `<p>item 1</p><p>item 2</p><p>item 3</p>`,
+	html: `<p>item 1</p><p>item 2</p><p>item 3</p>`,
+
+	async test({ assert, target }) {
+		await tick();
+		assert.htmlEqual(target.innerHTML, '<p>item 1</p><p>item 2</p><p>item 3</p>');
+	}
+});

packages/svelte/tests/runtime-runes/samples/async-each-item-duplication/main.svelte

@@ -0,0 +1,10 @@
+<script>
+	import Component from './Component.svelte'
+
+	const messages = await Promise.resolve(["item 1", "item 2", "item 3"])
+	const another = { test: 'test' }
+</script>
+
+{#each messages as message}
+	<Component {message} {another} />
+{/each}