From cd8d40af1ae755ca7c889f3aa1b6c3d8d0c14dd7 Mon Sep 17 00:00:00 2001
From: Simon H <5968653+dummdidumm@users.noreply.github.com>
Date: Mon, 2 Feb 2026 22:40:14 +0100
Subject: [PATCH 01/23] chore: robustify playground decode (#17606)

For some reason LLMs like to percent-encode stuff, this makes the download script still run in that case
---
 playgrounds/sandbox/scripts/download.js | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/playgrounds/sandbox/scripts/download.js b/playgrounds/sandbox/scripts/download.js
index e3c862cb61..538b4956fe 100644
--- a/playgrounds/sandbox/scripts/download.js
+++ b/playgrounds/sandbox/scripts/download.js
@@ -635,7 +635,19 @@ if (is_local) {
 } else if (url && url.origin === 'https://svelte.dev' && url.pathname.startsWith('/playground/')) {
 	// Svelte playground URL handling (existing logic)
 	if (url.hash.length > 1) {
-		const decoded = atob(url.hash.slice(1).replaceAll('-', '+').replaceAll('_', '/'));
+		// Decode percent-encoded characters (e.g., %5F => _), and replace base64 chars.
+		let decoded;
+		try {
+			// First, decode URI components to handle %xx encodings (e.g. %5F -> _) (LLMs calling this script sometimes encode them for some reason)
+			decoded = url.hash.slice(1);
+			decoded = decodeURIComponent(decoded);
+
+			// Now, restore for base64 (replace -/+, _/ /)
+			decoded = atob(decoded.replaceAll('-', '+').replaceAll('_', '/'));
+		} catch (e) {
+			console.error('Failed to decode URL hash:', e);
+			process.exit(1);
+		}
 		// putting it directly into the blob gives a corrupted file
 		const u8 = new Uint8Array(decoded.length);
 		for (let i = 0; i < decoded.length; i++) {

From bc4dc1d10d54ecbc61398a248f8a45a4f4bcfa13 Mon Sep 17 00:00:00 2001
From: Simon H <5968653+dummdidumm@users.noreply.github.com>
Date: Wed, 4 Feb 2026 10:28:32 +0100
Subject: [PATCH 02/23] fix: avoid erroneous async derived expressions for
 blocks (#17604)

fixes #17595

When an if/key/etc block has an expression that depends on an async blocker (e.g., is inside a component with top level `await`), the compiler incorrectly treats the expression as async - even when the expression itself contains no `await`.

This causes the expression to be added to `$.async`'s `expressions` array, which wraps it in an `async_derived`. This is not only unnecessary but also buggy: it breaks the direct reactive connection between the source and its dependent effects, causing inconsistent effect executions.

The fix is to only add expressions to `$.async`'s `expressions` array when they actually contain an `await`.

When a branch is speculatively marked for destruction (condition temporarily falsy), its child effects are reset to `CLEAN` to prevent them running in a doomed branch (as of #17581). However, if the branch survives (condition becomes truthy again), those effects remain `CLEAN` and never run - the source was already marked dirty before the reset, so no new dirty marking occurs.

The fix is to change `skipped_effects` from a `Set` to a `Map` that tracks which child effects were dirty/maybe_dirty before being reset. When a branch is unskipped (survives), restore their status and reschedule them.

---------

Co-authored-by: Rich Harris <rich.harris@vercel.com>
---
 .changeset/some-teams-pay.md                  |  5 ++
 .changeset/yummy-insects-wonder.md            |  5 ++
 .../3-transform/client/visitors/EachBlock.js  | 15 +++--
 .../3-transform/client/visitors/HtmlTag.js    | 14 ++--
 .../3-transform/client/visitors/IfBlock.js    | 14 ++--
 .../3-transform/client/visitors/KeyBlock.js   | 32 +++++----
 .../client/visitors/SvelteElement.js          | 14 ++--
 .../internal/client/dom/blocks/branches.js    |  8 +--
 .../src/internal/client/dom/blocks/each.js    |  4 +-
 .../src/internal/client/reactivity/batch.js   | 65 +++++++++++++++----
 .../svelte/tests/runtime-legacy/shared.ts     |  4 +-
 .../Child.svelte                              |  9 +++
 .../_config.js                                | 16 +++++
 .../main.svelte                               | 14 ++++
 14 files changed, 166 insertions(+), 53 deletions(-)
 create mode 100644 .changeset/some-teams-pay.md
 create mode 100644 .changeset/yummy-insects-wonder.md
 create mode 100644 packages/svelte/tests/runtime-runes/samples/async-derived-unmount-undefined-props/Child.svelte
 create mode 100644 packages/svelte/tests/runtime-runes/samples/async-derived-unmount-undefined-props/_config.js
 create mode 100644 packages/svelte/tests/runtime-runes/samples/async-derived-unmount-undefined-props/main.svelte

diff --git a/.changeset/some-teams-pay.md b/.changeset/some-teams-pay.md
new file mode 100644
index 0000000000..d7ae69566d
--- /dev/null
+++ b/.changeset/some-teams-pay.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: avoid erroneous async derived expressions for blocks
diff --git a/.changeset/yummy-insects-wonder.md b/.changeset/yummy-insects-wonder.md
new file mode 100644
index 0000000000..6e705cd8cf
--- /dev/null
+++ b/.changeset/yummy-insects-wonder.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: reschedule effects inside unskipped branches
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
index c0bfe272e5..1dbc34fdc3 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
@@ -312,10 +312,10 @@ export function EachBlock(node, context) {
 		declarations.push(b.let(node.index, index));
 	}
 
-	const is_async = node.metadata.expression.is_async();
+	const has_await = node.metadata.expression.has_await;
 
-	const get_collection = b.thunk(collection, node.metadata.expression.has_await);
-	const thunk = is_async ? b.thunk(b.call('$.get', b.id('$$collection'))) : get_collection;
+	const get_collection = b.thunk(collection, has_await);
+	const thunk = has_await ? b.thunk(b.call('$.get', b.id('$$collection'))) : get_collection;
 
 	const render_args = [b.id('$$anchor'), item];
 	if (uses_index || collection_id) render_args.push(index);
@@ -342,15 +342,18 @@ export function EachBlock(node, context) {
 		statements.unshift(b.stmt(b.call('$.validate_each_keys', thunk, key_function)));
 	}
 
-	if (is_async) {
+	if (node.metadata.expression.is_async()) {
 		context.state.init.push(
 			b.stmt(
 				b.call(
 					'$.async',
 					context.state.node,
 					node.metadata.expression.blockers(),
-					b.array([get_collection]),
-					b.arrow([context.state.node, b.id('$$collection')], b.block(statements))
+					has_await ? b.array([get_collection]) : b.void0,
+					b.arrow(
+						has_await ? [context.state.node, b.id('$$collection')] : [context.state.node],
+						b.block(statements)
+					)
 				)
 			)
 		);
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/HtmlTag.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/HtmlTag.js
index 0567edc610..2706cf7f0a 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/HtmlTag.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/HtmlTag.js
@@ -11,10 +11,11 @@ import { build_expression } from './shared/utils.js';
 export function HtmlTag(node, context) {
 	context.state.template.push_comment();
 
-	const is_async = node.metadata.expression.is_async();
+	const has_await = node.metadata.expression.has_await;
+	const has_blockers = node.metadata.expression.has_blockers();
 
 	const expression = build_expression(context, node.expression, node.metadata.expression);
-	const html = is_async ? b.call('$.get', b.id('$$html')) : expression;
+	const html = has_await ? b.call('$.get', b.id('$$html')) : expression;
 
 	const is_svg = context.state.metadata.namespace === 'svg';
 	const is_mathml = context.state.metadata.namespace === 'mathml';
@@ -31,15 +32,18 @@ export function HtmlTag(node, context) {
 	);
 
 	// push into init, so that bindings run afterwards, which might trigger another run and override hydration
-	if (is_async) {
+	if (has_await || has_blockers) {
 		context.state.init.push(
 			b.stmt(
 				b.call(
 					'$.async',
 					context.state.node,
 					node.metadata.expression.blockers(),
-					b.array([b.thunk(expression, node.metadata.expression.has_await)]),
-					b.arrow([context.state.node, b.id('$$html')], b.block([statement]))
+					has_await ? b.array([b.thunk(expression, true)]) : b.void0,
+					b.arrow(
+						has_await ? [context.state.node, b.id('$$html')] : [context.state.node],
+						b.block([statement])
+					)
 				)
 			)
 		);
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/IfBlock.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/IfBlock.js
index fcbb59ba74..c0e66635df 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/IfBlock.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/IfBlock.js
@@ -25,10 +25,11 @@ export function IfBlock(node, context) {
 		statements.push(b.var(alternate_id, b.arrow([b.id('$$anchor')], alternate)));
 	}
 
-	const is_async = node.metadata.expression.is_async();
+	const has_await = node.metadata.expression.has_await;
+	const has_blockers = node.metadata.expression.has_blockers();
 
 	const expression = build_expression(context, node.test, node.metadata.expression);
-	const test = is_async ? b.call('$.get', b.id('$$condition')) : expression;
+	const test = has_await ? b.call('$.get', b.id('$$condition')) : expression;
 
 	/** @type {Expression[]} */
 	const args = [
@@ -72,15 +73,18 @@ export function IfBlock(node, context) {
 
 	statements.push(add_svelte_meta(b.call('$.if', ...args), node, 'if'));
 
-	if (is_async) {
+	if (has_await || has_blockers) {
 		context.state.init.push(
 			b.stmt(
 				b.call(
 					'$.async',
 					context.state.node,
 					node.metadata.expression.blockers(),
-					b.array([b.thunk(expression, node.metadata.expression.has_await)]),
-					b.arrow([context.state.node, b.id('$$condition')], b.block(statements))
+					has_await ? b.array([b.thunk(expression, true)]) : b.void0,
+					b.arrow(
+						has_await ? [context.state.node, b.id('$$condition')] : [context.state.node],
+						b.block(statements)
+					)
 				)
 			)
 		);
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/KeyBlock.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/KeyBlock.js
index d050155e8b..143a4e8edd 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/KeyBlock.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/KeyBlock.js
@@ -11,29 +11,35 @@ import { build_expression, add_svelte_meta } from './shared/utils.js';
 export function KeyBlock(node, context) {
 	context.state.template.push_comment();
 
-	const is_async = node.metadata.expression.is_async();
+	const has_await = node.metadata.expression.has_await;
+	const has_blockers = node.metadata.expression.has_blockers();
 
 	const expression = build_expression(context, node.expression, node.metadata.expression);
-	const key = b.thunk(is_async ? b.call('$.get', b.id('$$key')) : expression);
+	const key = b.thunk(has_await ? b.call('$.get', b.id('$$key')) : expression);
 	const body = /** @type {Expression} */ (context.visit(node.fragment));
 
-	let statement = add_svelte_meta(
+	const statement = add_svelte_meta(
 		b.call('$.key', context.state.node, key, b.arrow([b.id('$$anchor')], body)),
 		node,
 		'key'
 	);
 
-	if (is_async) {
-		statement = b.stmt(
-			b.call(
-				'$.async',
-				context.state.node,
-				node.metadata.expression.blockers(),
-				b.array([b.thunk(expression, node.metadata.expression.has_await)]),
-				b.arrow([context.state.node, b.id('$$key')], b.block([statement]))
+	if (has_await || has_blockers) {
+		context.state.init.push(
+			b.stmt(
+				b.call(
+					'$.async',
+					context.state.node,
+					node.metadata.expression.blockers(),
+					has_await ? b.array([b.thunk(expression, true)]) : b.void0,
+					b.arrow(
+						has_await ? [context.state.node, b.id('$$key')] : [context.state.node],
+						b.block([statement])
+					)
+				)
 			)
 		);
+	} else {
+		context.state.init.push(statement);
 	}
-
-	context.state.init.push(statement);
 }
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/SvelteElement.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/SvelteElement.js
index c8192cf00a..10024298fa 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/SvelteElement.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/SvelteElement.js
@@ -93,10 +93,11 @@ export function SvelteElement(node, context) {
 		);
 	}
 
-	const is_async = node.metadata.expression.is_async();
+	const has_await = node.metadata.expression.has_await;
+	const has_blockers = node.metadata.expression.has_blockers();
 
 	const expression = /** @type {Expression} */ (context.visit(node.tag));
-	const get_tag = b.thunk(is_async ? b.call('$.get', b.id('$$tag')) : expression);
+	const get_tag = b.thunk(has_await ? b.call('$.get', b.id('$$tag')) : expression);
 
 	/** @type {Statement[]} */
 	const inner = inner_context.state.init;
@@ -139,15 +140,18 @@ export function SvelteElement(node, context) {
 		)
 	);
 
-	if (is_async) {
+	if (has_await || has_blockers) {
 		context.state.init.push(
 			b.stmt(
 				b.call(
 					'$.async',
 					context.state.node,
 					node.metadata.expression.blockers(),
-					b.array([b.thunk(expression, node.metadata.expression.has_await)]),
-					b.arrow([context.state.node, b.id('$$tag')], b.block(statements))
+					has_await ? b.array([b.thunk(expression, true)]) : b.void0,
+					b.arrow(
+						has_await ? [context.state.node, b.id('$$tag')] : [context.state.node],
+						b.block(statements)
+					)
 				)
 			)
 		);
diff --git a/packages/svelte/src/internal/client/dom/blocks/branches.js b/packages/svelte/src/internal/client/dom/blocks/branches.js
index 527f0b0a8f..6b77903574 100644
--- a/packages/svelte/src/internal/client/dom/blocks/branches.js
+++ b/packages/svelte/src/internal/client/dom/blocks/branches.js
@@ -200,17 +200,17 @@ export class BranchManager {
 		if (defer) {
 			for (const [k, effect] of this.#onscreen) {
 				if (k === key) {
-					batch.skipped_effects.delete(effect);
+					batch.unskip_effect(effect);
 				} else {
-					batch.skipped_effects.add(effect);
+					batch.skip_effect(effect);
 				}
 			}
 
 			for (const [k, branch] of this.#offscreen) {
 				if (k === key) {
-					batch.skipped_effects.delete(branch.effect);
+					batch.unskip_effect(branch.effect);
 				} else {
-					batch.skipped_effects.add(branch.effect);
+					batch.skip_effect(branch.effect);
 				}
 			}
 
diff --git a/packages/svelte/src/internal/client/dom/blocks/each.js b/packages/svelte/src/internal/client/dom/blocks/each.js
index 232656ec11..6eaeac0f38 100644
--- a/packages/svelte/src/internal/client/dom/blocks/each.js
+++ b/packages/svelte/src/internal/client/dom/blocks/each.js
@@ -257,7 +257,7 @@ export function each(node, flags, get_collection, get_key, render_fn, fallback_f
 				if (item.i) internal_set(item.i, index);
 
 				if (defer) {
-					batch.skipped_effects.delete(item.e);
+					batch.unskip_effect(item.e);
 				}
 			} else {
 				item = create_item(
@@ -299,7 +299,7 @@ export function each(node, flags, get_collection, get_key, render_fn, fallback_f
 			if (defer) {
 				for (const [key, item] of items) {
 					if (!keys.has(key)) {
-						batch.skipped_effects.add(item.e);
+						batch.skip_effect(item.e);
 					}
 				}
 
diff --git a/packages/svelte/src/internal/client/reactivity/batch.js b/packages/svelte/src/internal/client/reactivity/batch.js
index 2b6e84889b..cef2df4716 100644
--- a/packages/svelte/src/internal/client/reactivity/batch.js
+++ b/packages/svelte/src/internal/client/reactivity/batch.js
@@ -130,11 +130,13 @@ export class Batch {
 	#maybe_dirty_effects = new Set();
 
 	/**
-	 * A set of branches that still exist, but will be destroyed when this batch
-	 * is committed — we skip over these during `process`
-	 * @type {Set<Effect>}
+	 * A map of branches that still exist, but will be destroyed when this batch
+	 * is committed — we skip over these during `process`.
+	 * The value contains child effects that were dirty/maybe_dirty before being reset,
+	 * so they can be rescheduled if the branch survives.
+	 * @type {Map<Effect, { d: Effect[], m: Effect[] }>}
 	 */
-	skipped_effects = new Set();
+	#skipped_branches = new Map();
 
 	is_fork = false;
 
@@ -144,6 +146,38 @@ export class Batch {
 		return this.is_fork || this.#blocking_pending > 0;
 	}
 
+	/**
+	 * Add an effect to the #skipped_branches map and reset its children
+	 * @param {Effect} effect
+	 */
+	skip_effect(effect) {
+		if (!this.#skipped_branches.has(effect)) {
+			this.#skipped_branches.set(effect, { d: [], m: [] });
+		}
+	}
+
+	/**
+	 * Remove an effect from the #skipped_branches map and reschedule
+	 * any tracked dirty/maybe_dirty child effects
+	 * @param {Effect} effect
+	 */
+	unskip_effect(effect) {
+		var tracked = this.#skipped_branches.get(effect);
+		if (tracked) {
+			this.#skipped_branches.delete(effect);
+
+			for (var e of tracked.d) {
+				set_signal_status(e, DIRTY);
+				schedule_effect(e);
+			}
+
+			for (e of tracked.m) {
+				set_signal_status(e, MAYBE_DIRTY);
+				schedule_effect(e);
+			}
+		}
+	}
+
 	/**
 	 *
 	 * @param {Effect[]} root_effects
@@ -172,8 +206,8 @@ export class Batch {
 			this.#defer_effects(render_effects);
 			this.#defer_effects(effects);
 
-			for (const e of this.skipped_effects) {
-				reset_branch(e);
+			for (const [e, t] of this.#skipped_branches) {
+				reset_branch(e, t);
 			}
 		} else {
 			// append/remove branches
@@ -220,7 +254,7 @@ export class Batch {
 			var is_branch = (flags & (BRANCH_EFFECT | ROOT_EFFECT)) !== 0;
 			var is_skippable_branch = is_branch && (flags & CLEAN) !== 0;
 
-			var skip = is_skippable_branch || (flags & INERT) !== 0 || this.skipped_effects.has(effect);
+			var skip = is_skippable_branch || (flags & INERT) !== 0 || this.#skipped_branches.has(effect);
 
 			// Inside a `<svelte:boundary>` with a pending snippet,
 			// all effects are deferred until the boundary resolves
@@ -807,7 +841,8 @@ export function schedule_effect(signal) {
 		var flags = effect.f;
 
 		// if the effect is being scheduled because a parent (each/await/etc) block
-		// updated an internal source, bail out or we'll cause a second flush
+		// updated an internal source, or because a branch is being unskipped,
+		// bail out or we'll cause a second flush
 		if (
 			is_flushing &&
 			effect === active_effect &&
@@ -887,20 +922,28 @@ export function eager(fn) {
 
 /**
  * Mark all the effects inside a skipped branch CLEAN, so that
- * they can be correctly rescheduled later
+ * they can be correctly rescheduled later. Tracks dirty and maybe_dirty
+ * effects so they can be rescheduled if the branch survives.
  * @param {Effect} effect
+ * @param {{ d: Effect[], m: Effect[] }} tracked
  */
-function reset_branch(effect) {
+function reset_branch(effect, tracked) {
 	// clean branch = nothing dirty inside, no need to traverse further
 	if ((effect.f & BRANCH_EFFECT) !== 0 && (effect.f & CLEAN) !== 0) {
 		return;
 	}
 
+	if ((effect.f & DIRTY) !== 0) {
+		tracked.d.push(effect);
+	} else if ((effect.f & MAYBE_DIRTY) !== 0) {
+		tracked.m.push(effect);
+	}
+
 	set_signal_status(effect, CLEAN);
 
 	var e = effect.first;
 	while (e !== null) {
-		reset_branch(e);
+		reset_branch(e, tracked);
 		e = e.next;
 	}
 }
diff --git a/packages/svelte/tests/runtime-legacy/shared.ts b/packages/svelte/tests/runtime-legacy/shared.ts
index 13975c68ee..8c29a6ada2 100644
--- a/packages/svelte/tests/runtime-legacy/shared.ts
+++ b/packages/svelte/tests/runtime-legacy/shared.ts
@@ -47,9 +47,9 @@ export interface RuntimeTest<Props extends Record<string, any> = Record<string,
 	mode?: Array<'server' | 'async-server' | 'client' | 'hydrate'>;
 	/** Temporarily skip specific modes, without skipping the entire test */
 	skip_mode?: Array<'server' | 'async-server' | 'client' | 'hydrate'>;
-	/** Skip if running with process.env.NO_ASYNC */
+	/** Skip if running with process.env.SVELTE_NO_ASYNC */
 	skip_no_async?: boolean;
-	/** Skip if running without process.env.NO_ASYNC */
+	/** Skip if running without process.env.SVELTE_NO_ASYNC */
 	skip_async?: boolean;
 	html?: string;
 	ssrHtml?: string;
diff --git a/packages/svelte/tests/runtime-runes/samples/async-derived-unmount-undefined-props/Child.svelte b/packages/svelte/tests/runtime-runes/samples/async-derived-unmount-undefined-props/Child.svelte
new file mode 100644
index 0000000000..fecbe222e3
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/async-derived-unmount-undefined-props/Child.svelte
@@ -0,0 +1,9 @@
+<script>
+	let { id } = $props();
+
+	// BUG: This logs 'undefined' on unmount when parent has async derived
+	const data = $derived(await Promise.resolve(id).then((x) => {
+		console.log('promise resolved with:', x);
+		return x;
+	}));
+</script>
diff --git a/packages/svelte/tests/runtime-runes/samples/async-derived-unmount-undefined-props/_config.js b/packages/svelte/tests/runtime-runes/samples/async-derived-unmount-undefined-props/_config.js
new file mode 100644
index 0000000000..2f371bc6b7
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/async-derived-unmount-undefined-props/_config.js
@@ -0,0 +1,16 @@
+import { tick } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+	async test({ assert, target, logs }) {
+		await tick();
+
+		assert.deepEqual(logs, ['promise resolved with:', 'some-id']);
+
+		const button = target.querySelector('button');
+		button?.click();
+		await tick();
+
+		assert.deepEqual(logs, ['promise resolved with:', 'some-id']);
+	}
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/async-derived-unmount-undefined-props/main.svelte b/packages/svelte/tests/runtime-runes/samples/async-derived-unmount-undefined-props/main.svelte
new file mode 100644
index 0000000000..d5cdd5967e
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/async-derived-unmount-undefined-props/main.svelte
@@ -0,0 +1,14 @@
+<script>
+	import Child from './Child.svelte';
+
+	// This async derived in parent triggers the bug
+	const something = $derived(await Promise.resolve('test'));
+
+	let active = $state('some-id');
+</script>
+
+{#if active}
+	<Child id={active} />
+{/if}
+
+<button onclick={() => active = undefined}>close</button>

From baba15ab981a3b090eaabefe3425f5f4ea9a8074 Mon Sep 17 00:00:00 2001
From: Tee Ming <chewteeming01@gmail.com>
Date: Thu, 5 Feb 2026 00:31:33 +0800
Subject: [PATCH 03/23] fix: avoid 'node:crypto' cloudflare warnings (#17612)

* fix: avoid 'node:crypto' cloudflare warnings

* format

* changeset

* Apply suggestion from @teemingc
---
 .changeset/violet-pans-know.md                | 5 +++++
 packages/svelte/src/internal/server/crypto.js | 3 ++-
 2 files changed, 7 insertions(+), 1 deletion(-)
 create mode 100644 .changeset/violet-pans-know.md

diff --git a/.changeset/violet-pans-know.md b/.changeset/violet-pans-know.md
new file mode 100644
index 0000000000..59bf1dcaaf
--- /dev/null
+++ b/.changeset/violet-pans-know.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: avoid Cloudflare warnings about not having the "node:crypto" module
diff --git a/packages/svelte/src/internal/server/crypto.js b/packages/svelte/src/internal/server/crypto.js
index 8727635481..9bb6ecdd39 100644
--- a/packages/svelte/src/internal/server/crypto.js
+++ b/packages/svelte/src/internal/server/crypto.js
@@ -12,7 +12,8 @@ export async function sha256(data) {
 	crypto ??= globalThis.crypto?.subtle?.digest
 		? globalThis.crypto
 		: // @ts-ignore - we don't install node types in the prod build
-			(await import('node:crypto')).webcrypto;
+			// don't use 'node:crypto' because static analysers will think we rely on node when we don't
+			(await import('node:' + 'crypto')).webcrypto;
 
 	const hash_buffer = await crypto.subtle.digest('SHA-256', text_encoder.encode(data));
 

From 05229d96823cc88d11c0b4a81b357cdb67f69326 Mon Sep 17 00:00:00 2001
From: Tee Ming <chewteeming01@gmail.com>
Date: Thu, 5 Feb 2026 00:32:33 +0800
Subject: [PATCH 04/23] chore: remove SvelteKit data attributes from
 elements.d.ts (#17613)

* Remove SvelteKit data attributes from elements.d.ts

Removed SvelteKit specific data attributes from elements.d.ts.

* Remove SvelteKit data attributes from elements.d.ts

Removed SvelteKit data attributes from elements.d.ts.

---------

Co-authored-by: Simon H <5968653+dummdidumm@users.noreply.github.com>
---
 .changeset/quiet-buttons-bathe.md |  5 +++++
 packages/svelte/elements.d.ts     | 17 -----------------
 2 files changed, 5 insertions(+), 17 deletions(-)
 create mode 100644 .changeset/quiet-buttons-bathe.md

diff --git a/.changeset/quiet-buttons-bathe.md b/.changeset/quiet-buttons-bathe.md
new file mode 100644
index 0000000000..419a5569b4
--- /dev/null
+++ b/.changeset/quiet-buttons-bathe.md
@@ -0,0 +1,5 @@
+---
+"svelte": patch
+---
+
+chore: remove SvelteKit data attributes from elements.d.ts
diff --git a/packages/svelte/elements.d.ts b/packages/svelte/elements.d.ts
index fa74124472..885004dd2a 100644
--- a/packages/svelte/elements.d.ts
+++ b/packages/svelte/elements.d.ts
@@ -851,23 +851,6 @@ export interface HTMLAttributes<T extends EventTarget> extends AriaAttributes, D
 	readonly 'bind:offsetWidth'?: number | undefined | null;
 	readonly 'bind:offsetHeight'?: number | undefined | null;
 
-	// SvelteKit
-	'data-sveltekit-keepfocus'?: true | '' | 'off' | undefined | null;
-	'data-sveltekit-noscroll'?: true | '' | 'off' | undefined | null;
-	'data-sveltekit-preload-code'?:
-		| true
-		| ''
-		| 'eager'
-		| 'viewport'
-		| 'hover'
-		| 'tap'
-		| 'off'
-		| undefined
-		| null;
-	'data-sveltekit-preload-data'?: true | '' | 'hover' | 'tap' | 'off' | undefined | null;
-	'data-sveltekit-reload'?: true | '' | 'off' | undefined | null;
-	'data-sveltekit-replacestate'?: true | '' | 'off' | undefined | null;
-
 	// allow any data- attribute
 	[key: `data-${string}`]: any;
 

From eb63a6bbbaffec07890ae181b02edf4c52e2586a Mon Sep 17 00:00:00 2001
From: "github-actions[bot]"
 <41898282+github-actions[bot]@users.noreply.github.com>
Date: Wed, 4 Feb 2026 11:52:30 -0500
Subject: [PATCH 05/23] Version Packages (#17614)

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
---
 .changeset/quiet-buttons-bathe.md  |  5 -----
 .changeset/some-teams-pay.md       |  5 -----
 .changeset/violet-pans-know.md     |  5 -----
 .changeset/yummy-insects-wonder.md |  5 -----
 packages/svelte/CHANGELOG.md       | 12 ++++++++++++
 packages/svelte/package.json       |  2 +-
 packages/svelte/src/version.js     |  2 +-
 7 files changed, 14 insertions(+), 22 deletions(-)
 delete mode 100644 .changeset/quiet-buttons-bathe.md
 delete mode 100644 .changeset/some-teams-pay.md
 delete mode 100644 .changeset/violet-pans-know.md
 delete mode 100644 .changeset/yummy-insects-wonder.md

diff --git a/.changeset/quiet-buttons-bathe.md b/.changeset/quiet-buttons-bathe.md
deleted file mode 100644
index 419a5569b4..0000000000
--- a/.changeset/quiet-buttons-bathe.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-"svelte": patch
----
-
-chore: remove SvelteKit data attributes from elements.d.ts
diff --git a/.changeset/some-teams-pay.md b/.changeset/some-teams-pay.md
deleted file mode 100644
index d7ae69566d..0000000000
--- a/.changeset/some-teams-pay.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-'svelte': patch
----
-
-fix: avoid erroneous async derived expressions for blocks
diff --git a/.changeset/violet-pans-know.md b/.changeset/violet-pans-know.md
deleted file mode 100644
index 59bf1dcaaf..0000000000
--- a/.changeset/violet-pans-know.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-'svelte': patch
----
-
-fix: avoid Cloudflare warnings about not having the "node:crypto" module
diff --git a/.changeset/yummy-insects-wonder.md b/.changeset/yummy-insects-wonder.md
deleted file mode 100644
index 6e705cd8cf..0000000000
--- a/.changeset/yummy-insects-wonder.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-'svelte': patch
----
-
-fix: reschedule effects inside unskipped branches
diff --git a/packages/svelte/CHANGELOG.md b/packages/svelte/CHANGELOG.md
index c7c38302e8..a71effd5dd 100644
--- a/packages/svelte/CHANGELOG.md
+++ b/packages/svelte/CHANGELOG.md
@@ -1,5 +1,17 @@
 # svelte
 
+## 5.49.2
+
+### Patch Changes
+
+- chore: remove SvelteKit data attributes from elements.d.ts ([#17613](https://github.com/sveltejs/svelte/pull/17613))
+
+- fix: avoid erroneous async derived expressions for blocks ([#17604](https://github.com/sveltejs/svelte/pull/17604))
+
+- fix: avoid Cloudflare warnings about not having the "node:crypto" module ([#17612](https://github.com/sveltejs/svelte/pull/17612))
+
+- fix: reschedule effects inside unskipped branches ([#17604](https://github.com/sveltejs/svelte/pull/17604))
+
 ## 5.49.1
 
 ### Patch Changes
diff --git a/packages/svelte/package.json b/packages/svelte/package.json
index fd4b98679e..48f492783f 100644
--- a/packages/svelte/package.json
+++ b/packages/svelte/package.json
@@ -2,7 +2,7 @@
   "name": "svelte",
   "description": "Cybernetically enhanced web apps",
   "license": "MIT",
-  "version": "5.49.1",
+  "version": "5.49.2",
   "type": "module",
   "types": "./types/index.d.ts",
   "engines": {
diff --git a/packages/svelte/src/version.js b/packages/svelte/src/version.js
index 557b1ff156..31538c3fe7 100644
--- a/packages/svelte/src/version.js
+++ b/packages/svelte/src/version.js
@@ -4,5 +4,5 @@
  * The current version, as set in package.json.
  * @type {string}
  */
-export const VERSION = '5.49.1';
+export const VERSION = '5.49.2';
 export const PUBLIC_VERSION = '5';

From 4f41e816baa007fb6a4e31164da49576e87e342e Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Wed, 4 Feb 2026 13:07:46 -0500
Subject: [PATCH 06/23] fix: ensure infinite effect loops are cleared after
 flushing (#17601)

* failing effect-loop-infinite test

* fix
---
 .changeset/chatty-mammals-find.md                     |  5 +++++
 .../svelte/src/internal/client/reactivity/batch.js    |  3 ++-
 packages/svelte/tests/runtime-legacy/shared.ts        |  2 ++
 .../samples/effect-loop-infinite/_config.js           | 11 ++++++-----
 4 files changed, 15 insertions(+), 6 deletions(-)
 create mode 100644 .changeset/chatty-mammals-find.md

diff --git a/.changeset/chatty-mammals-find.md b/.changeset/chatty-mammals-find.md
new file mode 100644
index 0000000000..373dc0059a
--- /dev/null
+++ b/.changeset/chatty-mammals-find.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: ensure infinite effect loops are cleared after flushing
diff --git a/packages/svelte/src/internal/client/reactivity/batch.js b/packages/svelte/src/internal/client/reactivity/batch.js
index cef2df4716..9bf93c873f 100644
--- a/packages/svelte/src/internal/client/reactivity/batch.js
+++ b/packages/svelte/src/internal/client/reactivity/batch.js
@@ -647,8 +647,9 @@ function flush_effects() {
 			}
 		}
 	} finally {
-		is_flushing = false;
+		queued_root_effects = [];
 
+		is_flushing = false;
 		last_scheduled_effect = null;
 
 		if (DEV) {
diff --git a/packages/svelte/tests/runtime-legacy/shared.ts b/packages/svelte/tests/runtime-legacy/shared.ts
index 8c29a6ada2..c5317f822e 100644
--- a/packages/svelte/tests/runtime-legacy/shared.ts
+++ b/packages/svelte/tests/runtime-legacy/shared.ts
@@ -521,6 +521,8 @@ async function run_test_variant(
 						errors,
 						hydrate: hydrate_fn
 					});
+
+					flushSync();
 				}
 
 				if (config.runtime_error && !unhandled_rejection) {
diff --git a/packages/svelte/tests/runtime-runes/samples/effect-loop-infinite/_config.js b/packages/svelte/tests/runtime-runes/samples/effect-loop-infinite/_config.js
index 57f60c2b44..44cf5b09e2 100644
--- a/packages/svelte/tests/runtime-runes/samples/effect-loop-infinite/_config.js
+++ b/packages/svelte/tests/runtime-runes/samples/effect-loop-infinite/_config.js
@@ -11,11 +11,12 @@ export default test({
 	test({ assert, errors }) {
 		const [button] = document.querySelectorAll('button');
 
-		try {
+		assert.throws(() => {
 			flushSync(() => button.click());
-		} catch (e) {
-			assert.equal(errors.length, 1); // for whatever reason we can't get the name which should be 'updated at'
-			assert.ok(/** @type {Error} */ (e).message.startsWith('effect_update_depth_exceeded'));
-		}
+		}, /effect_update_depth_exceeded/);
+
+		assert.equal(errors.length, 1);
+
+		assert.doesNotThrow(flushSync);
 	}
 });

From d7a8e3d1300fbb802b84a6ebf0f3f71ed734a556 Mon Sep 17 00:00:00 2001
From: 7nik <kifiranet@gmail.com>
Date: Wed, 4 Feb 2026 21:51:50 +0200
Subject: [PATCH 07/23] fix: emit `each_key_duplicate` error in production
 (#16724)

* fix: emit `each_key_duplicate` error in production

* fix: preserve key

* Update packages/svelte/src/internal/client/dom/blocks/each.js

Co-authored-by: Rich Harris <rich.harris@vercel.com>

* Update packages/svelte/src/internal/client/dom/blocks/each.js

Co-authored-by: Rich Harris <rich.harris@vercel.com>

* fix: ensure keys are validated

* fix silly test name

* fix: cover other case of duplicate keys

* emit error on hydration

* ensure the error is handled

* drop useless tests

* unused

* finish merge

* add lost check back

* chore: bump playwright (#17565)

* chore: bump playwright

* maybe this will help somehow?

* err whatever

* fix

* chore: allow testing in production env 2 (#17590)

* Revert "chore: allow testing in production env (#16840)"

This reverts commit ffd65e90febc29feaca48e142126a4087fcaca9f.

* new approach

* fix: handle renderer.run rejections (#17591)

* fix: handle renderer run rejections

* add test

* changeset

* simplify

* explanatory comment

---------

Co-authored-by: Antonio Bennett <abennett@mabelslabels.com>
Co-authored-by: Rich Harris <rich.harris@vercel.com>

* fix: only create async functions in SSR output when necessary (#17593)

* fix: only create async functions in SSR output when necessary

* actually...

* simplify generated code a bit more

* simplify

* fix: merge consecutive text nodes during hydration for large text content (#17587)

* fix: merge consecutive text nodes during hydration for large text content

Fixes #17582

Browsers automatically split text nodes exceeding 65536 characters into
multiple consecutive text nodes during HTML parsing. This causes hydration
mismatches when Svelte expects a single text node.

The fix merges consecutive text nodes during hydration by:
- Detecting when the current node is a text node
- Finding all consecutive text node siblings
- Merging their content into the first text node
- Removing the extra text nodes

This restores correct hydration behavior for large text content.

* add test, fix

* fix

* fix

* changeset

---------

Co-authored-by: Miner <miner@example.com>
Co-authored-by: Rich Harris <rich.harris@vercel.com>

* Version Packages (#17585)

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

* Revert "drop useless tests"

This reverts commit 65f77ef8409d6e8c91163f36853d36b05ec01ae8.

* update tests

* fix test

* we don't need to expose this function any more

* figured it out... we cant have errors during reconcile

* simplify

* tweak

* unused

* revert no-longer-needed change

* unused

---------

Co-authored-by: Rich Harris <rich.harris@vercel.com>
Co-authored-by: Antonio Bennett <31296212+Antonio-Bennett@users.noreply.github.com>
Co-authored-by: Antonio Bennett <abennett@mabelslabels.com>
Co-authored-by: FORMI <239411042+Richman018@users.noreply.github.com>
Co-authored-by: Miner <miner@example.com>
Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
---
 .changeset/sharp-snakes-poke.md               |  5 +++
 .../3-transform/client/visitors/EachBlock.js  |  4 --
 .../src/internal/client/dom/blocks/each.js    | 37 +++++++++++++++++++
 packages/svelte/src/internal/client/index.js  |  2 +-
 .../svelte/src/internal/client/validate.js    | 34 -----------------
 .../samples/keyed-each-unique-2/_config.js    | 12 ++++++
 .../samples/keyed-each-unique-2/main.svelte   |  8 ++++
 .../samples/keyed-each-unique-3/_config.js    |  5 +++
 .../samples/keyed-each-unique-3/main.svelte   |  7 ++++
 .../samples/keyed-each-unique/_config.js      | 12 ++++++
 .../samples/keyed-each-unique/main.svelte     |  8 ++++
 11 files changed, 95 insertions(+), 39 deletions(-)
 create mode 100644 .changeset/sharp-snakes-poke.md
 create mode 100644 packages/svelte/tests/runtime-production/samples/keyed-each-unique-2/_config.js
 create mode 100644 packages/svelte/tests/runtime-production/samples/keyed-each-unique-2/main.svelte
 create mode 100644 packages/svelte/tests/runtime-production/samples/keyed-each-unique-3/_config.js
 create mode 100644 packages/svelte/tests/runtime-production/samples/keyed-each-unique-3/main.svelte
 create mode 100644 packages/svelte/tests/runtime-production/samples/keyed-each-unique/_config.js
 create mode 100644 packages/svelte/tests/runtime-production/samples/keyed-each-unique/main.svelte

diff --git a/.changeset/sharp-snakes-poke.md b/.changeset/sharp-snakes-poke.md
new file mode 100644
index 0000000000..7f7f8aa7b2
--- /dev/null
+++ b/.changeset/sharp-snakes-poke.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: emit `each_key_duplicate` error in production
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
index 1dbc34fdc3..b2724fa90f 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
@@ -338,10 +338,6 @@ export function EachBlock(node, context) {
 
 	const statements = [add_svelte_meta(b.call('$.each', ...args), node, 'each')];
 
-	if (dev && node.metadata.keyed) {
-		statements.unshift(b.stmt(b.call('$.validate_each_keys', thunk, key_function)));
-	}
-
 	if (node.metadata.expression.is_async()) {
 		context.state.init.push(
 			b.stmt(
diff --git a/packages/svelte/src/internal/client/dom/blocks/each.js b/packages/svelte/src/internal/client/dom/blocks/each.js
index 6eaeac0f38..25f7cf91eb 100644
--- a/packages/svelte/src/internal/client/dom/blocks/each.js
+++ b/packages/svelte/src/internal/client/dom/blocks/each.js
@@ -40,6 +40,7 @@ import { get } from '../../runtime.js';
 import { DEV } from 'esm-env';
 import { derived_safe_equal } from '../../reactivity/deriveds.js';
 import { current_batch } from '../../reactivity/batch.js';
+import * as e from '../../errors.js';
 
 // When making substantive changes to this file, validate them with the each block stress test:
 // https://svelte.dev/playground/1972b2cf46564476ad8c8c6405b23b7b
@@ -290,6 +291,15 @@ export function each(node, flags, get_collection, get_key, render_fn, fallback_f
 			}
 		}
 
+		if (length > keys.size) {
+			if (DEV) {
+				validate_each_keys(array, get_key);
+			} else {
+				// in prod, the additional information isn't printed, so don't bother computing it
+				e.each_key_duplicate('', '', '');
+			}
+		}
+
 		// remove excess nodes
 		if (hydrating && length > 0) {
 			set_hydrate_node(skip_nodes());
@@ -676,3 +686,30 @@ function link(state, prev, next) {
 		next.prev = prev;
 	}
 }
+
+/**
+ * @param {Array<any>} array
+ * @param {(item: any, index: number) => string} key_fn
+ * @returns {void}
+ */
+function validate_each_keys(array, key_fn) {
+	const keys = new Map();
+	const length = array.length;
+
+	for (let i = 0; i < length; i++) {
+		const key = key_fn(array[i], i);
+
+		if (keys.has(key)) {
+			const a = String(keys.get(key));
+			const b = String(i);
+
+			/** @type {string | null} */
+			let k = String(key);
+			if (k.startsWith('[object ')) k = null;
+
+			e.each_key_duplicate(a, b, k);
+		}
+
+		keys.set(key, i);
+	}
+}
diff --git a/packages/svelte/src/internal/client/index.js b/packages/svelte/src/internal/client/index.js
index 1d9f7dfff7..7fcaf77dc5 100644
--- a/packages/svelte/src/internal/client/index.js
+++ b/packages/svelte/src/internal/client/index.js
@@ -158,7 +158,7 @@ export {
 	deep_read_state,
 	active_effect
 } from './runtime.js';
-export { validate_binding, validate_each_keys } from './validate.js';
+export { validate_binding } from './validate.js';
 export { raf } from './timing.js';
 export { proxy } from './proxy.js';
 export { create_custom_element } from './dom/elements/custom-element.js';
diff --git a/packages/svelte/src/internal/client/validate.js b/packages/svelte/src/internal/client/validate.js
index 48a44db304..a169225f1e 100644
--- a/packages/svelte/src/internal/client/validate.js
+++ b/packages/svelte/src/internal/client/validate.js
@@ -1,45 +1,11 @@
 /** @import { Blocker } from '#client' */
 import { dev_current_component_function } from './context.js';
-import { is_array } from '../shared/utils.js';
-import * as e from './errors.js';
 import { FILENAME } from '../../constants.js';
 import { render_effect } from './reactivity/effects.js';
 import * as w from './warnings.js';
 import { capture_store_binding } from './reactivity/store.js';
 import { run_after_blockers } from './reactivity/async.js';
 
-/**
- * @param {() => any} collection
- * @param {(item: any, index: number) => string} key_fn
- * @returns {void}
- */
-export function validate_each_keys(collection, key_fn) {
-	render_effect(() => {
-		const keys = new Map();
-		const maybe_array = collection();
-		const array = is_array(maybe_array)
-			? maybe_array
-			: maybe_array == null
-				? []
-				: Array.from(maybe_array);
-		const length = array.length;
-		for (let i = 0; i < length; i++) {
-			const key = key_fn(array[i], i);
-			if (keys.has(key)) {
-				const a = String(keys.get(key));
-				const b = String(i);
-
-				/** @type {string | null} */
-				let k = String(key);
-				if (k.startsWith('[object ')) k = null;
-
-				e.each_key_duplicate(a, b, k);
-			}
-			keys.set(key, i);
-		}
-	});
-}
-
 /**
  * @param {string} binding
  * @param {Blocker[]} blockers
diff --git a/packages/svelte/tests/runtime-production/samples/keyed-each-unique-2/_config.js b/packages/svelte/tests/runtime-production/samples/keyed-each-unique-2/_config.js
new file mode 100644
index 0000000000..bc945876ea
--- /dev/null
+++ b/packages/svelte/tests/runtime-production/samples/keyed-each-unique-2/_config.js
@@ -0,0 +1,12 @@
+import { flushSync } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+	test({ assert, target }) {
+		let button = target.querySelector('button');
+
+		button?.click();
+
+		assert.throws(flushSync, 'https://svelte.dev/e/each_key_duplicate');
+	}
+});
diff --git a/packages/svelte/tests/runtime-production/samples/keyed-each-unique-2/main.svelte b/packages/svelte/tests/runtime-production/samples/keyed-each-unique-2/main.svelte
new file mode 100644
index 0000000000..f8ba50d866
--- /dev/null
+++ b/packages/svelte/tests/runtime-production/samples/keyed-each-unique-2/main.svelte
@@ -0,0 +1,8 @@
+<script>
+	let data = $state([1, 2, 3]);
+</script>
+
+<button onclick={() => data = [1, 1, 1]}>add</button>
+{#each data as d (d)}
+	{d}
+{/each}
diff --git a/packages/svelte/tests/runtime-production/samples/keyed-each-unique-3/_config.js b/packages/svelte/tests/runtime-production/samples/keyed-each-unique-3/_config.js
new file mode 100644
index 0000000000..7e1840200a
--- /dev/null
+++ b/packages/svelte/tests/runtime-production/samples/keyed-each-unique-3/_config.js
@@ -0,0 +1,5 @@
+import { test } from '../../test';
+
+export default test({
+	error: 'each_key_duplicate'
+});
diff --git a/packages/svelte/tests/runtime-production/samples/keyed-each-unique-3/main.svelte b/packages/svelte/tests/runtime-production/samples/keyed-each-unique-3/main.svelte
new file mode 100644
index 0000000000..a05781bcb9
--- /dev/null
+++ b/packages/svelte/tests/runtime-production/samples/keyed-each-unique-3/main.svelte
@@ -0,0 +1,7 @@
+<script>
+	let data = [1, 1, 1];
+</script>
+
+{#each data as d (d)}
+	{d}
+{/each}
diff --git a/packages/svelte/tests/runtime-production/samples/keyed-each-unique/_config.js b/packages/svelte/tests/runtime-production/samples/keyed-each-unique/_config.js
new file mode 100644
index 0000000000..bc945876ea
--- /dev/null
+++ b/packages/svelte/tests/runtime-production/samples/keyed-each-unique/_config.js
@@ -0,0 +1,12 @@
+import { flushSync } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+	test({ assert, target }) {
+		let button = target.querySelector('button');
+
+		button?.click();
+
+		assert.throws(flushSync, 'https://svelte.dev/e/each_key_duplicate');
+	}
+});
diff --git a/packages/svelte/tests/runtime-production/samples/keyed-each-unique/main.svelte b/packages/svelte/tests/runtime-production/samples/keyed-each-unique/main.svelte
new file mode 100644
index 0000000000..3d52179372
--- /dev/null
+++ b/packages/svelte/tests/runtime-production/samples/keyed-each-unique/main.svelte
@@ -0,0 +1,8 @@
+<script>
+	let data = $state([1, 2, 3, 4, 5]);
+</script>
+
+<button onclick={() => data = [1, 1, 3, 1]}>add</button>
+{#each data as d (d)}
+	{d}
+{/each}

From f05f946feafd804de3416742e5d2379651087b2e Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Thu, 5 Feb 2026 09:57:16 -0500
Subject: [PATCH 08/23] fix: add vite-ignore comment inside dynamic crypto
 import (#17623)

---
 .changeset/forty-worlds-attack.md             | 5 +++++
 packages/svelte/src/internal/server/crypto.js | 2 +-
 2 files changed, 6 insertions(+), 1 deletion(-)
 create mode 100644 .changeset/forty-worlds-attack.md

diff --git a/.changeset/forty-worlds-attack.md b/.changeset/forty-worlds-attack.md
new file mode 100644
index 0000000000..52bb3644c0
--- /dev/null
+++ b/.changeset/forty-worlds-attack.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: add vite-ignore comment inside dynamic crypto import
diff --git a/packages/svelte/src/internal/server/crypto.js b/packages/svelte/src/internal/server/crypto.js
index 9bb6ecdd39..76d66b6d1a 100644
--- a/packages/svelte/src/internal/server/crypto.js
+++ b/packages/svelte/src/internal/server/crypto.js
@@ -13,7 +13,7 @@ export async function sha256(data) {
 		? globalThis.crypto
 		: // @ts-ignore - we don't install node types in the prod build
 			// don't use 'node:crypto' because static analysers will think we rely on node when we don't
-			(await import('node:' + 'crypto')).webcrypto;
+			(await import(/* @vite-ignore */ 'node:' + 'crypto')).webcrypto;
 
 	const hash_buffer = await crypto.subtle.digest('SHA-256', text_encoder.encode(data));
 

From fcbd3e325a62c4a2c83ff51f721fdfe26b7451d9 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Thu, 5 Feb 2026 09:59:07 -0500
Subject: [PATCH 09/23] feat: allow use of createContext when instantiating
 components programmatically (#17575)

* feat: allow use of createContext when instantiating components programmatically

* docs
---
 .changeset/orange-ants-greet.md               |  5 ++++
 documentation/docs/06-runtime/02-context.md   | 26 +++++++++++++++++++
 packages/svelte/src/internal/client/render.js | 12 +++------
 .../svelte/src/internal/server/renderer.js    | 12 +++------
 .../create-context-programmatic/Child.svelte  |  7 +++++
 .../create-context-programmatic/_config.js    |  8 ++++++
 .../create-context-programmatic/main.svelte   | 20 ++++++++++++++
 7 files changed, 74 insertions(+), 16 deletions(-)
 create mode 100644 .changeset/orange-ants-greet.md
 create mode 100644 packages/svelte/tests/runtime-runes/samples/create-context-programmatic/Child.svelte
 create mode 100644 packages/svelte/tests/runtime-runes/samples/create-context-programmatic/_config.js
 create mode 100644 packages/svelte/tests/runtime-runes/samples/create-context-programmatic/main.svelte

diff --git a/.changeset/orange-ants-greet.md b/.changeset/orange-ants-greet.md
new file mode 100644
index 0000000000..6f7c684fee
--- /dev/null
+++ b/.changeset/orange-ants-greet.md
@@ -0,0 +1,5 @@
+---
+'svelte': minor
+---
+
+feat: allow use of createContext when instantiating components programmatically
diff --git a/documentation/docs/06-runtime/02-context.md b/documentation/docs/06-runtime/02-context.md
index 0dfb996164..61b203f93e 100644
--- a/documentation/docs/06-runtime/02-context.md
+++ b/documentation/docs/06-runtime/02-context.md
@@ -97,6 +97,32 @@ import { createContext } from 'svelte';
 export const [getUserContext, setUserContext] = createContext<User>();
 ```
 
+When writing [component tests](testing#Unit-and-component-tests-with-Vitest-Component-testing), it can be useful to create a wrapper component that sets the context in order to check the behaviour of a component that uses it. As of version 5.49, you can do this sort of thing:
+
+```js
+import { mount, unmount } from 'svelte';
+import { expect, test } from 'vitest';
+import { setUserContext } from './context';
+import MyComponent from './MyComponent.svelte';
+
+test('MyComponent', () => {
+	function Wrapper(...args) {
+		setUserContext({ name: 'Bob' });
+		return MyComponent(...args);
+	}
+
+	const component = mount(Wrapper, {
+		target: document.body
+	});
+
+	expect(document.body.innerHTML).toBe('<h1>Hello Bob!</h1>');
+
+	unmount(component);
+});
+```
+
+This approach also works with [`hydrate`](imperative-component-api#hydrate) and [`render`](imperative-component-api#render).
+
 ## Replacing global state
 
 When you have state shared by many different components, you might be tempted to put it in its own module and just import it wherever it's needed:
diff --git a/packages/svelte/src/internal/client/render.js b/packages/svelte/src/internal/client/render.js
index c76f0b1ce7..c09f5fdd05 100644
--- a/packages/svelte/src/internal/client/render.js
+++ b/packages/svelte/src/internal/client/render.js
@@ -208,11 +208,9 @@ function _mount(Component, { target, anchor, props = {}, events, context, intro
 				pending: () => {}
 			},
 			(anchor_node) => {
-				if (context) {
-					push({});
-					var ctx = /** @type {ComponentContext} */ (component_context);
-					ctx.c = context;
-				}
+				push({});
+				var ctx = /** @type {ComponentContext} */ (component_context);
+				if (context) ctx.c = context;
 
 				if (events) {
 					// We can't spread the object or else we'd lose the state proxy stuff, if it is one
@@ -241,9 +239,7 @@ function _mount(Component, { target, anchor, props = {}, events, context, intro
 					}
 				}
 
-				if (context) {
-					pop();
-				}
+				pop();
 			}
 		);
 
diff --git a/packages/svelte/src/internal/server/renderer.js b/packages/svelte/src/internal/server/renderer.js
index 65f9bcae6a..49f4c1b7d2 100644
--- a/packages/svelte/src/internal/server/renderer.js
+++ b/packages/svelte/src/internal/server/renderer.js
@@ -617,18 +617,14 @@ export class Renderer {
 
 		renderer.push(BLOCK_OPEN);
 
-		if (options.context) {
-			push();
-			/** @type {SSRContext} */ (ssr_context).c = options.context;
-			/** @type {SSRContext} */ (ssr_context).r = renderer;
-		}
+		push();
+		if (options.context) /** @type {SSRContext} */ (ssr_context).c = options.context;
+		/** @type {SSRContext} */ (ssr_context).r = renderer;
 
 		// @ts-expect-error
 		component(renderer, options.props ?? {});
 
-		if (options.context) {
-			pop();
-		}
+		pop();
 
 		renderer.push(BLOCK_CLOSE);
 
diff --git a/packages/svelte/tests/runtime-runes/samples/create-context-programmatic/Child.svelte b/packages/svelte/tests/runtime-runes/samples/create-context-programmatic/Child.svelte
new file mode 100644
index 0000000000..3e39d5043e
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/create-context-programmatic/Child.svelte
@@ -0,0 +1,7 @@
+<script>
+	import { get } from './main.svelte';
+
+	const message = get();
+</script>
+
+<h1>{message}</h1>
diff --git a/packages/svelte/tests/runtime-runes/samples/create-context-programmatic/_config.js b/packages/svelte/tests/runtime-runes/samples/create-context-programmatic/_config.js
new file mode 100644
index 0000000000..f4374c8759
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/create-context-programmatic/_config.js
@@ -0,0 +1,8 @@
+import { test } from '../../test';
+
+export default test({
+	ssrHtml: `<div></div>`,
+	html: `<div><h1>hello</h1></div>`,
+
+	test() {}
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/create-context-programmatic/main.svelte b/packages/svelte/tests/runtime-runes/samples/create-context-programmatic/main.svelte
new file mode 100644
index 0000000000..3c42dbf180
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/create-context-programmatic/main.svelte
@@ -0,0 +1,20 @@
+<script module>
+	import { createContext, mount } from 'svelte';
+	import Child from './Child.svelte';
+
+	/** @type {ReturnType<typeof createContext<string>>} */
+	const [get, set] = createContext();
+
+	export { get };
+
+	function Wrapper(Component) {
+		return (...args) => {
+			set('hello');
+			return Component(...args);
+		};
+	}
+</script>
+
+<div {@attach (target) => {
+	mount(Wrapper(Child), { target });
+}}></div>

From 3970e7a302e29fa09eb3c0351301f260401e32f0 Mon Sep 17 00:00:00 2001
From: Elliott Johnson <sejohnson@torchcloudconsulting.com>
Date: Thu, 5 Feb 2026 13:58:50 -0700
Subject: [PATCH 10/23] chore: fix pkg.pr.new workflow (#17633)

---
 .github/workflows/pkg.pr.new-comment.yml | 115 -------------
 .github/workflows/pkg.pr.new.yml         | 205 +++++++++++++++++++++--
 2 files changed, 190 insertions(+), 130 deletions(-)
 delete mode 100644 .github/workflows/pkg.pr.new-comment.yml

diff --git a/.github/workflows/pkg.pr.new-comment.yml b/.github/workflows/pkg.pr.new-comment.yml
deleted file mode 100644
index 64495cc5c8..0000000000
--- a/.github/workflows/pkg.pr.new-comment.yml
+++ /dev/null
@@ -1,115 +0,0 @@
-name: Update pkg.pr.new comment
-
-on:
-  workflow_run:
-    workflows: ['Publish Any Commit']
-    types:
-      - completed
-
-permissions:
-  pull-requests: write
-
-jobs:
-  build:
-    name: 'Update comment'
-    runs-on: ubuntu-latest
-    steps:
-      - name: Download artifact
-        uses: actions/download-artifact@v7
-        with:
-          name: output
-          github-token: ${{ secrets.GITHUB_TOKEN }}
-          run-id: ${{ github.event.workflow_run.id }}
-
-      - run: ls -R .
-      - name: 'Post or update comment'
-        uses: actions/github-script@v8
-        with:
-          github-token: ${{ secrets.GITHUB_TOKEN }}
-          script: |
-            const fs = require('fs');
-            const output = JSON.parse(fs.readFileSync('output.json', 'utf8'));
-
-            const bot_comment_identifier = `<!-- pkg.pr.new comment -->`;
-
-            const body = (number) => `${bot_comment_identifier}
-
-            [Playground](https://svelte.dev/playground?version=pr-${number})
-
-            \`\`\`
-            ${output.packages.map((p) => `pnpm add https://pkg.pr.new/${p.name}@${number}`).join('\n')}
-            \`\`\`
-            `;
-
-            async function find_bot_comment(issue_number) {
-              if (!issue_number) return null;
-              const comments = await github.rest.issues.listComments({
-                owner: context.repo.owner,
-                repo: context.repo.repo,
-                issue_number: issue_number,
-              });
-              return comments.data.find((comment) =>
-                comment.body.includes(bot_comment_identifier)
-              );
-            }
-
-            async function create_or_update_comment(issue_number) {
-              if (!issue_number) {
-                console.log('No issue number provided. Cannot post or update comment.');
-                return;
-              }
-
-              const existing_comment = await find_bot_comment(issue_number);
-              if (existing_comment) {
-                await github.rest.issues.updateComment({
-                  owner: context.repo.owner,
-                  repo: context.repo.repo,
-                  comment_id: existing_comment.id,
-                  body: body(issue_number),
-                });
-              } else {
-                await github.rest.issues.createComment({
-                  issue_number: issue_number,
-                  owner: context.repo.owner,
-                  repo: context.repo.repo,
-                  body: body(issue_number),
-                });
-              }
-            }
-
-            async function log_publish_info() {
-              const svelte_package = output.packages.find(p => p.name === 'svelte');
-              const svelte_sha = svelte_package.url.replace(/^.+@([^@]+)$/, '$1');
-              console.log('\n' + '='.repeat(50));
-              console.log('Publish Information');
-              console.log('='.repeat(50));
-              console.log('\nPublished Packages:');
-              console.log(output.packages.map((p) => `${p.name} - pnpm add https://pkg.pr.new/${p.name}@${p.url.replace(/^.+@([^@]+)$/, '$1')}`).join('\n'));
-              if(svelte_sha){
-                console.log('\nPlayground URL:');
-                console.log(`\nhttps://svelte.dev/playground?version=commit-${svelte_sha}`)
-              }
-              console.log('\n' + '='.repeat(50));
-            }
-
-            if (output.event_name === 'pull_request') {
-              if (output.number) {
-                await create_or_update_comment(output.number);
-              }
-            } else if (output.event_name === 'push') {
-              const pull_requests = await github.rest.pulls.list({
-                owner: context.repo.owner,
-                repo: context.repo.repo,
-                state: 'open',
-                head: `${context.repo.owner}:${output.ref.replace('refs/heads/', '')}`,
-              });
-
-              if (pull_requests.data.length > 0) {
-                await create_or_update_comment(pull_requests.data[0].number);
-              } else {
-                console.log(
-                  'No open pull request found for this push. Logging publish information to console:'
-                );
-                await log_publish_info();
-              }
-            }
diff --git a/.github/workflows/pkg.pr.new.yml b/.github/workflows/pkg.pr.new.yml
index 252cbed769..51b7472911 100644
--- a/.github/workflows/pkg.pr.new.yml
+++ b/.github/workflows/pkg.pr.new.yml
@@ -1,16 +1,51 @@
-name: Publish Any Commit
-on: [push, pull_request]
+name: pkg.pr.new
+on:
+  pull_request_target:
+    types: [opened, synchronize]
+  push:
+    branches: [main]
 
 permissions: {}
 
 jobs:
-  build:
-    permissions: {}
+  # This job determines the environment to use for the build job. It ensures that:
+  # - For pushes to main, we use the "Publish pkg.pr.new (maintainers)" environment.
+  # - For PRs from the same repository, we also use the "Publish pkg.pr.new (maintainers)" environment, since these are trusted.
+  # - For PRs from forks, we use the "Publish pkg.pr.new (external contributors)" environment, which requires manual approval by a maintainer before the build job can run.
+  #   This protects us from running untrusted code while still allowing external contributors to use pkg.pr.new.
+  resolve-env:
+    runs-on: ubuntu-latest
+    outputs:
+      environment: ${{ steps.resolve.outputs.environment }}
+    steps:
+      - name: Determine environment
+        id: resolve
+        run: |
+          if [[ "${{ github.event_name }}" == "push" ]]; then
+            echo "environment=Publish pkg.pr.new (maintainers)" >> "$GITHUB_OUTPUT"
+          elif [[ "${{ github.event.pull_request.head.repo.full_name }}" == "${{ github.repository }}" ]]; then
+            echo "environment=Publish pkg.pr.new (maintainers)" >> "$GITHUB_OUTPUT"
+          else
+            echo "environment=Publish pkg.pr.new (external contributors)" >> "$GITHUB_OUTPUT"
+          fi
 
+  build:
+    needs: resolve-env
     runs-on: ubuntu-latest
+    # This is the line that ensures forks require manual approval before running the build job
+    environment: ${{ needs.resolve-env.outputs.environment }}
+
+    # No permissions — this job runs user-controlled code
+    permissions: {}
 
     steps:
       - uses: actions/checkout@v6
+        with:
+          # For pull_request_target, we must explicitly check out the PR head.
+          # This is safe because the environment gate above has already fired —
+          # an org member has approved this specific commit for external PRs.
+          ref: ${{ github.event.pull_request.head.sha || github.sha }}
+
       - uses: pnpm/action-setup@v4
       - uses: actions/setup-node@v6
         with:
@@ -24,21 +59,161 @@ jobs:
         run: pnpm build
 
       - run: pnpx pkg-pr-new publish --comment=off --json output.json --compact --no-template './packages/svelte'
-      - name: Add metadata to output
+
+      - name: Upload output
+        uses: actions/upload-artifact@v4
+        with:
+          name: output
+          path: ./output.json
+
+  # Sanitizes the untrusted output from the build job before it's consumed by
+  # jobs with elevated permissions. This ensures that only known package names
+  # and valid SHA prefixes make it through.
+  sanitize:
+    needs: build
+    runs-on: ubuntu-latest
+
+    permissions: {}
+
+    steps:
+      - name: Download artifact
+        uses: actions/download-artifact@v7
+        with:
+          name: output
+
+      - name: Sanitize output
+        uses: actions/github-script@v8
+        with:
+          script: |
+            const fs = require('fs');
+            const raw = JSON.parse(fs.readFileSync('output.json', 'utf8'));
+
+            const ALLOWED_PACKAGES = new Set(['svelte']);
+            const SHA_PATTERN = /^[0-9a-f]{6}$/;
+
+            const packages = (raw.packages || [])
+              .filter(p => {
+                if (!ALLOWED_PACKAGES.has(p.name)) {
+                  console.log(`Skipping unexpected package: ${JSON.stringify(p.name)}`);
+                  return false;
+                }
+                const sha = p.url?.replace(/^.+@([^@]+)$/, '$1');
+                if (!sha || !SHA_PATTERN.test(sha)) {
+                  console.log(`Skipping package with invalid SHA: ${JSON.stringify(p.url)}`);
+                  return false;
+                }
+                return true;
+              })
+              .map(p => ({
+                name: p.name,
+                sha: p.url.replace(/^.+@([^@]+)$/, '$1'),
+              }));
+
+            fs.writeFileSync('sanitized-output.json', JSON.stringify({ packages }), 'utf8');
+
+      - name: Upload sanitized output
+        uses: actions/upload-artifact@v4
+        with:
+          name: sanitized-output
+          path: ./sanitized-output.json
+
+  comment:
+    needs: sanitize
+    if: github.event_name == 'pull_request_target'
+    runs-on: ubuntu-latest
+
+    permissions:
+      pull-requests: write
+
+    steps:
+      - name: Download sanitized artifact
+        uses: actions/download-artifact@v7
+        with:
+          name: sanitized-output
+
+      - name: Post or update comment
         uses: actions/github-script@v8
         with:
           github-token: ${{ secrets.GITHUB_TOKEN }}
           script: |
             const fs = require('fs');
-            const output = JSON.parse(fs.readFileSync('output.json', 'utf8'));
-            output.number = context.issue.number;
-            output.event_name = context.eventName;
-            output.ref = context.ref;
-            fs.writeFileSync('output.json', JSON.stringify(output), 'utf8');
-      - name: Upload output
-        uses: actions/upload-artifact@v6
+            const { packages } = JSON.parse(fs.readFileSync('sanitized-output.json', 'utf8'));
+
+            if (packages.length === 0) {
+              console.log('No valid packages found. Skipping comment.');
+              return;
+            }
+
+            // Issue number from trusted event context, never from the artifact
+            const issue_number = context.issue.number;
+
+            const bot_comment_identifier = `<!-- pkg.pr.new comment -->`;
+
+            const body = `${bot_comment_identifier}
+
+            [Playground](https://svelte.dev/playground?version=pr-${issue_number})
+
+            \`\`\`
+            ${packages.map(p => `pnpm add https://pkg.pr.new/${p.name}@${issue_number}`).join('\n')}
+            \`\`\`
+            `;
+
+            const comments = await github.rest.issues.listComments({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              issue_number,
+            });
+            const existing = comments.data.find(c => c.body.includes(bot_comment_identifier));
+
+            if (existing) {
+              await github.rest.issues.updateComment({
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                comment_id: existing.id,
+                body,
+              });
+            } else {
+              await github.rest.issues.createComment({
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                issue_number,
+                body,
+              });
+            }
+
+  log:
+    needs: sanitize
+    if: github.event_name == 'push'
+    runs-on: ubuntu-latest
+
+    permissions: {}
+
+    steps:
+      - name: Download sanitized artifact
+        uses: actions/download-artifact@v7
         with:
-          name: output
-          path: ./output.json
+          name: sanitized-output
+
+      - name: Log publish info
+        uses: actions/github-script@v8
+        with:
+          script: |
+            const fs = require('fs');
+            const { packages } = JSON.parse(fs.readFileSync('sanitized-output.json', 'utf8'));
+
+            if (packages.length === 0) {
+              console.log('No valid packages found.');
+              return;
+            }
 
-      - run: ls -R .
+            console.log('\n' + '='.repeat(50));
+            console.log('Publish Information');
+            console.log('='.repeat(50));
+            for (const p of packages) {
+              console.log(`${p.name} - pnpm add https://pkg.pr.new/${p.name}@${p.sha}`);
+            }
+            const svelte = packages.find(p => p.name === 'svelte');
+            if (svelte) {
+              console.log(`\nPlayground: https://svelte.dev/playground?version=commit-${svelte.sha}`);
+            }
+            console.log('='.repeat(50));

From 660c4c12b1e1c50d067dfd800465bea21d29651f Mon Sep 17 00:00:00 2001
From: Elliott Johnson <sejohnson@torchcloudconsulting.com>
Date: Thu, 5 Feb 2026 14:04:56 -0700
Subject: [PATCH 11/23] chore: off-by-one in workflow (#17634)

---
 .github/workflows/pkg.pr.new.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/pkg.pr.new.yml b/.github/workflows/pkg.pr.new.yml
index 51b7472911..0f0c433361 100644
--- a/.github/workflows/pkg.pr.new.yml
+++ b/.github/workflows/pkg.pr.new.yml
@@ -89,7 +89,7 @@ jobs:
             const raw = JSON.parse(fs.readFileSync('output.json', 'utf8'));
 
             const ALLOWED_PACKAGES = new Set(['svelte']);
-            const SHA_PATTERN = /^[0-9a-f]{6}$/;
+            const SHA_PATTERN = /^[0-9a-f]{7}$/;
 
             const packages = (raw.packages || [])
               .filter(p => {

From a75866f34d5b64e0c40b2888a5f89a69ec1151f9 Mon Sep 17 00:00:00 2001
From: Artyom Alekseevich <47069814+FrankFMY@users.noreply.github.com>
Date: Thu, 5 Feb 2026 23:03:40 +0100
Subject: [PATCH 12/23] fix: detect store in each block expression regardless
 of AST shape (#17636)

The store invalidation detection in each blocks only checked for
Identifier and MemberExpression AST node types. This caused bind:
on iteration variables to silently fail when the expression used
logical operators (e.g. `{#each $store.items ?? [] as item}`).

Use expression metadata dependencies instead of AST type checking
to find store_sub bindings, which correctly handles all expression
shapes.

Fixes #14625
---
 .changeset/fix-each-bind-store-logical.md     |  5 +++++
 .../3-transform/client/visitors/EachBlock.js  | 12 ++++------
 .../store-each-binding-logical/_config.js     | 22 +++++++++++++++++++
 .../store-each-binding-logical/main.svelte    | 13 +++++++++++
 4 files changed, 44 insertions(+), 8 deletions(-)
 create mode 100644 .changeset/fix-each-bind-store-logical.md
 create mode 100644 packages/svelte/tests/runtime-legacy/samples/store-each-binding-logical/_config.js
 create mode 100644 packages/svelte/tests/runtime-legacy/samples/store-each-binding-logical/main.svelte

diff --git a/.changeset/fix-each-bind-store-logical.md b/.changeset/fix-each-bind-store-logical.md
new file mode 100644
index 0000000000..1327015124
--- /dev/null
+++ b/.changeset/fix-each-bind-store-logical.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: detect store in each block expression regardless of AST shape
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
index b2724fa90f..a1371b516a 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/EachBlock.js
@@ -101,15 +101,11 @@ export function EachBlock(node, context) {
 	}
 
 	// If the array is a store expression, we need to invalidate it when the array is changed.
-	// This doesn't catch all cases, but all the ones that Svelte 4 catches, too.
 	let store_to_invalidate = '';
-	if (node.expression.type === 'Identifier' || node.expression.type === 'MemberExpression') {
-		const id = object(node.expression);
-		if (id) {
-			const binding = context.state.scope.get(id.name);
-			if (binding?.kind === 'store_sub') {
-				store_to_invalidate = id.name;
-			}
+	for (const binding of node.metadata.expression.dependencies) {
+		if (binding.kind === 'store_sub') {
+			store_to_invalidate = binding.node.name;
+			break;
 		}
 	}
 
diff --git a/packages/svelte/tests/runtime-legacy/samples/store-each-binding-logical/_config.js b/packages/svelte/tests/runtime-legacy/samples/store-each-binding-logical/_config.js
new file mode 100644
index 0000000000..1134b20d0c
--- /dev/null
+++ b/packages/svelte/tests/runtime-legacy/samples/store-each-binding-logical/_config.js
@@ -0,0 +1,22 @@
+import { flushSync } from 'svelte';
+import { ok, test } from '../../test';
+
+export default test({
+	test({ assert, target, window }) {
+		const input = target.querySelector('input');
+		ok(input);
+
+		const event = new window.Event('input');
+		input.value = 'changed';
+		input.dispatchEvent(event);
+		flushSync();
+
+		assert.htmlEqual(
+			target.innerHTML,
+			`
+			<input>
+			<p>changed</p>
+		`
+		);
+	}
+});
diff --git a/packages/svelte/tests/runtime-legacy/samples/store-each-binding-logical/main.svelte b/packages/svelte/tests/runtime-legacy/samples/store-each-binding-logical/main.svelte
new file mode 100644
index 0000000000..77731ea5a4
--- /dev/null
+++ b/packages/svelte/tests/runtime-legacy/samples/store-each-binding-logical/main.svelte
@@ -0,0 +1,13 @@
+<script>
+	import { writable } from 'svelte/store';
+
+	const items = writable([
+		{ id: 0, text: 'initial' }
+	]);
+</script>
+
+{#each $items ?? [] as item}
+	<input bind:value={item.text}>
+{/each}
+
+<p>{$items[0].text}</p>

From f5304ec8c944b1893e8150449d26cf07af910d7b Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 6 Feb 2026 04:11:26 -0500
Subject: [PATCH 13/23] chore: simplify SSR code (#17639)

creates a few abstractions in the compiler code around common "if-else" scenarios, as well as introducing a new runtime render helper

---------

Co-authored-by: Simon Holthausen <simon.holthausen@vercel.com>
Co-authored-by: Simon H <5968653+dummdidumm@users.noreply.github.com>
---
 .../3-transform/client/visitors/Fragment.js   |  40 +++---
 .../3-transform/server/transform-server.js    |  11 +-
 .../phases/3-transform/server/types.d.ts      |   3 +-
 .../3-transform/server/visitors/AwaitBlock.js |  15 ++-
 .../3-transform/server/visitors/EachBlock.js  |  30 ++---
 .../3-transform/server/visitors/Fragment.js   |   2 +-
 .../3-transform/server/visitors/HtmlTag.js    |  25 ++--
 .../3-transform/server/visitors/IfBlock.js    |  21 ++--
 .../server/visitors/RegularElement.js         |  55 ++------
 .../3-transform/server/visitors/RenderTag.js  |  14 +--
 .../server/visitors/SlotElement.js            |  11 +-
 .../server/visitors/SvelteElement.js          |  53 +++-----
 .../server/visitors/shared/component.js       |  41 ++----
 .../server/visitors/shared/utils.js           | 118 +++++++++---------
 .../svelte/src/internal/server/renderer.js    |   9 ++
 .../_expected/server/index.svelte.js          |   6 +-
 .../_expected/server/index.svelte.js          |   2 +-
 .../_expected/server/index.svelte.js          |   2 +-
 .../_expected/server/index.svelte.js          |   2 +-
 .../_expected/server/index.svelte.js          |   2 +-
 .../_expected/server/index.svelte.js          |   6 +-
 21 files changed, 184 insertions(+), 284 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/Fragment.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/Fragment.js
index 79a443967c..f463111c4d 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/Fragment.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/Fragment.js
@@ -120,34 +120,32 @@ export function Fragment(node, context) {
 
 			state.init.unshift(b.var(id, b.call('$.text')));
 			close = b.stmt(b.call('$.append', b.id('$$anchor'), id));
+		} else if (is_standalone) {
+			// no need to create a template, we can just use the existing block's anchor
+			process_children(trimmed, () => b.id('$$anchor'), false, { ...context, state });
 		} else {
-			if (is_standalone) {
-				// no need to create a template, we can just use the existing block's anchor
-				process_children(trimmed, () => b.id('$$anchor'), false, { ...context, state });
-			} else {
-				/** @type {(is_text: boolean) => Expression} */
-				const expression = (is_text) => b.call('$.first_child', id, is_text && b.true);
-
-				process_children(trimmed, expression, false, { ...context, state });
+			/** @type {(is_text: boolean) => Expression} */
+			const expression = (is_text) => b.call('$.first_child', id, is_text && b.true);
 
-				let flags = TEMPLATE_FRAGMENT;
+			process_children(trimmed, expression, false, { ...context, state });
 
-				if (state.template.needs_import_node) {
-					flags |= TEMPLATE_USE_IMPORT_NODE;
-				}
+			let flags = TEMPLATE_FRAGMENT;
 
-				if (state.template.nodes.length === 1 && state.template.nodes[0].type === 'comment') {
-					// special case — we can use `$.comment` instead of creating a unique template
-					state.init.unshift(b.var(id, b.call('$.comment')));
-				} else {
-					const template = transform_template(state, namespace, flags);
-					state.hoisted.push(b.var(template_name, template));
+			if (state.template.needs_import_node) {
+				flags |= TEMPLATE_USE_IMPORT_NODE;
+			}
 
-					state.init.unshift(b.var(id, b.call(template_name)));
-				}
+			if (state.template.nodes.length === 1 && state.template.nodes[0].type === 'comment') {
+				// special case — we can use `$.comment` instead of creating a unique template
+				state.init.unshift(b.var(id, b.call('$.comment')));
+			} else {
+				const template = transform_template(state, namespace, flags);
+				state.hoisted.push(b.var(template_name, template));
 
-				close = b.stmt(b.call('$.append', b.id('$$anchor'), id));
+				state.init.unshift(b.var(id, b.call(template_name)));
 			}
+
+			close = b.stmt(b.call('$.append', b.id('$$anchor'), id));
 		}
 	}
 
diff --git a/packages/svelte/src/compiler/phases/3-transform/server/transform-server.js b/packages/svelte/src/compiler/phases/3-transform/server/transform-server.js
index 0e2f68d0f5..b9f1441bff 100644
--- a/packages/svelte/src/compiler/phases/3-transform/server/transform-server.js
+++ b/packages/svelte/src/compiler/phases/3-transform/server/transform-server.js
@@ -41,7 +41,6 @@ import { TitleElement } from './visitors/TitleElement.js';
 import { UpdateExpression } from './visitors/UpdateExpression.js';
 import { VariableDeclaration } from './visitors/VariableDeclaration.js';
 import { SvelteBoundary } from './visitors/SvelteBoundary.js';
-import { call_component_renderer } from './visitors/shared/utils.js';
 
 /** @type {Visitors} */
 const global_visitors = {
@@ -105,7 +104,7 @@ export function server_component(analysis, options) {
 		namespace: options.namespace,
 		preserve_whitespace: options.preserveWhitespace,
 		state_fields: new Map(),
-		skip_hydration_boundaries: false,
+		is_standalone: false,
 		is_instance: false
 	};
 
@@ -260,7 +259,13 @@ export function server_component(analysis, options) {
 
 	if (should_inject_context) {
 		component_block = b.block([
-			call_component_renderer(component_block, dev && b.id(component_name))
+			b.stmt(
+				b.call(
+					'$$renderer.component',
+					b.arrow([b.id('$$renderer')], component_block, false),
+					dev && b.id(component_name)
+				)
+			)
 		]);
 	}
 
diff --git a/packages/svelte/src/compiler/phases/3-transform/server/types.d.ts b/packages/svelte/src/compiler/phases/3-transform/server/types.d.ts
index e7a72fb8ad..4912728a1e 100644
--- a/packages/svelte/src/compiler/phases/3-transform/server/types.d.ts
+++ b/packages/svelte/src/compiler/phases/3-transform/server/types.d.ts
@@ -26,7 +26,8 @@ export interface ComponentServerTransformState extends ServerTransformState {
 	readonly template: Array<Statement | Expression>;
 	readonly namespace: Namespace;
 	readonly preserve_whitespace: boolean;
-	readonly skip_hydration_boundaries: boolean;
+	/** True if the current node is a) a component or render tag and b) the sole child of a block  */
+	readonly is_standalone: boolean;
 	/** Transformed async `{@const }` declarations (if any) and those coming after them */
 	async_consts?: {
 		id: Identifier;
diff --git a/packages/svelte/src/compiler/phases/3-transform/server/visitors/AwaitBlock.js b/packages/svelte/src/compiler/phases/3-transform/server/visitors/AwaitBlock.js
index b8d2e42144..84c2a81612 100644
--- a/packages/svelte/src/compiler/phases/3-transform/server/visitors/AwaitBlock.js
+++ b/packages/svelte/src/compiler/phases/3-transform/server/visitors/AwaitBlock.js
@@ -2,7 +2,7 @@
 /** @import { AST } from '#compiler' */
 /** @import { ComponentContext } from '../types.js' */
 import * as b from '#compiler/builders';
-import { block_close, create_async_block } from './shared/utils.js';
+import { block_close, create_child_block } from './shared/utils.js';
 
 /**
  * @param {AST.AwaitBlock} node
@@ -25,13 +25,12 @@ export function AwaitBlock(node, context) {
 		)
 	);
 
-	if (node.metadata.expression.is_async()) {
-		statement = create_async_block(
-			b.block([statement]),
+	context.state.template.push(
+		...create_child_block(
+			[statement],
 			node.metadata.expression.blockers(),
 			node.metadata.expression.has_await
-		);
-	}
-
-	context.state.template.push(statement, block_close);
+		),
+		block_close
+	);
 }
diff --git a/packages/svelte/src/compiler/phases/3-transform/server/visitors/EachBlock.js b/packages/svelte/src/compiler/phases/3-transform/server/visitors/EachBlock.js
index 3c0a8c1676..cb5a61d52f 100644
--- a/packages/svelte/src/compiler/phases/3-transform/server/visitors/EachBlock.js
+++ b/packages/svelte/src/compiler/phases/3-transform/server/visitors/EachBlock.js
@@ -2,7 +2,7 @@
 /** @import { AST } from '#compiler' */
 /** @import { ComponentContext } from '../types.js' */
 import * as b from '#compiler/builders';
-import { block_close, block_open, block_open_else, create_async_block } from './shared/utils.js';
+import { block_close, block_open, block_open_else, create_child_block } from './shared/utils.js';
 
 /**
  * @param {AST.EachBlock} node
@@ -18,8 +18,8 @@ export function EachBlock(node, context) {
 
 	const array_id = state.scope.root.unique('each_array');
 
-	/** @type {Statement} */
-	let block = b.block([b.const(array_id, b.call('$.ensure_array_like', collection))]);
+	/** @type {Statement[]} */
+	let statements = [b.const(array_id, b.call('$.ensure_array_like', collection))];
 
 	/** @type {Statement[]} */
 	const each = [];
@@ -53,7 +53,7 @@ export function EachBlock(node, context) {
 
 		fallback.body.unshift(b.stmt(b.call(b.id('$$renderer.push'), block_open_else)));
 
-		block.body.push(
+		statements.push(
 			b.if(
 				b.binary('!==', b.member(array_id, 'length'), b.literal(0)),
 				b.block([open, for_loop]),
@@ -62,19 +62,15 @@ export function EachBlock(node, context) {
 		);
 	} else {
 		state.template.push(block_open);
-		block.body.push(for_loop);
+		statements.push(for_loop);
 	}
 
-	if (node.metadata.expression.is_async()) {
-		state.template.push(
-			create_async_block(
-				block,
-				node.metadata.expression.blockers(),
-				node.metadata.expression.has_await
-			),
-			block_close
-		);
-	} else {
-		state.template.push(...block.body, block_close);
-	}
+	state.template.push(
+		...create_child_block(
+			statements,
+			node.metadata.expression.blockers(),
+			node.metadata.expression.has_await
+		),
+		block_close
+	);
 }
diff --git a/packages/svelte/src/compiler/phases/3-transform/server/visitors/Fragment.js b/packages/svelte/src/compiler/phases/3-transform/server/visitors/Fragment.js
index ef5bd985ae..a6ff33c7ab 100644
--- a/packages/svelte/src/compiler/phases/3-transform/server/visitors/Fragment.js
+++ b/packages/svelte/src/compiler/phases/3-transform/server/visitors/Fragment.js
@@ -28,7 +28,7 @@ export function Fragment(node, context) {
 		init: [],
 		template: [],
 		namespace,
-		skip_hydration_boundaries: is_standalone,
+		is_standalone,
 		async_consts: undefined
 	};
 
diff --git a/packages/svelte/src/compiler/phases/3-transform/server/visitors/HtmlTag.js b/packages/svelte/src/compiler/phases/3-transform/server/visitors/HtmlTag.js
index 3f423fa60d..ee790c3e7c 100644
--- a/packages/svelte/src/compiler/phases/3-transform/server/visitors/HtmlTag.js
+++ b/packages/svelte/src/compiler/phases/3-transform/server/visitors/HtmlTag.js
@@ -2,25 +2,24 @@
 /** @import { AST } from '#compiler' */
 /** @import { ComponentContext } from '../types.js' */
 import * as b from '#compiler/builders';
-import { block_close, block_open, create_push } from './shared/utils.js';
+import { create_child_block } from './shared/utils.js';
 
 /**
  * @param {AST.HtmlTag} node
  * @param {ComponentContext} context
  */
 export function HtmlTag(node, context) {
-	const expression = /** @type {Expression} */ (context.visit(node.expression));
-	const call = b.call('$.html', expression);
+	const expression = b.call('$.html', /** @type {Expression} */ (context.visit(node.expression)));
 
-	const has_await = node.metadata.expression.has_await;
-
-	if (has_await) {
-		context.state.template.push(block_open);
-	}
-
-	context.state.template.push(create_push(call, node.metadata.expression, true));
-
-	if (has_await) {
-		context.state.template.push(block_close);
+	if (node.metadata.expression.is_async()) {
+		context.state.template.push(
+			...create_child_block(
+				[b.stmt(b.call('$$renderer.push', expression))],
+				node.metadata.expression.blockers(),
+				node.metadata.expression.has_await
+			)
+		);
+	} else {
+		context.state.template.push(expression);
 	}
 }
diff --git a/packages/svelte/src/compiler/phases/3-transform/server/visitors/IfBlock.js b/packages/svelte/src/compiler/phases/3-transform/server/visitors/IfBlock.js
index e8418343be..06b1b1e966 100644
--- a/packages/svelte/src/compiler/phases/3-transform/server/visitors/IfBlock.js
+++ b/packages/svelte/src/compiler/phases/3-transform/server/visitors/IfBlock.js
@@ -2,7 +2,7 @@
 /** @import { AST } from '#compiler' */
 /** @import { ComponentContext } from '../types.js' */
 import * as b from '#compiler/builders';
-import { block_close, block_open, block_open_else, create_async_block } from './shared/utils.js';
+import { block_close, block_open, block_open_else, create_child_block } from './shared/utils.js';
 
 /**
  * @param {AST.IfBlock} node
@@ -23,17 +23,12 @@ export function IfBlock(node, context) {
 	/** @type {Statement} */
 	let statement = b.if(test, consequent, alternate);
 
-	const is_async = node.metadata.expression.is_async();
-
-	const has_await = node.metadata.expression.has_await;
-
-	if (is_async || has_await) {
-		statement = create_async_block(
-			b.block([statement]),
+	context.state.template.push(
+		...create_child_block(
+			[statement],
 			node.metadata.expression.blockers(),
-			!!has_await
-		);
-	}
-
-	context.state.template.push(statement, block_close);
+			node.metadata.expression.has_await
+		),
+		block_close
+	);
 }
diff --git a/packages/svelte/src/compiler/phases/3-transform/server/visitors/RegularElement.js b/packages/svelte/src/compiler/phases/3-transform/server/visitors/RegularElement.js
index 5b905752f4..1c6bb0a198 100644
--- a/packages/svelte/src/compiler/phases/3-transform/server/visitors/RegularElement.js
+++ b/packages/svelte/src/compiler/phases/3-transform/server/visitors/RegularElement.js
@@ -1,5 +1,4 @@
 /** @import { Expression } from 'estree' */
-/** @import { Location } from 'locate-character' */
 /** @import { AST } from '#compiler' */
 /** @import { ComponentContext, ComponentServerTransformState } from '../types.js' */
 /** @import { Scope } from '../../../scope.js' */
@@ -8,13 +7,7 @@ import { dev, locator } from '../../../../state.js';
 import * as b from '#compiler/builders';
 import { clean_nodes, determine_namespace_for_children } from '../../utils.js';
 import { build_element_attributes, prepare_element_spread_object } from './shared/element.js';
-import {
-	process_children,
-	build_template,
-	create_child_block,
-	PromiseOptimiser,
-	create_async_block
-} from './shared/utils.js';
+import { process_children, build_template, PromiseOptimiser } from './shared/utils.js';
 import { is_customizable_select_element } from '../../../nodes.js';
 
 /**
@@ -66,17 +59,9 @@ export function RegularElement(node, context) {
 			b.literal(`</${node.name}>`)
 		);
 
-		// TODO this is a real edge case, would be good to DRY this out
-		if (optimiser.expressions.length > 0) {
-			context.state.template.push(
-				create_child_block(
-					b.block([optimiser.apply(), ...state.init, ...build_template(state.template)])
-				)
-			);
-		} else {
-			context.state.init.push(...state.init);
-			context.state.template.push(...state.template);
-		}
+		context.state.template.push(
+			...optimiser.render([...state.init, ...build_template(state.template)])
+		);
 
 		return;
 	}
@@ -130,13 +115,7 @@ export function RegularElement(node, context) {
 
 		const statement = b.stmt(b.call('$$renderer.select', attributes, fn, ...rest));
 
-		if (optimiser.expressions.length > 0) {
-			context.state.template.push(
-				create_child_block(b.block([optimiser.apply(), ...state.init, statement]))
-			);
-		} else {
-			context.state.template.push(...state.init, statement);
-		}
+		context.state.template.push(...optimiser.render([...state.init, statement]));
 
 		return;
 	}
@@ -183,13 +162,7 @@ export function RegularElement(node, context) {
 
 		const statement = b.stmt(b.call('$$renderer.option', attributes, body, ...rest));
 
-		if (optimiser.expressions.length > 0) {
-			context.state.template.push(
-				create_child_block(b.block([optimiser.apply(), ...state.init, statement]))
-			);
-		} else {
-			context.state.template.push(...state.init, statement);
-		}
+		context.state.template.push(...optimiser.render([...state.init, statement]));
 
 		return;
 	}
@@ -235,19 +208,9 @@ export function RegularElement(node, context) {
 	}
 
 	if (optimiser.is_async()) {
-		let statements = [...state.init, ...build_template(state.template)];
-
-		if (optimiser.has_await) {
-			statements = [create_child_block(b.block([optimiser.apply(), ...statements]))];
-		}
-
-		const blockers = optimiser.blockers();
-
-		if (blockers.elements.length > 0) {
-			statements = [create_async_block(b.block(statements), blockers, false, false)];
-		}
-
-		context.state.template.push(...statements);
+		context.state.template.push(
+			...optimiser.render([...state.init, ...build_template(state.template)])
+		);
 	} else {
 		context.state.init.push(...state.init);
 		context.state.template.push(...state.template);
diff --git a/packages/svelte/src/compiler/phases/3-transform/server/visitors/RenderTag.js b/packages/svelte/src/compiler/phases/3-transform/server/visitors/RenderTag.js
index 6d7cef0d95..fe20e85e1b 100644
--- a/packages/svelte/src/compiler/phases/3-transform/server/visitors/RenderTag.js
+++ b/packages/svelte/src/compiler/phases/3-transform/server/visitors/RenderTag.js
@@ -3,7 +3,7 @@
 /** @import { ComponentContext } from '../types.js' */
 import { unwrap_optional } from '../../../../utils/ast.js';
 import * as b from '#compiler/builders';
-import { create_async_block, empty_comment, PromiseOptimiser } from './shared/utils.js';
+import { empty_comment, PromiseOptimiser } from './shared/utils.js';
 
 /**
  * @param {AST.RenderTag} node
@@ -35,17 +35,9 @@ export function RenderTag(node, context) {
 		)
 	);
 
-	if (optimiser.is_async()) {
-		statement = create_async_block(
-			b.block([optimiser.apply(), statement]),
-			optimiser.blockers(),
-			optimiser.has_await
-		);
-	}
-
-	context.state.template.push(statement);
+	context.state.template.push(...optimiser.render_block([statement]));
 
-	if (!context.state.skip_hydration_boundaries) {
+	if (!context.state.is_standalone) {
 		context.state.template.push(empty_comment);
 	}
 }
diff --git a/packages/svelte/src/compiler/phases/3-transform/server/visitors/SlotElement.js b/packages/svelte/src/compiler/phases/3-transform/server/visitors/SlotElement.js
index d0f8e25d02..3cebdf4541 100644
--- a/packages/svelte/src/compiler/phases/3-transform/server/visitors/SlotElement.js
+++ b/packages/svelte/src/compiler/phases/3-transform/server/visitors/SlotElement.js
@@ -5,7 +5,6 @@ import * as b from '#compiler/builders';
 import {
 	build_attribute_value,
 	PromiseOptimiser,
-	create_async_block,
 	block_open,
 	block_close
 } from './shared/utils.js';
@@ -65,13 +64,5 @@ export function SlotElement(node, context) {
 		fallback
 	);
 
-	const statement = optimiser.is_async()
-		? create_async_block(
-				b.block([optimiser.apply(), b.stmt(slot)]),
-				optimiser.blockers(),
-				optimiser.has_await
-			)
-		: b.stmt(slot);
-
-	context.state.template.push(block_open, statement, block_close);
+	context.state.template.push(block_open, ...optimiser.render_block([b.stmt(slot)]), block_close);
 }
diff --git a/packages/svelte/src/compiler/phases/3-transform/server/visitors/SvelteElement.js b/packages/svelte/src/compiler/phases/3-transform/server/visitors/SvelteElement.js
index 75ba323e20..398ecc68a2 100644
--- a/packages/svelte/src/compiler/phases/3-transform/server/visitors/SvelteElement.js
+++ b/packages/svelte/src/compiler/phases/3-transform/server/visitors/SvelteElement.js
@@ -1,4 +1,3 @@
-/** @import { Location } from 'locate-character' */
 /** @import { BlockStatement, Expression, Statement } from 'estree' */
 /** @import { AST } from '#compiler' */
 /** @import { ComponentContext } from '../types.js' */
@@ -6,12 +5,7 @@ import { dev, locator } from '../../../../state.js';
 import * as b from '#compiler/builders';
 import { determine_namespace_for_children } from '../../utils.js';
 import { build_element_attributes } from './shared/element.js';
-import {
-	build_template,
-	create_async_block,
-	create_child_block,
-	PromiseOptimiser
-} from './shared/utils.js';
+import { build_template, create_child_block, PromiseOptimiser } from './shared/utils.js';
 
 /**
  * @param {AST.SvelteElement} node
@@ -67,36 +61,29 @@ export function SvelteElement(node, context) {
 	const attributes = b.block([...state.init, ...build_template(state.template)]);
 	const children = /** @type {BlockStatement} */ (context.visit(node.fragment, state));
 
-	/** @type {Statement} */
-	let statement = b.stmt(
-		b.call(
-			'$.element',
-			b.id('$$renderer'),
-			tag,
-			attributes.body.length > 0 && b.thunk(attributes),
-			children.body.length > 0 && b.thunk(children)
-		)
+	statements.push(
+		...optimiser.render([
+			b.stmt(
+				b.call(
+					'$.element',
+					b.id('$$renderer'),
+					tag,
+					attributes.body.length > 0 && b.thunk(attributes),
+					children.body.length > 0 && b.thunk(children)
+				)
+			)
+		])
 	);
 
-	if (optimiser.expressions.length > 0) {
-		statement = create_child_block(b.block([optimiser.apply(), statement]));
-	}
-
-	statements.push(statement);
-
 	if (dev) {
 		statements.push(b.stmt(b.call('$.pop_element')));
 	}
 
-	if (node.metadata.expression.is_async()) {
-		statements = [
-			create_async_block(
-				b.block(statements),
-				node.metadata.expression.blockers(),
-				node.metadata.expression.has_await
-			)
-		];
-	}
-
-	context.state.template.push(...statements);
+	context.state.template.push(
+		...create_child_block(
+			statements,
+			node.metadata.expression.blockers(),
+			node.metadata.expression.has_await
+		)
+	);
 }
diff --git a/packages/svelte/src/compiler/phases/3-transform/server/visitors/shared/component.js b/packages/svelte/src/compiler/phases/3-transform/server/visitors/shared/component.js
index cfd9a27d7b..fe49a67b28 100644
--- a/packages/svelte/src/compiler/phases/3-transform/server/visitors/shared/component.js
+++ b/packages/svelte/src/compiler/phases/3-transform/server/visitors/shared/component.js
@@ -1,12 +1,7 @@
 /** @import { BlockStatement, Expression, Pattern, Property, SequenceExpression, Statement } from 'estree' */
 /** @import { AST } from '#compiler' */
 /** @import { ComponentContext } from '../../types.js' */
-import {
-	empty_comment,
-	build_attribute_value,
-	create_async_block,
-	PromiseOptimiser
-} from './utils.js';
+import { empty_comment, build_attribute_value, PromiseOptimiser } from './utils.js';
 import * as b from '#compiler/builders';
 import { is_element_node } from '../../../../nodes.js';
 import { dev } from '../../../../../state.js';
@@ -325,32 +320,16 @@ export function build_inline_component(node, expression, context) {
 		optimiser.check_blockers(node.metadata.expression);
 	}
 
-	const is_async = optimiser.is_async();
-
-	if (is_async) {
-		statement = create_async_block(
-			b.block([
-				optimiser.apply(),
-				dynamic && custom_css_props.length === 0
-					? b.stmt(b.call('$$renderer.push', empty_comment))
-					: b.empty,
-				statement
-			]),
-			optimiser.blockers(),
-			optimiser.has_await
-		);
-	} else if (dynamic && custom_css_props.length === 0) {
-		context.state.template.push(empty_comment);
-	}
-
-	context.state.template.push(statement);
+	context.state.template.push(
+		...optimiser.render_block([
+			dynamic && custom_css_props.length === 0
+				? b.stmt(b.call('$$renderer.push', empty_comment))
+				: b.empty,
+			statement
+		])
+	);
 
-	if (
-		!is_async &&
-		!context.state.skip_hydration_boundaries &&
-		custom_css_props.length === 0 &&
-		optimiser.expressions.length === 0
-	) {
+	if (!optimiser.is_async() && !context.state.is_standalone && custom_css_props.length === 0) {
 		context.state.template.push(empty_comment);
 	}
 }
diff --git a/packages/svelte/src/compiler/phases/3-transform/server/visitors/shared/utils.js b/packages/svelte/src/compiler/phases/3-transform/server/visitors/shared/utils.js
index b02a935ed2..ee14a4d135 100644
--- a/packages/svelte/src/compiler/phases/3-transform/server/visitors/shared/utils.js
+++ b/packages/svelte/src/compiler/phases/3-transform/server/visitors/shared/utils.js
@@ -81,7 +81,19 @@ export function process_children(nodes, { visit, state }) {
 			flush();
 
 			const expression = /** @type {Expression} */ (visit(node.expression));
-			state.template.push(create_push(b.call('$.escape', expression), node.metadata.expression));
+
+			let call = b.call(
+				'$$renderer.push',
+				b.thunk(b.call('$.escape', expression), node.metadata.expression.has_await)
+			);
+
+			const blockers = node.metadata.expression.blockers();
+
+			if (blockers.elements.length > 0) {
+				call = b.call('$$renderer.async', blockers, b.arrow([b.id('$$renderer')], call));
+			}
+
+			state.template.push(b.stmt(call));
 		} else if (node.type === 'Text' || node.type === 'Comment' || node.type === 'ExpressionTag') {
 			sequence.push(node);
 		} else {
@@ -262,72 +274,20 @@ export function build_getter(node, state) {
 }
 
 /**
- * Creates a `$$renderer.child(...)` expression statement
- * @param {BlockStatement | Expression} body
- * @returns {Statement}
- */
-export function create_child_block(body) {
-	return b.stmt(b.call('$$renderer.child', b.arrow([b.id('$$renderer')], body, true)));
-}
-
-/**
- * Creates a `$$renderer.async(...)` expression statement
- * @param {BlockStatement | Expression} body
+ * @param {Statement[]} statements
  * @param {ArrayExpression} blockers
  * @param {boolean} has_await
- * @param {boolean} needs_hydration_markers
  */
-export function create_async_block(
-	body,
-	blockers = b.array([]),
-	has_await = true,
-	needs_hydration_markers = true
-) {
-	return b.stmt(
-		b.call(
-			needs_hydration_markers ? '$$renderer.async_block' : '$$renderer.async',
-			blockers,
-			b.arrow([b.id('$$renderer')], body, has_await)
-		)
-	);
-}
-
-/**
- * @param {Expression} expression
- * @param {ExpressionMetadata} metadata
- * @param {boolean} needs_hydration_markers
- * @returns {Expression | Statement}
- */
-export function create_push(expression, metadata, needs_hydration_markers = false) {
-	if (metadata.is_async()) {
-		let statement = b.stmt(b.call('$$renderer.push', b.thunk(expression, metadata.has_await)));
-
-		const blockers = metadata.blockers();
-
-		if (blockers.elements.length > 0) {
-			statement = create_async_block(
-				b.block([statement]),
-				blockers,
-				false,
-				needs_hydration_markers
-			);
-		}
-
-		return statement;
+export function create_child_block(statements, blockers, has_await) {
+	if (blockers.elements.length === 0 && !has_await) {
+		return statements;
 	}
 
-	return expression;
-}
+	const fn = b.arrow([b.id('$$renderer')], b.block(statements), has_await);
 
-/**
- * @param {BlockStatement | Expression} body
- * @param {Identifier | false} component_fn_id
- * @returns {Statement}
- */
-export function call_component_renderer(body, component_fn_id) {
-	return b.stmt(
-		b.call('$$renderer.component', b.arrow([b.id('$$renderer')], body, false), component_fn_id)
-	);
+	return blockers.elements.length > 0
+		? [b.stmt(b.call('$$renderer.async_block', blockers, fn))]
+		: [b.stmt(b.call('$$renderer.child_block', fn))];
 }
 
 /**
@@ -373,7 +333,7 @@ export class PromiseOptimiser {
 		}
 	}
 
-	apply() {
+	#apply() {
 		if (this.expressions.length === 0) {
 			return b.empty;
 		}
@@ -403,4 +363,38 @@ export class PromiseOptimiser {
 	is_async() {
 		return this.expressions.length > 0 || this.#blockers.size > 0;
 	}
+
+	/**
+	 * @param {Statement[]} statements
+	 * @returns {Statement[]}
+	 */
+	render(statements) {
+		if (!this.is_async()) {
+			return statements;
+		}
+
+		const fn = b.arrow(
+			[b.id('$$renderer')],
+			b.block([this.#apply(), ...statements]),
+			this.has_await
+		);
+
+		const blockers = this.blockers();
+
+		return blockers.elements.length > 0
+			? [b.stmt(b.call('$$renderer.async', blockers, fn))]
+			: [b.stmt(b.call('$$renderer.child', fn))];
+	}
+
+	/**
+	 * @param {Statement[]} statements
+	 * @returns {Statement[]}
+	 */
+	render_block(statements) {
+		if (!this.is_async()) {
+			return statements;
+		}
+
+		return create_child_block([this.#apply(), ...statements], this.blockers(), this.has_await);
+	}
 }
diff --git a/packages/svelte/src/internal/server/renderer.js b/packages/svelte/src/internal/server/renderer.js
index 49f4c1b7d2..62196350bf 100644
--- a/packages/svelte/src/internal/server/renderer.js
+++ b/packages/svelte/src/internal/server/renderer.js
@@ -171,6 +171,15 @@ export class Renderer {
 		return promises;
 	}
 
+	/**
+	 * @param {(renderer: Renderer) => MaybePromise<void>} fn
+	 */
+	child_block(fn) {
+		this.#out.push(BLOCK_OPEN);
+		this.child(fn);
+		this.#out.push(BLOCK_CLOSE);
+	}
+
 	/**
 	 * Create a child renderer. The child renderer inherits the state from the parent,
 	 * but has its own content.
diff --git a/packages/svelte/tests/snapshot/samples/async-const/_expected/server/index.svelte.js b/packages/svelte/tests/snapshot/samples/async-const/_expected/server/index.svelte.js
index a726b903bc..03bbc5ba88 100644
--- a/packages/svelte/tests/snapshot/samples/async-const/_expected/server/index.svelte.js
+++ b/packages/svelte/tests/snapshot/samples/async-const/_expected/server/index.svelte.js
@@ -19,11 +19,7 @@ export default function Async_const($$renderer) {
 		]);
 
 		$$renderer.push(`<p>`);
-
-		$$renderer.async([promises[1]], ($$renderer) => {
-			$$renderer.push(() => $.escape(b));
-		});
-
+		$$renderer.async([promises[1]], ($$renderer) => $$renderer.push(() => $.escape(b)));
 		$$renderer.push(`</p>`);
 	} else {
 		$$renderer.push('<!--[!-->');
diff --git a/packages/svelte/tests/snapshot/samples/async-each-fallback-hoisting/_expected/server/index.svelte.js b/packages/svelte/tests/snapshot/samples/async-each-fallback-hoisting/_expected/server/index.svelte.js
index 7249fd6e4f..b331875d04 100644
--- a/packages/svelte/tests/snapshot/samples/async-each-fallback-hoisting/_expected/server/index.svelte.js
+++ b/packages/svelte/tests/snapshot/samples/async-each-fallback-hoisting/_expected/server/index.svelte.js
@@ -2,7 +2,7 @@ import 'svelte/internal/flags/async';
 import * as $ from 'svelte/internal/server';
 
 export default function Async_each_fallback_hoisting($$renderer) {
-	$$renderer.async_block([], async ($$renderer) => {
+	$$renderer.child_block(async ($$renderer) => {
 		const each_array = $.ensure_array_like((await $.save(Promise.resolve([])))());
 
 		if (each_array.length !== 0) {
diff --git a/packages/svelte/tests/snapshot/samples/async-each-hoisting/_expected/server/index.svelte.js b/packages/svelte/tests/snapshot/samples/async-each-hoisting/_expected/server/index.svelte.js
index 43fe9414eb..86948b4a3a 100644
--- a/packages/svelte/tests/snapshot/samples/async-each-hoisting/_expected/server/index.svelte.js
+++ b/packages/svelte/tests/snapshot/samples/async-each-hoisting/_expected/server/index.svelte.js
@@ -8,7 +8,7 @@ export default function Async_each_hoisting($$renderer) {
 
 	$$renderer.push(`<!--[-->`);
 
-	$$renderer.async_block([], async ($$renderer) => {
+	$$renderer.child_block(async ($$renderer) => {
 		const each_array = $.ensure_array_like((await $.save(Promise.resolve([first, second, third])))());
 
 		for (let $$index = 0, $$length = each_array.length; $$index < $$length; $$index++) {
diff --git a/packages/svelte/tests/snapshot/samples/async-if-alternate-hoisting/_expected/server/index.svelte.js b/packages/svelte/tests/snapshot/samples/async-if-alternate-hoisting/_expected/server/index.svelte.js
index 1e7330429a..c69c038973 100644
--- a/packages/svelte/tests/snapshot/samples/async-if-alternate-hoisting/_expected/server/index.svelte.js
+++ b/packages/svelte/tests/snapshot/samples/async-if-alternate-hoisting/_expected/server/index.svelte.js
@@ -2,7 +2,7 @@ import 'svelte/internal/flags/async';
 import * as $ from 'svelte/internal/server';
 
 export default function Async_if_alternate_hoisting($$renderer) {
-	$$renderer.async_block([], async ($$renderer) => {
+	$$renderer.child_block(async ($$renderer) => {
 		if ((await $.save(Promise.resolve(false)))()) {
 			$$renderer.push('<!--[-->');
 			$$renderer.push(async () => $.escape(await Promise.reject('no no no')));
diff --git a/packages/svelte/tests/snapshot/samples/async-if-hoisting/_expected/server/index.svelte.js b/packages/svelte/tests/snapshot/samples/async-if-hoisting/_expected/server/index.svelte.js
index 1ca24cf81a..1355ba34f0 100644
--- a/packages/svelte/tests/snapshot/samples/async-if-hoisting/_expected/server/index.svelte.js
+++ b/packages/svelte/tests/snapshot/samples/async-if-hoisting/_expected/server/index.svelte.js
@@ -2,7 +2,7 @@ import 'svelte/internal/flags/async';
 import * as $ from 'svelte/internal/server';
 
 export default function Async_if_hoisting($$renderer) {
-	$$renderer.async_block([], async ($$renderer) => {
+	$$renderer.child_block(async ($$renderer) => {
 		if ((await $.save(Promise.resolve(true)))()) {
 			$$renderer.push('<!--[-->');
 			$$renderer.push(async () => $.escape(await Promise.resolve('yes yes yes')));
diff --git a/packages/svelte/tests/snapshot/samples/async-top-level-inspect-server/_expected/server/index.svelte.js b/packages/svelte/tests/snapshot/samples/async-top-level-inspect-server/_expected/server/index.svelte.js
index eb99a2fe1d..cff5f2d569 100644
--- a/packages/svelte/tests/snapshot/samples/async-top-level-inspect-server/_expected/server/index.svelte.js
+++ b/packages/svelte/tests/snapshot/samples/async-top-level-inspect-server/_expected/server/index.svelte.js
@@ -6,10 +6,6 @@ export default function Async_top_level_inspect_server($$renderer) {
 	var $$promises = $$renderer.run([async () => data = await Promise.resolve(42),,]);
 
 	$$renderer.push(`<p>`);
-
-	$$renderer.async([$$promises[1]], ($$renderer) => {
-		$$renderer.push(() => $.escape(data));
-	});
-
+	$$renderer.async([$$promises[1]], ($$renderer) => $$renderer.push(() => $.escape(data)));
 	$$renderer.push(`</p>`);
 }
\ No newline at end of file

From bc449758695ec0b5cd34b4cdfa7aaf1ccbc5105b Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 6 Feb 2026 04:19:14 -0500
Subject: [PATCH 14/23] fix: properly hydrate already-resolved async blocks
 (alternative) (#17641)

This is basically #17611, minus #17640, plus #17639. We need to add the $.next() call after render tags as well as components; rather than duplicating the logic, we can use is_standalone to determine when this is necessary (since this is what prevents $.append(...) from being used).

Fixes #17261
Fixes #17608
---------

Co-authored-by: Simon H <5968653+dummdidumm@users.noreply.github.com>
---
 .changeset/poor-students-nail.md              |  5 ++++
 .../3-transform/client/transform-client.js    |  1 +
 .../phases/3-transform/client/types.d.ts      |  3 +++
 .../3-transform/client/visitors/Fragment.js   |  5 +++-
 .../3-transform/client/visitors/RenderTag.js  |  4 ++++
 .../client/visitors/shared/component.js       | 24 ++++++++++++-------
 .../server/visitors/shared/component.js       |  8 ++++++-
 .../Inner.svelte                              |  4 ++++
 .../Outer.svelte                              |  4 ++++
 .../Trigger.svelte                            |  7 ++++++
 .../_config.js                                | 10 ++++++++
 .../main.svelte                               | 16 +++++++++++++
 .../Component.svelte                          |  5 ++++
 .../async-each-item-duplication/_config.js    | 14 +++++++++++
 .../async-each-item-duplication/main.svelte   | 10 ++++++++
 15 files changed, 109 insertions(+), 11 deletions(-)
 create mode 100644 .changeset/poor-students-nail.md
 create mode 100644 packages/svelte/tests/runtime-runes/samples/async-attach-hydration-mismatch/Inner.svelte
 create mode 100644 packages/svelte/tests/runtime-runes/samples/async-attach-hydration-mismatch/Outer.svelte
 create mode 100644 packages/svelte/tests/runtime-runes/samples/async-attach-hydration-mismatch/Trigger.svelte
 create mode 100644 packages/svelte/tests/runtime-runes/samples/async-attach-hydration-mismatch/_config.js
 create mode 100644 packages/svelte/tests/runtime-runes/samples/async-attach-hydration-mismatch/main.svelte
 create mode 100644 packages/svelte/tests/runtime-runes/samples/async-each-item-duplication/Component.svelte
 create mode 100644 packages/svelte/tests/runtime-runes/samples/async-each-item-duplication/_config.js
 create mode 100644 packages/svelte/tests/runtime-runes/samples/async-each-item-duplication/main.svelte

diff --git a/.changeset/poor-students-nail.md b/.changeset/poor-students-nail.md
new file mode 100644
index 0000000000..cee650c002
--- /dev/null
+++ b/.changeset/poor-students-nail.md
@@ -0,0 +1,5 @@
+---
+"svelte": patch
+---
+
+fix: properly hydrate already-resolved async blocks
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js b/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
index d5ce3caaa9..b50a73b8b6 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/transform-client.js
@@ -166,6 +166,7 @@ export function client_component(analysis, options) {
 		in_constructor: false,
 		instance_level_snippets: [],
 		module_level_snippets: [],
+		is_standalone: false,
 
 		// these are set inside the `Fragment` visitor, and cannot be used until then
 		init: /** @type {any} */ (null),
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts b/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts
index 4438ec015b..287bf24ac6 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts
+++ b/packages/svelte/src/compiler/phases/3-transform/client/types.d.ts
@@ -83,6 +83,9 @@ export interface ComponentClientTransformState extends ClientTransformState {
 	readonly instance_level_snippets: VariableDeclaration[];
 	/** Snippets hoisted to the module */
 	readonly module_level_snippets: VariableDeclaration[];
+
+	/** True if the current node is a) a component or render tag and b) the sole child of a block  */
+	readonly is_standalone: boolean;
 }
 
 export type Context = import('zimmerframe').Context<AST.SvelteNode, ClientTransformState>;
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/Fragment.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/Fragment.js
index f463111c4d..00b0cfaa2e 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/Fragment.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/Fragment.js
@@ -122,7 +122,10 @@ export function Fragment(node, context) {
 			close = b.stmt(b.call('$.append', b.id('$$anchor'), id));
 		} else if (is_standalone) {
 			// no need to create a template, we can just use the existing block's anchor
-			process_children(trimmed, () => b.id('$$anchor'), false, { ...context, state });
+			process_children(trimmed, () => b.id('$$anchor'), false, {
+				...context,
+				state: { ...state, is_standalone }
+			});
 		} else {
 			/** @type {(is_text: boolean) => Expression} */
 			const expression = (is_text) => b.call('$.first_child', id, is_text && b.true);
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/RenderTag.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/RenderTag.js
index d14336bb7e..5d39cf2216 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/RenderTag.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/RenderTag.js
@@ -85,6 +85,10 @@ export function RenderTag(node, context) {
 				)
 			)
 		);
+
+		if (context.state.is_standalone) {
+			context.state.init.push(b.stmt(b.call('$.next')));
+		}
 	} else {
 		context.state.init.push(statements.length === 1 ? statements[0] : b.block(statements));
 	}
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/component.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/component.js
index bb72794af8..1d6d3413bf 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/component.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/component.js
@@ -461,7 +461,7 @@ export function build_component(node, component_name, loc, context) {
 		memoizer.check_blockers(node.metadata.expression);
 	}
 
-	const statements = [...snippet_declarations, ...memoizer.deriveds(context.state.analysis.runes)];
+	let statements = [...snippet_declarations, ...memoizer.deriveds(context.state.analysis.runes)];
 
 	if (is_component_dynamic) {
 		const prev = fn;
@@ -515,15 +515,21 @@ export function build_component(node, component_name, loc, context) {
 	const blockers = memoizer.blockers();
 
 	if (async_values || blockers) {
-		return b.stmt(
-			b.call(
-				'$.async',
-				anchor,
-				blockers,
-				async_values,
-				b.arrow([b.id('$$anchor'), ...memoizer.async_ids()], b.block(statements))
+		statements = [
+			b.stmt(
+				b.call(
+					'$.async',
+					anchor,
+					blockers,
+					async_values,
+					b.arrow([b.id('$$anchor'), ...memoizer.async_ids()], b.block(statements))
+				)
 			)
-		);
+		];
+
+		if (context.state.is_standalone) {
+			statements.push(b.stmt(b.call('$.next')));
+		}
 	}
 
 	return statements.length > 1 ? b.block(statements) : statements[0];
diff --git a/packages/svelte/src/compiler/phases/3-transform/server/visitors/shared/component.js b/packages/svelte/src/compiler/phases/3-transform/server/visitors/shared/component.js
index fe49a67b28..6a2c6eb0be 100644
--- a/packages/svelte/src/compiler/phases/3-transform/server/visitors/shared/component.js
+++ b/packages/svelte/src/compiler/phases/3-transform/server/visitors/shared/component.js
@@ -101,10 +101,16 @@ export function build_inline_component(node, expression, context) {
 			}
 
 			push_prop(b.prop('init', b.key(attribute.name), value));
-		} else if (attribute.type === 'BindDirective' && attribute.name !== 'this') {
+		} else if (attribute.type === 'BindDirective') {
 			// Bindings are a bit special: we don't want to add them to (async) deriveds but we need to check if they have blockers
 			optimiser.check_blockers(attribute.metadata.expression);
 
+			if (attribute.name === 'this') {
+				// bind:this is client-only, but we still need to check for blockers to ensure
+				// the server generates matching hydration markers if the client wraps in $.async
+				continue;
+			}
+
 			if (attribute.expression.type === 'SequenceExpression') {
 				const [get, set] = /** @type {SequenceExpression} */ (context.visit(attribute.expression))
 					.expressions;
diff --git a/packages/svelte/tests/runtime-runes/samples/async-attach-hydration-mismatch/Inner.svelte b/packages/svelte/tests/runtime-runes/samples/async-attach-hydration-mismatch/Inner.svelte
new file mode 100644
index 0000000000..99f885189b
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/async-attach-hydration-mismatch/Inner.svelte
@@ -0,0 +1,4 @@
+<script>
+  let { children } = $props()
+</script>
+<div>{@render children?.()}</div>
diff --git a/packages/svelte/tests/runtime-runes/samples/async-attach-hydration-mismatch/Outer.svelte b/packages/svelte/tests/runtime-runes/samples/async-attach-hydration-mismatch/Outer.svelte
new file mode 100644
index 0000000000..99f885189b
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/async-attach-hydration-mismatch/Outer.svelte
@@ -0,0 +1,4 @@
+<script>
+  let { children } = $props()
+</script>
+<div>{@render children?.()}</div>
diff --git a/packages/svelte/tests/runtime-runes/samples/async-attach-hydration-mismatch/Trigger.svelte b/packages/svelte/tests/runtime-runes/samples/async-attach-hydration-mismatch/Trigger.svelte
new file mode 100644
index 0000000000..fc434d748e
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/async-attach-hydration-mismatch/Trigger.svelte
@@ -0,0 +1,7 @@
+<script lang='ts'>
+  import type { Attachment } from 'svelte/attachments'
+
+  export function action(): Attachment<HTMLElement> {
+    return ()=>{}
+  }
+</script>
diff --git a/packages/svelte/tests/runtime-runes/samples/async-attach-hydration-mismatch/_config.js b/packages/svelte/tests/runtime-runes/samples/async-attach-hydration-mismatch/_config.js
new file mode 100644
index 0000000000..d77ba45ae4
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/async-attach-hydration-mismatch/_config.js
@@ -0,0 +1,10 @@
+import { tick } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+	mode: ['hydrate'],
+	async test({ assert, target }) {
+		await tick();
+		assert.htmlEqual(target.innerHTML, '<div><div>foo</div></div>');
+	}
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/async-attach-hydration-mismatch/main.svelte b/packages/svelte/tests/runtime-runes/samples/async-attach-hydration-mismatch/main.svelte
new file mode 100644
index 0000000000..6cfc73ca25
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/async-attach-hydration-mismatch/main.svelte
@@ -0,0 +1,16 @@
+<script>
+  import Outer from './Outer.svelte'
+  import Inner from './Inner.svelte'
+  import Trigger from './Trigger.svelte'
+
+  const data = $derived(await Promise.resolve(['a', 'b']))
+  let trigger = $state()
+</script>
+
+<Outer>
+  <Inner {@attach trigger?.action}>
+    foo
+  </Inner>
+</Outer>
+
+<Trigger bind:this={trigger} />
diff --git a/packages/svelte/tests/runtime-runes/samples/async-each-item-duplication/Component.svelte b/packages/svelte/tests/runtime-runes/samples/async-each-item-duplication/Component.svelte
new file mode 100644
index 0000000000..9f4e638629
--- /dev/null
+++ b/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>
diff --git a/packages/svelte/tests/runtime-runes/samples/async-each-item-duplication/_config.js b/packages/svelte/tests/runtime-runes/samples/async-each-item-duplication/_config.js
new file mode 100644
index 0000000000..2e20f83f7f
--- /dev/null
+++ b/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>');
+	}
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/async-each-item-duplication/main.svelte b/packages/svelte/tests/runtime-runes/samples/async-each-item-duplication/main.svelte
new file mode 100644
index 0000000000..ae54b63414
--- /dev/null
+++ b/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}

From 6e5f2b157a02df4dd1f4e2ad3275655bc52cd023 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 6 Feb 2026 10:54:15 -0500
Subject: [PATCH 15/23] fix: exit resolved async blocks on correct node when
 hydrating (#17640)

* fix: exit resolved async blocks on correct node when hydrating

* expand test + fix

* tweak, add note to self

---------

Co-authored-by: Simon H <5968653+dummdidumm@users.noreply.github.com>
Co-authored-by: Simon Holthausen <simon.holthausen@vercel.com>
---
 .changeset/tiny-owls-pay.md                    |  5 +++++
 .../src/internal/client/dom/blocks/async.js    | 15 ++++++++++++++-
 .../samples/async-if-hydration/Child.svelte    |  5 +++++
 .../samples/async-if-hydration/_config.js      | 11 +++++++++++
 .../samples/async-if-hydration/main.svelte     | 18 ++++++++++++++++++
 5 files changed, 53 insertions(+), 1 deletion(-)
 create mode 100644 .changeset/tiny-owls-pay.md
 create mode 100644 packages/svelte/tests/runtime-runes/samples/async-if-hydration/Child.svelte
 create mode 100644 packages/svelte/tests/runtime-runes/samples/async-if-hydration/_config.js
 create mode 100644 packages/svelte/tests/runtime-runes/samples/async-if-hydration/main.svelte

diff --git a/.changeset/tiny-owls-pay.md b/.changeset/tiny-owls-pay.md
new file mode 100644
index 0000000000..ac25500258
--- /dev/null
+++ b/.changeset/tiny-owls-pay.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: exit resolved async blocks on correct node when hydrating
diff --git a/packages/svelte/src/internal/client/dom/blocks/async.js b/packages/svelte/src/internal/client/dom/blocks/async.js
index 0e3ab33dda..e8c9cf0643 100644
--- a/packages/svelte/src/internal/client/dom/blocks/async.js
+++ b/packages/svelte/src/internal/client/dom/blocks/async.js
@@ -20,13 +20,27 @@ import { get_boundary } from './boundary.js';
  */
 export function async(node, blockers = [], expressions = [], fn) {
 	var was_hydrating = hydrating;
+	var end = null;
 
 	if (was_hydrating) {
 		hydrate_next();
+		end = skip_nodes(false);
 	}
 
 	if (expressions.length === 0 && blockers.every((b) => b.settled)) {
 		fn(node);
+
+		// This is necessary because it is not guaranteed that the render function will
+		// advance the hydration node to $.async's end marker: it may stop at an inner
+		// block's end marker (in case of an inner if block for example), but it also may
+		// stop at the correct $.async end marker (in case of component child) - hence
+		// we can't just use hydrate_next()
+		// TODO this feels indicative of a bug elsewhere; ideally we wouldn't need
+		// to double-traverse in the already-resolved case
+		if (was_hydrating) {
+			set_hydrate_node(end);
+		}
+
 		return;
 	}
 
@@ -39,7 +53,6 @@ export function async(node, blockers = [], expressions = [], fn) {
 
 	if (was_hydrating) {
 		var previous_hydrate_node = hydrate_node;
-		var end = skip_nodes(false);
 		set_hydrate_node(end);
 	}
 
diff --git a/packages/svelte/tests/runtime-runes/samples/async-if-hydration/Child.svelte b/packages/svelte/tests/runtime-runes/samples/async-if-hydration/Child.svelte
new file mode 100644
index 0000000000..02ef294d99
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/async-if-hydration/Child.svelte
@@ -0,0 +1,5 @@
+<script>
+    let { b } = $props();
+</script>
+
+{b}
diff --git a/packages/svelte/tests/runtime-runes/samples/async-if-hydration/_config.js b/packages/svelte/tests/runtime-runes/samples/async-if-hydration/_config.js
new file mode 100644
index 0000000000..8132e9c522
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/async-if-hydration/_config.js
@@ -0,0 +1,11 @@
+import { tick } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+	mode: ['hydrate'],
+
+	async test({ assert, target }) {
+		await tick();
+		assert.htmlEqual(target.innerHTML, `<div><p>hello</p></div> <div>true</div>`);
+	}
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/async-if-hydration/main.svelte b/packages/svelte/tests/runtime-runes/samples/async-if-hydration/main.svelte
new file mode 100644
index 0000000000..3b08d41640
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/async-if-hydration/main.svelte
@@ -0,0 +1,18 @@
+<script lang="ts">
+	import Child from "./Child.svelte";
+
+	await 1;
+	let b = true;
+	let a = true;
+</script>
+
+{#if a}
+	<div>
+		{#if b}
+			<p>hello</p>
+		{/if}
+	</div>
+	<div>
+		<Child {b} />
+	</div>
+{/if}

From 989492f0572cb6dd4beaf621dfbba0bcd409913c Mon Sep 17 00:00:00 2001
From: Artyom Alekseevich <47069814+FrankFMY@users.noreply.github.com>
Date: Fri, 6 Feb 2026 17:01:41 +0100
Subject: [PATCH 16/23] fix: use "set up" (verb) instead of "setup" (noun) in
 comments (#17632)

"Setup" is a noun/adjective, while "set up" is the verb form.
---
 documentation/docs/07-misc/02-testing.md | 2 +-
 packages/svelte/tests/signals/test.ts    | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/documentation/docs/07-misc/02-testing.md b/documentation/docs/07-misc/02-testing.md
index 85db7fc01f..c1bc69c1c2 100644
--- a/documentation/docs/07-misc/02-testing.md
+++ b/documentation/docs/07-misc/02-testing.md
@@ -181,7 +181,7 @@ export default defineConfig({
 		/* ... */
 	],
 	test: {
-		// If you are testing components client-side, you need to setup a DOM environment.
+		// If you are testing components client-side, you need to set up a DOM environment.
 		// If not all your files should have this environment, you can use a
 		// `// @vitest-environment jsdom` comment at the top of the test files instead.
 		environment: 'jsdom'
diff --git a/packages/svelte/tests/signals/test.ts b/packages/svelte/tests/signals/test.ts
index 23c4bb42f9..5486ccdb45 100644
--- a/packages/svelte/tests/signals/test.ts
+++ b/packages/svelte/tests/signals/test.ts
@@ -21,7 +21,7 @@ import { disable_async_mode_flag, enable_async_mode_flag } from '../../src/inter
 
 /**
  * @param runes runes mode
- * @param fn A function that returns a function because we first need to setup all the signals
+ * @param fn A function that returns a function because we first need to set up all the signals
  * 			 and then execute the test in order to simulate a real component
  */
 function run_test(runes: boolean, fn: (runes: boolean) => () => void) {

From 01db7b8c2a0dbc7eb1fb8f1eff116f2b5b5b3ba9 Mon Sep 17 00:00:00 2001
From: Artyom Alekseevich <47069814+FrankFMY@users.noreply.github.com>
Date: Fri, 6 Feb 2026 17:03:14 +0100
Subject: [PATCH 17/23] fix: update migration guide to reflect current passive
 events (#17631)

Remove `onwheel` and `onmousewheel` from the list of passive events
in the v5 migration guide. Since #13322, only `ontouchstart` and
`ontouchmove` are passive by default, matching the basic-markup docs.

Closes #17430
---
 documentation/docs/07-misc/07-v5-migration-guide.md | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/documentation/docs/07-misc/07-v5-migration-guide.md b/documentation/docs/07-misc/07-v5-migration-guide.md
index 40cbc3bd9e..5a80734b7a 100644
--- a/documentation/docs/07-misc/07-v5-migration-guide.md
+++ b/documentation/docs/07-misc/07-v5-migration-guide.md
@@ -778,9 +778,9 @@ In Svelte 4, doing the following triggered reactivity:
 
 This is because the Svelte compiler treated the assignment to `foo.value` as an instruction to update anything that referenced `foo`. In Svelte 5, reactivity is determined at runtime rather than compile time, so you should define `value` as a reactive `$state` field on the `Foo` class. Wrapping `new Foo()` with `$state(...)` will have no effect — only vanilla objects and arrays are made deeply reactive.
 
-### Touch and wheel events are passive
+### Touch events are passive
 
-When using `onwheel`, `onmousewheel`, `ontouchstart` and `ontouchmove` event attributes, the handlers are [passive](https://developer.mozilla.org/en-US/docs/Web/API/EventTarget/addEventListener#using_passive_listeners) to align with browser defaults. This greatly improves responsiveness by allowing the browser to scroll the document immediately, rather than waiting to see if the event handler calls `event.preventDefault()`.
+When using `ontouchstart` and `ontouchmove` event attributes, the handlers are [passive](https://developer.mozilla.org/en-US/docs/Web/API/EventTarget/addEventListener#using_passive_listeners) to align with browser defaults. This greatly improves responsiveness by allowing the browser to scroll the document immediately, rather than waiting to see if the event handler calls `event.preventDefault()`.
 
 In the very rare cases that you need to prevent these event defaults, you should use [`on`](/docs/svelte/svelte-events#on) instead (for example inside an action).
 

From 0c715afdab2c3077b32793a41a7ddccb3be65c64 Mon Sep 17 00:00:00 2001
From: Artyom Alekseevich <47069814+FrankFMY@users.noreply.github.com>
Date: Fri, 6 Feb 2026 17:03:58 +0100
Subject: [PATCH 18/23] fix: correct spelling errors in test files (#17630)

Fix "wich" -> "which", "aswell" -> "as well" in CSS global-block test,
and "occurence" -> "occurrence" in sourcemaps test type definition.
---
 packages/svelte/tests/css/samples/global-block/expected.css | 4 ++--
 packages/svelte/tests/css/samples/global-block/input.svelte | 4 ++--
 packages/svelte/tests/sourcemaps/test.ts                    | 4 ++--
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/packages/svelte/tests/css/samples/global-block/expected.css b/packages/svelte/tests/css/samples/global-block/expected.css
index be1838fd98..ef68280093 100644
--- a/packages/svelte/tests/css/samples/global-block/expected.css
+++ b/packages/svelte/tests/css/samples/global-block/expected.css
@@ -39,7 +39,7 @@
 		/*}*/
 	}
 
-	/* ...wich is equivalent to `div :global { &.x { ...} }` ... */
+	/* ...which is equivalent to `div :global { &.x { ...} }` ... */
 	div.svelte-xyz {
 		&.x {
 			color: green;
@@ -51,7 +51,7 @@
 		color: green;
 	}
 
-	/* ...and therefore `div { :global.x { ... }` aswell */
+	/* ...and therefore `div { :global.x { ... }` as well */
 	div.svelte-xyz {
 		&.x {
 			color: green;
diff --git a/packages/svelte/tests/css/samples/global-block/input.svelte b/packages/svelte/tests/css/samples/global-block/input.svelte
index 86d438031a..1a9993bfe0 100644
--- a/packages/svelte/tests/css/samples/global-block/input.svelte
+++ b/packages/svelte/tests/css/samples/global-block/input.svelte
@@ -41,7 +41,7 @@
 		}
 	}
 
-	/* ...wich is equivalent to `div :global { &.x { ...} }` ... */
+	/* ...which is equivalent to `div :global { &.x { ...} }` ... */
 	div :global {
 		&.x {
 			color: green;
@@ -53,7 +53,7 @@
 		color: green;
 	}
 
-	/* ...and therefore `div { :global.x { ... }` aswell */
+	/* ...and therefore `div { :global.x { ... }` as well */
 	div {
 		:global.x {
 			color: green;
diff --git a/packages/svelte/tests/sourcemaps/test.ts b/packages/svelte/tests/sourcemaps/test.ts
index 0ac0e6f905..6749483079 100644
--- a/packages/svelte/tests/sourcemaps/test.ts
+++ b/packages/svelte/tests/sourcemaps/test.ts
@@ -8,9 +8,9 @@ import { decode } from '@jridgewell/sourcemap-codec';
 type SourceMapEntry =
 	| string
 	| {
-			/** If not the first occurence, but the nth should be found */
+			/** If not the first occurrence, but the nth should be found */
 			idxOriginal?: number;
-			/** If not the first occurence, but the nth should be found */
+			/** If not the first occurrence, but the nth should be found */
 			idxGenerated?: number;
 			/** The original string to find */
 			str: string;

From 4453e4895d407df6895f481257b675a43ed702c6 Mon Sep 17 00:00:00 2001
From: Artyom Alekseevich <47069814+FrankFMY@users.noreply.github.com>
Date: Fri, 6 Feb 2026 17:04:42 +0100
Subject: [PATCH 19/23] fix: fix spelling errors in media-query and test file
 (#17628)

- media-query.js: parentehesis -> parenthesis
- error-boundary-12/main.svelte: occured -> occurred
---
 packages/svelte/src/reactivity/media-query.js                   | 2 +-
 .../tests/runtime-runes/samples/error-boundary-12/main.svelte   | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages/svelte/src/reactivity/media-query.js b/packages/svelte/src/reactivity/media-query.js
index d286709719..6d1d084298 100644
--- a/packages/svelte/src/reactivity/media-query.js
+++ b/packages/svelte/src/reactivity/media-query.js
@@ -7,7 +7,7 @@ const parenthesis_regex = /\(.+\)/;
 //
 // eg: new MediaQuery('screen')
 //
-// however because of the auto-parenthesis logic in the constructor since there's no parentehesis
+// however because of the auto-parenthesis logic in the constructor since there's no parenthesis
 // in the media query they'll be surrounded by parenthesis
 //
 // however we can check if the media query is only composed of these keywords
diff --git a/packages/svelte/tests/runtime-runes/samples/error-boundary-12/main.svelte b/packages/svelte/tests/runtime-runes/samples/error-boundary-12/main.svelte
index d9dee1e2b0..748acab91e 100644
--- a/packages/svelte/tests/runtime-runes/samples/error-boundary-12/main.svelte
+++ b/packages/svelte/tests/runtime-runes/samples/error-boundary-12/main.svelte
@@ -15,6 +15,6 @@
 	{d}
 
 	{#snippet failed()}
-		<p>Error occured</p>
+		<p>Error occurred</p>
 	{/snippet}
 </svelte:boundary>

From f71a6813b7bf9c53b1dce0b5f3a1232f55b1f26a Mon Sep 17 00:00:00 2001
From: Artyom Alekseevich <47069814+FrankFMY@users.noreply.github.com>
Date: Fri, 6 Feb 2026 17:13:54 +0100
Subject: [PATCH 20/23] fix: treat menu element like ul/ol for a11y role checks
 (#17638)

* treat menu element like ul/ol for a11y role checks

The <menu> element has the same implicit role (list) as <ul> and <ol>,
so it should receive the same treatment in a11y checks:

- Allow <menu role="list"> without redundant role warning (CSS
  list-style:none can remove semantics, role restores them)
- Allow <menu> with interactive roles like menu, menubar, radiogroup,
  tablist, tree, treegrid (same exceptions as ul/ol)

Fixes #8529

* changeset

---------

Co-authored-by: Simon H <5968653+dummdidumm@users.noreply.github.com>
---
 .changeset/fix-menu-element-a11y-roles.md            |  5 +++++
 .../2-analyze/visitors/shared/a11y/constants.js      |  1 +
 .../phases/2-analyze/visitors/shared/a11y/index.js   |  2 +-
 .../input.svelte                                     |  7 +++++++
 .../samples/a11y-no-redundant-roles/input.svelte     |  4 ++--
 .../samples/a11y-no-redundant-roles/warnings.json    | 12 ------------
 6 files changed, 16 insertions(+), 15 deletions(-)
 create mode 100644 .changeset/fix-menu-element-a11y-roles.md

diff --git a/.changeset/fix-menu-element-a11y-roles.md b/.changeset/fix-menu-element-a11y-roles.md
new file mode 100644
index 0000000000..75cfe8d310
--- /dev/null
+++ b/.changeset/fix-menu-element-a11y-roles.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: treat `<menu>` like `<ul>`/`<ol>` for a11y role checks
diff --git a/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/a11y/constants.js b/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/a11y/constants.js
index 684ea92094..49099c2cb1 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/a11y/constants.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/a11y/constants.js
@@ -174,6 +174,7 @@ export const input_type_to_implicit_role = new Map([
 export const a11y_non_interactive_element_to_interactive_role_exceptions = {
 	ul: ['listbox', 'menu', 'menubar', 'radiogroup', 'tablist', 'tree', 'treegrid'],
 	ol: ['listbox', 'menu', 'menubar', 'radiogroup', 'tablist', 'tree', 'treegrid'],
+	menu: ['listbox', 'menu', 'menubar', 'radiogroup', 'tablist', 'tree', 'treegrid'],
 	li: ['menuitem', 'option', 'row', 'tab', 'treeitem'],
 	table: ['grid'],
 	td: ['gridcell'],
diff --git a/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/a11y/index.js b/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/a11y/index.js
index f5f4982ed2..45de8b10a1 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/a11y/index.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/a11y/index.js
@@ -167,7 +167,7 @@ export function check_element(node, context) {
 					if (
 						current_role === get_implicit_role(node.name, attribute_map) &&
 						// <ul role="list"> is ok because CSS list-style:none removes the semantics and this is a way to bring them back
-						!['ul', 'ol', 'li'].includes(node.name) &&
+						!['ul', 'ol', 'li', 'menu'].includes(node.name) &&
 						// <a role="link" /> is ok because without href the a tag doesn't have a role of link
 						!(node.name === 'a' && !attribute_map.has('href'))
 					) {
diff --git a/packages/svelte/tests/validator/samples/a11y-no-noninteractive-element-to-interactive-role/input.svelte b/packages/svelte/tests/validator/samples/a11y-no-noninteractive-element-to-interactive-role/input.svelte
index e5db8719b0..edfa3eeada 100644
--- a/packages/svelte/tests/validator/samples/a11y-no-noninteractive-element-to-interactive-role/input.svelte
+++ b/packages/svelte/tests/validator/samples/a11y-no-noninteractive-element-to-interactive-role/input.svelte
@@ -69,6 +69,13 @@
 <li role="menuitem"></li>
 <li role="row"></li>
 <li role="treeitem" aria-selected={false}></li>
+<!-- menu -->
+<menu role="menu"></menu>
+<menu role="menubar"></menu>
+<menu role="radiogroup"></menu>
+<menu role="tablist"></menu>
+<menu role="tree"></menu>
+<menu role="treegrid"></menu>
 
 <!-- VALID: elements assigned an interactive role. -->
 <div role="button"></div>
diff --git a/packages/svelte/tests/validator/samples/a11y-no-redundant-roles/input.svelte b/packages/svelte/tests/validator/samples/a11y-no-redundant-roles/input.svelte
index 2ccd765aa2..9e06ebe420 100644
--- a/packages/svelte/tests/validator/samples/a11y-no-redundant-roles/input.svelte
+++ b/packages/svelte/tests/validator/samples/a11y-no-redundant-roles/input.svelte
@@ -22,7 +22,7 @@
 <!-- <li role="listitem" /> allowed since CSS list-style none removes semantic meaning and role brings it back -->
 <link role="link" />
 <main role="main"></main>
-<menu role="list"></menu>
+<!-- <menu role="list" /> allowed, same as ul/ol above -->
 <nav role="navigation"></nav>
 <!-- <ol role="list" /> allowed, see comment above -->
 <optgroup role="group"></optgroup>
@@ -44,5 +44,5 @@
 <footer role="contentinfo"></footer>
 
 <!-- Allowed -->
-<!-- svelte-ignore a11y_no_noninteractive_element_to_interactive_role -->
+<!-- menu has same interactive role exceptions as ul/ol -->
 <menu role="menu"></menu>
diff --git a/packages/svelte/tests/validator/samples/a11y-no-redundant-roles/warnings.json b/packages/svelte/tests/validator/samples/a11y-no-redundant-roles/warnings.json
index 861f000aef..e041037d71 100644
--- a/packages/svelte/tests/validator/samples/a11y-no-redundant-roles/warnings.json
+++ b/packages/svelte/tests/validator/samples/a11y-no-redundant-roles/warnings.json
@@ -275,18 +275,6 @@
 			"line": 24
 		}
 	},
-	{
-		"code": "a11y_no_redundant_roles",
-		"end": {
-			"column": 17,
-			"line": 25
-		},
-		"message": "Redundant role 'list'",
-		"start": {
-			"column": 6,
-			"line": 25
-		}
-	},
 	{
 		"code": "a11y_no_redundant_roles",
 		"end": {

From bd7b8aa10807be8884f5e7224340f8d980d971ec Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 6 Feb 2026 11:37:25 -0500
Subject: [PATCH 21/23] chore: fix broken css test (#17644)

---
 packages/svelte/tests/css/samples/global-block/_config.js | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/packages/svelte/tests/css/samples/global-block/_config.js b/packages/svelte/tests/css/samples/global-block/_config.js
index 18a56e9a97..84b4989f76 100644
--- a/packages/svelte/tests/css/samples/global-block/_config.js
+++ b/packages/svelte/tests/css/samples/global-block/_config.js
@@ -9,12 +9,12 @@ export default test({
 			start: {
 				line: 73,
 				column: 1,
-				character: 964
+				character: 966
 			},
 			end: {
 				line: 73,
 				column: 16,
-				character: 979
+				character: 981
 			}
 		},
 		{
@@ -23,12 +23,12 @@ export default test({
 			start: {
 				line: 104,
 				column: 29,
-				character: 1270
+				character: 1272
 			},
 			end: {
 				line: 104,
 				column: 43,
-				character: 1284
+				character: 1286
 			}
 		}
 	]

From 57cb393796841538c1b38ef99dd2be48815604a5 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 6 Feb 2026 11:57:49 -0500
Subject: [PATCH 22/23] fix: allow NaN in key blocks (#17642)

* fix: allow NaN in key blocks

* lol whoops

* Update packages/svelte/src/internal/client/dom/blocks/key.js

Co-authored-by: Simon H <5968653+dummdidumm@users.noreply.github.com>

---------

Co-authored-by: Simon H <5968653+dummdidumm@users.noreply.github.com>
---
 .changeset/clear-olives-share.md                |  5 +++++
 .../src/internal/client/dom/blocks/key.js       |  7 +++++++
 .../runtime-runes/samples/key-nan/_config.js    | 17 +++++++++++++++++
 .../runtime-runes/samples/key-nan/main.svelte   | 10 ++++++++++
 4 files changed, 39 insertions(+)
 create mode 100644 .changeset/clear-olives-share.md
 create mode 100644 packages/svelte/tests/runtime-runes/samples/key-nan/_config.js
 create mode 100644 packages/svelte/tests/runtime-runes/samples/key-nan/main.svelte

diff --git a/.changeset/clear-olives-share.md b/.changeset/clear-olives-share.md
new file mode 100644
index 0000000000..975b2b21b6
--- /dev/null
+++ b/.changeset/clear-olives-share.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: allow `{#key NaN}`
diff --git a/packages/svelte/src/internal/client/dom/blocks/key.js b/packages/svelte/src/internal/client/dom/blocks/key.js
index 849b1c2447..dd40d8a1b8 100644
--- a/packages/svelte/src/internal/client/dom/blocks/key.js
+++ b/packages/svelte/src/internal/client/dom/blocks/key.js
@@ -4,6 +4,8 @@ import { block } from '../../reactivity/effects.js';
 import { hydrate_next, hydrating } from '../hydration.js';
 import { BranchManager } from './branches.js';
 
+const NAN = Symbol('NaN');
+
 /**
  * @template V
  * @param {TemplateNode} node
@@ -23,6 +25,11 @@ export function key(node, get_key, render_fn) {
 	block(() => {
 		var key = get_key();
 
+		// NaN !== NaN, hence we do this workaround to not trigger remounts unnecessarily
+		if (key !== key) {
+			key = /** @type {any} */ (NAN);
+		}
+
 		// key blocks in Svelte <5 had stupid semantics
 		if (legacy && key !== null && typeof key === 'object') {
 			key = /** @type {V} */ ({});
diff --git a/packages/svelte/tests/runtime-runes/samples/key-nan/_config.js b/packages/svelte/tests/runtime-runes/samples/key-nan/_config.js
new file mode 100644
index 0000000000..bd0dd06761
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/key-nan/_config.js
@@ -0,0 +1,17 @@
+import { flushSync } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+	html: '<button>update</button><p>it rendered</p>',
+
+	test({ assert, target, logs }) {
+		assert.deepEqual(logs, ['rendering']);
+
+		const btn = target.querySelector('button');
+		flushSync(() => btn?.click());
+
+		// should not re-render
+		assert.deepEqual(logs, ['rendering']);
+		assert.htmlEqual(target.innerHTML, '<button>update</button><p>it rendered</p>');
+	}
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/key-nan/main.svelte b/packages/svelte/tests/runtime-runes/samples/key-nan/main.svelte
new file mode 100644
index 0000000000..24f7f2d179
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/key-nan/main.svelte
@@ -0,0 +1,10 @@
+<script>
+	let x = $state(NaN);
+</script>
+
+<button onclick={() => x = NaN}>update</button>
+
+{#key x}
+	{console.log('rendering')}
+	<p>it rendered</p>
+{/key}

From 863c9d6875470ad7699614fe278c0d99903d30f8 Mon Sep 17 00:00:00 2001
From: Andrew Aquino <dawneraq@gmail.com>
Date: Fri, 6 Feb 2026 10:27:13 -0800
Subject: [PATCH 23/23] chore: wrap JSDoc URLs in @see and @link tags (#17617)

* docs: wrap JSDoc URLs in @see and @link tags

* fix: move curly brace to end of URL

* chore: add changeset

* add link text

* regenerate

---------

Co-authored-by: Rich Harris <rich.harris@vercel.com>
---
 .changeset/loud-bottles-own.md                |  5 ++++
 packages/svelte/src/ambient.d.ts              | 28 +++++++++----------
 .../src/compiler/phases/1-parse/read/style.js |  2 +-
 .../client/dom/elements/bindings/size.js      |  5 ++--
 .../samples/transition-component/_config.js   |  2 +-
 packages/svelte/types/index.d.ts              | 28 +++++++++----------
 6 files changed, 37 insertions(+), 33 deletions(-)
 create mode 100644 .changeset/loud-bottles-own.md

diff --git a/.changeset/loud-bottles-own.md b/.changeset/loud-bottles-own.md
new file mode 100644
index 0000000000..493dc6c47f
--- /dev/null
+++ b/.changeset/loud-bottles-own.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+chore: wrap JSDoc URLs in `@see` and `@link` tags
diff --git a/packages/svelte/src/ambient.d.ts b/packages/svelte/src/ambient.d.ts
index ec5b799470..159a568477 100644
--- a/packages/svelte/src/ambient.d.ts
+++ b/packages/svelte/src/ambient.d.ts
@@ -16,7 +16,7 @@ declare module '*.svelte' {
  * let count = $state(0);
  * ```
  *
- * https://svelte.dev/docs/svelte/$state
+ * @see {@link https://svelte.dev/docs/svelte/$state Documentation}
  *
  * @param initial The initial value
  */
@@ -126,7 +126,7 @@ declare namespace $state {
 	 * </button>
 	 * ```
 	 *
-	 * https://svelte.dev/docs/svelte/$state#$state.raw
+	 * @see {@link https://svelte.dev/docs/svelte/$state#$state.raw Documentation}
 	 *
 	 * @param initial The initial value
 	 */
@@ -147,7 +147,7 @@ declare namespace $state {
 	 * </script>
 	 * ```
 	 *
-	 * https://svelte.dev/docs/svelte/$state#$state.snapshot
+	 * @see {@link https://svelte.dev/docs/svelte/$state#$state.snapshot Documentation}
 	 *
 	 * @param state The value to snapshot
 	 */
@@ -187,7 +187,7 @@ declare namespace $state {
  * let double = $derived(count * 2);
  * ```
  *
- * https://svelte.dev/docs/svelte/$derived
+ * @see {@link https://svelte.dev/docs/svelte/$derived Documentation}
  *
  * @param expression The derived state expression
  */
@@ -209,7 +209,7 @@ declare namespace $derived {
 	 * });
 	 * ```
 	 *
-	 * https://svelte.dev/docs/svelte/$derived#$derived.by
+	 * @see {@link https://svelte.dev/docs/svelte/$derived#$derived.by Documentation}
 	 */
 	export function by<T>(fn: () => T): T;
 
@@ -251,7 +251,7 @@ declare namespace $derived {
  *
  * Does not run during server-side rendering.
  *
- * https://svelte.dev/docs/svelte/$effect
+ * @see {@link https://svelte.dev/docs/svelte/$effect Documentation}
  * @param fn The function to execute
  */
 declare function $effect(fn: () => void | (() => void)): void;
@@ -270,7 +270,7 @@ declare namespace $effect {
 	 *
 	 * Does not run during server-side rendering.
 	 *
-	 * https://svelte.dev/docs/svelte/$effect#$effect.pre
+	 * @see {@link https://svelte.dev/docs/svelte/$effect#$effect.pre Documentation}
 	 * @param fn The function to execute
 	 */
 	export function pre(fn: () => void | (() => void)): void;
@@ -278,7 +278,7 @@ declare namespace $effect {
 	/**
 	 * Returns the number of promises that are pending in the current boundary, not including child boundaries.
 	 *
-	 * https://svelte.dev/docs/svelte/$effect#$effect.pending
+	 * @see {@link https://svelte.dev/docs/svelte/$effect#$effect.pending Documentation}
 	 */
 	export function pending(): number;
 
@@ -300,7 +300,7 @@ declare namespace $effect {
 	 *
 	 * This allows you to (for example) add things like subscriptions without causing memory leaks, by putting them in child effects.
 	 *
-	 * https://svelte.dev/docs/svelte/$effect#$effect.tracking
+	 * @see {@link https://svelte.dev/docs/svelte/$effect#$effect.tracking Documentation}
 	 */
 	export function tracking(): boolean;
 
@@ -328,7 +328,7 @@ declare namespace $effect {
 	 * <button onclick={() => cleanup()}>cleanup</button>
 	 * ```
 	 *
-	 * https://svelte.dev/docs/svelte/$effect#$effect.root
+	 * @see {@link https://svelte.dev/docs/svelte/$effect#$effect.root Documentation}
 	 */
 	export function root(fn: () => void | (() => void)): () => void;
 
@@ -364,7 +364,7 @@ declare namespace $effect {
  * let { optionalProp = 42, requiredProp, bindableProp = $bindable() }: { optionalProp?: number; requiredProps: string; bindableProp: boolean } = $props();
  * ```
  *
- * https://svelte.dev/docs/svelte/$props
+ * @see {@link https://svelte.dev/docs/svelte/$props Documentation}
  */
 declare function $props(): any;
 
@@ -410,7 +410,7 @@ declare namespace $props {
  * let { propName = $bindable() }: { propName: boolean } = $props();
  * ```
  *
- * https://svelte.dev/docs/svelte/$bindable
+ * @see {@link https://svelte.dev/docs/svelte/$bindable Documentation}
  */
 declare function $bindable<T>(fallback?: T): T;
 
@@ -456,7 +456,7 @@ declare namespace $bindable {
  * $inspect(x, y).with(() => { debugger; });
  * ```
  *
- * https://svelte.dev/docs/svelte/$inspect
+ * @see {@link https://svelte.dev/docs/svelte/$inspect Documentation}
  */
 declare function $inspect<T extends any[]>(
 	...values: T
@@ -522,7 +522,7 @@ declare namespace $inspect {
  *
  * Only available inside custom element components, and only on the client-side.
  *
- * https://svelte.dev/docs/svelte/$host
+ * @see {@link https://svelte.dev/docs/svelte/$host Documentation}
  */
 declare function $host<El extends HTMLElement = HTMLElement>(): El;
 
diff --git a/packages/svelte/src/compiler/phases/1-parse/read/style.js b/packages/svelte/src/compiler/phases/1-parse/read/style.js
index 55647b2c94..4f2db349cd 100644
--- a/packages/svelte/src/compiler/phases/1-parse/read/style.js
+++ b/packages/svelte/src/compiler/phases/1-parse/read/style.js
@@ -568,7 +568,7 @@ function read_attribute_value(parser) {
 }
 
 /**
- * https://www.w3.org/TR/css-syntax-3/#ident-token-diagram
+ * @see {@link https://www.w3.org/TR/css-syntax-3/#ident-token-diagram CSS Syntax Module Level 3}
  * @param {Parser} parser
  */
 function read_identifier(parser) {
diff --git a/packages/svelte/src/internal/client/dom/elements/bindings/size.js b/packages/svelte/src/internal/client/dom/elements/bindings/size.js
index a76c70aab1..016ee5a547 100644
--- a/packages/svelte/src/internal/client/dom/elements/bindings/size.js
+++ b/packages/svelte/src/internal/client/dom/elements/bindings/size.js
@@ -2,9 +2,8 @@ import { effect, teardown } from '../../../reactivity/effects.js';
 import { untrack } from '../../../runtime.js';
 
 /**
- * Resize observer singleton.
- * One listener per element only!
- * https://groups.google.com/a/chromium.org/g/blink-dev/c/z6ienONUb5A/m/F5-VcUZtBAAJ
+ * We create one listener for all elements
+ * @see {@link https://groups.google.com/a/chromium.org/g/blink-dev/c/z6ienONUb5A/m/F5-VcUZtBAAJ Explanation}
  */
 class ResizeObserverSingleton {
 	/** */
diff --git a/packages/svelte/tests/runtime-runes/samples/transition-component/_config.js b/packages/svelte/tests/runtime-runes/samples/transition-component/_config.js
index 414a8b0cc2..1bdf3a5a2e 100644
--- a/packages/svelte/tests/runtime-runes/samples/transition-component/_config.js
+++ b/packages/svelte/tests/runtime-runes/samples/transition-component/_config.js
@@ -3,7 +3,7 @@ import { test } from '../../test';
 
 /**
  * $.component() should not break transition
- * https://github.com/sveltejs/svelte/issues/13645
+ * @see {@link https://github.com/sveltejs/svelte/issues/13645}
  */
 export default test({
 	test({ assert, raf, target }) {
diff --git a/packages/svelte/types/index.d.ts b/packages/svelte/types/index.d.ts
index 730e0ff655..62c0e210be 100644
--- a/packages/svelte/types/index.d.ts
+++ b/packages/svelte/types/index.d.ts
@@ -3188,7 +3188,7 @@ declare module 'svelte/types/compiler/interfaces' {
  * let count = $state(0);
  * ```
  *
- * https://svelte.dev/docs/svelte/$state
+ * @see {@link https://svelte.dev/docs/svelte/$state Documentation}
  *
  * @param initial The initial value
  */
@@ -3298,7 +3298,7 @@ declare namespace $state {
 	 * </button>
 	 * ```
 	 *
-	 * https://svelte.dev/docs/svelte/$state#$state.raw
+	 * @see {@link https://svelte.dev/docs/svelte/$state#$state.raw Documentation}
 	 *
 	 * @param initial The initial value
 	 */
@@ -3319,7 +3319,7 @@ declare namespace $state {
 	 * </script>
 	 * ```
 	 *
-	 * https://svelte.dev/docs/svelte/$state#$state.snapshot
+	 * @see {@link https://svelte.dev/docs/svelte/$state#$state.snapshot Documentation}
 	 *
 	 * @param state The value to snapshot
 	 */
@@ -3359,7 +3359,7 @@ declare namespace $state {
  * let double = $derived(count * 2);
  * ```
  *
- * https://svelte.dev/docs/svelte/$derived
+ * @see {@link https://svelte.dev/docs/svelte/$derived Documentation}
  *
  * @param expression The derived state expression
  */
@@ -3381,7 +3381,7 @@ declare namespace $derived {
 	 * });
 	 * ```
 	 *
-	 * https://svelte.dev/docs/svelte/$derived#$derived.by
+	 * @see {@link https://svelte.dev/docs/svelte/$derived#$derived.by Documentation}
 	 */
 	export function by<T>(fn: () => T): T;
 
@@ -3423,7 +3423,7 @@ declare namespace $derived {
  *
  * Does not run during server-side rendering.
  *
- * https://svelte.dev/docs/svelte/$effect
+ * @see {@link https://svelte.dev/docs/svelte/$effect Documentation}
  * @param fn The function to execute
  */
 declare function $effect(fn: () => void | (() => void)): void;
@@ -3442,7 +3442,7 @@ declare namespace $effect {
 	 *
 	 * Does not run during server-side rendering.
 	 *
-	 * https://svelte.dev/docs/svelte/$effect#$effect.pre
+	 * @see {@link https://svelte.dev/docs/svelte/$effect#$effect.pre Documentation}
 	 * @param fn The function to execute
 	 */
 	export function pre(fn: () => void | (() => void)): void;
@@ -3450,7 +3450,7 @@ declare namespace $effect {
 	/**
 	 * Returns the number of promises that are pending in the current boundary, not including child boundaries.
 	 *
-	 * https://svelte.dev/docs/svelte/$effect#$effect.pending
+	 * @see {@link https://svelte.dev/docs/svelte/$effect#$effect.pending Documentation}
 	 */
 	export function pending(): number;
 
@@ -3472,7 +3472,7 @@ declare namespace $effect {
 	 *
 	 * This allows you to (for example) add things like subscriptions without causing memory leaks, by putting them in child effects.
 	 *
-	 * https://svelte.dev/docs/svelte/$effect#$effect.tracking
+	 * @see {@link https://svelte.dev/docs/svelte/$effect#$effect.tracking Documentation}
 	 */
 	export function tracking(): boolean;
 
@@ -3500,7 +3500,7 @@ declare namespace $effect {
 	 * <button onclick={() => cleanup()}>cleanup</button>
 	 * ```
 	 *
-	 * https://svelte.dev/docs/svelte/$effect#$effect.root
+	 * @see {@link https://svelte.dev/docs/svelte/$effect#$effect.root Documentation}
 	 */
 	export function root(fn: () => void | (() => void)): () => void;
 
@@ -3536,7 +3536,7 @@ declare namespace $effect {
  * let { optionalProp = 42, requiredProp, bindableProp = $bindable() }: { optionalProp?: number; requiredProps: string; bindableProp: boolean } = $props();
  * ```
  *
- * https://svelte.dev/docs/svelte/$props
+ * @see {@link https://svelte.dev/docs/svelte/$props Documentation}
  */
 declare function $props(): any;
 
@@ -3582,7 +3582,7 @@ declare namespace $props {
  * let { propName = $bindable() }: { propName: boolean } = $props();
  * ```
  *
- * https://svelte.dev/docs/svelte/$bindable
+ * @see {@link https://svelte.dev/docs/svelte/$bindable Documentation}
  */
 declare function $bindable<T>(fallback?: T): T;
 
@@ -3628,7 +3628,7 @@ declare namespace $bindable {
  * $inspect(x, y).with(() => { debugger; });
  * ```
  *
- * https://svelte.dev/docs/svelte/$inspect
+ * @see {@link https://svelte.dev/docs/svelte/$inspect Documentation}
  */
 declare function $inspect<T extends any[]>(
 	...values: T
@@ -3694,7 +3694,7 @@ declare namespace $inspect {
  *
  * Only available inside custom element components, and only on the client-side.
  *
- * https://svelte.dev/docs/svelte/$host
+ * @see {@link https://svelte.dev/docs/svelte/$host Documentation}
  */
 declare function $host<El extends HTMLElement = HTMLElement>(): El;