From 8e2f4b51c50a2e10bc482fac6d900be921dd8b74 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Wed, 23 Jul 2025 07:55:51 -0400
Subject: [PATCH 01/60] fix: unset batch before flushing queued effects
 (#16482)
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

* - add state changes resulting from an $effect to a separate new batch
- schedule rerunning effects based on the sources that are dirty, not just rerunning them all blindly (excempting async effects which will have run by that time already)

* test

* better fix

* tests

* this fixes the last test somehow

* fix #16477

* typo

* copy over changeset from #16477

* copy over changeset from #16464

* changeset

* dedupe

* move flushing_sync check inside Batch.ensure

* unused

* flushing_sync -> is_flushing_sync

* remove flush_effects method

* dedupe declaration

* tweak

* tweak

* update comment — it _does_ feel slightly wrong, but no wronger than the rest of this cursed function

---------

Co-authored-by: Simon Holthausen <simon.holthausen@vercel.com>
---
 .changeset/grumpy-boats-beg.md                |   5 +
 .changeset/shiny-walls-fix.md                 |   5 +
 .changeset/thick-mice-kick.md                 |   5 +
 .../src/internal/client/reactivity/batch.js   | 190 ++++++++++--------
 .../src/internal/client/reactivity/sources.js |  11 +-
 .../Component.svelte                          |   7 +
 .../1000-reading-derived-effects/_config.js   |   5 +
 .../1000-reading-derived-effects/main.svelte  |   8 +
 .../_config.js                                |  26 +++
 .../main.svelte                               |  27 +++
 .../async-effect-triggers-await/_config.js    |  32 +++
 .../async-effect-triggers-await/main.svelte   |  24 +++
 .../binding-update-while-focused-2/_config.js |  24 +++
 .../main.svelte                               |  21 ++
 14 files changed, 298 insertions(+), 92 deletions(-)
 create mode 100644 .changeset/grumpy-boats-beg.md
 create mode 100644 .changeset/shiny-walls-fix.md
 create mode 100644 .changeset/thick-mice-kick.md
 create mode 100644 packages/svelte/tests/runtime-runes/samples/1000-reading-derived-effects/Component.svelte
 create mode 100644 packages/svelte/tests/runtime-runes/samples/1000-reading-derived-effects/_config.js
 create mode 100644 packages/svelte/tests/runtime-runes/samples/1000-reading-derived-effects/main.svelte
 create mode 100644 packages/svelte/tests/runtime-runes/samples/async-binding-update-while-focused/_config.js
 create mode 100644 packages/svelte/tests/runtime-runes/samples/async-binding-update-while-focused/main.svelte
 create mode 100644 packages/svelte/tests/runtime-runes/samples/async-effect-triggers-await/_config.js
 create mode 100644 packages/svelte/tests/runtime-runes/samples/async-effect-triggers-await/main.svelte
 create mode 100644 packages/svelte/tests/runtime-runes/samples/binding-update-while-focused-2/_config.js
 create mode 100644 packages/svelte/tests/runtime-runes/samples/binding-update-while-focused-2/main.svelte

diff --git a/.changeset/grumpy-boats-beg.md b/.changeset/grumpy-boats-beg.md
new file mode 100644
index 0000000000..f677743def
--- /dev/null
+++ b/.changeset/grumpy-boats-beg.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: keep input in sync when binding updated via effect
diff --git a/.changeset/shiny-walls-fix.md b/.changeset/shiny-walls-fix.md
new file mode 100644
index 0000000000..91ed548728
--- /dev/null
+++ b/.changeset/shiny-walls-fix.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: prevent infinite async loop
diff --git a/.changeset/thick-mice-kick.md b/.changeset/thick-mice-kick.md
new file mode 100644
index 0000000000..eec55b77ee
--- /dev/null
+++ b/.changeset/thick-mice-kick.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: exclude derived writes from effect abort and rescheduling
diff --git a/packages/svelte/src/internal/client/reactivity/batch.js b/packages/svelte/src/internal/client/reactivity/batch.js
index c452211894..ce413fa1e1 100644
--- a/packages/svelte/src/internal/client/reactivity/batch.js
+++ b/packages/svelte/src/internal/client/reactivity/batch.js
@@ -21,14 +21,13 @@ import {
 	is_updating_effect,
 	set_is_updating_effect,
 	set_signal_status,
-	update_effect,
-	write_version
+	update_effect
 } from '../runtime.js';
 import * as e from '../errors.js';
 import { flush_tasks } from '../dom/task.js';
 import { DEV } from 'esm-env';
 import { invoke_error_boundary } from '../error-handling.js';
-import { old_values } from './sources.js';
+import { mark_reactions, old_values } from './sources.js';
 import { unlink_effect } from './effects.js';
 import { unset_context } from './async.js';
 
@@ -70,13 +69,15 @@ let last_scheduled_effect = null;
 
 let is_flushing = false;
 
+let is_flushing_sync = false;
+
 export class Batch {
 	/**
 	 * The current values of any sources that are updated in this batch
 	 * They keys of this map are identical to `this.#previous`
 	 * @type {Map<Source, any>}
 	 */
-	#current = new Map();
+	current = new Map();
 
 	/**
 	 * The values of any sources that are updated in this batch _before_ those updates took place.
@@ -156,7 +157,7 @@ export class Batch {
 	 *
 	 * @param {Effect[]} root_effects
 	 */
-	#process(root_effects) {
+	process(root_effects) {
 		queued_root_effects = [];
 
 		/** @type {Map<Source, { v: unknown, wv: number }> | null} */
@@ -169,7 +170,7 @@ export class Batch {
 			current_values = new Map();
 			batch_deriveds = new Map();
 
-			for (const [source, current] of this.#current) {
+			for (const [source, current] of this.current) {
 				current_values.set(source, { v: source.v, wv: source.wv });
 				source.v = current;
 			}
@@ -202,9 +203,22 @@ export class Batch {
 			this.#effects = [];
 			this.#block_effects = [];
 
+			// If sources are written to, then work needs to happen in a separate batch, else prior sources would be mixed with
+			// newly updated sources, which could lead to infinite loops when effects run over and over again.
+			current_batch = null;
+
 			flush_queued_effects(render_effects);
 			flush_queued_effects(effects);
 
+			// Reinstate the current batch if there was no new one created, as `process()` runs in a loop in `flush_effects()`.
+			// That method expects `current_batch` to be set, and could run the loop again if effects result in new effects
+			// being scheduled but without writes happening in which case no new batch is created.
+			if (current_batch === null) {
+				current_batch = this;
+			} else {
+				batches.delete(this);
+			}
+
 			this.#deferred?.resolve();
 		} else {
 			// otherwise mark effects clean so they get scheduled on the next run
@@ -300,7 +314,7 @@ export class Batch {
 			this.#previous.set(source, value);
 		}
 
-		this.#current.set(source, source.v);
+		this.current.set(source, source.v);
 	}
 
 	activate() {
@@ -327,13 +341,13 @@ export class Batch {
 
 	flush() {
 		if (queued_root_effects.length > 0) {
-			this.flush_effects();
+			flush_effects();
 		} else {
 			this.#commit();
 		}
 
 		if (current_batch !== this) {
-			// this can happen if a `flushSync` occurred during `this.flush_effects()`,
+			// this can happen if a `flushSync` occurred during `flush_effects()`,
 			// which is permitted in legacy mode despite being a terrible idea
 			return;
 		}
@@ -345,52 +359,6 @@ export class Batch {
 		this.deactivate();
 	}
 
-	flush_effects() {
-		var was_updating_effect = is_updating_effect;
-		is_flushing = true;
-
-		try {
-			var flush_count = 0;
-			set_is_updating_effect(true);
-
-			while (queued_root_effects.length > 0) {
-				if (flush_count++ > 1000) {
-					if (DEV) {
-						var updates = new Map();
-
-						for (const source of this.#current.keys()) {
-							for (const [stack, update] of source.updated ?? []) {
-								var entry = updates.get(stack);
-
-								if (!entry) {
-									entry = { error: update.error, count: 0 };
-									updates.set(stack, entry);
-								}
-
-								entry.count += update.count;
-							}
-						}
-
-						for (const update of updates.values()) {
-							// eslint-disable-next-line no-console
-							console.error(update.error);
-						}
-					}
-
-					infinite_loop_guard();
-				}
-
-				this.#process(queued_root_effects);
-				old_values.clear();
-			}
-		} finally {
-			is_flushing = false;
-			set_is_updating_effect(was_updating_effect);
-
-			last_scheduled_effect = null;
-		}
-	}
-
 	/**
 	 * Append and remove branches to/from the DOM
 	 */
@@ -412,19 +380,8 @@ export class Batch {
 		this.#pending -= 1;
 
 		if (this.#pending === 0) {
-			for (const e of this.#render_effects) {
-				set_signal_status(e, DIRTY);
-				schedule_effect(e);
-			}
-
-			for (const e of this.#effects) {
-				set_signal_status(e, DIRTY);
-				schedule_effect(e);
-			}
-
-			for (const e of this.#block_effects) {
-				set_signal_status(e, DIRTY);
-				schedule_effect(e);
+			for (const source of this.current.keys()) {
+				mark_reactions(source, DIRTY, false);
 			}
 
 			this.#render_effects = [];
@@ -445,12 +402,12 @@ export class Batch {
 		return (this.#deferred ??= deferred()).promise;
 	}
 
-	static ensure(autoflush = true) {
+	static ensure() {
 		if (current_batch === null) {
 			const batch = (current_batch = new Batch());
 			batches.add(current_batch);
 
-			if (autoflush) {
+			if (!is_flushing_sync) {
 				Batch.enqueue(() => {
 					if (current_batch !== batch) {
 						// a flushSync happened in the meantime
@@ -487,32 +444,85 @@ export function flushSync(fn) {
 		e.flush_sync_in_effect();
 	}
 
-	var result;
+	var was_flushing_sync = is_flushing_sync;
+	is_flushing_sync = true;
 
-	const batch = Batch.ensure(false);
+	try {
+		var result;
 
-	if (fn) {
-		batch.flush_effects();
+		if (fn) {
+			flush_effects();
+			result = fn();
+		}
 
-		result = fn();
-	}
+		while (true) {
+			flush_tasks();
 
-	while (true) {
-		flush_tasks();
+			if (queued_root_effects.length === 0) {
+				current_batch?.flush();
 
-		if (queued_root_effects.length === 0) {
-			if (batch === current_batch) {
-				batch.flush();
+				// we need to check again, in case we just updated an `$effect.pending()`
+				if (queued_root_effects.length === 0) {
+					// this would be reset in `flush_effects()` but since we are early returning here,
+					// we need to reset it here as well in case the first time there's 0 queued root effects
+					last_scheduled_effect = null;
+
+					return /** @type {T} */ (result);
+				}
 			}
 
-			// this would be reset in `batch.flush_effects()` but since we are early returning here,
-			// we need to reset it here as well in case the first time there's 0 queued root effects
-			last_scheduled_effect = null;
+			flush_effects();
+		}
+	} finally {
+		is_flushing_sync = was_flushing_sync;
+	}
+}
+
+function flush_effects() {
+	var was_updating_effect = is_updating_effect;
+	is_flushing = true;
+
+	try {
+		var flush_count = 0;
+		set_is_updating_effect(true);
+
+		while (queued_root_effects.length > 0) {
+			var batch = Batch.ensure();
+
+			if (flush_count++ > 1000) {
+				if (DEV) {
+					var updates = new Map();
+
+					for (const source of batch.current.keys()) {
+						for (const [stack, update] of source.updated ?? []) {
+							var entry = updates.get(stack);
+
+							if (!entry) {
+								entry = { error: update.error, count: 0 };
+								updates.set(stack, entry);
+							}
+
+							entry.count += update.count;
+						}
+					}
+
+					for (const update of updates.values()) {
+						// eslint-disable-next-line no-console
+						console.error(update.error);
+					}
+				}
+
+				infinite_loop_guard();
+			}
 
-			return /** @type {T} */ (result);
+			batch.process(queued_root_effects);
+			old_values.clear();
 		}
+	} finally {
+		is_flushing = false;
+		set_is_updating_effect(was_updating_effect);
 
-		batch.flush_effects();
+		last_scheduled_effect = null;
 	}
 }
 
@@ -545,7 +555,7 @@ function flush_queued_effects(effects) {
 		var effect = effects[i++];
 
 		if ((effect.f & (DESTROYED | INERT)) === 0 && is_dirty(effect)) {
-			var wv = write_version;
+			var n = current_batch ? current_batch.current.size : 0;
 
 			update_effect(effect);
 
@@ -568,7 +578,11 @@ function flush_queued_effects(effects) {
 
 			// if state is written in a user effect, abort and re-schedule, lest we run
 			// effects that should be removed as a result of the state change
-			if (write_version > wv && (effect.f & USER_EFFECT) !== 0) {
+			if (
+				current_batch !== null &&
+				current_batch.current.size > n &&
+				(effect.f & USER_EFFECT) !== 0
+			) {
 				break;
 			}
 		}
diff --git a/packages/svelte/src/internal/client/reactivity/sources.js b/packages/svelte/src/internal/client/reactivity/sources.js
index f6b14f3360..3b28c8fdce 100644
--- a/packages/svelte/src/internal/client/reactivity/sources.js
+++ b/packages/svelte/src/internal/client/reactivity/sources.js
@@ -179,7 +179,7 @@ export function internal_set(source, value) {
 
 		source.v = value;
 
-		const batch = Batch.ensure();
+		var batch = Batch.ensure();
 		batch.capture(source, old_value);
 
 		if (DEV) {
@@ -301,9 +301,10 @@ export function increment(source) {
 /**
  * @param {Value} signal
  * @param {number} status should be DIRTY or MAYBE_DIRTY
+ * @param {boolean} schedule_async
  * @returns {void}
  */
-function mark_reactions(signal, status) {
+export function mark_reactions(signal, status, schedule_async = true) {
 	var reactions = signal.reactions;
 	if (reactions === null) return;
 
@@ -323,14 +324,16 @@ function mark_reactions(signal, status) {
 			continue;
 		}
 
+		var should_schedule = (flags & DIRTY) === 0 && (schedule_async || (flags & ASYNC) === 0);
+
 		// don't set a DIRTY reaction to MAYBE_DIRTY
-		if ((flags & DIRTY) === 0) {
+		if (should_schedule) {
 			set_signal_status(reaction, status);
 		}
 
 		if ((flags & DERIVED) !== 0) {
 			mark_reactions(/** @type {Derived} */ (reaction), MAYBE_DIRTY);
-		} else if ((flags & DIRTY) === 0) {
+		} else if (should_schedule) {
 			schedule_effect(/** @type {Effect} */ (reaction));
 		}
 	}
diff --git a/packages/svelte/tests/runtime-runes/samples/1000-reading-derived-effects/Component.svelte b/packages/svelte/tests/runtime-runes/samples/1000-reading-derived-effects/Component.svelte
new file mode 100644
index 0000000000..7a54323cb9
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/1000-reading-derived-effects/Component.svelte
@@ -0,0 +1,7 @@
+<script>
+	const der = $derived(false);
+
+	$effect(() => {
+		der
+	});
+</script>
\ No newline at end of file
diff --git a/packages/svelte/tests/runtime-runes/samples/1000-reading-derived-effects/_config.js b/packages/svelte/tests/runtime-runes/samples/1000-reading-derived-effects/_config.js
new file mode 100644
index 0000000000..2e4a27cf09
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/1000-reading-derived-effects/_config.js
@@ -0,0 +1,5 @@
+import { test } from '../../test';
+
+export default test({
+	async test() {}
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/1000-reading-derived-effects/main.svelte b/packages/svelte/tests/runtime-runes/samples/1000-reading-derived-effects/main.svelte
new file mode 100644
index 0000000000..bd326edfb9
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/1000-reading-derived-effects/main.svelte
@@ -0,0 +1,8 @@
+<script>
+	import Component from './Component.svelte';
+	const arr = Array.from({length: 10001});
+</script>
+
+{#each arr}
+	<Component />
+{/each}
diff --git a/packages/svelte/tests/runtime-runes/samples/async-binding-update-while-focused/_config.js b/packages/svelte/tests/runtime-runes/samples/async-binding-update-while-focused/_config.js
new file mode 100644
index 0000000000..782ae945f9
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/async-binding-update-while-focused/_config.js
@@ -0,0 +1,26 @@
+import { tick } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+	async test({ assert, target }) {
+		await tick();
+
+		const [input] = target.querySelectorAll('input');
+
+		input.focus();
+		input.value = '3';
+		input.dispatchEvent(new InputEvent('input', { bubbles: true }));
+		await tick();
+
+		assert.equal(input.value, '3');
+		assert.htmlEqual(target.innerHTML, `<p>3</p> <input type="number" />`);
+
+		input.focus();
+		input.value = '1';
+		input.dispatchEvent(new InputEvent('input', { bubbles: true }));
+		await tick();
+
+		assert.equal(input.value, '2');
+		assert.htmlEqual(target.innerHTML, `<p>2</p> <input type="number" />`);
+	}
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/async-binding-update-while-focused/main.svelte b/packages/svelte/tests/runtime-runes/samples/async-binding-update-while-focused/main.svelte
new file mode 100644
index 0000000000..763ce6ebf0
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/async-binding-update-while-focused/main.svelte
@@ -0,0 +1,27 @@
+<script>
+	let value = $state(0)
+	const min = 2
+	const max = 5
+
+	$effect(() => {
+		setValue()
+	})
+
+	function setValue() {
+		if (value < min) {
+			value = min
+		}
+		if (value > max) {
+			value = max
+		}
+	}
+</script>
+
+<svelte:boundary>
+	<p>{await value}</p>
+	<input type="number" bind:value />
+
+	{#snippet pending()}
+		<p>loading...</p>
+	{/snippet}
+</svelte:boundary>
diff --git a/packages/svelte/tests/runtime-runes/samples/async-effect-triggers-await/_config.js b/packages/svelte/tests/runtime-runes/samples/async-effect-triggers-await/_config.js
new file mode 100644
index 0000000000..c551cc6b8c
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/async-effect-triggers-await/_config.js
@@ -0,0 +1,32 @@
+import { tick } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+	async test({ assert, target }) {
+		await tick();
+
+		const [increment] = target.querySelectorAll('button');
+
+		increment.click();
+		await tick();
+		assert.htmlEqual(
+			target.innerHTML,
+			`
+				<button>increment</button>
+				<p>1</p>
+				<p>1</p>
+			`
+		);
+
+		increment.click();
+		await tick();
+		assert.htmlEqual(
+			target.innerHTML,
+			`
+				<button>increment</button>
+				<p>2</p>
+				<p>2</p>
+			`
+		);
+	}
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/async-effect-triggers-await/main.svelte b/packages/svelte/tests/runtime-runes/samples/async-effect-triggers-await/main.svelte
new file mode 100644
index 0000000000..153fe03f0d
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/async-effect-triggers-await/main.svelte
@@ -0,0 +1,24 @@
+<script lang="ts">
+	let data = $state(Promise.resolve(0));
+
+	let count = $state(0);
+	let unrelated = $state(0);
+
+	$effect(() => {
+		data = Promise.resolve(count)
+		unrelated = count;
+	});
+</script>
+
+<svelte:boundary>
+	<button onclick={() => count += 1}>increment</button>
+	<p>{JSON.stringify((await data), null, 2)}</p>
+	{#if true}
+		<!-- inside if block to force it into a different render effect -->
+		<p>{unrelated}</p>
+	{/if}
+
+	{#snippet pending()}
+		<p>loading...</p>
+	{/snippet}
+</svelte:boundary>
diff --git a/packages/svelte/tests/runtime-runes/samples/binding-update-while-focused-2/_config.js b/packages/svelte/tests/runtime-runes/samples/binding-update-while-focused-2/_config.js
new file mode 100644
index 0000000000..7a56c79d71
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/binding-update-while-focused-2/_config.js
@@ -0,0 +1,24 @@
+import { flushSync } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+	test({ assert, target }) {
+		const [input] = target.querySelectorAll('input');
+
+		input.focus();
+		input.value = '3';
+		input.dispatchEvent(new InputEvent('input', { bubbles: true }));
+		flushSync();
+
+		assert.equal(input.value, '3');
+		assert.htmlEqual(target.innerHTML, `<p>3</p> <input type="number" />`);
+
+		input.focus();
+		input.value = '1';
+		input.dispatchEvent(new InputEvent('input', { bubbles: true }));
+		flushSync();
+
+		assert.equal(input.value, '2');
+		assert.htmlEqual(target.innerHTML, `<p>2</p> <input type="number" />`);
+	}
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/binding-update-while-focused-2/main.svelte b/packages/svelte/tests/runtime-runes/samples/binding-update-while-focused-2/main.svelte
new file mode 100644
index 0000000000..b0597c223b
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/binding-update-while-focused-2/main.svelte
@@ -0,0 +1,21 @@
+<script>
+	let value = $state(0)
+	const min = 2
+	const max = 5
+
+	$effect(() => {
+		setValue()
+	})
+
+	function setValue() {
+		if (value < min) {
+			value = min
+		}
+		if (value > max) {
+			value = max
+		}
+	}
+</script>
+
+<p>{value}</p>
+<input type="number" bind:value />

From c26365bdda1a13e98a2e75f17da655e08ff4f8bc Mon Sep 17 00:00:00 2001
From: Hyunbin Seo <47051820+hyunbinseo@users.noreply.github.com>
Date: Wed, 23 Jul 2025 21:02:28 +0900
Subject: [PATCH 02/60] chore: rename form `accept-charset` attribute (#16478)

* chore: rename form accept-charset attribute

* chore: utf-8 to lowercase

Co-authored-by: Rich Harris <hello@rich-harris.dev>

* Update .changeset/healthy-carpets-deny.md

---------

Co-authored-by: Rich Harris <hello@rich-harris.dev>
---
 .changeset/healthy-carpets-deny.md | 5 +++++
 packages/svelte/elements.d.ts      | 2 +-
 2 files changed, 6 insertions(+), 1 deletion(-)
 create mode 100644 .changeset/healthy-carpets-deny.md

diff --git a/.changeset/healthy-carpets-deny.md b/.changeset/healthy-carpets-deny.md
new file mode 100644
index 0000000000..8f8db7fa9c
--- /dev/null
+++ b/.changeset/healthy-carpets-deny.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: rename form accept-charset attribute
diff --git a/packages/svelte/elements.d.ts b/packages/svelte/elements.d.ts
index 1492f77792..604241592a 100644
--- a/packages/svelte/elements.d.ts
+++ b/packages/svelte/elements.d.ts
@@ -996,7 +996,7 @@ export interface HTMLFieldsetAttributes extends HTMLAttributes<HTMLFieldSetEleme
 }
 
 export interface HTMLFormAttributes extends HTMLAttributes<HTMLFormElement> {
-	acceptcharset?: string | undefined | null;
+	'accept-charset'?: 'utf-8' | (string & {}) | undefined | null;
 	action?: string | undefined | null;
 	autocomplete?: AutoFillBase | undefined | null;
 	enctype?:

From f8820956d2591288de53927c5e173242a13f125a Mon Sep 17 00:00:00 2001
From: "github-actions[bot]"
 <41898282+github-actions[bot]@users.noreply.github.com>
Date: Wed, 23 Jul 2025 11:23:52 -0400
Subject: [PATCH 03/60] Version Packages (#16484)

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
---
 .changeset/grumpy-boats-beg.md     |  5 -----
 .changeset/healthy-carpets-deny.md |  5 -----
 .changeset/shiny-walls-fix.md      |  5 -----
 .changeset/thick-mice-kick.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/grumpy-boats-beg.md
 delete mode 100644 .changeset/healthy-carpets-deny.md
 delete mode 100644 .changeset/shiny-walls-fix.md
 delete mode 100644 .changeset/thick-mice-kick.md

diff --git a/.changeset/grumpy-boats-beg.md b/.changeset/grumpy-boats-beg.md
deleted file mode 100644
index f677743def..0000000000
--- a/.changeset/grumpy-boats-beg.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-'svelte': patch
----
-
-fix: keep input in sync when binding updated via effect
diff --git a/.changeset/healthy-carpets-deny.md b/.changeset/healthy-carpets-deny.md
deleted file mode 100644
index 8f8db7fa9c..0000000000
--- a/.changeset/healthy-carpets-deny.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-'svelte': patch
----
-
-fix: rename form accept-charset attribute
diff --git a/.changeset/shiny-walls-fix.md b/.changeset/shiny-walls-fix.md
deleted file mode 100644
index 91ed548728..0000000000
--- a/.changeset/shiny-walls-fix.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-'svelte': patch
----
-
-fix: prevent infinite async loop
diff --git a/.changeset/thick-mice-kick.md b/.changeset/thick-mice-kick.md
deleted file mode 100644
index eec55b77ee..0000000000
--- a/.changeset/thick-mice-kick.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-'svelte': patch
----
-
-fix: exclude derived writes from effect abort and rescheduling
diff --git a/packages/svelte/CHANGELOG.md b/packages/svelte/CHANGELOG.md
index 5a5e532a08..8cd3850460 100644
--- a/packages/svelte/CHANGELOG.md
+++ b/packages/svelte/CHANGELOG.md
@@ -1,5 +1,17 @@
 # svelte
 
+## 5.36.14
+
+### Patch Changes
+
+- fix: keep input in sync when binding updated via effect ([#16482](https://github.com/sveltejs/svelte/pull/16482))
+
+- fix: rename form accept-charset attribute ([#16478](https://github.com/sveltejs/svelte/pull/16478))
+
+- fix: prevent infinite async loop ([#16482](https://github.com/sveltejs/svelte/pull/16482))
+
+- fix: exclude derived writes from effect abort and rescheduling ([#16482](https://github.com/sveltejs/svelte/pull/16482))
+
 ## 5.36.13
 
 ### Patch Changes
diff --git a/packages/svelte/package.json b/packages/svelte/package.json
index 4bf9a5df22..7fe1d161f2 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": "5.36.13",
+  "version": "5.36.14",
   "type": "module",
   "types": "./types/index.d.ts",
   "engines": {
diff --git a/packages/svelte/src/version.js b/packages/svelte/src/version.js
index 7d47fbc5f1..cd9d8b459c 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 = '5.36.13';
+export const VERSION = '5.36.14';
 export const PUBLIC_VERSION = '5';

From 53417ea8f785f2ec884b095ac1bacd08aa30da86 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Thu, 24 Jul 2025 01:48:32 -0400
Subject: [PATCH 04/60] fix: preserve dirty status of deferred effects (#16487)

* don't mark_reactions inside decrement, it can cause infinite loops

* revert mark_reactions changes

* preserve DIRTY/MAYBE_DIRTY status of deferred effects

* changeset

* tweak
---
 .changeset/cool-insects-argue.md              |  5 ++
 .../src/internal/client/reactivity/batch.js   | 63 ++++++++++++++-----
 .../src/internal/client/reactivity/sources.js |  9 +--
 .../async-effect-conservative/_config.js      | 28 +++++++++
 .../async-effect-conservative/main.svelte     | 17 +++++
 5 files changed, 101 insertions(+), 21 deletions(-)
 create mode 100644 .changeset/cool-insects-argue.md
 create mode 100644 packages/svelte/tests/runtime-runes/samples/async-effect-conservative/_config.js
 create mode 100644 packages/svelte/tests/runtime-runes/samples/async-effect-conservative/main.svelte

diff --git a/.changeset/cool-insects-argue.md b/.changeset/cool-insects-argue.md
new file mode 100644
index 0000000000..ff1c520b7b
--- /dev/null
+++ b/.changeset/cool-insects-argue.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: preserve dirty status of deferred effects
diff --git a/packages/svelte/src/internal/client/reactivity/batch.js b/packages/svelte/src/internal/client/reactivity/batch.js
index ce413fa1e1..89bad947c7 100644
--- a/packages/svelte/src/internal/client/reactivity/batch.js
+++ b/packages/svelte/src/internal/client/reactivity/batch.js
@@ -10,7 +10,8 @@ import {
 	INERT,
 	RENDER_EFFECT,
 	ROOT_EFFECT,
-	USER_EFFECT
+	USER_EFFECT,
+	MAYBE_DIRTY
 } from '#client/constants';
 import { async_mode_flag } from '../../flags/index.js';
 import { deferred, define_property } from '../../shared/utils.js';
@@ -27,7 +28,7 @@ import * as e from '../errors.js';
 import { flush_tasks } from '../dom/task.js';
 import { DEV } from 'esm-env';
 import { invoke_error_boundary } from '../error-handling.js';
-import { mark_reactions, old_values } from './sources.js';
+import { old_values } from './sources.js';
 import { unlink_effect } from './effects.js';
 import { unset_context } from './async.js';
 
@@ -146,6 +147,18 @@ export class Batch {
 	 */
 	#block_effects = [];
 
+	/**
+	 * Deferred effects (which run after async work has completed) that are DIRTY
+	 * @type {Effect[]}
+	 */
+	#dirty_effects = [];
+
+	/**
+	 * Deferred effects that are MAYBE_DIRTY
+	 * @type {Effect[]}
+	 */
+	#maybe_dirty_effects = [];
+
 	/**
 	 * A set of branches that still exist, but will be destroyed when this batch
 	 * is committed — we skip over these during `process`
@@ -221,10 +234,9 @@ export class Batch {
 
 			this.#deferred?.resolve();
 		} else {
-			// otherwise mark effects clean so they get scheduled on the next run
-			for (const e of this.#render_effects) set_signal_status(e, CLEAN);
-			for (const e of this.#effects) set_signal_status(e, CLEAN);
-			for (const e of this.#block_effects) set_signal_status(e, CLEAN);
+			this.#defer_effects(this.#render_effects);
+			this.#defer_effects(this.#effects);
+			this.#defer_effects(this.#block_effects);
 		}
 
 		if (current_values) {
@@ -271,15 +283,15 @@ export class Batch {
 			if (!skip && effect.fn !== null) {
 				if (is_branch) {
 					effect.f ^= CLEAN;
-				} else if ((flags & EFFECT) !== 0) {
-					this.#effects.push(effect);
-				} else if (async_mode_flag && (flags & RENDER_EFFECT) !== 0) {
-					this.#render_effects.push(effect);
-				} else if (is_dirty(effect)) {
-					if ((flags & ASYNC) !== 0) {
+				} else if ((flags & CLEAN) === 0) {
+					if ((flags & EFFECT) !== 0) {
+						this.#effects.push(effect);
+					} else if (async_mode_flag && (flags & RENDER_EFFECT) !== 0) {
+						this.#render_effects.push(effect);
+					} else if ((flags & ASYNC) !== 0) {
 						var effects = effect.b?.pending ? this.#boundary_async_effects : this.#async_effects;
 						effects.push(effect);
-					} else {
+					} else if (is_dirty(effect)) {
 						if ((effect.f & BLOCK_EFFECT) !== 0) this.#block_effects.push(effect);
 						update_effect(effect);
 					}
@@ -303,6 +315,21 @@ export class Batch {
 		}
 	}
 
+	/**
+	 * @param {Effect[]} effects
+	 */
+	#defer_effects(effects) {
+		for (const e of effects) {
+			const target = (e.f & DIRTY) !== 0 ? this.#dirty_effects : this.#maybe_dirty_effects;
+			target.push(e);
+
+			// mark as clean so they get scheduled if they depend on pending async state
+			set_signal_status(e, CLEAN);
+		}
+
+		effects.length = 0;
+	}
+
 	/**
 	 * Associate a change to a given source with the current
 	 * batch, noting its previous and current values
@@ -380,8 +407,14 @@ export class Batch {
 		this.#pending -= 1;
 
 		if (this.#pending === 0) {
-			for (const source of this.current.keys()) {
-				mark_reactions(source, DIRTY, false);
+			for (const e of this.#dirty_effects) {
+				set_signal_status(e, DIRTY);
+				schedule_effect(e);
+			}
+
+			for (const e of this.#maybe_dirty_effects) {
+				set_signal_status(e, MAYBE_DIRTY);
+				schedule_effect(e);
 			}
 
 			this.#render_effects = [];
diff --git a/packages/svelte/src/internal/client/reactivity/sources.js b/packages/svelte/src/internal/client/reactivity/sources.js
index 3b28c8fdce..7b5198542a 100644
--- a/packages/svelte/src/internal/client/reactivity/sources.js
+++ b/packages/svelte/src/internal/client/reactivity/sources.js
@@ -301,10 +301,9 @@ export function increment(source) {
 /**
  * @param {Value} signal
  * @param {number} status should be DIRTY or MAYBE_DIRTY
- * @param {boolean} schedule_async
  * @returns {void}
  */
-export function mark_reactions(signal, status, schedule_async = true) {
+function mark_reactions(signal, status) {
 	var reactions = signal.reactions;
 	if (reactions === null) return;
 
@@ -324,16 +323,14 @@ export function mark_reactions(signal, status, schedule_async = true) {
 			continue;
 		}
 
-		var should_schedule = (flags & DIRTY) === 0 && (schedule_async || (flags & ASYNC) === 0);
-
 		// don't set a DIRTY reaction to MAYBE_DIRTY
-		if (should_schedule) {
+		if ((flags & DIRTY) === 0) {
 			set_signal_status(reaction, status);
 		}
 
 		if ((flags & DERIVED) !== 0) {
 			mark_reactions(/** @type {Derived} */ (reaction), MAYBE_DIRTY);
-		} else if (should_schedule) {
+		} else {
 			schedule_effect(/** @type {Effect} */ (reaction));
 		}
 	}
diff --git a/packages/svelte/tests/runtime-runes/samples/async-effect-conservative/_config.js b/packages/svelte/tests/runtime-runes/samples/async-effect-conservative/_config.js
new file mode 100644
index 0000000000..bab06a203d
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/async-effect-conservative/_config.js
@@ -0,0 +1,28 @@
+import { tick } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+	async test({ assert, target, logs }) {
+		await tick();
+
+		const [increment] = target.querySelectorAll('button');
+
+		assert.deepEqual(logs, [false]);
+		assert.htmlEqual(target.innerHTML, '<button>increment</button><p>0</p>');
+
+		increment.click();
+		await tick();
+		assert.deepEqual(logs, [false]);
+		assert.htmlEqual(target.innerHTML, '<button>increment</button><p>1</p>');
+
+		increment.click();
+		await tick();
+		assert.deepEqual(logs, [false, true]);
+		assert.htmlEqual(target.innerHTML, '<button>increment</button><p>2</p>');
+
+		increment.click();
+		await tick();
+		assert.deepEqual(logs, [false, true]);
+		assert.htmlEqual(target.innerHTML, '<button>increment</button><p>3</p>');
+	}
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/async-effect-conservative/main.svelte b/packages/svelte/tests/runtime-runes/samples/async-effect-conservative/main.svelte
new file mode 100644
index 0000000000..5305067a5a
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/async-effect-conservative/main.svelte
@@ -0,0 +1,17 @@
+<script lang="ts">
+	let count = $state(0);
+	let two_or_larger = $derived(count >= 2);
+
+	$effect(() => {
+		console.log(two_or_larger);
+	});
+</script>
+
+<svelte:boundary>
+	<button onclick={() => count += 1}>increment</button>
+	<p>{await count}</p>
+
+	{#snippet pending()}
+		<p>loading...</p>
+	{/snippet}
+</svelte:boundary>

From 46d3261ed9a7d6acb9908f52e989013795555a56 Mon Sep 17 00:00:00 2001
From: Simon H <5968653+dummdidumm@users.noreply.github.com>
Date: Thu, 24 Jul 2025 11:39:54 +0200
Subject: [PATCH 05/60] chore: don't do effect scheduling unnecessarily
 (#16489)

mini-cleanup post #16487 - we don't need to do the work of scheduling an effect that's already dirty which means it already scheduled its root effect to run
---
 packages/svelte/src/internal/client/reactivity/sources.js | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/packages/svelte/src/internal/client/reactivity/sources.js b/packages/svelte/src/internal/client/reactivity/sources.js
index 7b5198542a..3b2087d56b 100644
--- a/packages/svelte/src/internal/client/reactivity/sources.js
+++ b/packages/svelte/src/internal/client/reactivity/sources.js
@@ -323,14 +323,16 @@ function mark_reactions(signal, status) {
 			continue;
 		}
 
+		var not_dirty = (flags & DIRTY) === 0;
+
 		// don't set a DIRTY reaction to MAYBE_DIRTY
-		if ((flags & DIRTY) === 0) {
+		if (not_dirty) {
 			set_signal_status(reaction, status);
 		}
 
 		if ((flags & DERIVED) !== 0) {
 			mark_reactions(/** @type {Derived} */ (reaction), MAYBE_DIRTY);
-		} else {
+		} else if (not_dirty) {
 			schedule_effect(/** @type {Effect} */ (reaction));
 		}
 	}

From 4e74cd35fedf55e65b60c957041f79ca94dfc197 Mon Sep 17 00:00:00 2001
From: "github-actions[bot]"
 <41898282+github-actions[bot]@users.noreply.github.com>
Date: Thu, 24 Jul 2025 11:43:28 +0200
Subject: [PATCH 06/60] Version Packages (#16488)

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
---
 .changeset/cool-insects-argue.md | 5 -----
 packages/svelte/CHANGELOG.md     | 6 ++++++
 packages/svelte/package.json     | 2 +-
 packages/svelte/src/version.js   | 2 +-
 4 files changed, 8 insertions(+), 7 deletions(-)
 delete mode 100644 .changeset/cool-insects-argue.md

diff --git a/.changeset/cool-insects-argue.md b/.changeset/cool-insects-argue.md
deleted file mode 100644
index ff1c520b7b..0000000000
--- a/.changeset/cool-insects-argue.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-'svelte': patch
----
-
-fix: preserve dirty status of deferred effects
diff --git a/packages/svelte/CHANGELOG.md b/packages/svelte/CHANGELOG.md
index 8cd3850460..5bffa5f70e 100644
--- a/packages/svelte/CHANGELOG.md
+++ b/packages/svelte/CHANGELOG.md
@@ -1,5 +1,11 @@
 # svelte
 
+## 5.36.15
+
+### Patch Changes
+
+- fix: preserve dirty status of deferred effects ([#16487](https://github.com/sveltejs/svelte/pull/16487))
+
 ## 5.36.14
 
 ### Patch Changes
diff --git a/packages/svelte/package.json b/packages/svelte/package.json
index 7fe1d161f2..051f82ec3a 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": "5.36.14",
+  "version": "5.36.15",
   "type": "module",
   "types": "./types/index.d.ts",
   "engines": {
diff --git a/packages/svelte/src/version.js b/packages/svelte/src/version.js
index cd9d8b459c..1d469f29b0 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 = '5.36.14';
+export const VERSION = '5.36.15';
 export const PUBLIC_VERSION = '5';

From 7eb11e0e247d9da4edb88dc5652101ceb55fc530 Mon Sep 17 00:00:00 2001
From: Simon H <5968653+dummdidumm@users.noreply.github.com>
Date: Thu, 24 Jul 2025 16:00:43 +0200
Subject: [PATCH 07/60] fix: don't destroy effect roots created inside of
 deriveds (#16492)

We were wrongfully adding effect roots to `derived.effects`, too, which meant those were destroyed when the derived reran.
---
 .changeset/lemon-weeks-call.md                |  5 ++
 .../src/internal/client/reactivity/effects.js |  6 ++-
 .../src/internal/client/reactivity/types.d.ts |  2 +-
 packages/svelte/tests/signals/test.ts         | 51 +++++++++++++++++++
 4 files changed, 62 insertions(+), 2 deletions(-)
 create mode 100644 .changeset/lemon-weeks-call.md

diff --git a/.changeset/lemon-weeks-call.md b/.changeset/lemon-weeks-call.md
new file mode 100644
index 0000000000..ae62305630
--- /dev/null
+++ b/.changeset/lemon-weeks-call.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: don't destroy effect roots created inside of deriveds
diff --git a/packages/svelte/src/internal/client/reactivity/effects.js b/packages/svelte/src/internal/client/reactivity/effects.js
index c4edd2bf8d..f44efa32f1 100644
--- a/packages/svelte/src/internal/client/reactivity/effects.js
+++ b/packages/svelte/src/internal/client/reactivity/effects.js
@@ -148,7 +148,11 @@ function create_effect(type, fn, sync, push = true) {
 		}
 
 		// if we're in a derived, add the effect there too
-		if (active_reaction !== null && (active_reaction.f & DERIVED) !== 0) {
+		if (
+			active_reaction !== null &&
+			(active_reaction.f & DERIVED) !== 0 &&
+			(type & ROOT_EFFECT) === 0
+		) {
 			var derived = /** @type {Derived} */ (active_reaction);
 			(derived.effects ??= []).push(effect);
 		}
diff --git a/packages/svelte/src/internal/client/reactivity/types.d.ts b/packages/svelte/src/internal/client/reactivity/types.d.ts
index 72187e84a7..81f7197b80 100644
--- a/packages/svelte/src/internal/client/reactivity/types.d.ts
+++ b/packages/svelte/src/internal/client/reactivity/types.d.ts
@@ -54,7 +54,7 @@ export interface Reaction extends Signal {
 export interface Derived<V = unknown> extends Value<V>, Reaction {
 	/** The derived function */
 	fn: () => V;
-	/** Effects created inside this signal */
+	/** Effects created inside this signal. Used to destroy those effects when the derived reruns or is cleaned up */
 	effects: null | Effect[];
 	/** Parent effect or derived */
 	parent: Effect | Derived | null;
diff --git a/packages/svelte/tests/signals/test.ts b/packages/svelte/tests/signals/test.ts
index 937324727b..eff6d6166a 100644
--- a/packages/svelte/tests/signals/test.ts
+++ b/packages/svelte/tests/signals/test.ts
@@ -1390,4 +1390,55 @@ describe('signals', () => {
 			destroy();
 		};
 	});
+
+	test('$effect.root inside deriveds stay alive independently', () => {
+		const log: any[] = [];
+		const c = state(0);
+		const cleanup: any[] = [];
+		const inner_states: any[] = [];
+
+		const d = derived(() => {
+			const destroy = effect_root(() => {
+				const x = state(0);
+				inner_states.push(x);
+
+				effect(() => {
+					log.push('inner ' + $.get(x));
+					return () => {
+						log.push('inner destroyed');
+					};
+				});
+			});
+
+			cleanup.push(destroy);
+
+			return $.get(c);
+		});
+
+		return () => {
+			log.push($.get(d));
+			flushSync();
+
+			assert.deepEqual(log, [0, 'inner 0']);
+			log.length = 0;
+
+			set(inner_states[0], 1);
+			flushSync();
+
+			assert.deepEqual(log, ['inner destroyed', 'inner 1']);
+			log.length = 0;
+
+			set(c, 1);
+			log.push($.get(d));
+			flushSync();
+
+			assert.deepEqual(log, [1, 'inner 0']);
+			log.length = 0;
+
+			cleanup.forEach((fn) => fn());
+			flushSync();
+
+			assert.deepEqual(log, ['inner destroyed', 'inner destroyed']);
+		};
+	});
 });

From dc043fb2d3c87619e1c26315f600acd4fe19dfa4 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Thu, 24 Jul 2025 10:16:15 -0400
Subject: [PATCH 08/60] fix: don't update a focused input with values from its
 own past (#16491)

* fix: don't update a focused input with values from its own past

* remove

* fix
---
 .changeset/fast-mails-fail.md                 |  5 +++
 .../client/dom/elements/bindings/input.js     | 11 ++++--
 .../src/internal/client/reactivity/batch.js   | 12 +++++-
 .../_config.js                                | 37 +++++++++++++++++++
 .../main.svelte                               | 25 +++++++++++++
 5 files changed, 86 insertions(+), 4 deletions(-)
 create mode 100644 .changeset/fast-mails-fail.md
 create mode 100644 packages/svelte/tests/runtime-runes/samples/async-binding-update-while-focused-2/_config.js
 create mode 100644 packages/svelte/tests/runtime-runes/samples/async-binding-update-while-focused-2/main.svelte

diff --git a/.changeset/fast-mails-fail.md b/.changeset/fast-mails-fail.md
new file mode 100644
index 0000000000..027cb01548
--- /dev/null
+++ b/.changeset/fast-mails-fail.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: don't update a focused input with values from its own past
diff --git a/packages/svelte/src/internal/client/dom/elements/bindings/input.js b/packages/svelte/src/internal/client/dom/elements/bindings/input.js
index 7c1fccea0f..7c73280dd6 100644
--- a/packages/svelte/src/internal/client/dom/elements/bindings/input.js
+++ b/packages/svelte/src/internal/client/dom/elements/bindings/input.js
@@ -8,7 +8,7 @@ import { queue_micro_task } from '../../task.js';
 import { hydrating } from '../../hydration.js';
 import { untrack } from '../../../runtime.js';
 import { is_runes } from '../../../context.js';
-import { current_batch } from '../../../reactivity/batch.js';
+import { current_batch, previous_batch } from '../../../reactivity/batch.js';
 
 /**
  * @param {HTMLInputElement} input
@@ -76,13 +76,18 @@ export function bind_value(input, get, set = get) {
 
 		var value = get();
 
-		if (input === document.activeElement && batches.has(/** @type {Batch} */ (current_batch))) {
+		if (input === document.activeElement) {
+			// we need both, because in non-async mode, render effects run before previous_batch is set
+			var batch = /** @type {Batch} */ (previous_batch ?? current_batch);
+
 			// Never rewrite the contents of a focused input. We can get here if, for example,
 			// an update is deferred because of async work depending on the input:
 			//
 			// <input bind:value={query}>
 			// <p>{await find(query)}</p>
-			return;
+			if (batches.has(batch)) {
+				return;
+			}
 		}
 
 		if (is_numberlike_input(input) && value === to_number(input.value)) {
diff --git a/packages/svelte/src/internal/client/reactivity/batch.js b/packages/svelte/src/internal/client/reactivity/batch.js
index 89bad947c7..123bc95d16 100644
--- a/packages/svelte/src/internal/client/reactivity/batch.js
+++ b/packages/svelte/src/internal/client/reactivity/batch.js
@@ -38,6 +38,13 @@ const batches = new Set();
 /** @type {Batch | null} */
 export let current_batch = null;
 
+/**
+ * This is needed to avoid overwriting inputs in non-async mode
+ * TODO 6.0 remove this, as non-async mode will go away
+ * @type {Batch | null}
+ */
+export let previous_batch = null;
+
 /**
  * When time travelling, we re-evaluate deriveds based on the temporary
  * values of their dependencies rather than their actual values, and cache
@@ -71,7 +78,6 @@ let last_scheduled_effect = null;
 let is_flushing = false;
 
 let is_flushing_sync = false;
-
 export class Batch {
 	/**
 	 * The current values of any sources that are updated in this batch
@@ -173,6 +179,8 @@ export class Batch {
 	process(root_effects) {
 		queued_root_effects = [];
 
+		previous_batch = null;
+
 		/** @type {Map<Source, { v: unknown, wv: number }> | null} */
 		var current_values = null;
 
@@ -218,6 +226,7 @@ export class Batch {
 
 			// If sources are written to, then work needs to happen in a separate batch, else prior sources would be mixed with
 			// newly updated sources, which could lead to infinite loops when effects run over and over again.
+			previous_batch = current_batch;
 			current_batch = null;
 
 			flush_queued_effects(render_effects);
@@ -350,6 +359,7 @@ export class Batch {
 
 	deactivate() {
 		current_batch = null;
+		previous_batch = null;
 
 		for (const update of effect_pending_updates) {
 			effect_pending_updates.delete(update);
diff --git a/packages/svelte/tests/runtime-runes/samples/async-binding-update-while-focused-2/_config.js b/packages/svelte/tests/runtime-runes/samples/async-binding-update-while-focused-2/_config.js
new file mode 100644
index 0000000000..b0772ad3c0
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/async-binding-update-while-focused-2/_config.js
@@ -0,0 +1,37 @@
+import { tick } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+	async test({ assert, target, instance }) {
+		instance.shift();
+		await tick();
+
+		const [input] = target.querySelectorAll('input');
+
+		input.focus();
+		input.value = '1';
+		input.dispatchEvent(new InputEvent('input', { bubbles: true }));
+		await tick();
+
+		assert.htmlEqual(target.innerHTML, `<input type="number" /> <p>0</p>`);
+		assert.equal(input.value, '1');
+
+		input.focus();
+		input.value = '2';
+		input.dispatchEvent(new InputEvent('input', { bubbles: true }));
+		await tick();
+
+		assert.htmlEqual(target.innerHTML, `<input type="number" /> <p>0</p>`);
+		assert.equal(input.value, '2');
+
+		instance.shift();
+		await tick();
+		assert.htmlEqual(target.innerHTML, `<input type="number" /> <p>1</p>`);
+		assert.equal(input.value, '2');
+
+		instance.shift();
+		await tick();
+		assert.htmlEqual(target.innerHTML, `<input type="number" /> <p>2</p>`);
+		assert.equal(input.value, '2');
+	}
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/async-binding-update-while-focused-2/main.svelte b/packages/svelte/tests/runtime-runes/samples/async-binding-update-while-focused-2/main.svelte
new file mode 100644
index 0000000000..2fc898e654
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/async-binding-update-while-focused-2/main.svelte
@@ -0,0 +1,25 @@
+<script lang="ts">
+	let count = $state(0);
+
+	let deferreds = [];
+
+	export function shift() {
+		const d = deferreds.shift();
+		d.d.resolve(d.v);
+	}
+
+	function push(v) {
+		const d = Promise.withResolvers();
+		deferreds.push({ d, v });
+		return d.promise;
+	}
+</script>
+
+<svelte:boundary>
+	<input type="number" bind:value={count} />
+	<p>{await push(count)}</p>
+
+	{#snippet pending()}
+		<p>loading...</p>
+	{/snippet}
+</svelte:boundary>

From 8ad02e4a8c920823034051e5e2a13df58f25ebd5 Mon Sep 17 00:00:00 2001
From: "github-actions[bot]"
 <41898282+github-actions[bot]@users.noreply.github.com>
Date: Thu, 24 Jul 2025 16:22:30 +0200
Subject: [PATCH 09/60] Version Packages (#16493)

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
---
 .changeset/fast-mails-fail.md  | 5 -----
 .changeset/lemon-weeks-call.md | 5 -----
 packages/svelte/CHANGELOG.md   | 8 ++++++++
 packages/svelte/package.json   | 2 +-
 packages/svelte/src/version.js | 2 +-
 5 files changed, 10 insertions(+), 12 deletions(-)
 delete mode 100644 .changeset/fast-mails-fail.md
 delete mode 100644 .changeset/lemon-weeks-call.md

diff --git a/.changeset/fast-mails-fail.md b/.changeset/fast-mails-fail.md
deleted file mode 100644
index 027cb01548..0000000000
--- a/.changeset/fast-mails-fail.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-'svelte': patch
----
-
-fix: don't update a focused input with values from its own past
diff --git a/.changeset/lemon-weeks-call.md b/.changeset/lemon-weeks-call.md
deleted file mode 100644
index ae62305630..0000000000
--- a/.changeset/lemon-weeks-call.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-'svelte': patch
----
-
-fix: don't destroy effect roots created inside of deriveds
diff --git a/packages/svelte/CHANGELOG.md b/packages/svelte/CHANGELOG.md
index 5bffa5f70e..450ecde53b 100644
--- a/packages/svelte/CHANGELOG.md
+++ b/packages/svelte/CHANGELOG.md
@@ -1,5 +1,13 @@
 # svelte
 
+## 5.36.16
+
+### Patch Changes
+
+- fix: don't update a focused input with values from its own past ([#16491](https://github.com/sveltejs/svelte/pull/16491))
+
+- fix: don't destroy effect roots created inside of deriveds ([#16492](https://github.com/sveltejs/svelte/pull/16492))
+
 ## 5.36.15
 
 ### Patch Changes
diff --git a/packages/svelte/package.json b/packages/svelte/package.json
index 051f82ec3a..07954026b5 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": "5.36.15",
+  "version": "5.36.16",
   "type": "module",
   "types": "./types/index.d.ts",
   "engines": {
diff --git a/packages/svelte/src/version.js b/packages/svelte/src/version.js
index 1d469f29b0..5d76fc3f29 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 = '5.36.15';
+export const VERSION = '5.36.16';
 export const PUBLIC_VERSION = '5';

From 0bba84cc203c7cab945527cc3928597d3612a37d Mon Sep 17 00:00:00 2001
From: Bladesheng <keadr23@gmail.com>
Date: Fri, 25 Jul 2025 14:43:41 +0200
Subject: [PATCH 10/60] fix: add types for `part` attribute to svg attributes
 (#16499)

---
 .changeset/seven-colts-obey.md | 5 +++++
 packages/svelte/elements.d.ts  | 1 +
 2 files changed, 6 insertions(+)
 create mode 100644 .changeset/seven-colts-obey.md

diff --git a/.changeset/seven-colts-obey.md b/.changeset/seven-colts-obey.md
new file mode 100644
index 0000000000..b41216f649
--- /dev/null
+++ b/.changeset/seven-colts-obey.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: add types for `part` attribute to svg attributes
diff --git a/packages/svelte/elements.d.ts b/packages/svelte/elements.d.ts
index 604241592a..2e1042dfd6 100644
--- a/packages/svelte/elements.d.ts
+++ b/packages/svelte/elements.d.ts
@@ -1553,6 +1553,7 @@ export interface SVGAttributes<T extends EventTarget> extends AriaAttributes, DO
 	height?: number | string | undefined | null;
 	id?: string | undefined | null;
 	lang?: string | undefined | null;
+	part?: string | undefined | null;
 	max?: number | string | undefined | null;
 	media?: string | undefined | null;
 	// On the `textPath` element

From b0f9ea3ae62cfb9eb4437898bf8a6b90e0531657 Mon Sep 17 00:00:00 2001
From: ComputerGuy <63362464+Ocean-OS@users.noreply.github.com>
Date: Fri, 25 Jul 2025 15:57:32 -0700
Subject: [PATCH 11/60] fix: throw on duplicate class field declarations
 (#16502)

* fix: throw on duplicate class field declarations

* doh

* handle assignment in constructor

* fix

* apply suggestion from review

* fix

* fix failing test
---
 .changeset/odd-phones-taste.md                |  5 ++
 .../98-reference/.generated/compile-errors.md |  6 +++
 .../svelte/messages/compile-errors/script.md  |  4 ++
 packages/svelte/src/compiler/errors.js        | 10 ++++
 .../phases/2-analyze/visitors/ClassBody.js    | 53 ++++++++++++++++++-
 .../class-state-constructor-9/errors.json     | 12 ++---
 6 files changed, 82 insertions(+), 8 deletions(-)
 create mode 100644 .changeset/odd-phones-taste.md

diff --git a/.changeset/odd-phones-taste.md b/.changeset/odd-phones-taste.md
new file mode 100644
index 0000000000..ec9534b741
--- /dev/null
+++ b/.changeset/odd-phones-taste.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: throw on duplicate class field declarations
diff --git a/documentation/docs/98-reference/.generated/compile-errors.md b/documentation/docs/98-reference/.generated/compile-errors.md
index 20f57770d1..957a9f67c7 100644
--- a/documentation/docs/98-reference/.generated/compile-errors.md
+++ b/documentation/docs/98-reference/.generated/compile-errors.md
@@ -364,6 +364,12 @@ The $ name is reserved, and cannot be used for variables and imports
 The $ prefix is reserved, and cannot be used for variables and imports
 ```
 
+### duplicate_class_field
+
+```
+`%name%` has already been declared
+```
+
 ### each_item_invalid_assignment
 
 ```
diff --git a/packages/svelte/messages/compile-errors/script.md b/packages/svelte/messages/compile-errors/script.md
index 2b0c5eafdf..5c1080aced 100644
--- a/packages/svelte/messages/compile-errors/script.md
+++ b/packages/svelte/messages/compile-errors/script.md
@@ -30,6 +30,10 @@
 
 > The $ prefix is reserved, and cannot be used for variables and imports
 
+## duplicate_class_field
+
+> `%name%` has already been declared
+
 ## each_item_invalid_assignment
 
 > Cannot reassign or bind to each block argument in runes mode. Use the array and index variables instead (e.g. `array[i] = value` instead of `entry = value`, or `bind:value={array[i]}` instead of `bind:value={entry}`)
diff --git a/packages/svelte/src/compiler/errors.js b/packages/svelte/src/compiler/errors.js
index 599d3e8248..e763a6e073 100644
--- a/packages/svelte/src/compiler/errors.js
+++ b/packages/svelte/src/compiler/errors.js
@@ -152,6 +152,16 @@ export function dollar_prefix_invalid(node) {
 	e(node, 'dollar_prefix_invalid', `The $ prefix is reserved, and cannot be used for variables and imports\nhttps://svelte.dev/e/dollar_prefix_invalid`);
 }
 
+/**
+ * `%name%` has already been declared
+ * @param {null | number | NodeLike} node
+ * @param {string} name
+ * @returns {never}
+ */
+export function duplicate_class_field(node, name) {
+	e(node, 'duplicate_class_field', `\`${name}\` has already been declared\nhttps://svelte.dev/e/duplicate_class_field`);
+}
+
 /**
  * Cannot reassign or bind to each block argument in runes mode. Use the array and index variables instead (e.g. `array[i] = value` instead of `entry = value`, or `bind:value={array[i]}` instead of `bind:value={entry}`)
  * @param {null | number | NodeLike} node
diff --git a/packages/svelte/src/compiler/phases/2-analyze/visitors/ClassBody.js b/packages/svelte/src/compiler/phases/2-analyze/visitors/ClassBody.js
index ffc39ac00d..2bfc1dbce3 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/visitors/ClassBody.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/visitors/ClassBody.js
@@ -33,6 +33,9 @@ export function ClassBody(node, context) {
 	/** @type {Map<string, StateField>} */
 	const state_fields = new Map();
 
+	/** @type {Map<string, Array<MethodDefinition['kind'] | 'prop' | 'assigned_prop'>>} */
+	const fields = new Map();
+
 	context.state.analysis.classes.set(node, state_fields);
 
 	/** @type {MethodDefinition | null} */
@@ -54,6 +57,14 @@ export function ClassBody(node, context) {
 				e.state_field_duplicate(node, name);
 			}
 
+			const _key = (key.type === 'PrivateIdentifier' ? '#' : '') + name;
+			const field = fields.get(_key);
+
+			// if there's already a method or assigned field, error
+			if (field && !(field.length === 1 && field[0] === 'prop')) {
+				e.duplicate_class_field(node, _key);
+			}
+
 			state_fields.set(name, {
 				node,
 				type: rune,
@@ -67,10 +78,48 @@ export function ClassBody(node, context) {
 	for (const child of node.body) {
 		if (child.type === 'PropertyDefinition' && !child.computed && !child.static) {
 			handle(child, child.key, child.value);
+			const key = (child.key.type === 'PrivateIdentifier' ? '#' : '') + get_name(child.key);
+			const field = fields.get(key);
+			if (!field) {
+				fields.set(key, [child.value ? 'assigned_prop' : 'prop']);
+				continue;
+			}
+			e.duplicate_class_field(child, key);
 		}
 
-		if (child.type === 'MethodDefinition' && child.kind === 'constructor') {
-			constructor = child;
+		if (child.type === 'MethodDefinition') {
+			if (child.kind === 'constructor') {
+				constructor = child;
+			} else if (!child.computed) {
+				const key = (child.key.type === 'PrivateIdentifier' ? '#' : '') + get_name(child.key);
+				const field = fields.get(key);
+				if (!field) {
+					fields.set(key, [child.kind]);
+					continue;
+				}
+				if (
+					field.includes(child.kind) ||
+					field.includes('prop') ||
+					field.includes('assigned_prop')
+				) {
+					e.duplicate_class_field(child, key);
+				}
+				if (child.kind === 'get') {
+					if (field.length === 1 && field[0] === 'set') {
+						field.push('get');
+						continue;
+					}
+				} else if (child.kind === 'set') {
+					if (field.length === 1 && field[0] === 'get') {
+						field.push('set');
+						continue;
+					}
+				} else {
+					field.push(child.kind);
+					continue;
+				}
+				e.duplicate_class_field(child, key);
+			}
 		}
 	}
 
diff --git a/packages/svelte/tests/validator/samples/class-state-constructor-9/errors.json b/packages/svelte/tests/validator/samples/class-state-constructor-9/errors.json
index b7dd4c8ed4..94b5f191c2 100644
--- a/packages/svelte/tests/validator/samples/class-state-constructor-9/errors.json
+++ b/packages/svelte/tests/validator/samples/class-state-constructor-9/errors.json
@@ -1,14 +1,14 @@
 [
 	{
-		"code": "state_field_invalid_assignment",
-		"message": "Cannot assign to a state field before its declaration",
+		"code": "duplicate_class_field",
+		"message": "`count` has already been declared",
 		"start": {
-			"line": 2,
-			"column": 1
+			"line": 5,
+			"column": 2
 		},
 		"end": {
-			"line": 2,
-			"column": 12
+			"line": 5,
+			"column": 24
 		}
 	}
 ]

From d0ebd42986c4d3e4db0420f1aaebd337afdb230f Mon Sep 17 00:00:00 2001
From: "github-actions[bot]"
 <41898282+github-actions[bot]@users.noreply.github.com>
Date: Fri, 25 Jul 2025 16:46:12 -0700
Subject: [PATCH 12/60] Version Packages (#16500)

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
---
 .changeset/odd-phones-taste.md | 5 -----
 .changeset/seven-colts-obey.md | 5 -----
 packages/svelte/CHANGELOG.md   | 8 ++++++++
 packages/svelte/package.json   | 2 +-
 packages/svelte/src/version.js | 2 +-
 5 files changed, 10 insertions(+), 12 deletions(-)
 delete mode 100644 .changeset/odd-phones-taste.md
 delete mode 100644 .changeset/seven-colts-obey.md

diff --git a/.changeset/odd-phones-taste.md b/.changeset/odd-phones-taste.md
deleted file mode 100644
index ec9534b741..0000000000
--- a/.changeset/odd-phones-taste.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-'svelte': patch
----
-
-fix: throw on duplicate class field declarations
diff --git a/.changeset/seven-colts-obey.md b/.changeset/seven-colts-obey.md
deleted file mode 100644
index b41216f649..0000000000
--- a/.changeset/seven-colts-obey.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-'svelte': patch
----
-
-fix: add types for `part` attribute to svg attributes
diff --git a/packages/svelte/CHANGELOG.md b/packages/svelte/CHANGELOG.md
index 450ecde53b..766c83763a 100644
--- a/packages/svelte/CHANGELOG.md
+++ b/packages/svelte/CHANGELOG.md
@@ -1,5 +1,13 @@
 # svelte
 
+## 5.36.17
+
+### Patch Changes
+
+- fix: throw on duplicate class field declarations ([#16502](https://github.com/sveltejs/svelte/pull/16502))
+
+- fix: add types for `part` attribute to svg attributes ([#16499](https://github.com/sveltejs/svelte/pull/16499))
+
 ## 5.36.16
 
 ### Patch Changes
diff --git a/packages/svelte/package.json b/packages/svelte/package.json
index 07954026b5..22bc8cc8fa 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": "5.36.16",
+  "version": "5.36.17",
   "type": "module",
   "types": "./types/index.d.ts",
   "engines": {
diff --git a/packages/svelte/src/version.js b/packages/svelte/src/version.js
index 5d76fc3f29..d2992a3dcd 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 = '5.36.16';
+export const VERSION = '5.36.17';
 export const PUBLIC_VERSION = '5';

From c7851789d71cc3d0b5d89ce9c759a39be6caa51a Mon Sep 17 00:00:00 2001
From: 7nik <kifiranet@gmail.com>
Date: Sat, 26 Jul 2025 21:27:22 +0300
Subject: [PATCH 13/60] fix: always mark props as stateful (#16504)

---
 .changeset/gorgeous-jeans-begin.md                |  5 +++++
 .../phases/2-analyze/visitors/Identifier.js       |  5 ++++-
 .../props-default-value-function/_config.js       | 15 +++++++++++++++
 .../props-default-value-function/inner.svelte     |  4 ++++
 .../props-default-value-function/main.svelte      | 14 ++++++++++++++
 .../props-default-value-function/wrapper.svelte   |  7 +++++++
 .../props-default-value-function/wrapper2.svelte  |  7 +++++++
 7 files changed, 56 insertions(+), 1 deletion(-)
 create mode 100644 .changeset/gorgeous-jeans-begin.md
 create mode 100644 packages/svelte/tests/runtime-runes/samples/props-default-value-function/_config.js
 create mode 100644 packages/svelte/tests/runtime-runes/samples/props-default-value-function/inner.svelte
 create mode 100644 packages/svelte/tests/runtime-runes/samples/props-default-value-function/main.svelte
 create mode 100644 packages/svelte/tests/runtime-runes/samples/props-default-value-function/wrapper.svelte
 create mode 100644 packages/svelte/tests/runtime-runes/samples/props-default-value-function/wrapper2.svelte

diff --git a/.changeset/gorgeous-jeans-begin.md b/.changeset/gorgeous-jeans-begin.md
new file mode 100644
index 0000000000..586c4d8a57
--- /dev/null
+++ b/.changeset/gorgeous-jeans-begin.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: always mark props as stateful
diff --git a/packages/svelte/src/compiler/phases/2-analyze/visitors/Identifier.js b/packages/svelte/src/compiler/phases/2-analyze/visitors/Identifier.js
index cced326f9b..4dfdfe5af1 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/visitors/Identifier.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/visitors/Identifier.js
@@ -93,7 +93,10 @@ export function Identifier(node, context) {
 			context.state.expression.references.add(binding);
 			context.state.expression.has_state ||=
 				binding.kind !== 'static' &&
-				!binding.is_function() &&
+				(binding.kind === 'prop' ||
+					binding.kind === 'bindable_prop' ||
+					binding.kind === 'rest_prop' ||
+					!binding.is_function()) &&
 				!context.state.scope.evaluate(node).is_known;
 		}
 
diff --git a/packages/svelte/tests/runtime-runes/samples/props-default-value-function/_config.js b/packages/svelte/tests/runtime-runes/samples/props-default-value-function/_config.js
new file mode 100644
index 0000000000..6b281f04f0
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/props-default-value-function/_config.js
@@ -0,0 +1,15 @@
+import { flushSync } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+	mode: ['client'],
+
+	test({ assert, target }) {
+		const btn = target.querySelector('button');
+
+		assert.htmlEqual(target.innerHTML, `<button>inc</button> Inner: 0 Inner: 0`);
+		btn?.click();
+		flushSync();
+		assert.htmlEqual(target.innerHTML, `<button>inc</button> Inner: 1 Inner: 1`);
+	}
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/props-default-value-function/inner.svelte b/packages/svelte/tests/runtime-runes/samples/props-default-value-function/inner.svelte
new file mode 100644
index 0000000000..6bde0a15a8
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/props-default-value-function/inner.svelte
@@ -0,0 +1,4 @@
+<script>
+	let { getter } = $props()
+</script>
+Inner: {getter()}
diff --git a/packages/svelte/tests/runtime-runes/samples/props-default-value-function/main.svelte b/packages/svelte/tests/runtime-runes/samples/props-default-value-function/main.svelte
new file mode 100644
index 0000000000..2cb2f67b82
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/props-default-value-function/main.svelte
@@ -0,0 +1,14 @@
+<script>
+	import Wrapper1 from "./wrapper.svelte"
+	import Wrapper2 from "./wrapper2.svelte"
+	let count = $state(0);
+
+	let getter = $derived.by(() => {
+		const copy = count;
+		return () => copy;
+	});
+</script>
+
+<button onclick={() => count++}>inc</button>
+<Wrapper1 {getter}/>
+<Wrapper2 {getter}/>
\ No newline at end of file
diff --git a/packages/svelte/tests/runtime-runes/samples/props-default-value-function/wrapper.svelte b/packages/svelte/tests/runtime-runes/samples/props-default-value-function/wrapper.svelte
new file mode 100644
index 0000000000..525494ddfb
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/props-default-value-function/wrapper.svelte
@@ -0,0 +1,7 @@
+<script >
+  import Inner from "./inner.svelte";
+
+  const { getter = () => -1} = $props();
+</script>
+
+<Inner {getter} />
diff --git a/packages/svelte/tests/runtime-runes/samples/props-default-value-function/wrapper2.svelte b/packages/svelte/tests/runtime-runes/samples/props-default-value-function/wrapper2.svelte
new file mode 100644
index 0000000000..9498f432d8
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/props-default-value-function/wrapper2.svelte
@@ -0,0 +1,7 @@
+<script >
+  import Inner from "./inner.svelte";
+
+  const { getter = $bindable(() => -1)} = $props();
+</script>
+
+<Inner {getter} />

From 7cc4d56263f724c4d76ab6140af4d117cbb41f1d Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Sat, 26 Jul 2025 22:16:40 -0400
Subject: [PATCH 14/60] feat: ignore component options in `compileModule`
 (#16362)

---
 .changeset/violet-ways-sleep.md               |   5 +
 .../svelte/src/compiler/validate-options.js   | 172 +++++++++---------
 2 files changed, 96 insertions(+), 81 deletions(-)
 create mode 100644 .changeset/violet-ways-sleep.md

diff --git a/.changeset/violet-ways-sleep.md b/.changeset/violet-ways-sleep.md
new file mode 100644
index 0000000000..749ecb1719
--- /dev/null
+++ b/.changeset/violet-ways-sleep.md
@@ -0,0 +1,5 @@
+---
+'svelte': minor
+---
+
+feat: ignore component options in `compileModule`
diff --git a/packages/svelte/src/compiler/validate-options.js b/packages/svelte/src/compiler/validate-options.js
index ed83375d22..2b727ad093 100644
--- a/packages/svelte/src/compiler/validate-options.js
+++ b/packages/svelte/src/compiler/validate-options.js
@@ -8,7 +8,7 @@ import * as w from './warnings.js';
  * @typedef {(input: Input, keypath: string) => Required<Output>} Validator
  */
 
-const common = {
+const common_options = {
 	filename: string('(unknown)'),
 
 	// default to process.cwd() where it exists to replicate svelte4 behavior (and make Deno work with this as well)
@@ -48,110 +48,120 @@ const common = {
 	})
 };
 
-export const validate_module_options =
-	/** @type {Validator<ModuleCompileOptions, ValidatedModuleCompileOptions>} */ (
-		object({
-			...common
-		})
-	);
+const component_options = {
+	accessors: deprecate(w.options_deprecated_accessors, boolean(false)),
 
-export const validate_component_options =
-	/** @type {Validator<CompileOptions, ValidatedCompileOptions>} */ (
-		object({
-			...common,
+	css: validator('external', (input) => {
+		if (input === true || input === false) {
+			throw_error(
+				'The boolean options have been removed from the css option. Use "external" instead of false and "injected" instead of true'
+			);
+		}
+		if (input === 'none') {
+			throw_error(
+				'css: "none" is no longer a valid option. If this was crucial for you, please open an issue on GitHub with your use case.'
+			);
+		}
 
-			accessors: deprecate(w.options_deprecated_accessors, boolean(false)),
+		if (input !== 'external' && input !== 'injected') {
+			throw_error(`css should be either "external" (default, recommended) or "injected"`);
+		}
 
-			css: validator('external', (input) => {
-				if (input === true || input === false) {
-					throw_error(
-						'The boolean options have been removed from the css option. Use "external" instead of false and "injected" instead of true'
-					);
-				}
-				if (input === 'none') {
-					throw_error(
-						'css: "none" is no longer a valid option. If this was crucial for you, please open an issue on GitHub with your use case.'
-					);
-				}
+		return input;
+	}),
 
-				if (input !== 'external' && input !== 'injected') {
-					throw_error(`css should be either "external" (default, recommended) or "injected"`);
-				}
+	cssHash: fun(({ css, hash }) => {
+		return `svelte-${hash(css)}`;
+	}),
+
+	// TODO this is a sourcemap option, would be good to put under a sourcemap namespace
+	cssOutputFilename: string(undefined),
+
+	customElement: boolean(false),
+
+	discloseVersion: boolean(true),
 
-				return input;
-			}),
+	immutable: deprecate(w.options_deprecated_immutable, boolean(false)),
 
-			cssHash: fun(({ css, hash }) => {
-				return `svelte-${hash(css)}`;
-			}),
+	legacy: removed(
+		'The legacy option has been removed. If you are using this because of legacy.componentApi, use compatibility.componentApi instead'
+	),
+
+	compatibility: object({
+		componentApi: list([4, 5], 5)
+	}),
+
+	loopGuardTimeout: warn_removed(w.options_removed_loop_guard_timeout),
+
+	name: string(undefined),
 
-			// TODO this is a sourcemap option, would be good to put under a sourcemap namespace
-			cssOutputFilename: string(undefined),
+	namespace: list(['html', 'mathml', 'svg']),
 
-			customElement: boolean(false),
+	modernAst: boolean(false),
 
-			discloseVersion: boolean(true),
+	outputFilename: string(undefined),
 
-			immutable: deprecate(w.options_deprecated_immutable, boolean(false)),
+	preserveComments: boolean(false),
 
-			legacy: removed(
-				'The legacy option has been removed. If you are using this because of legacy.componentApi, use compatibility.componentApi instead'
-			),
+	fragments: list(['html', 'tree']),
 
-			compatibility: object({
-				componentApi: list([4, 5], 5)
-			}),
+	preserveWhitespace: boolean(false),
 
-			loopGuardTimeout: warn_removed(w.options_removed_loop_guard_timeout),
+	runes: boolean(undefined),
 
-			name: string(undefined),
+	hmr: boolean(false),
 
-			namespace: list(['html', 'mathml', 'svg']),
+	sourcemap: validator(undefined, (input) => {
+		// Source maps can take on a variety of values, including string, JSON, map objects from magic-string and source-map,
+		// so there's no good way to check type validity here
+		return input;
+	}),
 
-			modernAst: boolean(false),
+	enableSourcemap: warn_removed(w.options_removed_enable_sourcemap),
 
-			outputFilename: string(undefined),
+	hydratable: warn_removed(w.options_removed_hydratable),
 
-			preserveComments: boolean(false),
+	format: removed(
+		'The format option has been removed in Svelte 4, the compiler only outputs ESM now. Remove "format" from your compiler options. ' +
+			'If you did not set this yourself, bump the version of your bundler plugin (vite-plugin-svelte/rollup-plugin-svelte/svelte-loader)'
+	),
 
-			fragments: list(['html', 'tree']),
+	tag: removed(
+		'The tag option has been removed in Svelte 5. Use `<svelte:options customElement="tag-name" />` inside the component instead. ' +
+			'If that does not solve your use case, please open an issue on GitHub with details.'
+	),
 
-			preserveWhitespace: boolean(false),
+	sveltePath: removed(
+		'The sveltePath option has been removed in Svelte 5. ' +
+			'If this option was crucial for you, please open an issue on GitHub with your use case.'
+	),
 
-			runes: boolean(undefined),
+	// These two were primarily created for svelte-preprocess (https://github.com/sveltejs/svelte/pull/6194),
+	// but with new TypeScript compilation modes strictly separating types it's not necessary anymore
+	errorMode: removed(
+		'The errorMode option has been removed. If you are using this through svelte-preprocess with TypeScript, ' +
+			'use the https://www.typescriptlang.org/tsconfig#verbatimModuleSyntax setting instead'
+	),
 
-			hmr: boolean(false),
+	varsReport: removed(
+		'The vars option has been removed. If you are using this through svelte-preprocess with TypeScript, ' +
+			'use the https://www.typescriptlang.org/tsconfig#verbatimModuleSyntax setting instead'
+	)
+};
 
-			sourcemap: validator(undefined, (input) => {
-				// Source maps can take on a variety of values, including string, JSON, map objects from magic-string and source-map,
-				// so there's no good way to check type validity here
-				return input;
-			}),
+export const validate_module_options =
+	/** @type {Validator<ModuleCompileOptions, ValidatedModuleCompileOptions>} */ (
+		object({
+			...common_options,
+			...Object.fromEntries(Object.keys(component_options).map((key) => [key, () => {}]))
+		})
+	);
 
-			enableSourcemap: warn_removed(w.options_removed_enable_sourcemap),
-			hydratable: warn_removed(w.options_removed_hydratable),
-			format: removed(
-				'The format option has been removed in Svelte 4, the compiler only outputs ESM now. Remove "format" from your compiler options. ' +
-					'If you did not set this yourself, bump the version of your bundler plugin (vite-plugin-svelte/rollup-plugin-svelte/svelte-loader)'
-			),
-			tag: removed(
-				'The tag option has been removed in Svelte 5. Use `<svelte:options customElement="tag-name" />` inside the component instead. ' +
-					'If that does not solve your use case, please open an issue on GitHub with details.'
-			),
-			sveltePath: removed(
-				'The sveltePath option has been removed in Svelte 5. ' +
-					'If this option was crucial for you, please open an issue on GitHub with your use case.'
-			),
-			// These two were primarily created for svelte-preprocess (https://github.com/sveltejs/svelte/pull/6194),
-			// but with new TypeScript compilation modes strictly separating types it's not necessary anymore
-			errorMode: removed(
-				'The errorMode option has been removed. If you are using this through svelte-preprocess with TypeScript, ' +
-					'use the https://www.typescriptlang.org/tsconfig#verbatimModuleSyntax setting instead'
-			),
-			varsReport: removed(
-				'The vars option has been removed. If you are using this through svelte-preprocess with TypeScript, ' +
-					'use the https://www.typescriptlang.org/tsconfig#verbatimModuleSyntax setting instead'
-			)
+export const validate_component_options =
+	/** @type {Validator<CompileOptions, ValidatedCompileOptions>} */ (
+		object({
+			...common_options,
+			...component_options
 		})
 	);
 

From 39ee7cf4c247965ebacdd16fc365a31f00506026 Mon Sep 17 00:00:00 2001
From: "github-actions[bot]"
 <41898282+github-actions[bot]@users.noreply.github.com>
Date: Sat, 26 Jul 2025 22:22:14 -0700
Subject: [PATCH 15/60] Version Packages (#16505)

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
---
 .changeset/gorgeous-jeans-begin.md |  5 -----
 .changeset/violet-ways-sleep.md    |  5 -----
 packages/svelte/CHANGELOG.md       | 10 ++++++++++
 packages/svelte/package.json       |  2 +-
 packages/svelte/src/version.js     |  2 +-
 5 files changed, 12 insertions(+), 12 deletions(-)
 delete mode 100644 .changeset/gorgeous-jeans-begin.md
 delete mode 100644 .changeset/violet-ways-sleep.md

diff --git a/.changeset/gorgeous-jeans-begin.md b/.changeset/gorgeous-jeans-begin.md
deleted file mode 100644
index 586c4d8a57..0000000000
--- a/.changeset/gorgeous-jeans-begin.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-'svelte': patch
----
-
-fix: always mark props as stateful
diff --git a/.changeset/violet-ways-sleep.md b/.changeset/violet-ways-sleep.md
deleted file mode 100644
index 749ecb1719..0000000000
--- a/.changeset/violet-ways-sleep.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-'svelte': minor
----
-
-feat: ignore component options in `compileModule`
diff --git a/packages/svelte/CHANGELOG.md b/packages/svelte/CHANGELOG.md
index 766c83763a..f939f69d28 100644
--- a/packages/svelte/CHANGELOG.md
+++ b/packages/svelte/CHANGELOG.md
@@ -1,5 +1,15 @@
 # svelte
 
+## 5.37.0
+
+### Minor Changes
+
+- feat: ignore component options in `compileModule` ([#16362](https://github.com/sveltejs/svelte/pull/16362))
+
+### Patch Changes
+
+- fix: always mark props as stateful ([#16504](https://github.com/sveltejs/svelte/pull/16504))
+
 ## 5.36.17
 
 ### Patch Changes
diff --git a/packages/svelte/package.json b/packages/svelte/package.json
index 22bc8cc8fa..c781eda8c8 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": "5.36.17",
+  "version": "5.37.0",
   "type": "module",
   "types": "./types/index.d.ts",
   "engines": {
diff --git a/packages/svelte/src/version.js b/packages/svelte/src/version.js
index d2992a3dcd..e83ba6fb30 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 = '5.36.17';
+export const VERSION = '5.37.0';
 export const PUBLIC_VERSION = '5';

From 1773df94845bc53d55a1c9e9eb033d08056c845a Mon Sep 17 00:00:00 2001
From: fkobi <fkobi@pm.me>
Date: Sun, 27 Jul 2025 14:17:50 +0000
Subject: [PATCH 16/60] docs: use sh instead of bash in source blocks (#16506)

* use sh instead of bash in source blocks

no bash-specific functionality is used

* regenerate

---------

Co-authored-by: Rich Harris <rich.harris@vercel.com>
---
 CONTRIBUTING.md                                               | 4 ++--
 documentation/docs/01-introduction/02-getting-started.md      | 2 +-
 documentation/docs/07-misc/02-testing.md                      | 4 ++--
 .../docs/98-reference/.generated/compile-warnings.md          | 2 +-
 packages/svelte/README.md                                     | 2 +-
 packages/svelte/messages/compile-warnings/template.md         | 2 +-
 6 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index c2d3e45049..0653b08b76 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -101,13 +101,13 @@ Test samples are kept in `/test/xxx/samples` folder.
 1. To run test, run `pnpm test`.
 1. To run a particular test suite, use `pnpm test <suite-name>`, for example:
 
-   ```bash
+   ```sh
    pnpm test validator
    ```
 
 1. To filter tests _within_ a test suite, use `pnpm test <suite-name> -t <test-name>`, for example:
 
-   ```bash
+   ```sh
    pnpm test validator -t a11y-alt-text
    ```
 
diff --git a/documentation/docs/01-introduction/02-getting-started.md b/documentation/docs/01-introduction/02-getting-started.md
index c7351729ff..e97a46ad34 100644
--- a/documentation/docs/01-introduction/02-getting-started.md
+++ b/documentation/docs/01-introduction/02-getting-started.md
@@ -4,7 +4,7 @@ title: Getting started
 
 We recommend using [SvelteKit](../kit), which lets you [build almost anything](../kit/project-types). It's the official application framework from the Svelte team and powered by [Vite](https://vite.dev/). Create a new project with:
 
-```bash
+```sh
 npx sv create myapp
 cd myapp
 npm install
diff --git a/documentation/docs/07-misc/02-testing.md b/documentation/docs/07-misc/02-testing.md
index db99b70770..bcec4db0a3 100644
--- a/documentation/docs/07-misc/02-testing.md
+++ b/documentation/docs/07-misc/02-testing.md
@@ -10,7 +10,7 @@ Unit tests allow you to test small isolated parts of your code. Integration test
 
 To setup Vitest manually, first install it:
 
-```bash
+```sh
 npm install -D vitest
 ```
 
@@ -166,7 +166,7 @@ It is possible to test your components in isolation using Vitest.
 
 To get started, install jsdom (a library that shims DOM APIs):
 
-```bash
+```sh
 npm install -D jsdom
 ```
 
diff --git a/documentation/docs/98-reference/.generated/compile-warnings.md b/documentation/docs/98-reference/.generated/compile-warnings.md
index 2af9021a6a..01003f30c5 100644
--- a/documentation/docs/98-reference/.generated/compile-warnings.md
+++ b/documentation/docs/98-reference/.generated/compile-warnings.md
@@ -683,7 +683,7 @@ Some templating languages (including Svelte) will 'fix' HTML by turning `<span /
 
 To automate this, run the dedicated migration:
 
-```bash
+```sh
 npx sv migrate self-closing-tags
 ```
 
diff --git a/packages/svelte/README.md b/packages/svelte/README.md
index c37617da30..03e4db5db0 100644
--- a/packages/svelte/README.md
+++ b/packages/svelte/README.md
@@ -19,7 +19,7 @@ You can play around with Svelte in the [tutorial](https://svelte.dev/tutorial),
 
 When you're ready to build a full-fledge application, we recommend using [SvelteKit](https://svelte.dev/docs/kit):
 
-```bash
+```sh
 npx sv create my-app
 cd my-app
 npm install
diff --git a/packages/svelte/messages/compile-warnings/template.md b/packages/svelte/messages/compile-warnings/template.md
index d61a61d950..8af5aa2b98 100644
--- a/packages/svelte/messages/compile-warnings/template.md
+++ b/packages/svelte/messages/compile-warnings/template.md
@@ -71,7 +71,7 @@ Some templating languages (including Svelte) will 'fix' HTML by turning `<span /
 
 To automate this, run the dedicated migration:
 
-```bash
+```sh
 npx sv migrate self-closing-tags
 ```
 

From 99452053af5d3280caa9773ac45f9c7cc6b9ad5d Mon Sep 17 00:00:00 2001
From: Paolo Ricciuti <ricciutipaolo@gmail.com>
Date: Sun, 27 Jul 2025 19:50:22 +0200
Subject: [PATCH 17/60] fix: `append_styles` in an effect to make them
 available on mount (#16509)

Co-authored-by: Rich Harris <rich.harris@vercel.com>
---
 .changeset/shaggy-comics-fail.md              |  5 +++++
 .changeset/wise-hairs-pay.md                  |  5 +++++
 .../src/compiler/phases/2-analyze/index.js    | 16 +++++++-------
 .../3-transform/client/transform-client.js    |  5 +++--
 .../svelte/src/internal/client/dom/css.js     |  4 ++--
 .../host-rune-access-injected-css/_config.js  | 21 +++++++++++++++++++
 .../host-rune-access-injected-css/main.svelte | 16 ++++++++++++++
 .../Thing.svelte                              |  9 ++++++++
 .../custom-element-injected-styles/_config.js | 15 +++++++++++++
 .../main.svelte                               |  5 +++++
 10 files changed, 90 insertions(+), 11 deletions(-)
 create mode 100644 .changeset/shaggy-comics-fail.md
 create mode 100644 .changeset/wise-hairs-pay.md
 create mode 100644 packages/svelte/tests/runtime-browser/custom-elements-samples/host-rune-access-injected-css/_config.js
 create mode 100644 packages/svelte/tests/runtime-browser/custom-elements-samples/host-rune-access-injected-css/main.svelte
 create mode 100644 packages/svelte/tests/runtime-runes/samples/custom-element-injected-styles/Thing.svelte
 create mode 100644 packages/svelte/tests/runtime-runes/samples/custom-element-injected-styles/_config.js
 create mode 100644 packages/svelte/tests/runtime-runes/samples/custom-element-injected-styles/main.svelte

diff --git a/.changeset/shaggy-comics-fail.md b/.changeset/shaggy-comics-fail.md
new file mode 100644
index 0000000000..981a25c978
--- /dev/null
+++ b/.changeset/shaggy-comics-fail.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: `append_styles` in an effect to make them available on mount
diff --git a/.changeset/wise-hairs-pay.md b/.changeset/wise-hairs-pay.md
new file mode 100644
index 0000000000..7d96c1daab
--- /dev/null
+++ b/.changeset/wise-hairs-pay.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: always inject styles when compiling as a custom element
diff --git a/packages/svelte/src/compiler/phases/2-analyze/index.js b/packages/svelte/src/compiler/phases/2-analyze/index.js
index d407b44556..cd44fd998a 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/index.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/index.js
@@ -451,6 +451,8 @@ export function analyze_component(root, source, options) {
 		}
 	}
 
+	const is_custom_element = !!options.customElementOptions || options.customElement;
+
 	// TODO remove all the ?? stuff, we don't need it now that we're validating the config
 	/** @type {ComponentAnalysis} */
 	const analysis = {
@@ -500,13 +502,13 @@ export function analyze_component(root, source, options) {
 		needs_props: false,
 		event_directive_node: null,
 		uses_event_attributes: false,
-		custom_element: options.customElementOptions ?? options.customElement,
-		inject_styles: options.css === 'injected' || options.customElement,
-		accessors: options.customElement
-			? true
-			: (runes ? false : !!options.accessors) ||
-				// because $set method needs accessors
-				options.compatibility?.componentApi === 4,
+		custom_element: is_custom_element,
+		inject_styles: options.css === 'injected' || is_custom_element,
+		accessors:
+			is_custom_element ||
+			(runes ? false : !!options.accessors) ||
+			// because $set method needs accessors
+			options.compatibility?.componentApi === 4,
 		reactive_statements: new Map(),
 		binding_groups: new Map(),
 		slot_names: new Map(),
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 124438a9da..a56aca9c5f 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
@@ -621,8 +621,9 @@ export function client_component(analysis, options) {
 		);
 	}
 
-	if (analysis.custom_element) {
-		const ce = analysis.custom_element;
+	const ce = options.customElementOptions ?? options.customElement;
+
+	if (ce) {
 		const ce_props = typeof ce === 'boolean' ? {} : ce.props || {};
 
 		/** @type {ESTree.Property[]} */
diff --git a/packages/svelte/src/internal/client/dom/css.js b/packages/svelte/src/internal/client/dom/css.js
index 52be36aa1f..8e6faa0e32 100644
--- a/packages/svelte/src/internal/client/dom/css.js
+++ b/packages/svelte/src/internal/client/dom/css.js
@@ -1,6 +1,6 @@
 import { DEV } from 'esm-env';
-import { queue_micro_task } from './task.js';
 import { register_style } from '../dev/css.js';
+import { effect } from '../reactivity/effects.js';
 
 /**
  * @param {Node} anchor
@@ -8,7 +8,7 @@ import { register_style } from '../dev/css.js';
  */
 export function append_styles(anchor, css) {
 	// Use `queue_micro_task` to ensure `anchor` is in the DOM, otherwise getRootNode() will yield wrong results
-	queue_micro_task(() => {
+	effect(() => {
 		var root = anchor.getRootNode();
 
 		var target = /** @type {ShadowRoot} */ (root).host
diff --git a/packages/svelte/tests/runtime-browser/custom-elements-samples/host-rune-access-injected-css/_config.js b/packages/svelte/tests/runtime-browser/custom-elements-samples/host-rune-access-injected-css/_config.js
new file mode 100644
index 0000000000..99a223492b
--- /dev/null
+++ b/packages/svelte/tests/runtime-browser/custom-elements-samples/host-rune-access-injected-css/_config.js
@@ -0,0 +1,21 @@
+import { test } from '../../assert';
+const tick = () => Promise.resolve();
+
+export default test({
+	async test({ assert, target }) {
+		target.innerHTML = '<custom-element></custom-element>';
+		/** @type {any} */
+		const el = target.querySelector('custom-element');
+
+		/** @type {string} */
+		let html = '';
+		const handle_evt = (e) => (html = e.detail);
+		el.addEventListener('html', handle_evt);
+
+		await tick();
+		await tick();
+		await tick();
+
+		assert.ok(html.includes('<style'));
+	}
+});
diff --git a/packages/svelte/tests/runtime-browser/custom-elements-samples/host-rune-access-injected-css/main.svelte b/packages/svelte/tests/runtime-browser/custom-elements-samples/host-rune-access-injected-css/main.svelte
new file mode 100644
index 0000000000..ad8027f4d2
--- /dev/null
+++ b/packages/svelte/tests/runtime-browser/custom-elements-samples/host-rune-access-injected-css/main.svelte
@@ -0,0 +1,16 @@
+<svelte:options css="injected" customElement="custom-element"/>
+
+<script lang="ts">
+  $effect(() => {
+    $host().dispatchEvent(new CustomEvent("html", { detail: $host().shadowRoot?.innerHTML }));
+  })
+</script>
+
+<button class="btn">btn</button>
+
+<style >
+  .btn {
+    width: 123px;
+    height: 123px;
+  }
+</style>
\ No newline at end of file
diff --git a/packages/svelte/tests/runtime-runes/samples/custom-element-injected-styles/Thing.svelte b/packages/svelte/tests/runtime-runes/samples/custom-element-injected-styles/Thing.svelte
new file mode 100644
index 0000000000..0a2b139274
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/custom-element-injected-styles/Thing.svelte
@@ -0,0 +1,9 @@
+<svelte:options customElement={{ tag: 'my-thing' }} />
+
+<h1>hello</h1>
+
+<style>
+	h1 {
+		color: red;
+	}
+</style>
diff --git a/packages/svelte/tests/runtime-runes/samples/custom-element-injected-styles/_config.js b/packages/svelte/tests/runtime-runes/samples/custom-element-injected-styles/_config.js
new file mode 100644
index 0000000000..74597504bd
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/custom-element-injected-styles/_config.js
@@ -0,0 +1,15 @@
+import { tick } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+	mode: ['client'],
+	async test({ assert, target }) {
+		const thing = /** @type HTMLElement & { object: { test: true }; } */ (
+			target.querySelector('my-thing')
+		);
+
+		await tick();
+
+		assert.include(thing.shadowRoot?.innerHTML, 'red');
+	}
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/custom-element-injected-styles/main.svelte b/packages/svelte/tests/runtime-runes/samples/custom-element-injected-styles/main.svelte
new file mode 100644
index 0000000000..ba5b788da9
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/custom-element-injected-styles/main.svelte
@@ -0,0 +1,5 @@
+<script>
+	import './Thing.svelte';
+</script>
+
+<my-thing></my-thing>

From 51771447c6cf941da7a07733435a5b18a91ddd28 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Sun, 27 Jul 2025 16:59:29 -0400
Subject: [PATCH 18/60] chore: remove `parser.template_untrimmed` (#16511)

---
 .changeset/shiny-berries-call.md                          | 5 +++++
 packages/svelte/src/compiler/phases/1-parse/index.js      | 7 -------
 .../svelte/src/compiler/phases/1-parse/state/element.js   | 8 --------
 3 files changed, 5 insertions(+), 15 deletions(-)
 create mode 100644 .changeset/shiny-berries-call.md

diff --git a/.changeset/shiny-berries-call.md b/.changeset/shiny-berries-call.md
new file mode 100644
index 0000000000..adc62b3cd0
--- /dev/null
+++ b/.changeset/shiny-berries-call.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+chore: remove `parser.template_untrimmed`
diff --git a/packages/svelte/src/compiler/phases/1-parse/index.js b/packages/svelte/src/compiler/phases/1-parse/index.js
index 77cc2bf3fa..f5e0693b31 100644
--- a/packages/svelte/src/compiler/phases/1-parse/index.js
+++ b/packages/svelte/src/compiler/phases/1-parse/index.js
@@ -23,12 +23,6 @@ export class Parser {
 	 */
 	template;
 
-	/**
-	 * @readonly
-	 * @type {string}
-	 */
-	template_untrimmed;
-
 	/**
 	 * Whether or not we're in loose parsing mode, in which
 	 * case we try to continue parsing as much as possible
@@ -67,7 +61,6 @@ export class Parser {
 		}
 
 		this.loose = loose;
-		this.template_untrimmed = template;
 		this.template = template.trimEnd();
 
 		let match_lang;
diff --git a/packages/svelte/src/compiler/phases/1-parse/state/element.js b/packages/svelte/src/compiler/phases/1-parse/state/element.js
index 87332f647d..ed1b047d55 100644
--- a/packages/svelte/src/compiler/phases/1-parse/state/element.js
+++ b/packages/svelte/src/compiler/phases/1-parse/state/element.js
@@ -370,14 +370,6 @@ export default function element(parser) {
 				// ... or we're followed by whitespace, for example near the end of the template,
 				// which we want to take in so that language tools has more room to work with
 				parser.allow_whitespace();
-				if (parser.index === parser.template.length) {
-					while (
-						parser.index < parser.template_untrimmed.length &&
-						regex_whitespace.test(parser.template_untrimmed[parser.index])
-					) {
-						parser.index++;
-					}
-				}
 			}
 		}
 	}

From 03f2e44757925d0ca53f4e563965c3135ef81f16 Mon Sep 17 00:00:00 2001
From: ComputerGuy <63362464+Ocean-OS@users.noreply.github.com>
Date: Mon, 28 Jul 2025 11:56:41 -0700
Subject: [PATCH 19/60] chore: remove some todos (#16515)

* chore: remove some todos

* fix

* fix

* doh

* convert `TemplateComment` back to `Comment`

* `Evaluation.has_unknown`
---
 .changeset/happy-countries-dance.md                  |  5 +++++
 packages/svelte/src/compiler/migrate/index.js        |  4 ++--
 packages/svelte/src/compiler/phases/1-parse/index.js |  1 -
 .../3-transform/client/visitors/CallExpression.js    |  4 +++-
 .../3-transform/client/visitors/OnDirective.js       |  4 ++--
 packages/svelte/src/compiler/phases/scope.js         | 11 +++++++++++
 packages/svelte/src/compiler/types/template.d.ts     | 12 +++++++++++-
 packages/svelte/types/index.d.ts                     | 12 +++++++++++-
 8 files changed, 45 insertions(+), 8 deletions(-)
 create mode 100644 .changeset/happy-countries-dance.md

diff --git a/.changeset/happy-countries-dance.md b/.changeset/happy-countries-dance.md
new file mode 100644
index 0000000000..641cf21fd8
--- /dev/null
+++ b/.changeset/happy-countries-dance.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+chore: remove some todos
diff --git a/packages/svelte/src/compiler/migrate/index.js b/packages/svelte/src/compiler/migrate/index.js
index 6b2e6cda70..eb0e4eff8c 100644
--- a/packages/svelte/src/compiler/migrate/index.js
+++ b/packages/svelte/src/compiler/migrate/index.js
@@ -1707,14 +1707,14 @@ function extract_type_and_comment(declarator, state, path) {
 }
 
 // Ensure modifiers are applied in the same order as Svelte 4
-const modifier_order = [
+const modifier_order = /** @type {const} */ ([
 	'preventDefault',
 	'stopPropagation',
 	'stopImmediatePropagation',
 	'self',
 	'trusted',
 	'once'
-];
+]);
 
 /**
  * @param {AST.RegularElement | AST.SvelteElement | AST.SvelteWindow | AST.SvelteDocument | AST.SvelteBody} element
diff --git a/packages/svelte/src/compiler/phases/1-parse/index.js b/packages/svelte/src/compiler/phases/1-parse/index.js
index f5e0693b31..8f7ef76be5 100644
--- a/packages/svelte/src/compiler/phases/1-parse/index.js
+++ b/packages/svelte/src/compiler/phases/1-parse/index.js
@@ -1,5 +1,4 @@
 /** @import { AST } from '#compiler' */
-/** @import { Comment } from 'estree' */
 // @ts-expect-error acorn type definitions are borked in the release we use
 import { isIdentifierStart, isIdentifierChar } from 'acorn';
 import fragment from './state/fragment.js';
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/CallExpression.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/CallExpression.js
index 3e2f1414e6..c126742d3c 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/CallExpression.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/CallExpression.js
@@ -82,7 +82,9 @@ export function CallExpression(node, context) {
 		['debug', 'dir', 'error', 'group', 'groupCollapsed', 'info', 'log', 'trace', 'warn'].includes(
 			node.callee.property.name
 		) &&
-		node.arguments.some((arg) => arg.type !== 'Literal') // TODO more cases?
+		node.arguments.some(
+			(arg) => arg.type === 'SpreadElement' || context.state.scope.evaluate(arg).has_unknown
+		)
 	) {
 		return b.call(
 			node.callee,
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/OnDirective.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/OnDirective.js
index 7a66a8ecbb..0ee3b0fb10 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/OnDirective.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/OnDirective.js
@@ -3,14 +3,14 @@
 import * as b from '#compiler/builders';
 import { build_event, build_event_handler } from './shared/events.js';
 
-const modifiers = [
+const modifiers = /** @type {const} */ ([
 	'stopPropagation',
 	'stopImmediatePropagation',
 	'preventDefault',
 	'self',
 	'trusted',
 	'once'
-];
+]);
 
 /**
  * @param {AST.OnDirective} node
diff --git a/packages/svelte/src/compiler/phases/scope.js b/packages/svelte/src/compiler/phases/scope.js
index 700e098e45..eaacf5dda9 100644
--- a/packages/svelte/src/compiler/phases/scope.js
+++ b/packages/svelte/src/compiler/phases/scope.js
@@ -180,6 +180,13 @@ class Evaluation {
 	 */
 	is_known = true;
 
+	/**
+	 * True if the possible values contains `UNKNOWN`
+	 * @readonly
+	 * @type {boolean}
+	 */
+	has_unknown = false;
+
 	/**
 	 * True if the value is known to not be null/undefined
 	 * @readonly
@@ -540,6 +547,10 @@ class Evaluation {
 			if (value == null || value === UNKNOWN) {
 				this.is_defined = false;
 			}
+
+			if (value === UNKNOWN) {
+				this.has_unknown = true;
+			}
 		}
 
 		if (this.values.size > 1 || typeof this.value === 'symbol') {
diff --git a/packages/svelte/src/compiler/types/template.d.ts b/packages/svelte/src/compiler/types/template.d.ts
index de06a41469..058a1a8e66 100644
--- a/packages/svelte/src/compiler/types/template.d.ts
+++ b/packages/svelte/src/compiler/types/template.d.ts
@@ -247,7 +247,17 @@ export namespace AST {
 		name: string;
 		/** The 'y' in `on:x={y}` */
 		expression: null | Expression;
-		modifiers: string[]; // TODO specify
+		modifiers: Array<
+			| 'capture'
+			| 'nonpassive'
+			| 'once'
+			| 'passive'
+			| 'preventDefault'
+			| 'self'
+			| 'stopImmediatePropagation'
+			| 'stopPropagation'
+			| 'trusted'
+		>;
 		/** @internal */
 		metadata: {
 			expression: ExpressionMetadata;
diff --git a/packages/svelte/types/index.d.ts b/packages/svelte/types/index.d.ts
index 9ea45af7e6..64aa9e23ba 100644
--- a/packages/svelte/types/index.d.ts
+++ b/packages/svelte/types/index.d.ts
@@ -1296,7 +1296,17 @@ declare module 'svelte/compiler' {
 			name: string;
 			/** The 'y' in `on:x={y}` */
 			expression: null | Expression;
-			modifiers: string[];
+			modifiers: Array<
+				| 'capture'
+				| 'nonpassive'
+				| 'once'
+				| 'passive'
+				| 'preventDefault'
+				| 'self'
+				| 'stopImmediatePropagation'
+				| 'stopPropagation'
+				| 'trusted'
+			>;
 		}
 
 		/** A `style:` directive */

From 48f2fa22c0c941ac6e550151212845adc628b3de Mon Sep 17 00:00:00 2001
From: ComputerGuy <63362464+Ocean-OS@users.noreply.github.com>
Date: Mon, 28 Jul 2025 12:04:06 -0700
Subject: [PATCH 20/60] fix: allow await expressions inside `{#await ...}`
 argument (#16514)

* fix: allow await expressions inside `{#await ...}` argument

* add test

* apply suggestion from review

---------

Co-authored-by: 7nik <kifiranet@gmail.com>
---
 .changeset/long-roses-train.md                |  5 +++
 .../3-transform/client/visitors/AwaitBlock.js |  7 ++-
 .../samples/async-await/_config.js            | 43 +++++++++++++++++++
 .../samples/async-await/main.svelte           | 22 ++++++++++
 4 files changed, 75 insertions(+), 2 deletions(-)
 create mode 100644 .changeset/long-roses-train.md
 create mode 100644 packages/svelte/tests/runtime-runes/samples/async-await/_config.js
 create mode 100644 packages/svelte/tests/runtime-runes/samples/async-await/main.svelte

diff --git a/.changeset/long-roses-train.md b/.changeset/long-roses-train.md
new file mode 100644
index 0000000000..10920ac5c4
--- /dev/null
+++ b/.changeset/long-roses-train.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: allow await expressions inside `{#await ...}` argument
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AwaitBlock.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AwaitBlock.js
index c550c8e17b..4246091bcf 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AwaitBlock.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AwaitBlock.js
@@ -1,7 +1,7 @@
 /** @import { BlockStatement, Pattern, Statement } from 'estree' */
 /** @import { AST } from '#compiler' */
 /** @import { ComponentClientTransformState, ComponentContext } from '../types' */
-import { extract_identifiers } from '../../../../utils/ast.js';
+import { extract_identifiers, is_expression_async } from '../../../../utils/ast.js';
 import * as b from '#compiler/builders';
 import { create_derived } from '../utils.js';
 import { get_value } from './shared/declarations.js';
@@ -15,7 +15,10 @@ export function AwaitBlock(node, context) {
 	context.state.template.push_comment();
 
 	// Visit {#await <expression>} first to ensure that scopes are in the correct order
-	const expression = b.thunk(build_expression(context, node.expression, node.metadata.expression));
+	const expression = b.thunk(
+		build_expression(context, node.expression, node.metadata.expression),
+		node.metadata.expression.has_await
+	);
 
 	let then_block;
 	let catch_block;
diff --git a/packages/svelte/tests/runtime-runes/samples/async-await/_config.js b/packages/svelte/tests/runtime-runes/samples/async-await/_config.js
new file mode 100644
index 0000000000..dda6a7a895
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/async-await/_config.js
@@ -0,0 +1,43 @@
+import { tick } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+	async test({ assert, target }) {
+		const [reset, one, two, reject] = target.querySelectorAll('button');
+
+		await tick();
+		assert.htmlEqual(
+			target.innerHTML,
+			'<button>reset</button><button>one</button><button>two</button><button>reject</button> waiting'
+		);
+
+		one.click();
+		await tick();
+		assert.htmlEqual(
+			target.innerHTML,
+			'<button>reset</button><button>one</button><button>two</button><button>reject</button> one_res'
+		);
+
+		reset.click();
+		await tick();
+		assert.htmlEqual(
+			target.innerHTML,
+			'<button>reset</button><button>one</button><button>two</button><button>reject</button> waiting'
+		);
+
+		two.click();
+		await tick();
+		assert.htmlEqual(
+			target.innerHTML,
+			'<button>reset</button><button>one</button><button>two</button><button>reject</button> two_res'
+		);
+
+		reset.click();
+		reject.click();
+		await tick();
+		assert.htmlEqual(
+			target.innerHTML,
+			'<button>reset</button><button>one</button><button>two</button><button>reject</button> reject_catch'
+		);
+	}
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/async-await/main.svelte b/packages/svelte/tests/runtime-runes/samples/async-await/main.svelte
new file mode 100644
index 0000000000..8673e45414
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/async-await/main.svelte
@@ -0,0 +1,22 @@
+<script>
+	let deferred = $state(Promise.withResolvers());
+</script>
+
+<button onclick={() => deferred = Promise.withResolvers()}>reset</button>
+<button onclick={() => deferred.resolve("one")}>one</button>
+<button onclick={() => deferred.resolve("two")}>two</button>
+<button onclick={() => deferred.reject("reject")}>reject</button>
+
+<svelte:boundary>
+	{#await await deferred.promise + "_res"}
+		waiting
+	{:then res}
+		{res}
+	{:catch err}
+		{err}_catch
+	{/await}
+
+	{#snippet pending()}
+		<p>pending</p>
+	{/snippet}
+</svelte:boundary>

From d82edf6b1dfaac8af70462b1009f3b9da47a701a Mon Sep 17 00:00:00 2001
From: "github-actions[bot]"
 <41898282+github-actions[bot]@users.noreply.github.com>
Date: Mon, 28 Jul 2025 12:07:57 -0700
Subject: [PATCH 21/60] Version Packages (#16513)

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
---
 .changeset/happy-countries-dance.md |  5 -----
 .changeset/long-roses-train.md      |  5 -----
 .changeset/shaggy-comics-fail.md    |  5 -----
 .changeset/shiny-berries-call.md    |  5 -----
 .changeset/wise-hairs-pay.md        |  5 -----
 packages/svelte/CHANGELOG.md        | 14 ++++++++++++++
 packages/svelte/package.json        |  2 +-
 packages/svelte/src/version.js      |  2 +-
 8 files changed, 16 insertions(+), 27 deletions(-)
 delete mode 100644 .changeset/happy-countries-dance.md
 delete mode 100644 .changeset/long-roses-train.md
 delete mode 100644 .changeset/shaggy-comics-fail.md
 delete mode 100644 .changeset/shiny-berries-call.md
 delete mode 100644 .changeset/wise-hairs-pay.md

diff --git a/.changeset/happy-countries-dance.md b/.changeset/happy-countries-dance.md
deleted file mode 100644
index 641cf21fd8..0000000000
--- a/.changeset/happy-countries-dance.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-'svelte': patch
----
-
-chore: remove some todos
diff --git a/.changeset/long-roses-train.md b/.changeset/long-roses-train.md
deleted file mode 100644
index 10920ac5c4..0000000000
--- a/.changeset/long-roses-train.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-'svelte': patch
----
-
-fix: allow await expressions inside `{#await ...}` argument
diff --git a/.changeset/shaggy-comics-fail.md b/.changeset/shaggy-comics-fail.md
deleted file mode 100644
index 981a25c978..0000000000
--- a/.changeset/shaggy-comics-fail.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-'svelte': patch
----
-
-fix: `append_styles` in an effect to make them available on mount
diff --git a/.changeset/shiny-berries-call.md b/.changeset/shiny-berries-call.md
deleted file mode 100644
index adc62b3cd0..0000000000
--- a/.changeset/shiny-berries-call.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-'svelte': patch
----
-
-chore: remove `parser.template_untrimmed`
diff --git a/.changeset/wise-hairs-pay.md b/.changeset/wise-hairs-pay.md
deleted file mode 100644
index 7d96c1daab..0000000000
--- a/.changeset/wise-hairs-pay.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-'svelte': patch
----
-
-fix: always inject styles when compiling as a custom element
diff --git a/packages/svelte/CHANGELOG.md b/packages/svelte/CHANGELOG.md
index f939f69d28..59c44dd4f9 100644
--- a/packages/svelte/CHANGELOG.md
+++ b/packages/svelte/CHANGELOG.md
@@ -1,5 +1,19 @@
 # svelte
 
+## 5.37.1
+
+### Patch Changes
+
+- chore: remove some todos ([#16515](https://github.com/sveltejs/svelte/pull/16515))
+
+- fix: allow await expressions inside `{#await ...}` argument ([#16514](https://github.com/sveltejs/svelte/pull/16514))
+
+- fix: `append_styles` in an effect to make them available on mount ([#16509](https://github.com/sveltejs/svelte/pull/16509))
+
+- chore: remove `parser.template_untrimmed` ([#16511](https://github.com/sveltejs/svelte/pull/16511))
+
+- fix: always inject styles when compiling as a custom element ([#16509](https://github.com/sveltejs/svelte/pull/16509))
+
 ## 5.37.0
 
 ### Minor Changes
diff --git a/packages/svelte/package.json b/packages/svelte/package.json
index c781eda8c8..826850ea60 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": "5.37.0",
+  "version": "5.37.1",
   "type": "module",
   "types": "./types/index.d.ts",
   "engines": {
diff --git a/packages/svelte/src/version.js b/packages/svelte/src/version.js
index e83ba6fb30..2d5083a2a5 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 = '5.37.0';
+export const VERSION = '5.37.1';
 export const PUBLIC_VERSION = '5';

From a91e0154d4bc4b0a3209956647f868e518d0acba Mon Sep 17 00:00:00 2001
From: Laszlo Korte <laszlokorte@users.noreply.github.com>
Date: Thu, 31 Jul 2025 09:45:52 +0200
Subject: [PATCH 22/60] fix: double event processing in Firefox (#16522)
 (#16527)

* Fix double event processing (#16522)

Firefox seems to garbage collect event objects during event propagation if no global reference to the event object is kept.
That discards the __root marker set on the event object to early,
leading to duplicate processing.

* minor tweaks

---------

Co-authored-by: ComputerGuy <63362464+Ocean-OS@users.noreply.github.com>
---
 .changeset/chilly-bananas-train.md                       | 5 +++++
 .../svelte/src/internal/client/dom/elements/events.js    | 9 +++++++++
 2 files changed, 14 insertions(+)
 create mode 100644 .changeset/chilly-bananas-train.md

diff --git a/.changeset/chilly-bananas-train.md b/.changeset/chilly-bananas-train.md
new file mode 100644
index 0000000000..b0305f9e61
--- /dev/null
+++ b/.changeset/chilly-bananas-train.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: double event processing in firefox due to event object being garbage collected
diff --git a/packages/svelte/src/internal/client/dom/elements/events.js b/packages/svelte/src/internal/client/dom/elements/events.js
index fa3bf0b021..19bd1cfa18 100644
--- a/packages/svelte/src/internal/client/dom/elements/events.js
+++ b/packages/svelte/src/internal/client/dom/elements/events.js
@@ -141,6 +141,13 @@ export function delegate(events) {
 	}
 }
 
+// used to store the reference to the currently propagated event
+// to prevent garbage collection between microtasks in Firefox
+// If the event object is GCed too early, the expando __root property
+// set on the event object is lost, causing the event delegation
+// to process the event twice
+let last_propagated_event = null;
+
 /**
  * @this {EventTarget}
  * @param {Event} event
@@ -153,6 +160,8 @@ export function handle_event_propagation(event) {
 	var path = event.composedPath?.() || [];
 	var current_target = /** @type {null | Element} */ (path[0] || event.target);
 
+	last_propagated_event = event;
+
 	// composedPath contains list of nodes the event has propagated through.
 	// We check __root to skip all nodes below it in case this is a
 	// parent of the __root node, which indicates that there's nested

From f5950f866c51d9325a432ebfd5362bcf2647763a Mon Sep 17 00:00:00 2001
From: ComputerGuy <63362464+Ocean-OS@users.noreply.github.com>
Date: Thu, 31 Jul 2025 02:11:52 -0700
Subject: [PATCH 23/60] fix: correctly differentiate static fields before
 emitting `duplicate_class_field` (#16526)

* fix: correctly differentiate static fields before emitting `duplicate_class_field`

* remove unnecessary `#` concatenation

* add test
---
 .changeset/nine-cups-film.md                                | 5 +++++
 .../src/compiler/phases/2-analyze/visitors/ClassBody.js     | 6 +++---
 .../samples/class-state-constructor-9/input.svelte.js       | 2 +-
 3 files changed, 9 insertions(+), 4 deletions(-)
 create mode 100644 .changeset/nine-cups-film.md

diff --git a/.changeset/nine-cups-film.md b/.changeset/nine-cups-film.md
new file mode 100644
index 0000000000..ba72337dac
--- /dev/null
+++ b/.changeset/nine-cups-film.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: correctly differentiate static fields before emitting `duplicate_class_field`
diff --git a/packages/svelte/src/compiler/phases/2-analyze/visitors/ClassBody.js b/packages/svelte/src/compiler/phases/2-analyze/visitors/ClassBody.js
index 2bfc1dbce3..dd21637174 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/visitors/ClassBody.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/visitors/ClassBody.js
@@ -57,7 +57,7 @@ export function ClassBody(node, context) {
 				e.state_field_duplicate(node, name);
 			}
 
-			const _key = (key.type === 'PrivateIdentifier' ? '#' : '') + name;
+			const _key = (node.type === 'AssignmentExpression' || !node.static ? '' : '@') + name;
 			const field = fields.get(_key);
 
 			// if there's already a method or assigned field, error
@@ -78,7 +78,7 @@ export function ClassBody(node, context) {
 	for (const child of node.body) {
 		if (child.type === 'PropertyDefinition' && !child.computed && !child.static) {
 			handle(child, child.key, child.value);
-			const key = (child.key.type === 'PrivateIdentifier' ? '#' : '') + get_name(child.key);
+			const key = /** @type {string} */ (get_name(child.key));
 			const field = fields.get(key);
 			if (!field) {
 				fields.set(key, [child.value ? 'assigned_prop' : 'prop']);
@@ -91,7 +91,7 @@ export function ClassBody(node, context) {
 			if (child.kind === 'constructor') {
 				constructor = child;
 			} else if (!child.computed) {
-				const key = (child.key.type === 'PrivateIdentifier' ? '#' : '') + get_name(child.key);
+				const key = (child.static ? '@' : '') + get_name(child.key);
 				const field = fields.get(key);
 				if (!field) {
 					fields.set(key, [child.kind]);
diff --git a/packages/svelte/tests/validator/samples/class-state-constructor-9/input.svelte.js b/packages/svelte/tests/validator/samples/class-state-constructor-9/input.svelte.js
index a8469e13af..3806046f3f 100644
--- a/packages/svelte/tests/validator/samples/class-state-constructor-9/input.svelte.js
+++ b/packages/svelte/tests/validator/samples/class-state-constructor-9/input.svelte.js
@@ -1,6 +1,6 @@
 export class Counter {
 	count = -1;
-
+	static count() {}
 	constructor() {
 		this.count = $state(0);
 	}

From 72e46d31c075eeea232a1cc320efc272f5ef87d7 Mon Sep 17 00:00:00 2001
From: Elliot Bentley <mail@elliotbentley.com>
Date: Thu, 31 Jul 2025 11:34:28 +0100
Subject: [PATCH 24/60] fix: add types for SVG bindable attributes (#16525)

* fix: types for SVG bind: attributes

* add changeset and tweak

---------

Co-authored-by: 7nik <kifiranet@gmail.com>
---
 .changeset/cuddly-feet-doubt.md |  5 +++++
 packages/svelte/elements.d.ts   | 14 ++++++++------
 2 files changed, 13 insertions(+), 6 deletions(-)
 create mode 100644 .changeset/cuddly-feet-doubt.md

diff --git a/.changeset/cuddly-feet-doubt.md b/.changeset/cuddly-feet-doubt.md
new file mode 100644
index 0000000000..8d7d955daa
--- /dev/null
+++ b/.changeset/cuddly-feet-doubt.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: add bindable dimension attributes types to SVG and MathML elements
diff --git a/packages/svelte/elements.d.ts b/packages/svelte/elements.d.ts
index 2e1042dfd6..b3d44d9ed6 100644
--- a/packages/svelte/elements.d.ts
+++ b/packages/svelte/elements.d.ts
@@ -464,6 +464,14 @@ export interface DOMAttributes<T extends EventTarget> {
 	onfullscreenerror?: EventHandler<Event, T> | undefined | null;
 	onfullscreenerrorcapture?: EventHandler<Event, T> | undefined | null;
 
+	// Dimensions
+	readonly 'bind:contentRect'?: DOMRectReadOnly | undefined | null;
+	readonly 'bind:contentBoxSize'?: Array<ResizeObserverSize> | undefined | null;
+	readonly 'bind:borderBoxSize'?: Array<ResizeObserverSize> | undefined | null;
+	readonly 'bind:devicePixelContentBoxSize'?: Array<ResizeObserverSize> | undefined | null;
+	readonly 'bind:clientWidth'?: number | undefined | null;
+	readonly 'bind:clientHeight'?: number | undefined | null;
+
 	xmlns?: string | undefined | null;
 }
 
@@ -839,13 +847,7 @@ export interface HTMLAttributes<T extends EventTarget> extends AriaAttributes, D
 	 */
 	'bind:innerText'?: string | undefined | null;
 
-	readonly 'bind:contentRect'?: DOMRectReadOnly | undefined | null;
-	readonly 'bind:contentBoxSize'?: Array<ResizeObserverSize> | undefined | null;
-	readonly 'bind:borderBoxSize'?: Array<ResizeObserverSize> | undefined | null;
-	readonly 'bind:devicePixelContentBoxSize'?: Array<ResizeObserverSize> | undefined | null;
 	readonly 'bind:focused'?: boolean | undefined | null;
-	readonly 'bind:clientWidth'?: number | undefined | null;
-	readonly 'bind:clientHeight'?: number | undefined | null;
 	readonly 'bind:offsetWidth'?: number | undefined | null;
 	readonly 'bind:offsetHeight'?: number | undefined | null;
 

From c04975d3db74e59f8612ffd0f64d3b3bb3133ef1 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Thu, 31 Jul 2025 18:28:01 -0400
Subject: [PATCH 25/60] fix: prevent last_propagated_event from being DCE'd
 (#16538)

* fix: prevent last_propagated_event from being DCE'd

* changeset
---
 .changeset/serious-cars-hear.md                            | 5 +++++
 packages/svelte/src/internal/client/dom/elements/events.js | 5 ++++-
 2 files changed, 9 insertions(+), 1 deletion(-)
 create mode 100644 .changeset/serious-cars-hear.md

diff --git a/.changeset/serious-cars-hear.md b/.changeset/serious-cars-hear.md
new file mode 100644
index 0000000000..4647e89ed9
--- /dev/null
+++ b/.changeset/serious-cars-hear.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: prevent last_propagated_event from being DCE'd
diff --git a/packages/svelte/src/internal/client/dom/elements/events.js b/packages/svelte/src/internal/client/dom/elements/events.js
index 19bd1cfa18..15544d7426 100644
--- a/packages/svelte/src/internal/client/dom/elements/events.js
+++ b/packages/svelte/src/internal/client/dom/elements/events.js
@@ -168,8 +168,11 @@ export function handle_event_propagation(event) {
 	// mounted apps. In this case we don't want to trigger events multiple times.
 	var path_idx = 0;
 
+	// the `last_propagated_event === event` check is redundant, but
+	// without it the variable will be DCE'd and things will
+	// fail mysteriously in Firefox
 	// @ts-expect-error is added below
-	var handled_at = event.__root;
+	var handled_at = last_propagated_event === event && event.__root;
 
 	if (handled_at) {
 		var at_idx = path.indexOf(handled_at);

From 9134856fece750608ba81da45c4a330b3d8ebb1e Mon Sep 17 00:00:00 2001
From: "github-actions[bot]"
 <41898282+github-actions[bot]@users.noreply.github.com>
Date: Thu, 31 Jul 2025 19:15:45 -0400
Subject: [PATCH 26/60] Version Packages (#16529)

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
---
 .changeset/chilly-bananas-train.md |  5 -----
 .changeset/cuddly-feet-doubt.md    |  5 -----
 .changeset/nine-cups-film.md       |  5 -----
 .changeset/serious-cars-hear.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/chilly-bananas-train.md
 delete mode 100644 .changeset/cuddly-feet-doubt.md
 delete mode 100644 .changeset/nine-cups-film.md
 delete mode 100644 .changeset/serious-cars-hear.md

diff --git a/.changeset/chilly-bananas-train.md b/.changeset/chilly-bananas-train.md
deleted file mode 100644
index b0305f9e61..0000000000
--- a/.changeset/chilly-bananas-train.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-'svelte': patch
----
-
-fix: double event processing in firefox due to event object being garbage collected
diff --git a/.changeset/cuddly-feet-doubt.md b/.changeset/cuddly-feet-doubt.md
deleted file mode 100644
index 8d7d955daa..0000000000
--- a/.changeset/cuddly-feet-doubt.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-'svelte': patch
----
-
-fix: add bindable dimension attributes types to SVG and MathML elements
diff --git a/.changeset/nine-cups-film.md b/.changeset/nine-cups-film.md
deleted file mode 100644
index ba72337dac..0000000000
--- a/.changeset/nine-cups-film.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-'svelte': patch
----
-
-fix: correctly differentiate static fields before emitting `duplicate_class_field`
diff --git a/.changeset/serious-cars-hear.md b/.changeset/serious-cars-hear.md
deleted file mode 100644
index 4647e89ed9..0000000000
--- a/.changeset/serious-cars-hear.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-'svelte': patch
----
-
-fix: prevent last_propagated_event from being DCE'd
diff --git a/packages/svelte/CHANGELOG.md b/packages/svelte/CHANGELOG.md
index 59c44dd4f9..6e0a199ddc 100644
--- a/packages/svelte/CHANGELOG.md
+++ b/packages/svelte/CHANGELOG.md
@@ -1,5 +1,17 @@
 # svelte
 
+## 5.37.2
+
+### Patch Changes
+
+- fix: double event processing in firefox due to event object being garbage collected ([#16527](https://github.com/sveltejs/svelte/pull/16527))
+
+- fix: add bindable dimension attributes types to SVG and MathML elements ([#16525](https://github.com/sveltejs/svelte/pull/16525))
+
+- fix: correctly differentiate static fields before emitting `duplicate_class_field` ([#16526](https://github.com/sveltejs/svelte/pull/16526))
+
+- fix: prevent last_propagated_event from being DCE'd ([#16538](https://github.com/sveltejs/svelte/pull/16538))
+
 ## 5.37.1
 
 ### Patch Changes
diff --git a/packages/svelte/package.json b/packages/svelte/package.json
index 826850ea60..8536135ca8 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": "5.37.1",
+  "version": "5.37.2",
   "type": "module",
   "types": "./types/index.d.ts",
   "engines": {
diff --git a/packages/svelte/src/version.js b/packages/svelte/src/version.js
index 2d5083a2a5..b8f3bcfdd5 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 = '5.37.1';
+export const VERSION = '5.37.2';
 export const PUBLIC_VERSION = '5';

From 80678411706e99c0224b8bf995959c2d4e7fd4db Mon Sep 17 00:00:00 2001
From: ComputerGuy <63362464+Ocean-OS@users.noreply.github.com>
Date: Thu, 31 Jul 2025 16:16:47 -0700
Subject: [PATCH 27/60] docs: add note about attachments to `svelte/action`
 docs (#16537)

---
 documentation/docs/98-reference/21-svelte-action.md | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/documentation/docs/98-reference/21-svelte-action.md b/documentation/docs/98-reference/21-svelte-action.md
index 53423ec409..ef3ebfbf70 100644
--- a/documentation/docs/98-reference/21-svelte-action.md
+++ b/documentation/docs/98-reference/21-svelte-action.md
@@ -2,4 +2,6 @@
 title: svelte/action
 ---
 
+This module provides types for [actions](use), which have been superseded by [attachments](@attach).
+
 > MODULE: svelte/action

From 540f1b19ec56a69dde85f24471f25d9d465937e4 Mon Sep 17 00:00:00 2001
From: 7nik <kifiranet@gmail.com>
Date: Sat, 2 Aug 2025 22:29:10 +0300
Subject: [PATCH 28/60] fix: reset attribute cache after setting corresponding
 property (#16543)

---
 .changeset/afraid-carrots-study.md            |  5 +++++
 .../client/dom/elements/attributes.js         |  4 +++-
 .../attribute-after-property/_config.js       | 19 +++++++++++++++++++
 .../attribute-after-property/main.svelte      |  6 ++++++
 4 files changed, 33 insertions(+), 1 deletion(-)
 create mode 100644 .changeset/afraid-carrots-study.md
 create mode 100644 packages/svelte/tests/runtime-legacy/samples/attribute-after-property/_config.js
 create mode 100644 packages/svelte/tests/runtime-legacy/samples/attribute-after-property/main.svelte

diff --git a/.changeset/afraid-carrots-study.md b/.changeset/afraid-carrots-study.md
new file mode 100644
index 0000000000..71f4232edb
--- /dev/null
+++ b/.changeset/afraid-carrots-study.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: reset attribute cache after setting corresponding property
diff --git a/packages/svelte/src/internal/client/dom/elements/attributes.js b/packages/svelte/src/internal/client/dom/elements/attributes.js
index 22e532f5e4..2fa5d4541c 100644
--- a/packages/svelte/src/internal/client/dom/elements/attributes.js
+++ b/packages/svelte/src/internal/client/dom/elements/attributes.js
@@ -19,7 +19,7 @@ import { attach } from './attachments.js';
 import { clsx } from '../../../shared/attributes.js';
 import { set_class } from './class.js';
 import { set_style } from './style.js';
-import { ATTACHMENT_KEY, NAMESPACE_HTML } from '../../../../constants.js';
+import { ATTACHMENT_KEY, NAMESPACE_HTML, UNINITIALIZED } from '../../../../constants.js';
 import { block, branch, destroy_effect, effect } from '../../reactivity/effects.js';
 import { init_select, select_option } from './bindings/select.js';
 import { flatten } from '../../reactivity/async.js';
@@ -446,6 +446,8 @@ export function set_attributes(element, prev, next, css_hash, skip_warning = fal
 			) {
 				// @ts-ignore
 				element[name] = value;
+				// remove it from attributes's cache
+				if (name in attributes) attributes[name] = UNINITIALIZED;
 			} else if (typeof value !== 'function') {
 				set_attribute(element, name, value, skip_warning);
 			}
diff --git a/packages/svelte/tests/runtime-legacy/samples/attribute-after-property/_config.js b/packages/svelte/tests/runtime-legacy/samples/attribute-after-property/_config.js
new file mode 100644
index 0000000000..f6a98b1797
--- /dev/null
+++ b/packages/svelte/tests/runtime-legacy/samples/attribute-after-property/_config.js
@@ -0,0 +1,19 @@
+import { flushSync } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+	test({ target, assert }) {
+		const input = target.querySelector('input');
+		const button = target.querySelector('button');
+
+		assert.equal(input?.step, 'any');
+
+		button?.click();
+		flushSync();
+		assert.equal(input?.step, '10');
+
+		button?.click();
+		flushSync();
+		assert.equal(input?.step, 'any');
+	}
+});
diff --git a/packages/svelte/tests/runtime-legacy/samples/attribute-after-property/main.svelte b/packages/svelte/tests/runtime-legacy/samples/attribute-after-property/main.svelte
new file mode 100644
index 0000000000..2921e4e241
--- /dev/null
+++ b/packages/svelte/tests/runtime-legacy/samples/attribute-after-property/main.svelte
@@ -0,0 +1,6 @@
+<script>
+    let step = "any";
+</script>
+
+<input type="range" {...{step}} />
+<button onclick={() => step = step === "any" ? 10 : "any"}>change step</button>
\ No newline at end of file

From 0cbb5becf6d62ae3334b78606a76d21a91eda32b Mon Sep 17 00:00:00 2001
From: "github-actions[bot]"
 <41898282+github-actions[bot]@users.noreply.github.com>
Date: Sat, 2 Aug 2025 21:17:58 -0700
Subject: [PATCH 29/60] Version Packages (#16544)

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
---
 .changeset/afraid-carrots-study.md | 5 -----
 packages/svelte/CHANGELOG.md       | 6 ++++++
 packages/svelte/package.json       | 2 +-
 packages/svelte/src/version.js     | 2 +-
 4 files changed, 8 insertions(+), 7 deletions(-)
 delete mode 100644 .changeset/afraid-carrots-study.md

diff --git a/.changeset/afraid-carrots-study.md b/.changeset/afraid-carrots-study.md
deleted file mode 100644
index 71f4232edb..0000000000
--- a/.changeset/afraid-carrots-study.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-'svelte': patch
----
-
-fix: reset attribute cache after setting corresponding property
diff --git a/packages/svelte/CHANGELOG.md b/packages/svelte/CHANGELOG.md
index 6e0a199ddc..9766e3f06b 100644
--- a/packages/svelte/CHANGELOG.md
+++ b/packages/svelte/CHANGELOG.md
@@ -1,5 +1,11 @@
 # svelte
 
+## 5.37.3
+
+### Patch Changes
+
+- fix: reset attribute cache after setting corresponding property ([#16543](https://github.com/sveltejs/svelte/pull/16543))
+
 ## 5.37.2
 
 ### Patch Changes
diff --git a/packages/svelte/package.json b/packages/svelte/package.json
index 8536135ca8..e8927fcf56 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": "5.37.2",
+  "version": "5.37.3",
   "type": "module",
   "types": "./types/index.d.ts",
   "engines": {
diff --git a/packages/svelte/src/version.js b/packages/svelte/src/version.js
index b8f3bcfdd5..127b43e205 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 = '5.37.2';
+export const VERSION = '5.37.3';
 export const PUBLIC_VERSION = '5';

From a3f18351af4f70df4b9029aaa7198ac5dfeac6dc Mon Sep 17 00:00:00 2001
From: Anthony <anthony@depasquale.org>
Date: Tue, 5 Aug 2025 05:38:30 +0200
Subject: [PATCH 30/60] docs: corrections (#16550)

* Add missing hyphen in "server-side rendering"

* Fix incorrect use of "as such"

* regenerate types

---------

Co-authored-by: Chew Tee Ming <chew.tee.ming@nindatech.com>
---
 documentation/docs/02-runes/04-$effect.md            |  2 +-
 documentation/docs/03-template-syntax/06-snippet.md  |  2 +-
 documentation/docs/03-template-syntax/08-@html.md    |  2 +-
 .../docs/05-special-elements/07-svelte-options.md    |  2 +-
 documentation/docs/06-runtime/03-lifecycle-hooks.md  |  2 +-
 documentation/docs/07-misc/07-v5-migration-guide.md  | 12 ++++++------
 .../docs/98-reference/.generated/compile-errors.md   |  2 +-
 .../docs/98-reference/.generated/compile-warnings.md |  2 +-
 packages/svelte/messages/compile-errors/script.md    |  2 +-
 .../svelte/messages/compile-warnings/template.md     |  2 +-
 packages/svelte/src/ambient.d.ts                     |  4 ++--
 packages/svelte/types/index.d.ts                     |  4 ++--
 12 files changed, 19 insertions(+), 19 deletions(-)

diff --git a/documentation/docs/02-runes/04-$effect.md b/documentation/docs/02-runes/04-$effect.md
index 5820e178a0..6c42f55795 100644
--- a/documentation/docs/02-runes/04-$effect.md
+++ b/documentation/docs/02-runes/04-$effect.md
@@ -135,7 +135,7 @@ An effect only reruns when the object it reads changes, not when a property insi
 
 An effect only depends on the values that it read the last time it ran. This has interesting implications for effects that have conditional code.
 
-For instance, if `condition` is `true` in the code snippet below, the code inside the `if` block will run and `color` will be evaluated. As such, changes to either `condition` or `color` [will cause the effect to re-run](/playground/untitled#H4sIAAAAAAAAE21RQW6DMBD8ytaNBJHaJFLViwNIVZ8RcnBgXVk1xsILTYT4e20TQg89IOPZ2fHM7siMaJBx9tmaWpFqjQNlAKXEihx7YVJpdIyfRkY3G4gB8Pi97cPanRtQU8AuwuF_eNUaQuPlOMtc1SlLRWlKUo1tOwJflUikQHZtA0klzCDc64Imx0ANn8bInV1CDhtHgjClrsftcSXotluLybOUb3g4JJHhOZs5WZpuIS9gjNqkJKQP5e2ClrR4SMdZ13E4xZ8zTPOTJU2A2uE_PQ9COCI926_hTVarIU4hu_REPlBrKq2q73ycrf1N-vS4TMUsulaVg3EtR8H9rFgsg8uUsT1B2F9eshigZHBRpuaD0D3mY8Qm2BfB5N2YyRzdNEYVDy0Ja-WsFjcOUuP1HvFLWA6H3XuHTUSmmDV2--0TXonxsKbp7G9C6R__NONS-MFNvxj_d6mBAgAA).
+For instance, if `condition` is `true` in the code snippet below, the code inside the `if` block will run and `color` will be evaluated. This means that changes to either `condition` or `color` [will cause the effect to re-run](/playground/untitled#H4sIAAAAAAAAE21RQW6DMBD8ytaNBJHaJFLViwNIVZ8RcnBgXVk1xsILTYT4e20TQg89IOPZ2fHM7siMaJBx9tmaWpFqjQNlAKXEihx7YVJpdIyfRkY3G4gB8Pi97cPanRtQU8AuwuF_eNUaQuPlOMtc1SlLRWlKUo1tOwJflUikQHZtA0klzCDc64Imx0ANn8bInV1CDhtHgjClrsftcSXotluLybOUb3g4JJHhOZs5WZpuIS9gjNqkJKQP5e2ClrR4SMdZ13E4xZ8zTPOTJU2A2uE_PQ9COCI926_hTVarIU4hu_REPlBrKq2q73ycrf1N-vS4TMUsulaVg3EtR8H9rFgsg8uUsT1B2F9eshigZHBRpuaD0D3mY8Qm2BfB5N2YyRzdNEYVDy0Ja-WsFjcOUuP1HvFLWA6H3XuHTUSmmDV2--0TXonxsKbp7G9C6R__NONS-MFNvxj_d6mBAgAA).
 
 Conversely, if `condition` is `false`, `color` will not be evaluated, and the effect will _only_ re-run again when `condition` changes.
 
diff --git a/documentation/docs/03-template-syntax/06-snippet.md b/documentation/docs/03-template-syntax/06-snippet.md
index ab536c6e5c..02f58e0f6c 100644
--- a/documentation/docs/03-template-syntax/06-snippet.md
+++ b/documentation/docs/03-template-syntax/06-snippet.md
@@ -277,4 +277,4 @@ Snippets can be created programmatically with the [`createRawSnippet`](svelte#cr
 
 ## Snippets and slots
 
-In Svelte 4, content can be passed to components using [slots](legacy-slots). Snippets are more powerful and flexible, and as such slots are deprecated in Svelte 5.
+In Svelte 4, content can be passed to components using [slots](legacy-slots). Snippets are more powerful and flexible, and so slots have been deprecated in Svelte 5.
diff --git a/documentation/docs/03-template-syntax/08-@html.md b/documentation/docs/03-template-syntax/08-@html.md
index 30456fa666..a92accd093 100644
--- a/documentation/docs/03-template-syntax/08-@html.md
+++ b/documentation/docs/03-template-syntax/08-@html.md
@@ -22,7 +22,7 @@ It also will not compile Svelte code.
 
 ## Styling
 
-Content rendered this way is 'invisible' to Svelte and as such will not receive [scoped styles](scoped-styles) — in other words, this will not work, and the `a` and `img` styles will be regarded as unused:
+Content rendered this way is 'invisible' to Svelte and thus will not receive [scoped styles](scoped-styles). In other words, this will not work, and the `a` and `img` styles will be regarded as unused:
 
 <!-- prettier-ignore -->
 ```svelte
diff --git a/documentation/docs/05-special-elements/07-svelte-options.md b/documentation/docs/05-special-elements/07-svelte-options.md
index d29042e278..a2e47aa04f 100644
--- a/documentation/docs/05-special-elements/07-svelte-options.md
+++ b/documentation/docs/05-special-elements/07-svelte-options.md
@@ -12,7 +12,7 @@ The `<svelte:options>` element provides a place to specify per-component compile
 - `runes={false}` — forces a component into _legacy mode_
 - `namespace="..."` — the namespace where this component will be used, can be "html" (the default), "svg" or "mathml"
 - `customElement={...}` — the [options](custom-elements#Component-options) to use when compiling this component as a custom element. If a string is passed, it is used as the `tag` option
-- `css="injected"` — the component will inject its styles inline: During server side rendering, it's injected as a `<style>` tag in the `head`, during client side rendering, it's loaded via JavaScript
+- `css="injected"` — the component will inject its styles inline: During server-side rendering, it's injected as a `<style>` tag in the `head`, during client side rendering, it's loaded via JavaScript
 
 > [!LEGACY] Deprecated options
 > Svelte 4 also included the following options. They are deprecated in Svelte 5 and non-functional in runes mode.
diff --git a/documentation/docs/06-runtime/03-lifecycle-hooks.md b/documentation/docs/06-runtime/03-lifecycle-hooks.md
index f051c46d73..f981572a2e 100644
--- a/documentation/docs/06-runtime/03-lifecycle-hooks.md
+++ b/documentation/docs/06-runtime/03-lifecycle-hooks.md
@@ -41,7 +41,7 @@ If a function is returned from `onMount`, it will be called when the component i
 </script>
 ```
 
-> [!NOTE] This behaviour will only work when the function passed to `onMount` _synchronously_ returns a value. `async` functions always return a `Promise`, and as such cannot _synchronously_ return a function.
+> [!NOTE] This behaviour will only work when the function passed to `onMount` _synchronously_ returns a value. `async` functions always return a `Promise`, and thus cannot _synchronously_ return a function.
 
 ## `onDestroy`
 
diff --git a/documentation/docs/07-misc/07-v5-migration-guide.md b/documentation/docs/07-misc/07-v5-migration-guide.md
index c24c1febee..5cd2bdbac3 100644
--- a/documentation/docs/07-misc/07-v5-migration-guide.md
+++ b/documentation/docs/07-misc/07-v5-migration-guide.md
@@ -245,7 +245,7 @@ In Svelte 4, you can add event modifiers to handlers:
 <button on:click|once|preventDefault={handler}>...</button>
 ```
 
-Modifiers are specific to `on:` and as such do not work with modern event handlers. Adding things like `event.preventDefault()` inside the handler itself is preferable, since all the logic lives in one place rather than being split between handler and modifiers.
+Modifiers are specific to `on:` and thus do not work with modern event handlers. Adding things like `event.preventDefault()` inside the handler itself is preferable, since all the logic lives in one place rather than being split between handler and modifiers.
 
 Since event handlers are just functions, you can create your own wrappers as necessary:
 
@@ -340,7 +340,7 @@ When spreading props, local event handlers must go _after_ the spread, or they r
 
 ## Snippets instead of slots
 
-In Svelte 4, content can be passed to components using slots. Svelte 5 replaces them with snippets which are more powerful and flexible, and as such slots are deprecated in Svelte 5.
+In Svelte 4, content can be passed to components using slots. Svelte 5 replaces them with snippets, which are more powerful and flexible, and so slots have been deprecated in Svelte 5.
 
 They continue to work, however, and you can pass snippets to a component that uses slots:
 
@@ -599,7 +599,7 @@ Note that `mount` and `hydrate` are _not_ synchronous, so things like `onMount`
 
 ### Server API changes
 
-Similarly, components no longer have a `render` method when compiled for server side rendering. Instead, pass the function to `render` from `svelte/server`:
+Similarly, components no longer have a `render` method when compiled for server-side rendering. Instead, pass the function to `render` from `svelte/server`:
 
 ```js
 +++import { render } from 'svelte/server';+++
@@ -803,7 +803,7 @@ Note that Svelte 5 will also warn if you have a single expression wrapped in quo
 
 ### HTML structure is stricter
 
-In Svelte 4, you were allowed to write HTML code that would be repaired by the browser when server side rendering it. For example you could write this...
+In Svelte 4, you were allowed to write HTML code that would be repaired by the browser when server-side rendering it. For example you could write this...
 
 ```svelte
 <table>
@@ -835,7 +835,7 @@ Assignments to destructured parts of a `@const` declaration are no longer allowe
 
 ### :is(...), :has(...), and :where(...) are scoped
 
-Previously, Svelte did not analyse selectors inside `:is(...)`, `:has(...)`, and `:where(...)`, effectively treating them as global. Svelte 5 analyses them in the context of the current component. As such, some selectors may now be treated as unused if they were relying on this treatment. To fix this, use `:global(...)` inside the `:is(...)/:has(...)/:where(...)` selectors.
+Previously, Svelte did not analyse selectors inside `:is(...)`, `:has(...)`, and `:where(...)`, effectively treating them as global. Svelte 5 analyses them in the context of the current component. Thus, some selectors may now be treated as unused if they were relying on this treatment. To fix this, use `:global(...)` inside the `:is(...)/:has(...)/:where(...)` selectors.
 
 When using Tailwind's `@apply` directive, add a `:global` selector to preserve rules that use Tailwind-generated `:is(...)` selectors:
 
@@ -964,7 +964,7 @@ Since these mismatches are extremely rare, Svelte 5 assumes that the values are
 
 ### Hydration works differently
 
-Svelte 5 makes use of comments during server side rendering which are used for more robust and efficient hydration on the client. As such, you shouldn't remove comments from your HTML output if you intend to hydrate it, and if you manually authored HTML to be hydrated by a Svelte component, you need to adjust that HTML to include said comments at the correct positions.
+Svelte 5 makes use of comments during server-side rendering which are used for more robust and efficient hydration on the client. Thus, you shouldn't remove comments from your HTML output if you intend to hydrate it, and if you manually authored HTML to be hydrated by a Svelte component, you need to adjust that HTML to include said comments at the correct positions.
 
 ### `onevent` attributes are delegated
 
diff --git a/documentation/docs/98-reference/.generated/compile-errors.md b/documentation/docs/98-reference/.generated/compile-errors.md
index 957a9f67c7..77f720ff93 100644
--- a/documentation/docs/98-reference/.generated/compile-errors.md
+++ b/documentation/docs/98-reference/.generated/compile-errors.md
@@ -392,7 +392,7 @@ In legacy mode, it was possible to reassign or bind to the each block argument i
 {/each}
 ```
 
-This turned out to be buggy and unpredictable, particularly when working with derived values (such as `array.map(...)`), and as such is forbidden in runes mode. You can achieve the same outcome by using the index instead:
+This turned out to be buggy and unpredictable, particularly when working with derived values (such as `array.map(...)`), and thus is forbidden in runes mode. You can achieve the same outcome by using the index instead:
 
 ```svelte
 <script>
diff --git a/documentation/docs/98-reference/.generated/compile-warnings.md b/documentation/docs/98-reference/.generated/compile-warnings.md
index 01003f30c5..17841b863c 100644
--- a/documentation/docs/98-reference/.generated/compile-warnings.md
+++ b/documentation/docs/98-reference/.generated/compile-warnings.md
@@ -679,7 +679,7 @@ In HTML, there's [no such thing as a self-closing tag](https://jakearchibald.com
 </div>
 ```
 
-Some templating languages (including Svelte) will 'fix' HTML by turning `<span />` into `<span></span>`. Others adhere to the spec. Both result in ambiguity and confusion when copy-pasting code between different contexts, and as such Svelte prompts you to resolve the ambiguity directly by having an explicit closing tag.
+Some templating languages (including Svelte) will 'fix' HTML by turning `<span />` into `<span></span>`. Others adhere to the spec. Both result in ambiguity and confusion when copy-pasting code between different contexts, so Svelte prompts you to resolve the ambiguity directly by having an explicit closing tag.
 
 To automate this, run the dedicated migration:
 
diff --git a/packages/svelte/messages/compile-errors/script.md b/packages/svelte/messages/compile-errors/script.md
index 5c1080aced..350d59c276 100644
--- a/packages/svelte/messages/compile-errors/script.md
+++ b/packages/svelte/messages/compile-errors/script.md
@@ -54,7 +54,7 @@ In legacy mode, it was possible to reassign or bind to the each block argument i
 {/each}
 ```
 
-This turned out to be buggy and unpredictable, particularly when working with derived values (such as `array.map(...)`), and as such is forbidden in runes mode. You can achieve the same outcome by using the index instead:
+This turned out to be buggy and unpredictable, particularly when working with derived values (such as `array.map(...)`), and thus is forbidden in runes mode. You can achieve the same outcome by using the index instead:
 
 ```svelte
 <script>
diff --git a/packages/svelte/messages/compile-warnings/template.md b/packages/svelte/messages/compile-warnings/template.md
index 8af5aa2b98..3650e07b47 100644
--- a/packages/svelte/messages/compile-warnings/template.md
+++ b/packages/svelte/messages/compile-warnings/template.md
@@ -67,7 +67,7 @@ In HTML, there's [no such thing as a self-closing tag](https://jakearchibald.com
 </div>
 ```
 
-Some templating languages (including Svelte) will 'fix' HTML by turning `<span />` into `<span></span>`. Others adhere to the spec. Both result in ambiguity and confusion when copy-pasting code between different contexts, and as such Svelte prompts you to resolve the ambiguity directly by having an explicit closing tag.
+Some templating languages (including Svelte) will 'fix' HTML by turning `<span />` into `<span></span>`. Others adhere to the spec. Both result in ambiguity and confusion when copy-pasting code between different contexts, so Svelte prompts you to resolve the ambiguity directly by having an explicit closing tag.
 
 To automate this, run the dedicated migration:
 
diff --git a/packages/svelte/src/ambient.d.ts b/packages/svelte/src/ambient.d.ts
index ad32eaa56f..59128e45f0 100644
--- a/packages/svelte/src/ambient.d.ts
+++ b/packages/svelte/src/ambient.d.ts
@@ -229,7 +229,7 @@ declare namespace $derived {
  *
  * If you return a function from the effect, it will be called right before the effect is run again, or when the component is unmounted.
  *
- * Does not run during server side rendering.
+ * Does not run during server-side rendering.
  *
  * https://svelte.dev/docs/svelte/$effect
  * @param fn The function to execute
@@ -248,7 +248,7 @@ declare namespace $effect {
 	 *
 	 * If you return a function from the effect, it will be called right before the effect is run again, or when the component is unmounted.
 	 *
-	 * Does not run during server side rendering.
+	 * Does not run during server-side rendering.
 	 *
 	 * https://svelte.dev/docs/svelte/$effect#$effect.pre
 	 * @param fn The function to execute
diff --git a/packages/svelte/types/index.d.ts b/packages/svelte/types/index.d.ts
index 64aa9e23ba..97e6f0f5a3 100644
--- a/packages/svelte/types/index.d.ts
+++ b/packages/svelte/types/index.d.ts
@@ -3313,7 +3313,7 @@ declare namespace $derived {
  *
  * If you return a function from the effect, it will be called right before the effect is run again, or when the component is unmounted.
  *
- * Does not run during server side rendering.
+ * Does not run during server-side rendering.
  *
  * https://svelte.dev/docs/svelte/$effect
  * @param fn The function to execute
@@ -3332,7 +3332,7 @@ declare namespace $effect {
 	 *
 	 * If you return a function from the effect, it will be called right before the effect is run again, or when the component is unmounted.
 	 *
-	 * Does not run during server side rendering.
+	 * Does not run during server-side rendering.
 	 *
 	 * https://svelte.dev/docs/svelte/$effect#$effect.pre
 	 * @param fn The function to execute

From e1ff6ddf175c1a3463b81e0a87d6bad5bef40072 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Isak=20Regnstr=C3=B6m?= <isak.regnstrom@gmail.com>
Date: Tue, 5 Aug 2025 21:01:49 +0200
Subject: [PATCH 31/60] Correct link in README.md (#16557)

Changed "master" to "main" in the link to the changelog. It was previously redirecting to the "svelte-4" branch.
---
 packages/svelte/README.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/svelte/README.md b/packages/svelte/README.md
index 03e4db5db0..026bc0d81d 100644
--- a/packages/svelte/README.md
+++ b/packages/svelte/README.md
@@ -30,7 +30,7 @@ See [the SvelteKit documentation](https://svelte.dev/docs/kit) to learn more.
 
 ## Changelog
 
-[The Changelog for this package is available on GitHub](https://github.com/sveltejs/svelte/blob/master/packages/svelte/CHANGELOG.md).
+[The Changelog for this package is available on GitHub](https://github.com/sveltejs/svelte/blob/main/packages/svelte/CHANGELOG.md).
 
 ## Supporting Svelte
 

From e7e8a9c7b7dad0e9467e4e1b4cce49bd89f57aaf Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Tue, 5 Aug 2025 20:09:35 -0400
Subject: [PATCH 32/60] docs: remove 'thus', fix some phrasing (#16559)

---
 documentation/docs/03-template-syntax/08-@html.md         | 2 +-
 documentation/docs/06-runtime/03-lifecycle-hooks.md       | 2 +-
 documentation/docs/07-misc/07-v5-migration-guide.md       | 8 ++++----
 .../docs/98-reference/.generated/compile-errors.md        | 2 +-
 packages/svelte/messages/compile-errors/script.md         | 2 +-
 5 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/documentation/docs/03-template-syntax/08-@html.md b/documentation/docs/03-template-syntax/08-@html.md
index a92accd093..6d8a8be0c6 100644
--- a/documentation/docs/03-template-syntax/08-@html.md
+++ b/documentation/docs/03-template-syntax/08-@html.md
@@ -22,7 +22,7 @@ It also will not compile Svelte code.
 
 ## Styling
 
-Content rendered this way is 'invisible' to Svelte and thus will not receive [scoped styles](scoped-styles). In other words, this will not work, and the `a` and `img` styles will be regarded as unused:
+Content rendered this way is 'invisible' to Svelte and as such will not receive [scoped styles](scoped-styles). In other words, this will not work, and the `a` and `img` styles will be regarded as unused:
 
 <!-- prettier-ignore -->
 ```svelte
diff --git a/documentation/docs/06-runtime/03-lifecycle-hooks.md b/documentation/docs/06-runtime/03-lifecycle-hooks.md
index f981572a2e..f7a78beec9 100644
--- a/documentation/docs/06-runtime/03-lifecycle-hooks.md
+++ b/documentation/docs/06-runtime/03-lifecycle-hooks.md
@@ -41,7 +41,7 @@ If a function is returned from `onMount`, it will be called when the component i
 </script>
 ```
 
-> [!NOTE] This behaviour will only work when the function passed to `onMount` _synchronously_ returns a value. `async` functions always return a `Promise`, and thus cannot _synchronously_ return a function.
+> [!NOTE] This behaviour will only work when the function passed to `onMount` is _synchronous_. `async` functions always return a `Promise`.
 
 ## `onDestroy`
 
diff --git a/documentation/docs/07-misc/07-v5-migration-guide.md b/documentation/docs/07-misc/07-v5-migration-guide.md
index 5cd2bdbac3..37da3b7b23 100644
--- a/documentation/docs/07-misc/07-v5-migration-guide.md
+++ b/documentation/docs/07-misc/07-v5-migration-guide.md
@@ -245,7 +245,7 @@ In Svelte 4, you can add event modifiers to handlers:
 <button on:click|once|preventDefault={handler}>...</button>
 ```
 
-Modifiers are specific to `on:` and thus do not work with modern event handlers. Adding things like `event.preventDefault()` inside the handler itself is preferable, since all the logic lives in one place rather than being split between handler and modifiers.
+Modifiers are specific to `on:` and so do not work with modern event handlers. Adding things like `event.preventDefault()` inside the handler itself is preferable, since all the logic lives in one place rather than being split between handler and modifiers.
 
 Since event handlers are just functions, you can create your own wrappers as necessary:
 
@@ -340,7 +340,7 @@ When spreading props, local event handlers must go _after_ the spread, or they r
 
 ## Snippets instead of slots
 
-In Svelte 4, content can be passed to components using slots. Svelte 5 replaces them with snippets, which are more powerful and flexible, and so slots have been deprecated in Svelte 5.
+In Svelte 4, content can be passed to components using slots. Svelte 5 replaces them with snippets, which are more powerful and flexible, and so slots are deprecated in Svelte 5.
 
 They continue to work, however, and you can pass snippets to a component that uses slots:
 
@@ -835,7 +835,7 @@ Assignments to destructured parts of a `@const` declaration are no longer allowe
 
 ### :is(...), :has(...), and :where(...) are scoped
 
-Previously, Svelte did not analyse selectors inside `:is(...)`, `:has(...)`, and `:where(...)`, effectively treating them as global. Svelte 5 analyses them in the context of the current component. Thus, some selectors may now be treated as unused if they were relying on this treatment. To fix this, use `:global(...)` inside the `:is(...)/:has(...)/:where(...)` selectors.
+Previously, Svelte did not analyse selectors inside `:is(...)`, `:has(...)`, and `:where(...)`, effectively treating them as global. Svelte 5 analyses them in the context of the current component. Some selectors may now therefore be treated as unused if they were relying on this treatment. To fix this, use `:global(...)` inside the `:is(...)/:has(...)/:where(...)` selectors.
 
 When using Tailwind's `@apply` directive, add a `:global` selector to preserve rules that use Tailwind-generated `:is(...)` selectors:
 
@@ -964,7 +964,7 @@ Since these mismatches are extremely rare, Svelte 5 assumes that the values are
 
 ### Hydration works differently
 
-Svelte 5 makes use of comments during server-side rendering which are used for more robust and efficient hydration on the client. Thus, you shouldn't remove comments from your HTML output if you intend to hydrate it, and if you manually authored HTML to be hydrated by a Svelte component, you need to adjust that HTML to include said comments at the correct positions.
+Svelte 5 makes use of comments during server-side rendering which are used for more robust and efficient hydration on the client. You therefore should not remove comments from your HTML output if you intend to hydrate it, and if you manually authored HTML to be hydrated by a Svelte component, you need to adjust that HTML to include said comments at the correct positions.
 
 ### `onevent` attributes are delegated
 
diff --git a/documentation/docs/98-reference/.generated/compile-errors.md b/documentation/docs/98-reference/.generated/compile-errors.md
index 77f720ff93..957a9f67c7 100644
--- a/documentation/docs/98-reference/.generated/compile-errors.md
+++ b/documentation/docs/98-reference/.generated/compile-errors.md
@@ -392,7 +392,7 @@ In legacy mode, it was possible to reassign or bind to the each block argument i
 {/each}
 ```
 
-This turned out to be buggy and unpredictable, particularly when working with derived values (such as `array.map(...)`), and thus is forbidden in runes mode. You can achieve the same outcome by using the index instead:
+This turned out to be buggy and unpredictable, particularly when working with derived values (such as `array.map(...)`), and as such is forbidden in runes mode. You can achieve the same outcome by using the index instead:
 
 ```svelte
 <script>
diff --git a/packages/svelte/messages/compile-errors/script.md b/packages/svelte/messages/compile-errors/script.md
index 350d59c276..5c1080aced 100644
--- a/packages/svelte/messages/compile-errors/script.md
+++ b/packages/svelte/messages/compile-errors/script.md
@@ -54,7 +54,7 @@ In legacy mode, it was possible to reassign or bind to the each block argument i
 {/each}
 ```
 
-This turned out to be buggy and unpredictable, particularly when working with derived values (such as `array.map(...)`), and thus is forbidden in runes mode. You can achieve the same outcome by using the index instead:
+This turned out to be buggy and unpredictable, particularly when working with derived values (such as `array.map(...)`), and as such is forbidden in runes mode. You can achieve the same outcome by using the index instead:
 
 ```svelte
 <script>

From d8c3f3d87e4f008ee902bb084f2820202d3f97c3 Mon Sep 17 00:00:00 2001
From: ComputerGuy <63362464+Ocean-OS@users.noreply.github.com>
Date: Tue, 5 Aug 2025 17:47:58 -0700
Subject: [PATCH 33/60] fix: emit `snippet_invalid_export` instead of
 `undefined_export` for exported snippets (#16539)

* fix: emit `snippet_invalid_export` instead of `undefined_export` for exported snippets

* try this

* this should work

* remove some junk (this never did anything)

* add test

---------

Co-authored-by: Rich Harris <rich.harris@vercel.com>
---
 .changeset/thick-snakes-look.md                     |  5 +++++
 .../svelte/src/compiler/phases/2-analyze/index.js   | 13 +++++++++----
 .../phases/2-analyze/visitors/SnippetBlock.js       |  5 -----
 packages/svelte/src/compiler/phases/types.d.ts      |  1 -
 .../samples/snippet-invalid-export/_config.js       | 10 ++++++++++
 .../samples/snippet-invalid-export/main.svelte      | 11 +++++++++++
 6 files changed, 35 insertions(+), 10 deletions(-)
 create mode 100644 .changeset/thick-snakes-look.md
 create mode 100644 packages/svelte/tests/compiler-errors/samples/snippet-invalid-export/_config.js
 create mode 100644 packages/svelte/tests/compiler-errors/samples/snippet-invalid-export/main.svelte

diff --git a/.changeset/thick-snakes-look.md b/.changeset/thick-snakes-look.md
new file mode 100644
index 0000000000..f5f22e8a6c
--- /dev/null
+++ b/.changeset/thick-snakes-look.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: emit `snippet_invalid_export` instead of `undefined_export` for exported snippets
diff --git a/packages/svelte/src/compiler/phases/2-analyze/index.js b/packages/svelte/src/compiler/phases/2-analyze/index.js
index cd44fd998a..ecc843d2f4 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/index.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/index.js
@@ -526,7 +526,6 @@ export function analyze_component(root, source, options) {
 			has_global: false
 		},
 		source,
-		undefined_exports: new Map(),
 		snippet_renderers: new Map(),
 		snippets: new Set(),
 		async_deriveds: new Set()
@@ -787,9 +786,15 @@ export function analyze_component(root, source, options) {
 		if (node.type === 'ExportNamedDeclaration' && node.specifiers !== null && node.source == null) {
 			for (const specifier of node.specifiers) {
 				if (specifier.local.type !== 'Identifier') continue;
-
-				const binding = analysis.module.scope.get(specifier.local.name);
-				if (!binding) e.export_undefined(specifier, specifier.local.name);
+				const name = specifier.local.name;
+				const binding = analysis.module.scope.get(name);
+				if (!binding) {
+					if ([...analysis.snippets].find((snippet) => snippet.expression.name === name)) {
+						e.snippet_invalid_export(specifier);
+					} else {
+						e.export_undefined(specifier, name);
+					}
+				}
 			}
 		}
 	}
diff --git a/packages/svelte/src/compiler/phases/2-analyze/visitors/SnippetBlock.js b/packages/svelte/src/compiler/phases/2-analyze/visitors/SnippetBlock.js
index 2f6bbd785a..7930c2b1a7 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/visitors/SnippetBlock.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/visitors/SnippetBlock.js
@@ -35,11 +35,6 @@ export function SnippetBlock(node, context) {
 	if (can_hoist) {
 		const binding = /** @type {Binding} */ (context.state.scope.get(name));
 		context.state.analysis.module.scope.declarations.set(name, binding);
-	} else {
-		const undefined_export = context.state.analysis.undefined_exports.get(name);
-		if (undefined_export) {
-			e.snippet_invalid_export(undefined_export);
-		}
 	}
 
 	node.metadata.can_hoist = can_hoist;
diff --git a/packages/svelte/src/compiler/phases/types.d.ts b/packages/svelte/src/compiler/phases/types.d.ts
index 4cbbc362c7..4da78f1482 100644
--- a/packages/svelte/src/compiler/phases/types.d.ts
+++ b/packages/svelte/src/compiler/phases/types.d.ts
@@ -95,7 +95,6 @@ export interface ComponentAnalysis extends Analysis {
 	};
 	/** @deprecated use `source` from `state.js` instead */
 	source: string;
-	undefined_exports: Map<string, Node>;
 	/**
 	 * Every render tag/component, and whether it could be definitively resolved or not
 	 */
diff --git a/packages/svelte/tests/compiler-errors/samples/snippet-invalid-export/_config.js b/packages/svelte/tests/compiler-errors/samples/snippet-invalid-export/_config.js
new file mode 100644
index 0000000000..cc0dd388f4
--- /dev/null
+++ b/packages/svelte/tests/compiler-errors/samples/snippet-invalid-export/_config.js
@@ -0,0 +1,10 @@
+import { test } from '../../test';
+
+export default test({
+	error: {
+		code: 'snippet_invalid_export',
+		message:
+			'An exported snippet can only reference things declared in a `<script module>`, or other exportable snippets',
+		position: [26, 29]
+	}
+});
diff --git a/packages/svelte/tests/compiler-errors/samples/snippet-invalid-export/main.svelte b/packages/svelte/tests/compiler-errors/samples/snippet-invalid-export/main.svelte
new file mode 100644
index 0000000000..eb776944c3
--- /dev/null
+++ b/packages/svelte/tests/compiler-errors/samples/snippet-invalid-export/main.svelte
@@ -0,0 +1,11 @@
+<script module>
+	export { foo }
+</script>
+
+<script>
+	let x = 42;
+</script>
+
+{#snippet foo()}
+	{x}
+{/snippet}

From bbd0b1ed8776cc34c19574a5f75a5cfe8ecddcfa Mon Sep 17 00:00:00 2001
From: 7nik <kifiranet@gmail.com>
Date: Wed, 6 Aug 2025 04:44:20 +0300
Subject: [PATCH 34/60] fix: remount at any hydration error (#16248)

* fix: remount at any hydration error

* re-throw svelte error immediately

* log error as warn

* fix?
---
 .changeset/hip-eagles-yawn.md                 |  5 ++++
 packages/svelte/src/internal/client/render.js | 30 ++++++++++++-------
 .../whitespace-at-block-start/Nested.svelte   |  1 +
 .../whitespace-at-block-start/_config.js      |  8 +++++
 .../whitespace-at-block-start/_expected.html  |  1 +
 .../whitespace-at-block-start/_override.html  |  2 ++
 .../whitespace-at-block-start/main.svelte     |  7 +++++
 7 files changed, 43 insertions(+), 11 deletions(-)
 create mode 100644 .changeset/hip-eagles-yawn.md
 create mode 100644 packages/svelte/tests/hydration/samples/whitespace-at-block-start/Nested.svelte
 create mode 100644 packages/svelte/tests/hydration/samples/whitespace-at-block-start/_config.js
 create mode 100644 packages/svelte/tests/hydration/samples/whitespace-at-block-start/_expected.html
 create mode 100644 packages/svelte/tests/hydration/samples/whitespace-at-block-start/_override.html
 create mode 100644 packages/svelte/tests/hydration/samples/whitespace-at-block-start/main.svelte

diff --git a/.changeset/hip-eagles-yawn.md b/.changeset/hip-eagles-yawn.md
new file mode 100644
index 0000000000..c987e7c7f2
--- /dev/null
+++ b/.changeset/hip-eagles-yawn.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: remount at any hydration error
diff --git a/packages/svelte/src/internal/client/render.js b/packages/svelte/src/internal/client/render.js
index ff6844453d..3a489f9f92 100644
--- a/packages/svelte/src/internal/client/render.js
+++ b/packages/svelte/src/internal/client/render.js
@@ -136,20 +136,28 @@ export function hydrate(component, options) {
 
 		return /**  @type {Exports} */ (instance);
 	} catch (error) {
-		if (error === HYDRATION_ERROR) {
-			if (options.recover === false) {
-				e.hydration_failed();
-			}
-
-			// If an error occured above, the operations might not yet have been initialised.
-			init_operations();
-			clear_text_content(target);
+		// re-throw Svelte errors - they are certainly not related to hydration
+		if (
+			error instanceof Error &&
+			error.message.split('\n').some((line) => line.startsWith('https://svelte.dev/e/'))
+		) {
+			throw error;
+		}
+		if (error !== HYDRATION_ERROR) {
+			// eslint-disable-next-line no-console
+			console.warn('Failed to hydrate: ', error);
+		}
 
-			set_hydrating(false);
-			return mount(component, options);
+		if (options.recover === false) {
+			e.hydration_failed();
 		}
 
-		throw error;
+		// If an error occured above, the operations might not yet have been initialised.
+		init_operations();
+		clear_text_content(target);
+
+		set_hydrating(false);
+		return mount(component, options);
 	} finally {
 		set_hydrating(was_hydrating);
 		set_hydrate_node(previous_hydrate_node);
diff --git a/packages/svelte/tests/hydration/samples/whitespace-at-block-start/Nested.svelte b/packages/svelte/tests/hydration/samples/whitespace-at-block-start/Nested.svelte
new file mode 100644
index 0000000000..70bf63ad9d
--- /dev/null
+++ b/packages/svelte/tests/hydration/samples/whitespace-at-block-start/Nested.svelte
@@ -0,0 +1 @@
+<p>nested</p>
\ No newline at end of file
diff --git a/packages/svelte/tests/hydration/samples/whitespace-at-block-start/_config.js b/packages/svelte/tests/hydration/samples/whitespace-at-block-start/_config.js
new file mode 100644
index 0000000000..457eeb2201
--- /dev/null
+++ b/packages/svelte/tests/hydration/samples/whitespace-at-block-start/_config.js
@@ -0,0 +1,8 @@
+import { test } from '../../test';
+
+export default test({
+	errors: [
+		'Failed to hydrate: ',
+		new DOMException("Node can't be inserted in a #text parent.", 'HierarchyRequestError')
+	]
+});
diff --git a/packages/svelte/tests/hydration/samples/whitespace-at-block-start/_expected.html b/packages/svelte/tests/hydration/samples/whitespace-at-block-start/_expected.html
new file mode 100644
index 0000000000..46f8e8a7ac
--- /dev/null
+++ b/packages/svelte/tests/hydration/samples/whitespace-at-block-start/_expected.html
@@ -0,0 +1 @@
+<main><p>nested</p><!----></main>
\ No newline at end of file
diff --git a/packages/svelte/tests/hydration/samples/whitespace-at-block-start/_override.html b/packages/svelte/tests/hydration/samples/whitespace-at-block-start/_override.html
new file mode 100644
index 0000000000..90ca4ef4b8
--- /dev/null
+++ b/packages/svelte/tests/hydration/samples/whitespace-at-block-start/_override.html
@@ -0,0 +1,2 @@
+<!--[-->
+<main><p>nested</p><!----></main><!--]-->
\ No newline at end of file
diff --git a/packages/svelte/tests/hydration/samples/whitespace-at-block-start/main.svelte b/packages/svelte/tests/hydration/samples/whitespace-at-block-start/main.svelte
new file mode 100644
index 0000000000..f1f962b958
--- /dev/null
+++ b/packages/svelte/tests/hydration/samples/whitespace-at-block-start/main.svelte
@@ -0,0 +1,7 @@
+<script>
+	import Nested from './Nested.svelte';
+</script>
+
+<main>
+	<Nested />
+</main>
\ No newline at end of file

From b181c454842cb46321641c867ec045cc90e3413a Mon Sep 17 00:00:00 2001
From: ComputerGuy <63362464+Ocean-OS@users.noreply.github.com>
Date: Tue, 5 Aug 2025 18:44:47 -0700
Subject: [PATCH 35/60] chore: emit `await_reactivity_loss` in `for await`
 loops (#16521)

* chore: emit `await_reactivity_loss` in `for await` loops

* oops

* fix lint

* fix import order

* input is an iterable, not an iterator

* handle non-iterables

* add test

* typescript. shrug

---------

Co-authored-by: Rich Harris <rich.harris@vercel.com>
---
 .changeset/quiet-donuts-wonder.md             |  5 +++
 .../3-transform/client/transform-client.js    |  2 +
 .../client/visitors/ForOfStatement.js         | 20 +++++++++
 .../svelte/src/compiler/utils/builders.js     | 17 +++++++
 packages/svelte/src/internal/client/index.js  |  6 ++-
 .../src/internal/client/reactivity/async.js   | 45 +++++++++++++++++++
 .../_config.js                                | 24 ++++++++++
 .../main.svelte                               | 24 ++++++++++
 8 files changed, 142 insertions(+), 1 deletion(-)
 create mode 100644 .changeset/quiet-donuts-wonder.md
 create mode 100644 packages/svelte/src/compiler/phases/3-transform/client/visitors/ForOfStatement.js
 create mode 100644 packages/svelte/tests/runtime-runes/samples/async-reactivity-loss-for-await/_config.js
 create mode 100644 packages/svelte/tests/runtime-runes/samples/async-reactivity-loss-for-await/main.svelte

diff --git a/.changeset/quiet-donuts-wonder.md b/.changeset/quiet-donuts-wonder.md
new file mode 100644
index 0000000000..a0ee39f4e2
--- /dev/null
+++ b/.changeset/quiet-donuts-wonder.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+chore: emit `await_reactivity_loss` in `for await` loops
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 a56aca9c5f..0737f531a5 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
@@ -26,6 +26,7 @@ import { DebugTag } from './visitors/DebugTag.js';
 import { EachBlock } from './visitors/EachBlock.js';
 import { ExportNamedDeclaration } from './visitors/ExportNamedDeclaration.js';
 import { ExpressionStatement } from './visitors/ExpressionStatement.js';
+import { ForOfStatement } from './visitors/ForOfStatement.js';
 import { Fragment } from './visitors/Fragment.js';
 import { FunctionDeclaration } from './visitors/FunctionDeclaration.js';
 import { FunctionExpression } from './visitors/FunctionExpression.js';
@@ -103,6 +104,7 @@ const visitors = {
 	EachBlock,
 	ExportNamedDeclaration,
 	ExpressionStatement,
+	ForOfStatement,
 	Fragment,
 	FunctionDeclaration,
 	FunctionExpression,
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/ForOfStatement.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/ForOfStatement.js
new file mode 100644
index 0000000000..a5d2751812
--- /dev/null
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/ForOfStatement.js
@@ -0,0 +1,20 @@
+/** @import { Expression, ForOfStatement, Pattern, Statement, VariableDeclaration } from 'estree' */
+/** @import { ComponentContext } from '../types' */
+import * as b from '#compiler/builders';
+import { dev, is_ignored } from '../../../../state.js';
+
+/**
+ * @param {ForOfStatement} node
+ * @param {ComponentContext} context
+ */
+export function ForOfStatement(node, context) {
+	if (node.await && dev && !is_ignored(node, 'await_reactivity_loss')) {
+		const left = /** @type {VariableDeclaration | Pattern} */ (context.visit(node.left));
+		const argument = /** @type {Expression} */ (context.visit(node.right));
+		const body = /** @type {Statement} */ (context.visit(node.body));
+		const right = b.call('$.for_await_track_reactivity_loss', argument);
+		return b.for_of(left, right, body, true);
+	}
+
+	context.next();
+}
diff --git a/packages/svelte/src/compiler/utils/builders.js b/packages/svelte/src/compiler/utils/builders.js
index c241cdb445..81c4e6b8e0 100644
--- a/packages/svelte/src/compiler/utils/builders.js
+++ b/packages/svelte/src/compiler/utils/builders.js
@@ -214,6 +214,23 @@ export function export_default(declaration) {
 	return { type: 'ExportDefaultDeclaration', declaration };
 }
 
+/**
+ * @param {ESTree.VariableDeclaration | ESTree.Pattern} left
+ * @param {ESTree.Expression} right
+ * @param {ESTree.Statement} body
+ * @param {boolean} [_await]
+ * @returns {ESTree.ForOfStatement}
+ */
+export function for_of(left, right, body, _await = false) {
+	return {
+		type: 'ForOfStatement',
+		left,
+		right,
+		body,
+		await: _await
+	};
+}
+
 /**
  * @param {ESTree.Identifier} id
  * @param {ESTree.Pattern[]} params
diff --git a/packages/svelte/src/internal/client/index.js b/packages/svelte/src/internal/client/index.js
index 90f0f9baac..c094c9e044 100644
--- a/packages/svelte/src/internal/client/index.js
+++ b/packages/svelte/src/internal/client/index.js
@@ -98,7 +98,11 @@ export {
 	props_id,
 	with_script
 } from './dom/template.js';
-export { save, track_reactivity_loss } from './reactivity/async.js';
+export {
+	for_await_track_reactivity_loss,
+	save,
+	track_reactivity_loss
+} from './reactivity/async.js';
 export { flushSync as flush, suspend } from './reactivity/batch.js';
 export {
 	async_derived,
diff --git a/packages/svelte/src/internal/client/reactivity/async.js b/packages/svelte/src/internal/client/reactivity/async.js
index c200f10dba..2b133e5f44 100644
--- a/packages/svelte/src/internal/client/reactivity/async.js
+++ b/packages/svelte/src/internal/client/reactivity/async.js
@@ -119,6 +119,51 @@ export async function track_reactivity_loss(promise) {
 	};
 }
 
+/**
+ * Used in `for await` loops in DEV, so
+ * that we can emit `await_reactivity_loss` warnings
+ * after each `async_iterator` result resolves and
+ * after the `async_iterator` return resolves (if it runs)
+ * @template T
+ * @template TReturn
+ * @param {Iterable<T> | AsyncIterable<T>} iterable
+ * @returns {AsyncGenerator<T, TReturn | undefined>}
+ */
+export async function* for_await_track_reactivity_loss(iterable) {
+	// This is based on the algorithms described in ECMA-262:
+	// ForIn/OfBodyEvaluation
+	// https://tc39.es/ecma262/multipage/ecmascript-language-statements-and-declarations.html#sec-runtime-semantics-forin-div-ofbodyevaluation-lhs-stmt-iterator-lhskind-labelset
+	// AsyncIteratorClose
+	// https://tc39.es/ecma262/multipage/abstract-operations.html#sec-asynciteratorclose
+
+	/** @type {AsyncIterator<T, TReturn>} */
+	// @ts-ignore
+	const iterator = iterable[Symbol.asyncIterator]?.() ?? iterable[Symbol.iterator]?.();
+
+	if (iterator === undefined) {
+		throw new TypeError('value is not async iterable');
+	}
+
+	/** Whether the completion of the iterator was "normal", meaning it wasn't ended via `break` or a similar method */
+	let normal_completion = false;
+	try {
+		while (true) {
+			const { done, value } = (await track_reactivity_loss(iterator.next()))();
+			if (done) {
+				normal_completion = true;
+				break;
+			}
+			yield value;
+		}
+	} finally {
+		// If the iterator had a normal completion and `return` is defined on the iterator, call it and return the value
+		if (normal_completion && iterator.return !== undefined) {
+			// eslint-disable-next-line no-unsafe-finally
+			return /** @type {TReturn} */ ((await track_reactivity_loss(iterator.return()))().value);
+		}
+	}
+}
+
 export function unset_context() {
 	set_active_effect(null);
 	set_active_reaction(null);
diff --git a/packages/svelte/tests/runtime-runes/samples/async-reactivity-loss-for-await/_config.js b/packages/svelte/tests/runtime-runes/samples/async-reactivity-loss-for-await/_config.js
new file mode 100644
index 0000000000..bde65a499f
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/async-reactivity-loss-for-await/_config.js
@@ -0,0 +1,24 @@
+import { tick } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+	compileOptions: {
+		dev: true
+	},
+
+	html: `<button>a</button><button>b</button><p>pending</p>`,
+
+	async test({ assert, target, warnings }) {
+		await tick();
+		assert.htmlEqual(target.innerHTML, '<button>a</button><button>b</button><h1>3</h1>');
+
+		assert.equal(
+			warnings[0],
+			'Detected reactivity loss when reading `values[1]`. This happens when state is read in an async function after an earlier `await`'
+		);
+
+		assert.equal(warnings[1].name, 'TracedAtError');
+
+		assert.equal(warnings.length, 2);
+	}
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/async-reactivity-loss-for-await/main.svelte b/packages/svelte/tests/runtime-runes/samples/async-reactivity-loss-for-await/main.svelte
new file mode 100644
index 0000000000..92a6ec18bc
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/async-reactivity-loss-for-await/main.svelte
@@ -0,0 +1,24 @@
+<script>
+	let values = $state([1, 2]);
+
+	async function get_total() {
+		let total = 0;
+
+		for await (const n of values) {
+			total += n;
+		}
+
+		return total;
+	}
+</script>
+
+<button onclick={() => values[0]++}>a</button>
+<button onclick={() => values[1]++}>b</button>
+
+<svelte:boundary>
+	<h1>{await get_total()}</h1>
+
+	{#snippet pending()}
+		<p>pending</p>
+	{/snippet}
+</svelte:boundary>

From 41a20aa975060d901f2ec9911b16a3e3cc0f1f43 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Wed, 6 Aug 2025 12:06:06 -0400
Subject: [PATCH 36/60] chore: remove `b.async` (#16566)

---
 .../compiler/phases/3-transform/shared/assignments.js    | 9 +++++----
 packages/svelte/src/compiler/utils/builders.js           | 9 ---------
 2 files changed, 5 insertions(+), 13 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/shared/assignments.js b/packages/svelte/src/compiler/phases/3-transform/shared/assignments.js
index 175b44f4fe..0853757775 100644
--- a/packages/svelte/src/compiler/phases/3-transform/shared/assignments.js
+++ b/packages/svelte/src/compiler/phases/3-transform/shared/assignments.js
@@ -65,13 +65,14 @@ export function visit_assignment_expression(node, context, build_assignment) {
 				statements.push(b.return(rhs));
 			}
 
-			const iife = b.arrow([rhs], b.block(statements));
-
-			const iife_is_async =
+			const async =
 				is_expression_async(value) ||
 				assignments.some((assignment) => is_expression_async(assignment));
 
-			return iife_is_async ? b.await(b.call(b.async(iife), value)) : b.call(iife, value);
+			const iife = b.arrow([rhs], b.block(statements), async);
+			const call = b.call(iife, value);
+
+			return async ? b.await(call) : call;
 		}
 
 		const sequence = b.sequence(assignments);
diff --git a/packages/svelte/src/compiler/utils/builders.js b/packages/svelte/src/compiler/utils/builders.js
index 81c4e6b8e0..defdb1642e 100644
--- a/packages/svelte/src/compiler/utils/builders.js
+++ b/packages/svelte/src/compiler/utils/builders.js
@@ -56,15 +56,6 @@ export function assignment(operator, left, right) {
 	return { type: 'AssignmentExpression', operator, left, right };
 }
 
-/**
- * @template T
- * @param {T & ESTree.BaseFunction} func
- * @returns {T & ESTree.BaseFunction}
- */
-export function async(func) {
-	return { ...func, async: true };
-}
-
 /**
  * @param {ESTree.Expression} argument
  * @returns {ESTree.AwaitExpression}

From 193f23fa055822635f0b3a2c06d717bac03a6dde Mon Sep 17 00:00:00 2001
From: ComputerGuy <63362464+Ocean-OS@users.noreply.github.com>
Date: Wed, 6 Aug 2025 10:53:08 -0700
Subject: [PATCH 37/60] feat: async fragments (#16542)

* init

* fix

* fix

* maybe this works?

* fix, minor cleanup

* maybe this'll fix hydration issues?

* apparently not, maybe this'll do it

* add test, changeset

* minor tweak

* tabs

* avoid timeouts in tests, they add up quickly

* tweak

* fix

* some is more 'correct' than find

* chore: remove `b.async`

* simplify

* apply suggestion from review

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

* Update .changeset/brave-baboons-teach.md

---------

Co-authored-by: Rich Harris <rich.harris@vercel.com>
---
 .changeset/brave-baboons-teach.md             |  5 +++
 .../compiler/phases/1-parse/utils/create.js   |  3 +-
 .../src/compiler/phases/2-analyze/index.js    |  5 +++
 .../src/compiler/phases/2-analyze/types.d.ts  |  1 +
 .../2-analyze/visitors/AwaitExpression.js     |  9 +++++
 .../phases/2-analyze/visitors/Fragment.js     | 10 +++++
 .../3-transform/client/transform-client.js    |  1 +
 .../phases/3-transform/client/types.d.ts      |  5 ++-
 .../phases/3-transform/client/utils.js        | 15 ++++++--
 .../3-transform/client/visitors/AwaitBlock.js |  4 +-
 .../3-transform/client/visitors/ConstTag.js   | 37 +++++++++++--------
 .../3-transform/client/visitors/Fragment.js   | 37 ++++++++++++++-----
 .../client/visitors/LetDirective.js           |  5 +--
 .../client/visitors/SnippetBlock.js           | 18 +++++----
 .../client/visitors/SvelteBoundary.js         |  2 +-
 .../svelte/src/compiler/types/template.d.ts   |  1 +
 .../svelte/src/compiler/utils/builders.js     |  4 +-
 .../samples/async-const/_config.js            | 12 ++++++
 .../samples/async-const/main.svelte           | 16 ++++++++
 19 files changed, 142 insertions(+), 48 deletions(-)
 create mode 100644 .changeset/brave-baboons-teach.md
 create mode 100644 packages/svelte/src/compiler/phases/2-analyze/visitors/Fragment.js
 create mode 100644 packages/svelte/tests/runtime-runes/samples/async-const/_config.js
 create mode 100644 packages/svelte/tests/runtime-runes/samples/async-const/main.svelte

diff --git a/.changeset/brave-baboons-teach.md b/.changeset/brave-baboons-teach.md
new file mode 100644
index 0000000000..55d7d2a988
--- /dev/null
+++ b/.changeset/brave-baboons-teach.md
@@ -0,0 +1,5 @@
+---
+'svelte': minor
+---
+
+feat: allow `await` inside `@const` declarations
diff --git a/packages/svelte/src/compiler/phases/1-parse/utils/create.js b/packages/svelte/src/compiler/phases/1-parse/utils/create.js
index 6030f1bd7b..2fba918f20 100644
--- a/packages/svelte/src/compiler/phases/1-parse/utils/create.js
+++ b/packages/svelte/src/compiler/phases/1-parse/utils/create.js
@@ -10,7 +10,8 @@ export function create_fragment(transparent = false) {
 		nodes: [],
 		metadata: {
 			transparent,
-			dynamic: false
+			dynamic: false,
+			has_await: false
 		}
 	};
 }
diff --git a/packages/svelte/src/compiler/phases/2-analyze/index.js b/packages/svelte/src/compiler/phases/2-analyze/index.js
index ecc843d2f4..1a7a23370d 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/index.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/index.js
@@ -37,6 +37,7 @@ import { ExportNamedDeclaration } from './visitors/ExportNamedDeclaration.js';
 import { ExportSpecifier } from './visitors/ExportSpecifier.js';
 import { ExpressionStatement } from './visitors/ExpressionStatement.js';
 import { ExpressionTag } from './visitors/ExpressionTag.js';
+import { Fragment } from './visitors/Fragment.js';
 import { FunctionDeclaration } from './visitors/FunctionDeclaration.js';
 import { FunctionExpression } from './visitors/FunctionExpression.js';
 import { HtmlTag } from './visitors/HtmlTag.js';
@@ -156,6 +157,7 @@ const visitors = {
 	ExportSpecifier,
 	ExpressionStatement,
 	ExpressionTag,
+	Fragment,
 	FunctionDeclaration,
 	FunctionExpression,
 	HtmlTag,
@@ -300,6 +302,7 @@ export function analyze_module(source, options) {
 			function_depth: 0,
 			has_props_rune: false,
 			options: /** @type {ValidatedCompileOptions} */ (options),
+			fragment: null,
 			parent_element: null,
 			reactive_statement: null
 		},
@@ -687,6 +690,7 @@ export function analyze_component(root, source, options) {
 				analysis,
 				options,
 				ast_type: ast === instance.ast ? 'instance' : ast === template.ast ? 'template' : 'module',
+				fragment: ast === template.ast ? ast : null,
 				parent_element: null,
 				has_props_rune: false,
 				component_slots: new Set(),
@@ -752,6 +756,7 @@ export function analyze_component(root, source, options) {
 				scopes,
 				analysis,
 				options,
+				fragment: ast === template.ast ? ast : null,
 				parent_element: null,
 				has_props_rune: false,
 				ast_type: ast === instance.ast ? 'instance' : ast === template.ast ? 'template' : 'module',
diff --git a/packages/svelte/src/compiler/phases/2-analyze/types.d.ts b/packages/svelte/src/compiler/phases/2-analyze/types.d.ts
index 080239bac0..2d99a2e155 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/types.d.ts
+++ b/packages/svelte/src/compiler/phases/2-analyze/types.d.ts
@@ -8,6 +8,7 @@ export interface AnalysisState {
 	analysis: ComponentAnalysis;
 	options: ValidatedCompileOptions;
 	ast_type: 'instance' | 'template' | 'module';
+	fragment: AST.Fragment | null;
 	/**
 	 * Tag name of the parent element. `null` if the parent is `svelte:element`, `#snippet`, a component or the root.
 	 * Parent doesn't necessarily mean direct path predecessor because there could be `#each`, `#if` etc in-between.
diff --git a/packages/svelte/src/compiler/phases/2-analyze/visitors/AwaitExpression.js b/packages/svelte/src/compiler/phases/2-analyze/visitors/AwaitExpression.js
index af7d0307e9..b2f59b849b 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/visitors/AwaitExpression.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/visitors/AwaitExpression.js
@@ -11,6 +11,15 @@ export function AwaitExpression(node, context) {
 
 	if (context.state.expression) {
 		context.state.expression.has_await = true;
+
+		if (
+			context.state.fragment &&
+			// TODO there's probably a better way to do this
+			context.path.some((node) => node.type === 'ConstTag')
+		) {
+			context.state.fragment.metadata.has_await = true;
+		}
+
 		suspend = true;
 	}
 
diff --git a/packages/svelte/src/compiler/phases/2-analyze/visitors/Fragment.js b/packages/svelte/src/compiler/phases/2-analyze/visitors/Fragment.js
new file mode 100644
index 0000000000..02d780dc0d
--- /dev/null
+++ b/packages/svelte/src/compiler/phases/2-analyze/visitors/Fragment.js
@@ -0,0 +1,10 @@
+/** @import { AST } from '#compiler' */
+/** @import { Context } from '../types.js' */
+
+/**
+ * @param {AST.Fragment} node
+ * @param {Context} context
+ */
+export function Fragment(node, context) {
+	context.next({ ...context.state, fragment: node });
+}
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 0737f531a5..166207f66a 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
@@ -172,6 +172,7 @@ export function client_component(analysis, options) {
 
 		// these are set inside the `Fragment` visitor, and cannot be used until then
 		init: /** @type {any} */ (null),
+		consts: /** @type {any} */ (null),
 		update: /** @type {any} */ (null),
 		after_update: /** @type {any} */ (null),
 		template: /** @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 e691be169b..59c024dfb7 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
@@ -6,7 +6,8 @@ import type {
 	Expression,
 	AssignmentExpression,
 	UpdateExpression,
-	VariableDeclaration
+	VariableDeclaration,
+	Declaration
 } from 'estree';
 import type { AST, Namespace, ValidatedCompileOptions } from '#compiler';
 import type { TransformState } from '../types.js';
@@ -57,6 +58,8 @@ export interface ComponentClientTransformState extends ClientTransformState {
 	readonly update: Statement[];
 	/** Stuff that happens after the render effect (control blocks, dynamic elements, bindings, actions, etc) */
 	readonly after_update: Statement[];
+	/** Transformed `{@const }` declarations */
+	readonly consts: Statement[];
 	/** Memoized expressions */
 	readonly memoizer: Memoizer;
 	/** The HTML template string */
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/utils.js b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
index 6d9dac8a33..19a4342b5e 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/utils.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
@@ -1,4 +1,4 @@
-/** @import { ArrowFunctionExpression, AssignmentExpression, Expression, FunctionDeclaration, FunctionExpression, Identifier, Node, Pattern, UpdateExpression } from 'estree' */
+/** @import { ArrowFunctionExpression, AssignmentExpression, BlockStatement, Expression, FunctionDeclaration, FunctionExpression, Identifier, Node, Pattern, UpdateExpression } from 'estree' */
 /** @import { Binding } from '#compiler' */
 /** @import { ClientTransformState, ComponentClientTransformState, ComponentContext } from './types.js' */
 /** @import { Analysis } from '../../types.js' */
@@ -289,8 +289,15 @@ export function should_proxy(node, scope) {
 /**
  * Svelte legacy mode should use safe equals in most places, runes mode shouldn't
  * @param {ComponentClientTransformState} state
- * @param {Expression} arg
+ * @param {Expression | BlockStatement} expression
+ * @param {boolean} [async]
  */
-export function create_derived(state, arg) {
-	return b.call(state.analysis.runes ? '$.derived' : '$.derived_safe_equal', arg);
+export function create_derived(state, expression, async = false) {
+	const thunk = b.thunk(expression, async);
+
+	if (async) {
+		return b.call(b.await(b.call('$.save', b.call('$.async_derived', thunk))));
+	} else {
+		return b.call(state.analysis.runes ? '$.derived' : '$.derived_safe_equal', thunk);
+	}
 }
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AwaitBlock.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AwaitBlock.js
index 4246091bcf..e2e8e93f76 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AwaitBlock.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AwaitBlock.js
@@ -96,13 +96,13 @@ function create_derived_block_argument(node, context) {
 		b.return(b.object(identifiers.map((identifier) => b.prop('init', identifier, identifier))))
 	]);
 
-	const declarations = [b.var(value, create_derived(context.state, b.thunk(block)))];
+	const declarations = [b.var(value, create_derived(context.state, block))];
 
 	for (const id of identifiers) {
 		context.state.transform[id.name] = { read: get_value };
 
 		declarations.push(
-			b.var(id, create_derived(context.state, b.thunk(b.member(b.call('$.get', value), id))))
+			b.var(id, create_derived(context.state, b.member(b.call('$.get', value), id)))
 		);
 	}
 
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/ConstTag.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/ConstTag.js
index 34acdd6bb9..b550dae890 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/ConstTag.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/ConstTag.js
@@ -16,21 +16,26 @@ export function ConstTag(node, context) {
 	const declaration = node.declaration.declarations[0];
 	// TODO we can almost certainly share some code with $derived(...)
 	if (declaration.id.type === 'Identifier') {
-		const init = build_expression(context, declaration.init, node.metadata.expression);
-		let expression = create_derived(context.state, b.thunk(init));
+		const init = build_expression(
+			{ ...context, state: { ...context.state, in_derived: true } },
+			declaration.init,
+			node.metadata.expression
+		);
+
+		let expression = create_derived(context.state, init, node.metadata.expression.has_await);
 
 		if (dev) {
 			expression = b.call('$.tag', expression, b.literal(declaration.id.name));
 		}
 
-		context.state.init.push(b.const(declaration.id, expression));
+		context.state.consts.push(b.const(declaration.id, expression));
 
 		context.state.transform[declaration.id.name] = { read: get_value };
 
 		// we need to eagerly evaluate the expression in order to hit any
 		// 'Cannot access x before initialization' errors
 		if (dev) {
-			context.state.init.push(b.stmt(b.call('$.get', declaration.id)));
+			context.state.consts.push(b.stmt(b.call('$.get', declaration.id)));
 		}
 	} else {
 		const identifiers = extract_identifiers(declaration.id);
@@ -44,7 +49,11 @@ export function ConstTag(node, context) {
 			delete transform[node.name];
 		}
 
-		const child_state = { ...context.state, transform };
+		const child_state = /** @type {ComponentContext['state']} */ ({
+			...context.state,
+			transform,
+			in_derived: true
+		});
 
 		// TODO optimise the simple `{ x } = y` case — we can just return `y`
 		// instead of destructuring it only to return a new object
@@ -53,26 +62,24 @@ export function ConstTag(node, context) {
 			declaration.init,
 			node.metadata.expression
 		);
-		const fn = b.arrow(
-			[],
-			b.block([
-				b.const(/** @type {Pattern} */ (context.visit(declaration.id, child_state)), init),
-				b.return(b.object(identifiers.map((node) => b.prop('init', node, node))))
-			])
-		);
 
-		let expression = create_derived(context.state, fn);
+		const block = b.block([
+			b.const(/** @type {Pattern} */ (context.visit(declaration.id, child_state)), init),
+			b.return(b.object(identifiers.map((node) => b.prop('init', node, node))))
+		]);
+
+		let expression = create_derived(context.state, block, node.metadata.expression.has_await);
 
 		if (dev) {
 			expression = b.call('$.tag', expression, b.literal('[@const]'));
 		}
 
-		context.state.init.push(b.const(tmp, expression));
+		context.state.consts.push(b.const(tmp, expression));
 
 		// we need to eagerly evaluate the expression in order to hit any
 		// 'Cannot access x before initialization' errors
 		if (dev) {
-			context.state.init.push(b.stmt(b.call('$.get', tmp)));
+			context.state.consts.push(b.stmt(b.call('$.get', tmp)));
 		}
 
 		for (const node of identifiers) {
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 0b10c02ffb..c7c576101e 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
@@ -48,8 +48,10 @@ export function Fragment(node, context) {
 	const is_single_child_not_needing_template =
 		trimmed.length === 1 &&
 		(trimmed[0].type === 'SvelteFragment' || trimmed[0].type === 'TitleElement');
+	const has_await = context.state.init !== null && (node.metadata.has_await || false);
 
 	const template_name = context.state.scope.root.unique('root'); // TODO infer name from parent
+	const unsuspend = b.id('$$unsuspend');
 
 	/** @type {Statement[]} */
 	const body = [];
@@ -61,6 +63,7 @@ export function Fragment(node, context) {
 	const state = {
 		...context.state,
 		init: [],
+		consts: [],
 		update: [],
 		after_update: [],
 		memoizer: new Memoizer(),
@@ -76,11 +79,6 @@ export function Fragment(node, context) {
 		context.visit(node, state);
 	}
 
-	if (is_text_first) {
-		// skip over inserted comment
-		body.push(b.stmt(b.call('$.next')));
-	}
-
 	if (is_single_element) {
 		const element = /** @type {AST.RegularElement} */ (trimmed[0]);
 
@@ -96,13 +94,13 @@ export function Fragment(node, context) {
 		const template = transform_template(state, namespace, flags);
 		state.hoisted.push(b.var(template_name, template));
 
-		body.push(b.var(id, b.call(template_name)));
+		state.init.unshift(b.var(id, b.call(template_name)));
 		close = b.stmt(b.call('$.append', b.id('$$anchor'), id));
 	} else if (is_single_child_not_needing_template) {
 		context.visit(trimmed[0], state);
 	} else if (trimmed.length === 1 && trimmed[0].type === 'Text') {
 		const id = b.id(context.state.scope.generate('text'));
-		body.push(b.var(id, b.call('$.text', b.literal(trimmed[0].data))));
+		state.init.unshift(b.var(id, b.call('$.text', b.literal(trimmed[0].data))));
 		close = b.stmt(b.call('$.append', b.id('$$anchor'), id));
 	} else if (trimmed.length > 0) {
 		const id = b.id(context.state.scope.generate('fragment'));
@@ -120,7 +118,7 @@ export function Fragment(node, context) {
 				state
 			});
 
-			body.push(b.var(id, b.call('$.text')));
+			state.init.unshift(b.var(id, b.call('$.text')));
 			close = b.stmt(b.call('$.append', b.id('$$anchor'), id));
 		} else {
 			if (is_standalone) {
@@ -140,12 +138,12 @@ export function Fragment(node, context) {
 
 				if (state.template.nodes.length === 1 && state.template.nodes[0].type === 'comment') {
 					// special case — we can use `$.comment` instead of creating a unique template
-					body.push(b.var(id, b.call('$.comment')));
+					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));
 
-					body.push(b.var(id, b.call(template_name)));
+					state.init.unshift(b.var(id, b.call(template_name)));
 				}
 
 				close = b.stmt(b.call('$.append', b.id('$$anchor'), id));
@@ -153,6 +151,21 @@ export function Fragment(node, context) {
 		}
 	}
 
+	if (has_await) {
+		body.push(b.var(unsuspend, b.call('$.suspend')));
+	}
+
+	body.push(...state.consts);
+
+	if (has_await) {
+		body.push(b.if(b.call('$.aborted'), b.return()));
+	}
+
+	if (is_text_first) {
+		// skip over inserted comment
+		body.push(b.stmt(b.call('$.next')));
+	}
+
 	body.push(...state.init);
 
 	if (state.update.length > 0) {
@@ -168,5 +181,9 @@ export function Fragment(node, context) {
 		body.push(close);
 	}
 
+	if (has_await) {
+		body.push(b.stmt(b.call(unsuspend)));
+	}
+
 	return b.block(body);
 }
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/LetDirective.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/LetDirective.js
index abdbc381d9..f33febeeb2 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/LetDirective.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/LetDirective.js
@@ -46,9 +46,6 @@ export function LetDirective(node, context) {
 			read: (node) => b.call('$.get', node)
 		};
 
-		return b.const(
-			name,
-			create_derived(context.state, b.thunk(b.member(b.id('$$slotProps'), node.name)))
-		);
+		return b.const(name, create_derived(context.state, b.member(b.id('$$slotProps'), node.name)));
 	}
 }
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/SnippetBlock.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/SnippetBlock.js
index 203cf62b37..895522d47a 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/SnippetBlock.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/SnippetBlock.js
@@ -14,6 +14,7 @@ export function SnippetBlock(node, context) {
 	// TODO hoist where possible
 	/** @type {(Identifier | AssignmentPattern)[]} */
 	const args = [b.id('$$anchor')];
+	const has_await = node.body.metadata.has_await || false;
 
 	/** @type {BlockStatement} */
 	let body;
@@ -21,10 +22,6 @@ export function SnippetBlock(node, context) {
 	/** @type {Statement[]} */
 	const declarations = [];
 
-	if (dev) {
-		declarations.push(b.stmt(b.call('$.validate_snippet_args', b.spread(b.id('arguments')))));
-	}
-
 	const transform = { ...context.state.transform };
 	const child_state = { ...context.state, transform };
 
@@ -72,16 +69,21 @@ export function SnippetBlock(node, context) {
 			}
 		}
 	}
-
+	const block = /** @type {BlockStatement} */ (context.visit(node.body, child_state)).body;
 	body = b.block([
+		dev ? b.stmt(b.call('$.validate_snippet_args', b.spread(b.id('arguments')))) : b.empty,
 		...declarations,
-		.../** @type {BlockStatement} */ (context.visit(node.body, child_state)).body
+		...block
 	]);
 
 	// in dev we use a FunctionExpression (not arrow function) so we can use `arguments`
 	let snippet = dev
-		? b.call('$.wrap_snippet', b.id(context.state.analysis.name), b.function(null, args, body))
-		: b.arrow(args, body);
+		? b.call(
+				'$.wrap_snippet',
+				b.id(context.state.analysis.name),
+				b.function(null, args, body, has_await)
+			)
+		: b.arrow(args, body, has_await);
 
 	const declaration = b.const(node.expression, snippet);
 
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/SvelteBoundary.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/SvelteBoundary.js
index d37b990440..70df022355 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/SvelteBoundary.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/SvelteBoundary.js
@@ -43,7 +43,7 @@ export function SvelteBoundary(node, context) {
 	// to resolve this we cheat: we duplicate const tags inside snippets
 	for (const child of node.fragment.nodes) {
 		if (child.type === 'ConstTag') {
-			context.visit(child, { ...context.state, init: const_tags });
+			context.visit(child, { ...context.state, consts: const_tags });
 		}
 	}
 
diff --git a/packages/svelte/src/compiler/types/template.d.ts b/packages/svelte/src/compiler/types/template.d.ts
index 058a1a8e66..060df2dcb2 100644
--- a/packages/svelte/src/compiler/types/template.d.ts
+++ b/packages/svelte/src/compiler/types/template.d.ts
@@ -56,6 +56,7 @@ export namespace AST {
 			 * Whether or not we need to traverse into the fragment during mount/hydrate
 			 */
 			dynamic: boolean;
+			has_await: boolean;
 		};
 	}
 
diff --git a/packages/svelte/src/compiler/utils/builders.js b/packages/svelte/src/compiler/utils/builders.js
index defdb1642e..56a5f31ffe 100644
--- a/packages/svelte/src/compiler/utils/builders.js
+++ b/packages/svelte/src/compiler/utils/builders.js
@@ -588,14 +588,14 @@ export function method(kind, key, params, body, computed = false, is_static = fa
  * @param {ESTree.BlockStatement} body
  * @returns {ESTree.FunctionExpression}
  */
-function function_builder(id, params, body) {
+function function_builder(id, params, body, async = false) {
 	return {
 		type: 'FunctionExpression',
 		id,
 		params,
 		body,
 		generator: false,
-		async: false,
+		async,
 		metadata: /** @type {any} */ (null) // should not be used by codegen
 	};
 }
diff --git a/packages/svelte/tests/runtime-runes/samples/async-const/_config.js b/packages/svelte/tests/runtime-runes/samples/async-const/_config.js
new file mode 100644
index 0000000000..084d9c3874
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/async-const/_config.js
@@ -0,0 +1,12 @@
+import { tick } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+	html: `<h1>Loading...</h1>`,
+
+	async test({ assert, target }) {
+		await tick();
+
+		assert.htmlEqual(target.innerHTML, `<h1>Hello, world!</h1>`);
+	}
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/async-const/main.svelte b/packages/svelte/tests/runtime-runes/samples/async-const/main.svelte
new file mode 100644
index 0000000000..9321bd7929
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/async-const/main.svelte
@@ -0,0 +1,16 @@
+<script>
+	let name = $state('world');
+</script>
+
+<svelte:boundary>
+	{#snippet pending()}
+		<h1>Loading...</h1>
+	{/snippet}
+
+	{#snippet greet()}
+		{@const greeting = await `Hello, ${name}!`}
+		<h1>{greeting}</h1>
+	{/snippet}
+
+	{@render greet()}
+</svelte:boundary>

From ec03c7ac366ee37568f5d9d600d61ac5f842155d Mon Sep 17 00:00:00 2001
From: "github-actions[bot]"
 <41898282+github-actions[bot]@users.noreply.github.com>
Date: Wed, 6 Aug 2025 11:06:18 -0700
Subject: [PATCH 38/60] Version Packages (#16560)

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
---
 .changeset/brave-baboons-teach.md |  5 -----
 .changeset/hip-eagles-yawn.md     |  5 -----
 .changeset/quiet-donuts-wonder.md |  5 -----
 .changeset/thick-snakes-look.md   |  5 -----
 packages/svelte/CHANGELOG.md      | 14 ++++++++++++++
 packages/svelte/package.json      |  2 +-
 packages/svelte/src/version.js    |  2 +-
 7 files changed, 16 insertions(+), 22 deletions(-)
 delete mode 100644 .changeset/brave-baboons-teach.md
 delete mode 100644 .changeset/hip-eagles-yawn.md
 delete mode 100644 .changeset/quiet-donuts-wonder.md
 delete mode 100644 .changeset/thick-snakes-look.md

diff --git a/.changeset/brave-baboons-teach.md b/.changeset/brave-baboons-teach.md
deleted file mode 100644
index 55d7d2a988..0000000000
--- a/.changeset/brave-baboons-teach.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-'svelte': minor
----
-
-feat: allow `await` inside `@const` declarations
diff --git a/.changeset/hip-eagles-yawn.md b/.changeset/hip-eagles-yawn.md
deleted file mode 100644
index c987e7c7f2..0000000000
--- a/.changeset/hip-eagles-yawn.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-'svelte': patch
----
-
-fix: remount at any hydration error
diff --git a/.changeset/quiet-donuts-wonder.md b/.changeset/quiet-donuts-wonder.md
deleted file mode 100644
index a0ee39f4e2..0000000000
--- a/.changeset/quiet-donuts-wonder.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-'svelte': patch
----
-
-chore: emit `await_reactivity_loss` in `for await` loops
diff --git a/.changeset/thick-snakes-look.md b/.changeset/thick-snakes-look.md
deleted file mode 100644
index f5f22e8a6c..0000000000
--- a/.changeset/thick-snakes-look.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-'svelte': patch
----
-
-fix: emit `snippet_invalid_export` instead of `undefined_export` for exported snippets
diff --git a/packages/svelte/CHANGELOG.md b/packages/svelte/CHANGELOG.md
index 9766e3f06b..77f97a1c11 100644
--- a/packages/svelte/CHANGELOG.md
+++ b/packages/svelte/CHANGELOG.md
@@ -1,5 +1,19 @@
 # svelte
 
+## 5.38.0
+
+### Minor Changes
+
+- feat: allow `await` inside `@const` declarations ([#16542](https://github.com/sveltejs/svelte/pull/16542))
+
+### Patch Changes
+
+- fix: remount at any hydration error ([#16248](https://github.com/sveltejs/svelte/pull/16248))
+
+- chore: emit `await_reactivity_loss` in `for await` loops ([#16521](https://github.com/sveltejs/svelte/pull/16521))
+
+- fix: emit `snippet_invalid_export` instead of `undefined_export` for exported snippets ([#16539](https://github.com/sveltejs/svelte/pull/16539))
+
 ## 5.37.3
 
 ### Patch Changes
diff --git a/packages/svelte/package.json b/packages/svelte/package.json
index e8927fcf56..d64ff30ed7 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": "5.37.3",
+  "version": "5.38.0",
   "type": "module",
   "types": "./types/index.d.ts",
   "engines": {
diff --git a/packages/svelte/src/version.js b/packages/svelte/src/version.js
index 127b43e205..0bba536c1d 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 = '5.37.3';
+export const VERSION = '5.38.0';
 export const PUBLIC_VERSION = '5';

From 9efe672df2540c51c2cfa817fd32e7667d5712ec Mon Sep 17 00:00:00 2001
From: Justin Paige <77657745+jhpaige@users.noreply.github.com>
Date: Wed, 6 Aug 2025 14:16:35 -0400
Subject: [PATCH 39/60] Update 18-class.md (#16558)

Rest of doc references 5.16 but this is from 5.19 so added the clarification.
---
 documentation/docs/03-template-syntax/18-class.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/documentation/docs/03-template-syntax/18-class.md b/documentation/docs/03-template-syntax/18-class.md
index 1ea4a208df..db85db4b37 100644
--- a/documentation/docs/03-template-syntax/18-class.md
+++ b/documentation/docs/03-template-syntax/18-class.md
@@ -71,7 +71,7 @@ The user of this component has the same flexibility to use a mixture of objects,
 </Button>
 ```
 
-Svelte also exposes the `ClassValue` type, which is the type of value that the `class` attribute on elements accept. This is useful if you want to use a type-safe class name in component props:
+Since Svelte 5.19, Svelte also exposes the `ClassValue` type, which is the type of value that the `class` attribute on elements accept. This is useful if you want to use a type-safe class name in component props:
 
 ```svelte
 <script lang="ts">

From 97f263c3d49002071a0c8fe19784f4b9fcd64f7e Mon Sep 17 00:00:00 2001
From: Nathan Shively-Sanders <293473+sandersn@users.noreply.github.com>
Date: Wed, 6 Aug 2025 11:25:55 -0700
Subject: [PATCH 40/60] chore:Update for TS7 (#16485)

* Update for TS7

I am testing Typescript 7's JS support, which I've largely rewritten
during the switch to Go. That means Javascript code will need to change
much more than Typescript code. Fortunately, most of the changes are for
the better: Javascript semantics are now nearly identical to Typescript
semantics. It's much stricter and no longer has some persistent bugs
that arose from shady JS handling I wrote years ago.

This PR changes Svelte so that it compiles both with TS5.* and TS7,
which means that occasionally there are duplicative or non-obvious
changes. I'll annotate the interesting changes to explain why I made them.

Because TS7 is quite a way off, I don't know whether you'll want to take
this PR. Most of the changes are for the better, because they're due to
stricter TS-aligned checking. But some are neutral and there is the
previously mentioned duplication in a few places.

* add changeset

* revert scribbles mistakenly added

* pnpm run format

* revert mistaken edit

* return to function declarations w/type tag

* add job to ci.yml

* skipLibCheck for now

* no need for a changeset here

---------

Co-authored-by: Rich Harris <rich.harris@vercel.com>
Co-authored-by: Rich Harris <hello@rich-harris.dev>
---
 .github/workflows/ci.yml                      | 17 +++++
 packages/svelte/package.json                  |  1 +
 packages/svelte/scripts/generate-types.js     |  8 ++-
 packages/svelte/src/compiler/legacy.js        |  4 +-
 .../phases/2-analyze/css/css-prune.js         |  4 +-
 .../src/compiler/phases/2-analyze/index.js    |  2 +-
 .../2-analyze/utils/check_graph_for_cycles.js |  1 +
 .../2-analyze/visitors/shared/a11y/index.js   |  2 +-
 .../2-analyze/visitors/shared/component.js    |  1 +
 packages/svelte/src/compiler/phases/scope.js  |  2 +-
 packages/svelte/src/compiler/state.js         |  2 +-
 packages/svelte/src/index-client.js           |  6 +-
 .../svelte/src/internal/client/dev/hmr.js     |  2 +-
 .../src/internal/client/dom/blocks/await.js   |  5 +-
 .../src/internal/client/dom/blocks/each.js    |  2 +-
 .../src/internal/client/dom/blocks/if.js      |  2 +-
 .../client/dom/elements/bindings/input.js     |  1 +
 .../src/internal/client/dom/template.js       |  2 +-
 .../src/internal/client/reactivity/props.js   | 70 ++++++++++---------
 .../src/internal/client/reactivity/sources.js |  1 +
 packages/svelte/src/internal/client/render.js |  1 +
 .../svelte/src/internal/client/runtime.js     |  3 +-
 .../svelte/src/internal/server/payload.js     |  7 +-
 .../svelte/src/internal/shared/validate.js    |  2 +-
 packages/svelte/src/utils.js                  |  6 +-
 packages/svelte/tests/animation-helpers.js    | 26 +++++--
 packages/svelte/tests/helpers.js              |  1 +
 .../svelte/tests/runtime-browser/assert.js    | 12 ++--
 28 files changed, 125 insertions(+), 68 deletions(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 046ad335f3..51408fc8cc 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -60,6 +60,23 @@ jobs:
         env:
           CI: true
           SVELTE_NO_ASYNC: true
+  TSGo:
+    permissions: {}
+    runs-on: ubuntu-latest
+    timeout-minutes: 5
+    steps:
+      - uses: actions/checkout@v4
+      - uses: pnpm/action-setup@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 24
+          cache: pnpm
+      - name: install
+        run: pnpm install --frozen-lockfile
+      - name: install tsgo
+        run: cd packages/svelte && pnpm i -D @typescript/native-preview
+      - name: type check
+        run: cd packages/svelte && pnpm check:tsgo
   Lint:
     permissions: {}
     runs-on: ubuntu-latest
diff --git a/packages/svelte/package.json b/packages/svelte/package.json
index d64ff30ed7..0b14ab4b40 100644
--- a/packages/svelte/package.json
+++ b/packages/svelte/package.json
@@ -141,6 +141,7 @@
     "build": "node scripts/process-messages && rollup -c && pnpm generate:types && node scripts/check-treeshakeability.js",
     "dev": "node scripts/process-messages -w & rollup -cw",
     "check": "tsc --project tsconfig.runtime.json && tsc && cd ./tests/types && tsc",
+    "check:tsgo": "tsgo --project tsconfig.runtime.json --skipLibCheck && tsgo --skipLibCheck",
     "check:watch": "tsc --watch",
     "generate:version": "node ./scripts/generate-version.js",
     "generate:types": "node ./scripts/generate-types.js && tsc -p tsconfig.generated.json",
diff --git a/packages/svelte/scripts/generate-types.js b/packages/svelte/scripts/generate-types.js
index c558a2bbf7..0ee6004d4a 100644
--- a/packages/svelte/scripts/generate-types.js
+++ b/packages/svelte/scripts/generate-types.js
@@ -26,9 +26,11 @@ await createBundle({
 		// so that types/properties with `@internal` (and its dependencies) are removed from the output
 		stripInternal: true,
 		paths: Object.fromEntries(
-			Object.entries(pkg.imports).map(([key, value]) => {
-				return [key, [value.types ?? value.default ?? value]];
-			})
+			Object.entries(pkg.imports).map(
+				/** @param {[string,any]} import */ ([key, value]) => {
+					return [key, [value.types ?? value.default ?? value]];
+				}
+			)
 		)
 	},
 	modules: {
diff --git a/packages/svelte/src/compiler/legacy.js b/packages/svelte/src/compiler/legacy.js
index 85345bca4a..b1bbcfcf74 100644
--- a/packages/svelte/src/compiler/legacy.js
+++ b/packages/svelte/src/compiler/legacy.js
@@ -55,7 +55,9 @@ export function convert(source, ast) {
 
 				// Insert svelte:options back into the root nodes
 				if (/** @type {any} */ (options)?.__raw__) {
-					let idx = node.fragment.nodes.findIndex((node) => options.end <= node.start);
+					let idx = node.fragment.nodes.findIndex(
+						(node) => /** @type {any} */ (options).end <= node.start
+					);
 					if (idx === -1) {
 						idx = node.fragment.nodes.length;
 					}
diff --git a/packages/svelte/src/compiler/phases/2-analyze/css/css-prune.js b/packages/svelte/src/compiler/phases/2-analyze/css/css-prune.js
index 79e8fbb02c..8a4d8cb350 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/css/css-prune.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/css/css-prune.js
@@ -9,8 +9,8 @@ import {
 import { regex_ends_with_whitespace, regex_starts_with_whitespace } from '../../patterns.js';
 import { get_attribute_chunks, is_text_attribute } from '../../../utils/ast.js';
 
-/** @typedef {NODE_PROBABLY_EXISTS | NODE_DEFINITELY_EXISTS} NodeExistsValue */
-/** @typedef {FORWARD | BACKWARD} Direction */
+/** @typedef {typeof NODE_PROBABLY_EXISTS | typeof NODE_DEFINITELY_EXISTS} NodeExistsValue */
+/** @typedef {typeof FORWARD | typeof BACKWARD} Direction */
 
 const NODE_PROBABLY_EXISTS = 0;
 const NODE_DEFINITELY_EXISTS = 1;
diff --git a/packages/svelte/src/compiler/phases/2-analyze/index.js b/packages/svelte/src/compiler/phases/2-analyze/index.js
index 1a7a23370d..92b89c588e 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/index.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/index.js
@@ -297,7 +297,7 @@ export function analyze_module(source, options) {
 			// TODO the following are not needed for modules, but we have to pass them in order to avoid type error,
 			// and reducing the type would result in a lot of tedious type casts elsewhere - find a good solution one day
 			ast_type: /** @type {any} */ (null),
-			component_slots: new Set(),
+			component_slots: /** @type {Set<string>} */ (new Set()),
 			expression: null,
 			function_depth: 0,
 			has_props_rune: false,
diff --git a/packages/svelte/src/compiler/phases/2-analyze/utils/check_graph_for_cycles.js b/packages/svelte/src/compiler/phases/2-analyze/utils/check_graph_for_cycles.js
index 67201d4825..83959248fe 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/utils/check_graph_for_cycles.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/utils/check_graph_for_cycles.js
@@ -14,6 +14,7 @@ export default function check_graph_for_cycles(edges) {
 	}, new Map());
 
 	const visited = new Set();
+	/** @type {Set<T>} */
 	const on_stack = new Set();
 	/** @type {Array<Array<T>>} */
 	const cycles = [];
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 f45a6c9a80..e2f84290e5 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
@@ -599,7 +599,7 @@ function has_disabled_attribute(attribute_map) {
 /**
  * @param {string} tag_name
  * @param {Map<string, AST.Attribute>} attribute_map
- * @returns {ElementInteractivity[keyof ElementInteractivity]}
+ * @returns {typeof ElementInteractivity[keyof typeof ElementInteractivity]}
  */
 function element_interactivity(tag_name, attribute_map) {
 	if (
diff --git a/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/component.js b/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/component.js
index aca87fab81..6d09398fb7 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/component.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/visitors/shared/component.js
@@ -145,6 +145,7 @@ export function visit_component(node, context) {
 		if (slot_name !== 'default') comments = [];
 	}
 
+	/** @type {Set<string>} */
 	const component_slots = new Set();
 
 	for (const slot_name in nodes) {
diff --git a/packages/svelte/src/compiler/phases/scope.js b/packages/svelte/src/compiler/phases/scope.js
index eaacf5dda9..f88f5ef8b1 100644
--- a/packages/svelte/src/compiler/phases/scope.js
+++ b/packages/svelte/src/compiler/phases/scope.js
@@ -22,7 +22,7 @@ const NUMBER = Symbol('number');
 const STRING = Symbol('string');
 const FUNCTION = Symbol('string');
 
-/** @type {Record<string, [type: NUMBER | STRING | UNKNOWN, fn?: Function]>} */
+/** @type {Record<string, [type: typeof NUMBER | typeof  STRING | typeof  UNKNOWN, fn?: Function]>} */
 const globals = {
 	BigInt: [NUMBER],
 	'Math.min': [NUMBER, Math.min],
diff --git a/packages/svelte/src/compiler/state.js b/packages/svelte/src/compiler/state.js
index 725d03b802..6d9873eb30 100644
--- a/packages/svelte/src/compiler/state.js
+++ b/packages/svelte/src/compiler/state.js
@@ -87,7 +87,7 @@ export function pop_ignore() {
 
 /**
  * @param {AST.SvelteNode | NodeLike} node
- * @param {import('../constants.js').IGNORABLE_RUNTIME_WARNINGS[number]} code
+ * @param {typeof import('../constants.js').IGNORABLE_RUNTIME_WARNINGS[number]} code
  * @returns
  */
 export function is_ignored(node, code) {
diff --git a/packages/svelte/src/index-client.js b/packages/svelte/src/index-client.js
index 397a81c319..85eeab7de9 100644
--- a/packages/svelte/src/index-client.js
+++ b/packages/svelte/src/index-client.js
@@ -160,10 +160,14 @@ export function createEventDispatcher() {
 		e.lifecycle_outside_component('createEventDispatcher');
 	}
 
+	/**
+	 * @param [detail]
+	 * @param [options]
+	 */
 	return (type, detail, options) => {
 		const events = /** @type {Record<string, Function | Function[]>} */ (
 			active_component_context.s.$$events
-		)?.[/** @type {any} */ (type)];
+		)?.[/** @type {string} */ (type)];
 
 		if (events) {
 			const callbacks = is_array(events) ? events.slice() : [events];
diff --git a/packages/svelte/src/internal/client/dev/hmr.js b/packages/svelte/src/internal/client/dev/hmr.js
index 27e2643d16..709a1b2722 100644
--- a/packages/svelte/src/internal/client/dev/hmr.js
+++ b/packages/svelte/src/internal/client/dev/hmr.js
@@ -64,7 +64,7 @@ export function hmr(original, get_source) {
 	// @ts-expect-error
 	wrapper[FILENAME] = original[FILENAME];
 
-	// @ts-expect-error
+	// @ts-ignore
 	wrapper[HMR] = {
 		// When we accept an update, we set the original source to the new component
 		original,
diff --git a/packages/svelte/src/internal/client/dom/blocks/await.js b/packages/svelte/src/internal/client/dom/blocks/await.js
index 4f68db57b1..42df41041e 100644
--- a/packages/svelte/src/internal/client/dom/blocks/await.js
+++ b/packages/svelte/src/internal/client/dom/blocks/await.js
@@ -28,6 +28,8 @@ const PENDING = 0;
 const THEN = 1;
 const CATCH = 2;
 
+/** @typedef {typeof PENDING | typeof THEN | typeof CATCH} AwaitState */
+
 /**
  * @template V
  * @param {TemplateNode} node
@@ -67,9 +69,8 @@ export function await_block(node, get_input, pending_fn, then_fn, catch_fn) {
 		: mutable_source(/** @type {V} */ (undefined), false, false);
 	var error_source = runes ? source(undefined) : mutable_source(undefined, false, false);
 	var resolved = false;
-
 	/**
-	 * @param {PENDING | THEN | CATCH} state
+	 * @param {AwaitState} state
 	 * @param {boolean} restore
 	 */
 	function update(state, restore) {
diff --git a/packages/svelte/src/internal/client/dom/blocks/each.js b/packages/svelte/src/internal/client/dom/blocks/each.js
index 43c75e2a37..006bf09257 100644
--- a/packages/svelte/src/internal/client/dom/blocks/each.js
+++ b/packages/svelte/src/internal/client/dom/blocks/each.js
@@ -191,7 +191,7 @@ export function each(node, flags, get_collection, get_key, render_fn, fallback_f
 		// store a reference to the effect so that we can update the start/end nodes in reconciliation
 		each_effect ??= /** @type {Effect} */ (active_effect);
 
-		array = get(each_array);
+		array = /** @type {V[]} */ (get(each_array));
 		var length = array.length;
 
 		if (was_empty && length === 0) {
diff --git a/packages/svelte/src/internal/client/dom/blocks/if.js b/packages/svelte/src/internal/client/dom/blocks/if.js
index 6ba9ad4936..f418d46538 100644
--- a/packages/svelte/src/internal/client/dom/blocks/if.js
+++ b/packages/svelte/src/internal/client/dom/blocks/if.js
@@ -36,7 +36,7 @@ export function if_block(node, fn, elseif = false) {
 	/** @type {Effect | null} */
 	var alternate_effect = null;
 
-	/** @type {UNINITIALIZED | boolean | null} */
+	/** @type {typeof UNINITIALIZED | boolean | null} */
 	var condition = UNINITIALIZED;
 
 	var flags = elseif ? EFFECT_TRANSPARENT : 0;
diff --git a/packages/svelte/src/internal/client/dom/elements/bindings/input.js b/packages/svelte/src/internal/client/dom/elements/bindings/input.js
index 7c73280dd6..67e6ff1dd2 100644
--- a/packages/svelte/src/internal/client/dom/elements/bindings/input.js
+++ b/packages/svelte/src/internal/client/dom/elements/bindings/input.js
@@ -245,6 +245,7 @@ export function bind_checked(input, get, set = get) {
  * @returns {V[]}
  */
 function get_binding_group_value(group, __value, checked) {
+	/** @type {Set<V>} */
 	var value = new Set();
 
 	for (var i = 0; i < group.length; i += 1) {
diff --git a/packages/svelte/src/internal/client/dom/template.js b/packages/svelte/src/internal/client/dom/template.js
index ebbf0039b2..265a52262f 100644
--- a/packages/svelte/src/internal/client/dom/template.js
+++ b/packages/svelte/src/internal/client/dom/template.js
@@ -156,7 +156,7 @@ export function from_mathml(content, flags) {
 
 /**
  * @param {TemplateStructure[]} structure
- * @param {NAMESPACE_SVG | NAMESPACE_MATHML | undefined} [ns]
+ * @param {typeof NAMESPACE_SVG | typeof NAMESPACE_MATHML | undefined} [ns]
  */
 function fragment_from_tree(structure, ns) {
 	var fragment = create_fragment();
diff --git a/packages/svelte/src/internal/client/reactivity/props.js b/packages/svelte/src/internal/client/reactivity/props.js
index 05b747a1c4..8353eb39e2 100644
--- a/packages/svelte/src/internal/client/reactivity/props.js
+++ b/packages/svelte/src/internal/client/reactivity/props.js
@@ -184,8 +184,7 @@ export function legacy_rest_props(props, exclude) {
  * The proxy handler for spread props. Handles the incoming array of props
  * that looks like `() => { dynamic: props }, { static: prop }, ..` and wraps
  * them so that the whole thing is passed to the component as the `$$props` argument.
- * @template {Record<string | symbol, unknown>} T
- * @type {ProxyHandler<{ props: Array<T | (() => T)> }>}}
+ * @type {ProxyHandler<{ props: Array<Record<string | symbol, unknown> | (() => Record<string | symbol, unknown>)> }>}}
  */
 const spread_props_handler = {
 	get(target, key) {
@@ -362,22 +361,23 @@ export function prop(props, key, flags, fallback) {
 	// means we can just call `$$props.foo = value` directly
 	if (setter) {
 		var legacy_parent = props.$$legacy;
-
-		return function (/** @type {any} */ value, /** @type {boolean} */ mutation) {
-			if (arguments.length > 0) {
-				// We don't want to notify if the value was mutated and the parent is in runes mode.
-				// In that case the state proxy (if it exists) should take care of the notification.
-				// If the parent is not in runes mode, we need to notify on mutation, too, that the prop
-				// has changed because the parent will not be able to detect the change otherwise.
-				if (!runes || !mutation || legacy_parent || is_store_sub) {
-					/** @type {Function} */ (setter)(mutation ? getter() : value);
+		return /** @type {() => V} */ (
+			function (/** @type {V} */ value, /** @type {boolean} */ mutation) {
+				if (arguments.length > 0) {
+					// We don't want to notify if the value was mutated and the parent is in runes mode.
+					// In that case the state proxy (if it exists) should take care of the notification.
+					// If the parent is not in runes mode, we need to notify on mutation, too, that the prop
+					// has changed because the parent will not be able to detect the change otherwise.
+					if (!runes || !mutation || legacy_parent || is_store_sub) {
+						/** @type {Function} */ (setter)(mutation ? getter() : value);
+					}
+
+					return value;
 				}
 
-				return value;
+				return getter();
 			}
-
-			return getter();
-		};
+		);
 	}
 
 	// Either prop is written to, but there's no binding, which means we
@@ -400,29 +400,31 @@ export function prop(props, key, flags, fallback) {
 
 	var parent_effect = /** @type {Effect} */ (active_effect);
 
-	return function (/** @type {any} */ value, /** @type {boolean} */ mutation) {
-		if (arguments.length > 0) {
-			const new_value = mutation ? get(d) : runes && bindable ? proxy(value) : value;
+	return /** @type {() => V} */ (
+		function (/** @type {any} */ value, /** @type {boolean} */ mutation) {
+			if (arguments.length > 0) {
+				const new_value = mutation ? get(d) : runes && bindable ? proxy(value) : value;
+
+				set(d, new_value);
+				overridden = true;
 
-			set(d, new_value);
-			overridden = true;
+				if (fallback_value !== undefined) {
+					fallback_value = new_value;
+				}
 
-			if (fallback_value !== undefined) {
-				fallback_value = new_value;
+				return value;
 			}
 
-			return value;
-		}
+			// special case — avoid recalculating the derived if we're in a
+			// teardown function and the prop was overridden locally, or the
+			// component was already destroyed (this latter part is necessary
+			// because `bind:this` can read props after the component has
+			// been destroyed. TODO simplify `bind:this`
+			if ((is_destroying_effect && overridden) || (parent_effect.f & DESTROYED) !== 0) {
+				return d.v;
+			}
 
-		// special case — avoid recalculating the derived if we're in a
-		// teardown function and the prop was overridden locally, or the
-		// component was already destroyed (this latter part is necessary
-		// because `bind:this` can read props after the component has
-		// been destroyed. TODO simplify `bind:this`
-		if ((is_destroying_effect && overridden) || (parent_effect.f & DESTROYED) !== 0) {
-			return d.v;
+			return get(d);
 		}
-
-		return get(d);
-	};
+	);
 }
diff --git a/packages/svelte/src/internal/client/reactivity/sources.js b/packages/svelte/src/internal/client/reactivity/sources.js
index 3b2087d56b..7fb3135708 100644
--- a/packages/svelte/src/internal/client/reactivity/sources.js
+++ b/packages/svelte/src/internal/client/reactivity/sources.js
@@ -37,6 +37,7 @@ import { Batch, schedule_effect } from './batch.js';
 import { proxy } from '../proxy.js';
 import { execute_derived } from './deriveds.js';
 
+/** @type {Set<any>} */
 export let inspect_effects = new Set();
 
 /** @type {Map<Source, any>} */
diff --git a/packages/svelte/src/internal/client/render.js b/packages/svelte/src/internal/client/render.js
index 3a489f9f92..c5015875a8 100644
--- a/packages/svelte/src/internal/client/render.js
+++ b/packages/svelte/src/internal/client/render.js
@@ -177,6 +177,7 @@ const document_listeners = new Map();
 function _mount(Component, { target, anchor, props = {}, events, context, intro = true }) {
 	init_operations();
 
+	/** @type {Set<string>} */
 	var registered_events = new Set();
 
 	/** @param {Array<string>} events */
diff --git a/packages/svelte/src/internal/client/runtime.js b/packages/svelte/src/internal/client/runtime.js
index e86866af2a..3d760e4b9e 100644
--- a/packages/svelte/src/internal/client/runtime.js
+++ b/packages/svelte/src/internal/client/runtime.js
@@ -284,7 +284,8 @@ export function update_reaction(reaction) {
 
 	try {
 		reaction.f |= REACTION_IS_UPDATING;
-		var result = /** @type {Function} */ (0, reaction.fn)();
+		var fn = /** @type {Function} */ (reaction.fn);
+		var result = fn();
 		var deps = reaction.deps;
 
 		if (new_deps !== null) {
diff --git a/packages/svelte/src/internal/server/payload.js b/packages/svelte/src/internal/server/payload.js
index 195488e061..a7e40ad1db 100644
--- a/packages/svelte/src/internal/server/payload.js
+++ b/packages/svelte/src/internal/server/payload.js
@@ -6,7 +6,12 @@ export class HeadPayload {
 	uid = () => '';
 	title = '';
 
-	constructor(css = new Set(), /** @type {string[]} */ out = [], title = '', uid = () => '') {
+	constructor(
+		/** @type {Set<{ hash: string; code: string }>} */ css = new Set(),
+		/** @type {string[]} */ out = [],
+		title = '',
+		uid = () => ''
+	) {
 		this.css = css;
 		this.out = out;
 		this.title = title;
diff --git a/packages/svelte/src/internal/shared/validate.js b/packages/svelte/src/internal/shared/validate.js
index 8f3e2807e7..48e76f0958 100644
--- a/packages/svelte/src/internal/shared/validate.js
+++ b/packages/svelte/src/internal/shared/validate.js
@@ -35,7 +35,7 @@ export function validate_store(store, name) {
 }
 
 /**
- * @template {() => unknown} T
+ * @template {(...args: any[]) => unknown} T
  * @param {T} fn
  */
 export function prevent_snippet_stringification(fn) {
diff --git a/packages/svelte/src/utils.js b/packages/svelte/src/utils.js
index cd79cfc274..f8c39253ac 100644
--- a/packages/svelte/src/utils.js
+++ b/packages/svelte/src/utils.js
@@ -452,7 +452,7 @@ const RUNES = /** @type {const} */ ([
 	'$host'
 ]);
 
-/** @typedef {RUNES[number]} RuneName */
+/** @typedef {typeof RUNES[number]} RuneName */
 
 /**
  * @param {string} name
@@ -462,7 +462,7 @@ export function is_rune(name) {
 	return RUNES.includes(/** @type {RuneName} */ (name));
 }
 
-/** @typedef {STATE_CREATION_RUNES[number]} StateCreationRuneName */
+/** @typedef {typeof STATE_CREATION_RUNES[number]} StateCreationRuneName */
 
 /**
  * @param {string} name
@@ -477,7 +477,7 @@ const RAW_TEXT_ELEMENTS = /** @type {const} */ (['textarea', 'script', 'style',
 
 /** @param {string} name */
 export function is_raw_text_element(name) {
-	return RAW_TEXT_ELEMENTS.includes(/** @type {RAW_TEXT_ELEMENTS[number]} */ (name));
+	return RAW_TEXT_ELEMENTS.includes(/** @type {typeof RAW_TEXT_ELEMENTS[number]} */ (name));
 }
 
 /**
diff --git a/packages/svelte/tests/animation-helpers.js b/packages/svelte/tests/animation-helpers.js
index dcbb062923..0452a0d643 100644
--- a/packages/svelte/tests/animation-helpers.js
+++ b/packages/svelte/tests/animation-helpers.js
@@ -3,7 +3,9 @@ import { raf as svelte_raf } from 'svelte/internal/client';
 import { queue_micro_task } from '../src/internal/client/dom/task.js';
 
 export const raf = {
+	/** @type {Set<Animation>} */
 	animations: new Set(),
+	/** @type {Set<(n: number) => void>} */
 	ticks: new Set(),
 	tick,
 	time: 0,
@@ -54,14 +56,24 @@ class Animation {
 
 	/**
 	 * @param {HTMLElement} target
-	 * @param {Keyframe[]} keyframes
-	 * @param {{ duration: number, delay: number }} options
+	 * @param {Keyframe[] | PropertyIndexedKeyframes | null} keyframes
+	 * @param {number | KeyframeAnimationOptions | undefined} options
 	 */
-	constructor(target, keyframes, { duration, delay }) {
+	constructor(target, keyframes, options) {
 		this.target = target;
-		this.#keyframes = keyframes;
-		this.#duration = Math.round(duration);
-		this.#delay = delay ?? 0;
+		this.#keyframes = Array.isArray(keyframes) ? keyframes : [];
+		if (typeof options === 'number') {
+			this.#duration = options;
+			this.#delay = 0;
+		} else {
+			const { duration = 0, delay = 0 } = options ?? {};
+			if (typeof duration === 'object') {
+				this.#duration = 0;
+			} else {
+				this.#duration = Math.round(+duration);
+			}
+			this.#delay = delay;
+		}
 
 		this._update();
 	}
@@ -189,6 +201,7 @@ function interpolate(a, b, p) {
  * @param {{duration: number, delay: number}} options
  * @returns {globalThis.Animation}
  */
+// @ts-ignore
 HTMLElement.prototype.animate = function (keyframes, options) {
 	const animation = new Animation(this, keyframes, options);
 	raf.animations.add(animation);
@@ -196,6 +209,7 @@ HTMLElement.prototype.animate = function (keyframes, options) {
 	return animation;
 };
 
+// @ts-ignore
 HTMLElement.prototype.getAnimations = function () {
 	return Array.from(raf.animations).filter((animation) => animation.target === this);
 };
diff --git a/packages/svelte/tests/helpers.js b/packages/svelte/tests/helpers.js
index 410838829e..7a9640636c 100644
--- a/packages/svelte/tests/helpers.js
+++ b/packages/svelte/tests/helpers.js
@@ -43,6 +43,7 @@ export function create_deferred() {
 	/** @param {any} [reason] */
 	let reject = (reason) => {};
 
+	/** @type {Promise<any>} */
 	const promise = new Promise((f, r) => {
 		resolve = f;
 		reject = r;
diff --git a/packages/svelte/tests/runtime-browser/assert.js b/packages/svelte/tests/runtime-browser/assert.js
index 48bde01410..9a294a48c7 100644
--- a/packages/svelte/tests/runtime-browser/assert.js
+++ b/packages/svelte/tests/runtime-browser/assert.js
@@ -87,15 +87,17 @@ function normalize_html(window, html) {
 /** @param {any} node */
 function normalize_children(node) {
 	// sort attributes
-	const attributes = Array.from(node.attributes).sort((a, b) => {
-		return a.name < b.name ? -1 : 1;
-	});
+	const attributes = Array.from(node.attributes).sort(
+		(/** @type {any} */ a, /** @type {any} */ b) => {
+			return a.name < b.name ? -1 : 1;
+		}
+	);
 
-	attributes.forEach((attr) => {
+	attributes.forEach((/** @type{any} */ attr) => {
 		node.removeAttribute(attr.name);
 	});
 
-	attributes.forEach((attr) => {
+	attributes.forEach((/** @type{any} */ attr) => {
 		node.setAttribute(attr.name, attr.value);
 	});
 

From 548ad7b7ebc6d495a78b3dfb5f34e7842d70e73d Mon Sep 17 00:00:00 2001
From: Paolo Ricciuti <ricciutipaolo@gmail.com>
Date: Wed, 6 Aug 2025 23:24:28 +0200
Subject: [PATCH 41/60] fix: wrap `abort` in `without_reactive_context`
 (#16570)

* fix: wrap `abort` in `without_reactive_context`

* only call without_reactive_context when the controller exists

---------

Co-authored-by: Rich Harris <rich.harris@vercel.com>
---
 .changeset/khaki-feet-teach.md                |  5 ++++
 .../src/internal/client/reactivity/effects.js |  9 ++++++-
 .../svelte/src/internal/client/runtime.js     |  6 ++++-
 .../abort-signal-derived-set-state/_config.js | 12 ++++++++++
 .../main.svelte                               | 24 +++++++++++++++++++
 5 files changed, 54 insertions(+), 2 deletions(-)
 create mode 100644 .changeset/khaki-feet-teach.md
 create mode 100644 packages/svelte/tests/runtime-runes/samples/abort-signal-derived-set-state/_config.js
 create mode 100644 packages/svelte/tests/runtime-runes/samples/abort-signal-derived-set-state/main.svelte

diff --git a/.changeset/khaki-feet-teach.md b/.changeset/khaki-feet-teach.md
new file mode 100644
index 0000000000..51b724428f
--- /dev/null
+++ b/.changeset/khaki-feet-teach.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: wrap `abort` in `without_reactive_context`
diff --git a/packages/svelte/src/internal/client/reactivity/effects.js b/packages/svelte/src/internal/client/reactivity/effects.js
index f44efa32f1..68a1555032 100644
--- a/packages/svelte/src/internal/client/reactivity/effects.js
+++ b/packages/svelte/src/internal/client/reactivity/effects.js
@@ -42,6 +42,7 @@ import { get_next_sibling } from '../dom/operations.js';
 import { component_context, dev_current_component_function, dev_stack } from '../context.js';
 import { Batch, schedule_effect } from './batch.js';
 import { flatten } from './async.js';
+import { without_reactive_context } from '../dom/elements/bindings/shared.js';
 
 /**
  * @param {'$effect' | '$effect.pre' | '$inspect'} rune
@@ -406,7 +407,13 @@ export function destroy_effect_children(signal, remove_dom = false) {
 	signal.first = signal.last = null;
 
 	while (effect !== null) {
-		effect.ac?.abort(STALE_REACTION);
+		const controller = effect.ac;
+
+		if (controller !== null) {
+			without_reactive_context(() => {
+				controller.abort(STALE_REACTION);
+			});
+		}
 
 		var next = effect.next;
 
diff --git a/packages/svelte/src/internal/client/runtime.js b/packages/svelte/src/internal/client/runtime.js
index 3d760e4b9e..22a1890e0f 100644
--- a/packages/svelte/src/internal/client/runtime.js
+++ b/packages/svelte/src/internal/client/runtime.js
@@ -46,6 +46,7 @@ import { Batch, batch_deriveds, flushSync, schedule_effect } from './reactivity/
 import { handle_error } from './error-handling.js';
 import { UNINITIALIZED } from '../../constants.js';
 import { captured_signals } from './legacy.js';
+import { without_reactive_context } from './dom/elements/bindings/shared.js';
 
 export let is_updating_effect = false;
 
@@ -278,7 +279,10 @@ export function update_reaction(reaction) {
 	update_version = ++read_version;
 
 	if (reaction.ac !== null) {
-		reaction.ac.abort(STALE_REACTION);
+		without_reactive_context(() => {
+			/** @type {AbortController} */ (reaction.ac).abort(STALE_REACTION);
+		});
+
 		reaction.ac = null;
 	}
 
diff --git a/packages/svelte/tests/runtime-runes/samples/abort-signal-derived-set-state/_config.js b/packages/svelte/tests/runtime-runes/samples/abort-signal-derived-set-state/_config.js
new file mode 100644
index 0000000000..2dacf188d7
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/abort-signal-derived-set-state/_config.js
@@ -0,0 +1,12 @@
+import { ok, test } from '../../test';
+import { flushSync } from 'svelte';
+
+export default test({
+	async test({ assert, target, errors }) {
+		const btn = target.querySelector('button');
+		flushSync(() => {
+			btn?.click();
+		});
+		assert.deepEqual(errors, []);
+	}
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/abort-signal-derived-set-state/main.svelte b/packages/svelte/tests/runtime-runes/samples/abort-signal-derived-set-state/main.svelte
new file mode 100644
index 0000000000..ebefe38fb2
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/abort-signal-derived-set-state/main.svelte
@@ -0,0 +1,24 @@
+<script lang="ts">
+	import { getAbortSignal } from "svelte";
+
+	let aborted = $state(0);
+
+	let count = $state(0);
+
+	let der = $derived.by(()=>{
+		const signal = getAbortSignal();
+
+		signal.addEventListener("abort", () => {
+			try{
+				aborted++;
+			}catch(e){
+				console.error(e);
+			}
+		});
+		return count;
+	})
+</script>
+
+{der}
+
+<button onclick={() => count++}></button>
\ No newline at end of file

From f00b364d5b5380f430ed6ba0c1b0be7de0a5a2c1 Mon Sep 17 00:00:00 2001
From: Ben McCann <322311+benmccann@users.noreply.github.com>
Date: Sat, 9 Aug 2025 09:24:44 -0700
Subject: [PATCH 42/60] chore: switch to jrdigewell version of remapping
 library (#16587)

---
 packages/svelte/package.json                       |  2 +-
 packages/svelte/src/compiler/preprocess/index.js   |  4 ++--
 .../svelte/src/compiler/preprocess/private.d.ts    |  2 +-
 packages/svelte/src/compiler/utils/mapped_code.js  |  4 ++--
 pnpm-lock.yaml                                     | 14 +++++++++++---
 5 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/packages/svelte/package.json b/packages/svelte/package.json
index 0b14ab4b40..2269d5603f 100644
--- a/packages/svelte/package.json
+++ b/packages/svelte/package.json
@@ -166,7 +166,7 @@
     "vitest": "^2.1.9"
   },
   "dependencies": {
-    "@ampproject/remapping": "^2.3.0",
+    "@jridgewell/remapping": "^2.3.4",
     "@jridgewell/sourcemap-codec": "^1.5.0",
     "@sveltejs/acorn-typescript": "^1.0.5",
     "@types/estree": "^1.0.5",
diff --git a/packages/svelte/src/compiler/preprocess/index.js b/packages/svelte/src/compiler/preprocess/index.js
index afef898471..429c2dcff1 100644
--- a/packages/svelte/src/compiler/preprocess/index.js
+++ b/packages/svelte/src/compiler/preprocess/index.js
@@ -1,6 +1,6 @@
 /** @import { Processed, Preprocessor, MarkupPreprocessor, PreprocessorGroup } from './public.js' */
 /** @import { SourceUpdate, Source } from './private.js' */
-/** @import { DecodedSourceMap, RawSourceMap } from '@ampproject/remapping' */
+/** @import { DecodedSourceMap, RawSourceMap } from '@jridgewell/remapping' */
 import { getLocator } from 'locate-character';
 import {
 	MappedCode,
@@ -25,7 +25,7 @@ class PreprocessResult {
 
 	// sourcemap_list is sorted in reverse order from last map (index 0) to first map (index -1)
 	// so we use sourcemap_list.unshift() to add new maps
-	// https://github.com/ampproject/remapping#multiple-transformations-of-a-file
+	// https://github.com/jridgewell/sourcemaps/tree/main/packages/remapping#multiple-transformations-of-a-file
 
 	/**
 	 * @default []
diff --git a/packages/svelte/src/compiler/preprocess/private.d.ts b/packages/svelte/src/compiler/preprocess/private.d.ts
index 5d8c5ed44e..2c331cee12 100644
--- a/packages/svelte/src/compiler/preprocess/private.d.ts
+++ b/packages/svelte/src/compiler/preprocess/private.d.ts
@@ -1,4 +1,4 @@
-import { DecodedSourceMap } from '@ampproject/remapping';
+import { DecodedSourceMap } from '@jridgewell/remapping';
 import { Location } from 'locate-character';
 import { MappedCode } from '../utils/mapped_code.js';
 
diff --git a/packages/svelte/src/compiler/utils/mapped_code.js b/packages/svelte/src/compiler/utils/mapped_code.js
index f23e3be245..7686ba59c6 100644
--- a/packages/svelte/src/compiler/utils/mapped_code.js
+++ b/packages/svelte/src/compiler/utils/mapped_code.js
@@ -2,8 +2,8 @@
 /** @import { Processed } from '../preprocess/public.js' */
 /** @import { SourceMap } from 'magic-string' */
 /** @import { Source } from '../preprocess/private.js' */
-/** @import { DecodedSourceMap, SourceMapSegment, RawSourceMap } from '@ampproject/remapping' */
-import remapping from '@ampproject/remapping';
+/** @import { DecodedSourceMap, SourceMapSegment, RawSourceMap } from '@jridgewell/remapping' */
+import remapping from '@jridgewell/remapping';
 import { push_array } from './push_array.js';
 
 /**
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 315d699e25..cad5fefdf8 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -62,9 +62,9 @@ importers:
 
   packages/svelte:
     dependencies:
-      '@ampproject/remapping':
-        specifier: ^2.3.0
-        version: 2.3.0
+      '@jridgewell/remapping':
+        specifier: ^2.3.4
+        version: 2.3.4
       '@jridgewell/sourcemap-codec':
         specifier: ^1.5.0
         version: 1.5.0
@@ -457,6 +457,9 @@ packages:
     resolution: {integrity: sha512-IzL8ZoEDIBRWEzlCcRhOaCupYyN5gdIK+Q6fbFdPDg6HqX6jpkItn7DFIpW9LQzXG6Df9sA7+OKnq0qlz/GaQg==}
     engines: {node: '>=6.0.0'}
 
+  '@jridgewell/remapping@2.3.4':
+    resolution: {integrity: sha512-aG+WvAz17rhbzhKNkSeMLgbkPPK82ovXdONvmucbGhUqcroRFLLVhoGAk4xEI17gHpXgNX3sr0/B1ybRUsbEWw==}
+
   '@jridgewell/resolve-uri@3.1.1':
     resolution: {integrity: sha512-dSYZh7HhCDtCKm4QakX0xFpsRDqjjtZf/kjI/v3T3Nwt5r8/qz/M19F9ySyOqU94SXBmeG9ttTul+YnR4LOxFA==}
     engines: {node: '>=6.0.0'}
@@ -2777,6 +2780,11 @@ snapshots:
       '@jridgewell/sourcemap-codec': 1.5.0
       '@jridgewell/trace-mapping': 0.3.25
 
+  '@jridgewell/remapping@2.3.4':
+    dependencies:
+      '@jridgewell/gen-mapping': 0.3.5
+      '@jridgewell/trace-mapping': 0.3.25
+
   '@jridgewell/resolve-uri@3.1.1': {}
 
   '@jridgewell/set-array@1.2.1': {}

From d2ba2589fee2ec6985c0fe0fbd800ab34518378e Mon Sep 17 00:00:00 2001
From: shamokit <91047157+shamokit@users.noreply.github.com>
Date: Sun, 10 Aug 2025 01:26:16 +0900
Subject: [PATCH 43/60] fix: add hint popover (#16581)

* fix: add hint popover

* changeset

---------

Co-authored-by: Rich Harris <hello@rich-harris.dev>
---
 .changeset/metal-months-fail.md | 5 +++++
 packages/svelte/elements.d.ts   | 2 +-
 2 files changed, 6 insertions(+), 1 deletion(-)
 create mode 100644 .changeset/metal-months-fail.md

diff --git a/.changeset/metal-months-fail.md b/.changeset/metal-months-fail.md
new file mode 100644
index 0000000000..555ec2c0e8
--- /dev/null
+++ b/.changeset/metal-months-fail.md
@@ -0,0 +1,5 @@
+---
+"svelte": patch
+---
+
+fix: add `hint` as a possible value for `popover` attribute
diff --git a/packages/svelte/elements.d.ts b/packages/svelte/elements.d.ts
index b3d44d9ed6..f63a31a96b 100644
--- a/packages/svelte/elements.d.ts
+++ b/packages/svelte/elements.d.ts
@@ -781,7 +781,7 @@ export interface HTMLAttributes<T extends EventTarget> extends AriaAttributes, D
 	title?: string | undefined | null;
 	translate?: 'yes' | 'no' | '' | undefined | null;
 	inert?: boolean | undefined | null;
-	popover?: 'auto' | 'manual' | '' | undefined | null;
+	popover?: 'auto' | 'manual' | 'hint' | '' | undefined | null;
 	writingsuggestions?: Booleanish | undefined | null;
 
 	// Unknown

From 0480f040c0f220dc090a263e81cfcd4a8db9737f Mon Sep 17 00:00:00 2001
From: Simon H <5968653+dummdidumm@users.noreply.github.com>
Date: Mon, 11 Aug 2025 20:41:34 +0200
Subject: [PATCH 44/60] fix: skip effects inside dynamic component that is
 about to be destroyed (#16601)

* fix: skip effects inside dynamic component that is about to be destroyed

When a dynamic component was updated to a different instance and its props were updated at the same time, effects inside the component were still called with the already-changed props.
The fix is to mark the branch as skipped to never got to those effects.

Fixes #16387

* undo accidental commit
---
 .changeset/neat-files-do.md                      |  5 +++++
 .../client/dom/blocks/svelte-component.js        |  4 +++-
 .../svelte-component-props-update/Comp-1.svelte  |  7 +++++++
 .../svelte-component-props-update/Comp-2.svelte  |  1 +
 .../svelte-component-props-update/_config.js     | 11 +++++++++++
 .../svelte-component-props-update/main.svelte    | 16 ++++++++++++++++
 6 files changed, 43 insertions(+), 1 deletion(-)
 create mode 100644 .changeset/neat-files-do.md
 create mode 100644 packages/svelte/tests/runtime-runes/samples/svelte-component-props-update/Comp-1.svelte
 create mode 100644 packages/svelte/tests/runtime-runes/samples/svelte-component-props-update/Comp-2.svelte
 create mode 100644 packages/svelte/tests/runtime-runes/samples/svelte-component-props-update/_config.js
 create mode 100644 packages/svelte/tests/runtime-runes/samples/svelte-component-props-update/main.svelte

diff --git a/.changeset/neat-files-do.md b/.changeset/neat-files-do.md
new file mode 100644
index 0000000000..ddba170c78
--- /dev/null
+++ b/.changeset/neat-files-do.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: skip effects inside dynamic component that is about to be destroyed
diff --git a/packages/svelte/src/internal/client/dom/blocks/svelte-component.js b/packages/svelte/src/internal/client/dom/blocks/svelte-component.js
index f16da9c427..2697722b39 100644
--- a/packages/svelte/src/internal/client/dom/blocks/svelte-component.js
+++ b/packages/svelte/src/internal/client/dom/blocks/svelte-component.js
@@ -62,8 +62,10 @@ export function component(node, get_component, render_fn) {
 			if (defer) {
 				offscreen_fragment = document.createDocumentFragment();
 				offscreen_fragment.append((target = create_text()));
+				if (effect) {
+					/** @type {Batch} */ (current_batch).skipped_effects.add(effect);
+				}
 			}
-
 			pending_effect = branch(() => render_fn(target, component));
 		}
 
diff --git a/packages/svelte/tests/runtime-runes/samples/svelte-component-props-update/Comp-1.svelte b/packages/svelte/tests/runtime-runes/samples/svelte-component-props-update/Comp-1.svelte
new file mode 100644
index 0000000000..fdafa27c3c
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/svelte-component-props-update/Comp-1.svelte
@@ -0,0 +1,7 @@
+<script>
+	let { data } = $props();
+</script>
+
+{#each data.obj.arr as i}
+	<p>{i}</p>
+{/each}
\ No newline at end of file
diff --git a/packages/svelte/tests/runtime-runes/samples/svelte-component-props-update/Comp-2.svelte b/packages/svelte/tests/runtime-runes/samples/svelte-component-props-update/Comp-2.svelte
new file mode 100644
index 0000000000..e345a7697c
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/svelte-component-props-update/Comp-2.svelte
@@ -0,0 +1 @@
+<p>Comp 2</p>
\ No newline at end of file
diff --git a/packages/svelte/tests/runtime-runes/samples/svelte-component-props-update/_config.js b/packages/svelte/tests/runtime-runes/samples/svelte-component-props-update/_config.js
new file mode 100644
index 0000000000..ff5ca12dbf
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/svelte-component-props-update/_config.js
@@ -0,0 +1,11 @@
+import { flushSync } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+	async test({ assert, target }) {
+		const [btn] = target.querySelectorAll('button');
+		btn.click();
+		flushSync();
+		assert.htmlEqual(target.innerHTML, `<button>Change</button> <p>Comp 2</p>`);
+	}
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/svelte-component-props-update/main.svelte b/packages/svelte/tests/runtime-runes/samples/svelte-component-props-update/main.svelte
new file mode 100644
index 0000000000..abd785fff3
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/svelte-component-props-update/main.svelte
@@ -0,0 +1,16 @@
+<script>
+	import Comp_1 from './Comp-1.svelte';
+	import Comp_2 from './Comp-2.svelte';
+
+	let Comp = $state.raw(Comp_1);
+	let data = $state.raw({ obj: { arr: [1, 2, 3] } });
+
+	function change() {
+		Comp = Comp_2;
+		data = {};
+	}
+</script>
+
+<button onclick={change}>Change</button>
+
+<Comp {data} />

From ca442e4f54c5335dbe65e51e0a4293f6d7e712a7 Mon Sep 17 00:00:00 2001
From: Simon H <5968653+dummdidumm@users.noreply.github.com>
Date: Mon, 11 Aug 2025 21:18:55 +0200
Subject: [PATCH 45/60] chore: add script to generate test from playground
 (#16602)

* chore: add script to generate test from playground

I often play around with stuff locally and then turn it into a test, this automates the last mile of that

* ask if should override
---
 playgrounds/sandbox/package.json           |   3 +-
 playgrounds/sandbox/scripts/create-test.js | 155 +++++++++++++++++++++
 2 files changed, 157 insertions(+), 1 deletion(-)
 create mode 100644 playgrounds/sandbox/scripts/create-test.js

diff --git a/playgrounds/sandbox/package.json b/playgrounds/sandbox/package.json
index 3ab65ac4b5..f11da983f6 100644
--- a/playgrounds/sandbox/package.json
+++ b/playgrounds/sandbox/package.json
@@ -11,7 +11,8 @@
     "prod": "npm run build && node dist/server/ssr-prod",
     "preview": "vite preview",
     "download": "node scripts/download.js",
-    "hash": "node scripts/hash.js"
+    "hash": "node scripts/hash.js",
+    "create-test": "node scripts/create-test.js"
   },
   "devDependencies": {
     "@sveltejs/vite-plugin-svelte": "^4.0.0-next.6",
diff --git a/playgrounds/sandbox/scripts/create-test.js b/playgrounds/sandbox/scripts/create-test.js
new file mode 100644
index 0000000000..c733f19419
--- /dev/null
+++ b/playgrounds/sandbox/scripts/create-test.js
@@ -0,0 +1,155 @@
+// Creates a test from the existing playground. cwd needs to be playground/sandbox
+import fs from 'fs';
+import path from 'path';
+
+// Get target folder from command line arguments
+let target_folder = process.argv[2];
+if (!target_folder) {
+	console.error(
+		'Please provide a target folder as an argument. Example: node create-test.js runtime-runes/my-test'
+	);
+	process.exit(1);
+}
+if (!target_folder.includes('/')) {
+	target_folder = 'runtime-runes/' + target_folder;
+}
+if (!target_folder.startsWith('runtime-')) {
+	console.error(
+		'Target folder must start with "runtime-" (can only convert to these kinds of tests)'
+	);
+	process.exit(1);
+}
+target_folder = path.join(
+	path.resolve('../../packages/svelte/tests', target_folder.split('/')[0]),
+	'samples',
+	target_folder.split('/')[1]
+);
+
+const exists = fs.existsSync(target_folder);
+
+// Check if target folder already exists and ask for confirmation
+if (exists) {
+	console.log(`Target folder "${target_folder}" already exists.`);
+	process.stdout.write('Do you want to override the existing test? (Y/n): ');
+
+	// Read user input synchronously
+	const stdin = process.stdin;
+	stdin.setRawMode(true);
+	stdin.resume();
+	stdin.setEncoding('utf8');
+
+	const response = await new Promise((resolve) => {
+		stdin.on('data', (key) => {
+			stdin.setRawMode(false);
+			stdin.pause();
+			process.stdout.write('\n');
+			resolve(key);
+		});
+	});
+
+	if (response.toLowerCase() === 'n') {
+		console.log('Operation cancelled.');
+		process.exit(0);
+	}
+
+	// Clear the existing target folder except for _config.js
+	const files = fs.readdirSync(target_folder);
+	for (const file of files) {
+		if (file !== '_config.js') {
+			const filePath = path.join(target_folder, file);
+			fs.rmSync(filePath, { recursive: true, force: true });
+		}
+	}
+} else {
+	fs.mkdirSync(target_folder, { recursive: true });
+}
+
+// Starting file
+const app_svelte_path = path.resolve('./src/App.svelte');
+const collected_files = new Set();
+const processed_files = new Set();
+
+function collect_imports(file_path) {
+	if (processed_files.has(file_path) || !fs.existsSync(file_path)) {
+		return;
+	}
+
+	processed_files.add(file_path);
+	collected_files.add(file_path);
+
+	const content = fs.readFileSync(file_path, 'utf8');
+
+	// Regex to match import statements
+	const import_regex = /import\s+(?:[^'"]*\s+from\s+)?['"]([^'"]+)['"]/g;
+	let match;
+
+	while ((match = import_regex.exec(content)) !== null) {
+		const import_path = match[1];
+
+		// Skip node_modules imports
+		if (!import_path.startsWith('.')) {
+			continue;
+		}
+
+		// Resolve relative import path
+		const resolved_path = path.resolve(path.dirname(file_path), import_path);
+
+		// Try different extensions if file doesn't exist
+		const extensions = ['', '.svelte', '.js', '.ts'];
+		let actual_path = null;
+
+		for (const ext of extensions) {
+			const test_path = resolved_path + ext;
+			if (fs.existsSync(test_path)) {
+				actual_path = test_path;
+				break;
+			}
+		}
+
+		if (actual_path) {
+			collect_imports(actual_path);
+		}
+	}
+}
+
+// Start collecting from App.svelte
+collect_imports(app_svelte_path);
+
+// Copy collected files to target folder
+for (const file_path of collected_files) {
+	const relative_path = path.relative(path.resolve('./src'), file_path);
+	let target_path = path.join(target_folder, relative_path);
+
+	// Rename App.svelte to main.svelte
+	if (path.basename(file_path) === 'App.svelte') {
+		target_path = path.join(target_folder, path.dirname(relative_path), 'main.svelte');
+	}
+
+	// Ensure target directory exists
+	const target_dir = path.dirname(target_path);
+	if (!fs.existsSync(target_dir)) {
+		fs.mkdirSync(target_dir, { recursive: true });
+	}
+
+	// Copy file
+	fs.copyFileSync(file_path, target_path);
+	console.log(`Copied: ${file_path} -> ${target_path}`);
+}
+
+// Create empty _config.js
+if (!exists) {
+	const config_path = path.join(target_folder, '_config.js');
+	fs.writeFileSync(
+		config_path,
+		`import { test } from '../../test';
+
+export default test({
+	async test({ assert, target }) {
+	}
+});
+`
+	);
+	console.log(`Created: ${config_path}`);
+}
+
+console.log(`\nTest files created in: ${target_folder}`);

From 2e02868ef1d97fd11ed9c13346543f4a8d941953 Mon Sep 17 00:00:00 2001
From: "github-actions[bot]"
 <41898282+github-actions[bot]@users.noreply.github.com>
Date: Mon, 11 Aug 2025 15:21:31 -0400
Subject: [PATCH 46/60] Version Packages (#16573)

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
---
 .changeset/khaki-feet-teach.md  |  5 -----
 .changeset/metal-months-fail.md |  5 -----
 .changeset/neat-files-do.md     |  5 -----
 packages/svelte/CHANGELOG.md    | 10 ++++++++++
 packages/svelte/package.json    |  2 +-
 packages/svelte/src/version.js  |  2 +-
 6 files changed, 12 insertions(+), 17 deletions(-)
 delete mode 100644 .changeset/khaki-feet-teach.md
 delete mode 100644 .changeset/metal-months-fail.md
 delete mode 100644 .changeset/neat-files-do.md

diff --git a/.changeset/khaki-feet-teach.md b/.changeset/khaki-feet-teach.md
deleted file mode 100644
index 51b724428f..0000000000
--- a/.changeset/khaki-feet-teach.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-'svelte': patch
----
-
-fix: wrap `abort` in `without_reactive_context`
diff --git a/.changeset/metal-months-fail.md b/.changeset/metal-months-fail.md
deleted file mode 100644
index 555ec2c0e8..0000000000
--- a/.changeset/metal-months-fail.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-"svelte": patch
----
-
-fix: add `hint` as a possible value for `popover` attribute
diff --git a/.changeset/neat-files-do.md b/.changeset/neat-files-do.md
deleted file mode 100644
index ddba170c78..0000000000
--- a/.changeset/neat-files-do.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-'svelte': patch
----
-
-fix: skip effects inside dynamic component that is about to be destroyed
diff --git a/packages/svelte/CHANGELOG.md b/packages/svelte/CHANGELOG.md
index 77f97a1c11..bb61b50dd5 100644
--- a/packages/svelte/CHANGELOG.md
+++ b/packages/svelte/CHANGELOG.md
@@ -1,5 +1,15 @@
 # svelte
 
+## 5.38.1
+
+### Patch Changes
+
+- fix: wrap `abort` in `without_reactive_context` ([#16570](https://github.com/sveltejs/svelte/pull/16570))
+
+- fix: add `hint` as a possible value for `popover` attribute ([#16581](https://github.com/sveltejs/svelte/pull/16581))
+
+- fix: skip effects inside dynamic component that is about to be destroyed ([#16601](https://github.com/sveltejs/svelte/pull/16601))
+
 ## 5.38.0
 
 ### Minor Changes
diff --git a/packages/svelte/package.json b/packages/svelte/package.json
index 2269d5603f..8904c103e3 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": "5.38.0",
+  "version": "5.38.1",
   "type": "module",
   "types": "./types/index.d.ts",
   "engines": {
diff --git a/packages/svelte/src/version.js b/packages/svelte/src/version.js
index 0bba536c1d..cf71ae709a 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 = '5.38.0';
+export const VERSION = '5.38.1';
 export const PUBLIC_VERSION = '5';

From ad19a1a0f5e4fccab6e2acd05e88eb58169ff74e Mon Sep 17 00:00:00 2001
From: ComputerGuy <63362464+Ocean-OS@users.noreply.github.com>
Date: Thu, 14 Aug 2025 12:50:59 -0700
Subject: [PATCH 47/60] fix: don't clone non-proxies in `$inspect` (#16617)

* fix: don't clone non-proxies in `$inspect`

* apply suggestion

* lint
---
 .changeset/itchy-games-guess.md              |  5 ++++
 packages/svelte/src/internal/shared/clone.js | 27 +++++++++++++-------
 2 files changed, 23 insertions(+), 9 deletions(-)
 create mode 100644 .changeset/itchy-games-guess.md

diff --git a/.changeset/itchy-games-guess.md b/.changeset/itchy-games-guess.md
new file mode 100644
index 0000000000..44516cfc21
--- /dev/null
+++ b/.changeset/itchy-games-guess.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: don't clone non-proxies in `$inspect`
diff --git a/packages/svelte/src/internal/shared/clone.js b/packages/svelte/src/internal/shared/clone.js
index 4632fc3d68..b8f99ee198 100644
--- a/packages/svelte/src/internal/shared/clone.js
+++ b/packages/svelte/src/internal/shared/clone.js
@@ -15,14 +15,15 @@ const empty = [];
  * @template T
  * @param {T} value
  * @param {boolean} [skip_warning]
+ * @param {boolean} [no_tojson]
  * @returns {Snapshot<T>}
  */
-export function snapshot(value, skip_warning = false) {
+export function snapshot(value, skip_warning = false, no_tojson = false) {
 	if (DEV && !skip_warning) {
 		/** @type {string[]} */
 		const paths = [];
 
-		const copy = clone(value, new Map(), '', paths);
+		const copy = clone(value, new Map(), '', paths, null, no_tojson);
 		if (paths.length === 1 && paths[0] === '') {
 			// value could not be cloned
 			w.state_snapshot_uncloneable();
@@ -40,7 +41,7 @@ export function snapshot(value, skip_warning = false) {
 		return copy;
 	}
 
-	return clone(value, new Map(), '', empty);
+	return clone(value, new Map(), '', empty, null, no_tojson);
 }
 
 /**
@@ -49,10 +50,11 @@ export function snapshot(value, skip_warning = false) {
  * @param {Map<T, Snapshot<T>>} cloned
  * @param {string} path
  * @param {string[]} paths
- * @param {null | T} original The original value, if `value` was produced from a `toJSON` call
+ * @param {null | T} [original] The original value, if `value` was produced from a `toJSON` call
+ * @param {boolean} [no_tojson]
  * @returns {Snapshot<T>}
  */
-function clone(value, cloned, path, paths, original = null) {
+function clone(value, cloned, path, paths, original = null, no_tojson = false) {
 	if (typeof value === 'object' && value !== null) {
 		var unwrapped = cloned.get(value);
 		if (unwrapped !== undefined) return unwrapped;
@@ -71,7 +73,7 @@ function clone(value, cloned, path, paths, original = null) {
 			for (var i = 0; i < value.length; i += 1) {
 				var element = value[i];
 				if (i in value) {
-					copy[i] = clone(element, cloned, DEV ? `${path}[${i}]` : path, paths);
+					copy[i] = clone(element, cloned, DEV ? `${path}[${i}]` : path, paths, null, no_tojson);
 				}
 			}
 
@@ -88,8 +90,15 @@ function clone(value, cloned, path, paths, original = null) {
 			}
 
 			for (var key in value) {
-				// @ts-expect-error
-				copy[key] = clone(value[key], cloned, DEV ? `${path}.${key}` : path, paths);
+				copy[key] = clone(
+					// @ts-expect-error
+					value[key],
+					cloned,
+					DEV ? `${path}.${key}` : path,
+					paths,
+					null,
+					no_tojson
+				);
 			}
 
 			return copy;
@@ -99,7 +108,7 @@ function clone(value, cloned, path, paths, original = null) {
 			return /** @type {Snapshot<T>} */ (structuredClone(value));
 		}
 
-		if (typeof (/** @type {T & { toJSON?: any } } */ (value).toJSON) === 'function') {
+		if (typeof (/** @type {T & { toJSON?: any } } */ (value).toJSON) === 'function' && !no_tojson) {
 			return clone(
 				/** @type {T & { toJSON(): any } } */ (value).toJSON(),
 				cloned,

From a543559acfb21ecc509873790158ba16db4089fd Mon Sep 17 00:00:00 2001
From: ComputerGuy <63362464+Ocean-OS@users.noreply.github.com>
Date: Thu, 14 Aug 2025 13:36:29 -0700
Subject: [PATCH 48/60] fix: avoid recursion error when tagging circular
 references (#16622)

* fix: avoid recursion error when tagging circular references

* try suggestion

* add some logging

* make logging clearer

* more

* try this

* add test

* tweak

* fix?

* fix??
---
 .changeset/six-shirts-scream.md               |  5 ++++
 packages/svelte/src/internal/client/proxy.js  | 11 +++++---
 .../_config.js                                | 26 +++++++++++++++++++
 .../main.svelte                               | 10 +++++++
 4 files changed, 48 insertions(+), 4 deletions(-)
 create mode 100644 .changeset/six-shirts-scream.md
 create mode 100644 packages/svelte/tests/runtime-runes/samples/inspect-trace-circular-reference/_config.js
 create mode 100644 packages/svelte/tests/runtime-runes/samples/inspect-trace-circular-reference/main.svelte

diff --git a/.changeset/six-shirts-scream.md b/.changeset/six-shirts-scream.md
new file mode 100644
index 0000000000..ac4d183474
--- /dev/null
+++ b/.changeset/six-shirts-scream.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: avoid recursion error when tagging circular references
diff --git a/packages/svelte/src/internal/client/proxy.js b/packages/svelte/src/internal/client/proxy.js
index 3ae4b87ed5..dae3791eb0 100644
--- a/packages/svelte/src/internal/client/proxy.js
+++ b/packages/svelte/src/internal/client/proxy.js
@@ -93,9 +93,11 @@ export function proxy(value) {
 
 	/** Used in dev for $inspect.trace() */
 	var path = '';
-
+	let updating = false;
 	/** @param {string} new_path */
 	function update_path(new_path) {
+		if (updating) return;
+		updating = true;
 		path = new_path;
 
 		tag(version, `${path} version`);
@@ -104,6 +106,7 @@ export function proxy(value) {
 		for (const [prop, source] of sources) {
 			tag(source, get_label(path, prop));
 		}
+		updating = false;
 	}
 
 	return new Proxy(/** @type {any} */ (value), {
@@ -284,13 +287,13 @@ export function proxy(value) {
 			if (s === undefined) {
 				if (!has || get_descriptor(target, prop)?.writable) {
 					s = with_parent(() => source(undefined, stack));
-					set(s, proxy(value));
-
-					sources.set(prop, s);
 
 					if (DEV) {
 						tag(s, get_label(path, prop));
 					}
+					set(s, proxy(value));
+
+					sources.set(prop, s);
 				}
 			} else {
 				has = s.v !== UNINITIALIZED;
diff --git a/packages/svelte/tests/runtime-runes/samples/inspect-trace-circular-reference/_config.js b/packages/svelte/tests/runtime-runes/samples/inspect-trace-circular-reference/_config.js
new file mode 100644
index 0000000000..ca81c7854a
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/inspect-trace-circular-reference/_config.js
@@ -0,0 +1,26 @@
+import { test } from '../../test';
+import { normalise_trace_logs } from '../../../helpers.js';
+
+export default test({
+	compileOptions: {
+		dev: true
+	},
+
+	test({ assert, logs }) {
+		const files = { id: 1, items: [{ id: 2, items: [{ id: 3 }, { id: 4 }] }] };
+		// @ts-expect-error
+		files.items[0].parent = files;
+		assert.deepEqual(normalise_trace_logs(logs), [
+			{ log: 'test (main.svelte:5:4)' },
+			{ log: '$state', highlighted: true },
+			{ log: 'filesState.files', highlighted: false },
+			{ log: files },
+			{ log: '$state', highlighted: true },
+			{ log: 'filesState.files.items[0].parent.items', highlighted: false },
+			{ log: files.items },
+			{ log: '$state', highlighted: true },
+			{ log: 'filesState.files.items[0].parent.items[0]', highlighted: false },
+			{ log: files.items[0] }
+		]);
+	}
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/inspect-trace-circular-reference/main.svelte b/packages/svelte/tests/runtime-runes/samples/inspect-trace-circular-reference/main.svelte
new file mode 100644
index 0000000000..7640d48f77
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/inspect-trace-circular-reference/main.svelte
@@ -0,0 +1,10 @@
+<script>
+    const filesState = $state({ files: {} });
+    let nodes = { id: 1, items: [{ id: 2, items: [{ id: 3 }, { id: 4 }] }] };
+    filesState.files = nodes;
+    function test() {
+        $inspect.trace();
+        filesState.files.items[0].parent = filesState.files;
+    }
+    $effect(test);
+</script>
\ No newline at end of file

From 036d4588abb0b053a22a156664b92474244dfe47 Mon Sep 17 00:00:00 2001
From: ComputerGuy <63362464+Ocean-OS@users.noreply.github.com>
Date: Thu, 14 Aug 2025 16:33:55 -0700
Subject: [PATCH 49/60] fix: actually use the changes from #16617 (#16626)

* quick fix

* fix failing test
---
 packages/svelte/src/internal/client/dev/inspect.js |  2 +-
 .../samples/inspect-recursive-2/main.svelte        | 14 ++++----------
 2 files changed, 5 insertions(+), 11 deletions(-)

diff --git a/packages/svelte/src/internal/client/dev/inspect.js b/packages/svelte/src/internal/client/dev/inspect.js
index c593f2622c..f79cf47299 100644
--- a/packages/svelte/src/internal/client/dev/inspect.js
+++ b/packages/svelte/src/internal/client/dev/inspect.js
@@ -26,7 +26,7 @@ export function inspect(get_value, inspector = console.log) {
 			return;
 		}
 
-		var snap = snapshot(value, true);
+		var snap = snapshot(value, true, true);
 		untrack(() => {
 			inspector(initial ? 'init' : 'update', ...snap);
 		});
diff --git a/packages/svelte/tests/runtime-runes/samples/inspect-recursive-2/main.svelte b/packages/svelte/tests/runtime-runes/samples/inspect-recursive-2/main.svelte
index f7874d2192..23a1c237c3 100644
--- a/packages/svelte/tests/runtime-runes/samples/inspect-recursive-2/main.svelte
+++ b/packages/svelte/tests/runtime-runes/samples/inspect-recursive-2/main.svelte
@@ -1,21 +1,15 @@
 <script>
 	class A {
-		toJSON(){
-			return {
-				a: this
-			}
+		constructor() {
+			this.a = this;
 		}
 	}
 	const state = $state(new A());
 	$inspect(state);
 
 	class B {
-		toJSON(){
-			return {
-				a: {
-					b: this
-				}
-			}
+		constructor() {
+			this.a = { b: this };
 		}
 	}
 	const state2 = $state(new B());

From 95e51755814329d596ced98fb1829d0f797e503d Mon Sep 17 00:00:00 2001
From: Harsh Mandan <harshsinghmandan@gmail.com>
Date: Sat, 16 Aug 2025 00:57:47 +0530
Subject: [PATCH 50/60] fix: do not defer unmount; immediately unmount
 components (#16624)

* fix: do not defer unmount; immediately unmount components

* fix: add changeset

* Update .changeset/few-geese-itch.md

Co-authored-by: Jeremiasz Major <jrh.mjr@gmail.com>

* add test

* update changeset

---------

Co-authored-by: Simon H <5968653+dummdidumm@users.noreply.github.com>
Co-authored-by: Jeremiasz Major <jrh.mjr@gmail.com>
Co-authored-by: Rich Harris <rich.harris@vercel.com>
---
 .changeset/few-geese-itch.md                        |  5 +++++
 .../internal/client/dom/blocks/svelte-component.js  | 10 +++++-----
 .../dynamic-component-destroy-then-create/A.svelte  |  8 ++++++++
 .../dynamic-component-destroy-then-create/B.svelte  |  8 ++++++++
 .../_config.js                                      | 13 +++++++++++++
 .../main.svelte                                     | 13 +++++++++++++
 6 files changed, 52 insertions(+), 5 deletions(-)
 create mode 100644 .changeset/few-geese-itch.md
 create mode 100644 packages/svelte/tests/runtime-runes/samples/dynamic-component-destroy-then-create/A.svelte
 create mode 100644 packages/svelte/tests/runtime-runes/samples/dynamic-component-destroy-then-create/B.svelte
 create mode 100644 packages/svelte/tests/runtime-runes/samples/dynamic-component-destroy-then-create/_config.js
 create mode 100644 packages/svelte/tests/runtime-runes/samples/dynamic-component-destroy-then-create/main.svelte

diff --git a/.changeset/few-geese-itch.md b/.changeset/few-geese-itch.md
new file mode 100644
index 0000000000..737aa01911
--- /dev/null
+++ b/.changeset/few-geese-itch.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: destroy dynamic component instance before creating new one
diff --git a/packages/svelte/src/internal/client/dom/blocks/svelte-component.js b/packages/svelte/src/internal/client/dom/blocks/svelte-component.js
index 2697722b39..be6611c96d 100644
--- a/packages/svelte/src/internal/client/dom/blocks/svelte-component.js
+++ b/packages/svelte/src/internal/client/dom/blocks/svelte-component.js
@@ -34,11 +34,6 @@ export function component(node, get_component, render_fn) {
 	var pending_effect = null;
 
 	function commit() {
-		if (effect) {
-			pause_effect(effect);
-			effect = null;
-		}
-
 		if (offscreen_fragment) {
 			// remove the anchor
 			/** @type {Text} */ (offscreen_fragment.lastChild).remove();
@@ -56,6 +51,11 @@ export function component(node, get_component, render_fn) {
 
 		var defer = should_defer_append();
 
+		if (effect) {
+			pause_effect(effect);
+			effect = null;
+		}
+
 		if (component) {
 			var target = anchor;
 
diff --git a/packages/svelte/tests/runtime-runes/samples/dynamic-component-destroy-then-create/A.svelte b/packages/svelte/tests/runtime-runes/samples/dynamic-component-destroy-then-create/A.svelte
new file mode 100644
index 0000000000..e73551cc28
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/dynamic-component-destroy-then-create/A.svelte
@@ -0,0 +1,8 @@
+<script>
+	$effect.pre(() => {
+		console.log('create A');
+		return () => console.log('destroy A');
+	});
+</script>
+
+<h1>A</h1>
diff --git a/packages/svelte/tests/runtime-runes/samples/dynamic-component-destroy-then-create/B.svelte b/packages/svelte/tests/runtime-runes/samples/dynamic-component-destroy-then-create/B.svelte
new file mode 100644
index 0000000000..459aa313c4
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/dynamic-component-destroy-then-create/B.svelte
@@ -0,0 +1,8 @@
+<script>
+	$effect.pre(() => {
+		console.log('create B');
+		return () => console.log('destroy B');
+	});
+</script>
+
+<h1>B</h1>
diff --git a/packages/svelte/tests/runtime-runes/samples/dynamic-component-destroy-then-create/_config.js b/packages/svelte/tests/runtime-runes/samples/dynamic-component-destroy-then-create/_config.js
new file mode 100644
index 0000000000..e750c48a00
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/dynamic-component-destroy-then-create/_config.js
@@ -0,0 +1,13 @@
+import { test } from '../../test';
+import { flushSync } from 'svelte';
+
+export default test({
+	mode: ['client', 'hydrate'],
+
+	async test({ assert, target, logs }) {
+		const [button] = target.querySelectorAll('button');
+
+		flushSync(() => button.click());
+		assert.deepEqual(logs, ['create A', 'destroy A', 'create B']);
+	}
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/dynamic-component-destroy-then-create/main.svelte b/packages/svelte/tests/runtime-runes/samples/dynamic-component-destroy-then-create/main.svelte
new file mode 100644
index 0000000000..c9ef5430a4
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/dynamic-component-destroy-then-create/main.svelte
@@ -0,0 +1,13 @@
+<script>
+	import A from './A.svelte';
+	import B from './B.svelte';
+
+	let condition = $state(true);
+	let Component = $derived(condition ? A : B);
+</script>
+
+<button onclick={() => condition = !condition}>
+	toggle ({condition})
+</button>
+
+<Component />

From 7b2d7746277dae6372ed7b836ad895bde536dc89 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 15 Aug 2025 17:09:33 -0400
Subject: [PATCH 51/60] chore: update/simplify test (#16630)

* update/simplify test

* oops

* simplify effect-order-7
---
 .../samples/effect-order-6/A.svelte           |  7 ++++---
 .../samples/effect-order-6/B.svelte           |  4 +---
 .../samples/effect-order-6/Child.svelte       | 20 -------------------
 .../samples/effect-order-6/_config.js         |  2 +-
 .../samples/effect-order-6/main.svelte        | 20 ++++++++++++-------
 .../samples/effect-order-7/A.svelte           |  6 +++---
 .../samples/effect-order-7/B.svelte           |  4 +---
 .../samples/effect-order-7/Child.svelte       | 20 -------------------
 .../samples/effect-order-7/main.svelte        | 19 ++++++++++++------
 9 files changed, 36 insertions(+), 66 deletions(-)
 delete mode 100644 packages/svelte/tests/runtime-runes/samples/effect-order-6/Child.svelte
 delete mode 100644 packages/svelte/tests/runtime-runes/samples/effect-order-7/Child.svelte

diff --git a/packages/svelte/tests/runtime-runes/samples/effect-order-6/A.svelte b/packages/svelte/tests/runtime-runes/samples/effect-order-6/A.svelte
index 2e789a0460..22b8ed0f20 100644
--- a/packages/svelte/tests/runtime-runes/samples/effect-order-6/A.svelte
+++ b/packages/svelte/tests/runtime-runes/samples/effect-order-6/A.svelte
@@ -1,11 +1,12 @@
 <script>
 	import B from './B.svelte';
 
-	let { boolean, closed } = $props();
+	let { boolean, closed, close } = $props();
 
+	// this runs after the effect in B, because child effects run first
 	$effect(() => {
-		console.log(boolean);
+		console.log({ boolean, closed });
 	});
 </script>
 
-<B {closed} />
+<B {closed} {close} />
diff --git a/packages/svelte/tests/runtime-runes/samples/effect-order-6/B.svelte b/packages/svelte/tests/runtime-runes/samples/effect-order-6/B.svelte
index 1fad19bc15..2233961177 100644
--- a/packages/svelte/tests/runtime-runes/samples/effect-order-6/B.svelte
+++ b/packages/svelte/tests/runtime-runes/samples/effect-order-6/B.svelte
@@ -1,7 +1,5 @@
 <script>
-	import { close } from './Child.svelte';
-
-	let { closed } = $props();
+	let { closed, close } = $props();
 
 	$effect(() => {
 		if (closed) close();
diff --git a/packages/svelte/tests/runtime-runes/samples/effect-order-6/Child.svelte b/packages/svelte/tests/runtime-runes/samples/effect-order-6/Child.svelte
deleted file mode 100644
index b905b4b4d7..0000000000
--- a/packages/svelte/tests/runtime-runes/samples/effect-order-6/Child.svelte
+++ /dev/null
@@ -1,20 +0,0 @@
-<script module>
-	let object = $state();
-
-	export function open() {
-		object = { boolean: true };
-	}
-
-	export function close() {
-		object = undefined;
-	}
-</script>
-
-<script>
-	let { children } = $props();
-</script>
-
-{#if object?.boolean}
-	<!-- error occurs here, this is executed when the if should already make it falsy -->
-	{@render children(object.boolean)}
-{/if}
diff --git a/packages/svelte/tests/runtime-runes/samples/effect-order-6/_config.js b/packages/svelte/tests/runtime-runes/samples/effect-order-6/_config.js
index 8f9077e954..91e1569e46 100644
--- a/packages/svelte/tests/runtime-runes/samples/effect-order-6/_config.js
+++ b/packages/svelte/tests/runtime-runes/samples/effect-order-6/_config.js
@@ -8,6 +8,6 @@ export default test({
 		flushSync(() => open.click());
 		flushSync(() => close.click());
 
-		assert.deepEqual(logs, [true]);
+		assert.deepEqual(logs, [{ boolean: true, closed: false }]);
 	}
 });
diff --git a/packages/svelte/tests/runtime-runes/samples/effect-order-6/main.svelte b/packages/svelte/tests/runtime-runes/samples/effect-order-6/main.svelte
index eee487fa13..08f6fc48da 100644
--- a/packages/svelte/tests/runtime-runes/samples/effect-order-6/main.svelte
+++ b/packages/svelte/tests/runtime-runes/samples/effect-order-6/main.svelte
@@ -1,6 +1,15 @@
 <script>
 	import A from './A.svelte';
-	import Child, { open } from './Child.svelte';
+
+	let object = $state();
+
+	function open() {
+		object = { boolean: true };
+	}
+
+	function close() {
+		object = undefined;
+	}
 
 	let closed = $state(false);
 </script>
@@ -15,9 +24,6 @@
 
 <hr>
 
-<Child>
-	{#snippet children(boolean)}
-		<A {closed} {boolean} />
-	{/snippet}
-</Child>
-
+{#if object}
+	<A {closed} {close} boolean={object.boolean} />
+{/if}
diff --git a/packages/svelte/tests/runtime-runes/samples/effect-order-7/A.svelte b/packages/svelte/tests/runtime-runes/samples/effect-order-7/A.svelte
index 54f4869d62..b55c8f4115 100644
--- a/packages/svelte/tests/runtime-runes/samples/effect-order-7/A.svelte
+++ b/packages/svelte/tests/runtime-runes/samples/effect-order-7/A.svelte
@@ -1,9 +1,9 @@
 <script>
 	import B from './B.svelte';
 
-	let { boolean, closed } = $props();
+	let { boolean, closed, close } = $props();
 </script>
 
-<span>{boolean}</span>
+<span>{boolean} {closed}</span>
 
-<B {closed} />
+<B {closed} {close} />
diff --git a/packages/svelte/tests/runtime-runes/samples/effect-order-7/B.svelte b/packages/svelte/tests/runtime-runes/samples/effect-order-7/B.svelte
index 2a2e634db1..7b33c342f5 100644
--- a/packages/svelte/tests/runtime-runes/samples/effect-order-7/B.svelte
+++ b/packages/svelte/tests/runtime-runes/samples/effect-order-7/B.svelte
@@ -1,7 +1,5 @@
 <script>
-	import { close } from './Child.svelte';
-
-	let { closed } = $props();
+	let { closed, close } = $props();
 
 	$effect.pre(() => {
 		if (closed) close();
diff --git a/packages/svelte/tests/runtime-runes/samples/effect-order-7/Child.svelte b/packages/svelte/tests/runtime-runes/samples/effect-order-7/Child.svelte
deleted file mode 100644
index 9606fd8602..0000000000
--- a/packages/svelte/tests/runtime-runes/samples/effect-order-7/Child.svelte
+++ /dev/null
@@ -1,20 +0,0 @@
-<script module>
-	let object = $state();
-
-	export function open() {
-		object = { nested: { boolean: true } };
-	}
-
-	export function close() {
-		object = undefined;
-	}
-</script>
-
-<script>
-	let { children } = $props();
-</script>
-
-{#if object?.nested}
-	<!-- error occurs here, this is executed when the if should already make it falsy -->
-	{@render children(object.nested)}
-{/if}
diff --git a/packages/svelte/tests/runtime-runes/samples/effect-order-7/main.svelte b/packages/svelte/tests/runtime-runes/samples/effect-order-7/main.svelte
index c9c45c50cf..d9e9eb17ad 100644
--- a/packages/svelte/tests/runtime-runes/samples/effect-order-7/main.svelte
+++ b/packages/svelte/tests/runtime-runes/samples/effect-order-7/main.svelte
@@ -1,6 +1,15 @@
 <script>
 	import A from './A.svelte';
-	import Child, { open } from './Child.svelte';
+
+	let object = $state();
+
+	function open() {
+		object = { boolean: true };
+	}
+
+	function close() {
+		object = undefined;
+	}
 
 	let closed = $state(false);
 </script>
@@ -15,8 +24,6 @@
 
 <hr>
 
-<Child>
-	{#snippet children(nested)}
-		<A {closed} boolean={nested.boolean} />
-	{/snippet}
-</Child>
+{#if object}
+	<A {close} {closed} boolean={object.boolean} />
+{/if}

From 2b85d2a544573d66c09a77c4100087cc183ae0fb Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Sun, 17 Aug 2025 08:31:20 -0400
Subject: [PATCH 52/60] fix: run blocks eagerly during flush (#16631)

fixes #16548

---------

Co-authored-by: Simon H <5968653+dummdidumm@users.noreply.github.com>
---
 .changeset/clever-months-clap.md              |  5 +++
 .../src/internal/client/dom/operations.js     |  2 ++
 .../src/internal/client/reactivity/batch.js   | 36 ++++++++++---------
 .../src/internal/client/reactivity/sources.js |  8 ++++-
 .../samples/effect-loop-3/Child.svelte        | 13 +++++++
 .../samples/effect-loop-3/_config.js          | 12 +++++++
 .../samples/effect-loop-3/main.svelte         | 15 ++++++++
 7 files changed, 73 insertions(+), 18 deletions(-)
 create mode 100644 .changeset/clever-months-clap.md
 create mode 100644 packages/svelte/tests/runtime-runes/samples/effect-loop-3/Child.svelte
 create mode 100644 packages/svelte/tests/runtime-runes/samples/effect-loop-3/_config.js
 create mode 100644 packages/svelte/tests/runtime-runes/samples/effect-loop-3/main.svelte

diff --git a/.changeset/clever-months-clap.md b/.changeset/clever-months-clap.md
new file mode 100644
index 0000000000..4a1b69e824
--- /dev/null
+++ b/.changeset/clever-months-clap.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+perf: run blocks eagerly during flush instead of aborting
diff --git a/packages/svelte/src/internal/client/dom/operations.js b/packages/svelte/src/internal/client/dom/operations.js
index fb269e47e0..abc29a7670 100644
--- a/packages/svelte/src/internal/client/dom/operations.js
+++ b/packages/svelte/src/internal/client/dom/operations.js
@@ -6,6 +6,7 @@ import { get_descriptor, is_extensible } from '../../shared/utils.js';
 import { active_effect } from '../runtime.js';
 import { async_mode_flag } from '../../flags/index.js';
 import { TEXT_NODE, EFFECT_RAN } from '#client/constants';
+import { eager_block_effects } from '../reactivity/batch.js';
 
 // export these for reference in the compiled code, making global name deduplication unnecessary
 /** @type {Window} */
@@ -214,6 +215,7 @@ export function clear_text_content(node) {
  */
 export function should_defer_append() {
 	if (!async_mode_flag) return false;
+	if (eager_block_effects !== null) return false;
 
 	var flags = /** @type {Effect} */ (active_effect).f;
 	return (flags & EFFECT_RAN) !== 0;
diff --git a/packages/svelte/src/internal/client/reactivity/batch.js b/packages/svelte/src/internal/client/reactivity/batch.js
index 123bc95d16..60fa03c56c 100644
--- a/packages/svelte/src/internal/client/reactivity/batch.js
+++ b/packages/svelte/src/internal/client/reactivity/batch.js
@@ -292,12 +292,12 @@ export class Batch {
 			if (!skip && effect.fn !== null) {
 				if (is_branch) {
 					effect.f ^= CLEAN;
+				} else if ((flags & EFFECT) !== 0) {
+					this.#effects.push(effect);
+				} else if (async_mode_flag && (flags & RENDER_EFFECT) !== 0) {
+					this.#render_effects.push(effect);
 				} else if ((flags & CLEAN) === 0) {
-					if ((flags & EFFECT) !== 0) {
-						this.#effects.push(effect);
-					} else if (async_mode_flag && (flags & RENDER_EFFECT) !== 0) {
-						this.#render_effects.push(effect);
-					} else if ((flags & ASYNC) !== 0) {
+					if ((flags & ASYNC) !== 0) {
 						var effects = effect.b?.pending ? this.#boundary_async_effects : this.#async_effects;
 						effects.push(effect);
 					} else if (is_dirty(effect)) {
@@ -584,6 +584,9 @@ function infinite_loop_guard() {
 	}
 }
 
+/** @type {Effect[] | null} */
+export let eager_block_effects = null;
+
 /**
  * @param {Array<Effect>} effects
  * @returns {void}
@@ -598,7 +601,7 @@ function flush_queued_effects(effects) {
 		var effect = effects[i++];
 
 		if ((effect.f & (DESTROYED | INERT)) === 0 && is_dirty(effect)) {
-			var n = current_batch ? current_batch.current.size : 0;
+			eager_block_effects = [];
 
 			update_effect(effect);
 
@@ -619,21 +622,20 @@ function flush_queued_effects(effects) {
 				}
 			}
 
-			// if state is written in a user effect, abort and re-schedule, lest we run
-			// effects that should be removed as a result of the state change
-			if (
-				current_batch !== null &&
-				current_batch.current.size > n &&
-				(effect.f & USER_EFFECT) !== 0
-			) {
-				break;
+			if (eager_block_effects.length > 0) {
+				// TODO this feels incorrect! it gets the tests passing
+				old_values.clear();
+
+				for (const e of eager_block_effects) {
+					update_effect(e);
+				}
+
+				eager_block_effects = [];
 			}
 		}
 	}
 
-	while (i < length) {
-		schedule_effect(effects[i++]);
-	}
+	eager_block_effects = null;
 }
 
 /**
diff --git a/packages/svelte/src/internal/client/reactivity/sources.js b/packages/svelte/src/internal/client/reactivity/sources.js
index 7fb3135708..cd0c28016d 100644
--- a/packages/svelte/src/internal/client/reactivity/sources.js
+++ b/packages/svelte/src/internal/client/reactivity/sources.js
@@ -33,7 +33,7 @@ import * as e from '../errors.js';
 import { legacy_mode_flag, tracing_mode_flag } from '../../flags/index.js';
 import { get_stack, tag_proxy } from '../dev/tracing.js';
 import { component_context, is_runes } from '../context.js';
-import { Batch, schedule_effect } from './batch.js';
+import { Batch, eager_block_effects, schedule_effect } from './batch.js';
 import { proxy } from '../proxy.js';
 import { execute_derived } from './deriveds.js';
 
@@ -334,6 +334,12 @@ function mark_reactions(signal, status) {
 		if ((flags & DERIVED) !== 0) {
 			mark_reactions(/** @type {Derived} */ (reaction), MAYBE_DIRTY);
 		} else if (not_dirty) {
+			if ((flags & BLOCK_EFFECT) !== 0) {
+				if (eager_block_effects !== null) {
+					eager_block_effects.push(/** @type {Effect} */ (reaction));
+				}
+			}
+
 			schedule_effect(/** @type {Effect} */ (reaction));
 		}
 	}
diff --git a/packages/svelte/tests/runtime-runes/samples/effect-loop-3/Child.svelte b/packages/svelte/tests/runtime-runes/samples/effect-loop-3/Child.svelte
new file mode 100644
index 0000000000..9bf4db52d6
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/effect-loop-3/Child.svelte
@@ -0,0 +1,13 @@
+<script>
+	let { children } = $props();
+
+	let inited = $state(false);
+
+	$effect(() => {
+		inited = true;
+	});
+</script>
+
+{#if inited}
+	<span>{@render children()}</span>
+{/if}
diff --git a/packages/svelte/tests/runtime-runes/samples/effect-loop-3/_config.js b/packages/svelte/tests/runtime-runes/samples/effect-loop-3/_config.js
new file mode 100644
index 0000000000..046c190432
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/effect-loop-3/_config.js
@@ -0,0 +1,12 @@
+import { flushSync } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+	async test({ assert, target }) {
+		const [button] = target.querySelectorAll('button');
+
+		assert.doesNotThrow(() => {
+			flushSync(() => button.click());
+		});
+	}
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/effect-loop-3/main.svelte b/packages/svelte/tests/runtime-runes/samples/effect-loop-3/main.svelte
new file mode 100644
index 0000000000..2b3a171798
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/effect-loop-3/main.svelte
@@ -0,0 +1,15 @@
+<script>
+	import Child from './Child.svelte';
+
+	let show = $state(false);
+</script>
+
+<button onclick={() => show = !show}>
+	toggle
+</button>
+
+{#if show}
+	{#each { length: 1234 } as i}
+		<Child>{i}</Child>
+	{/each}
+{/if}

From f5d4350f3d60606c556e195a80f21427a4b6738c Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Mon, 18 Aug 2025 08:52:44 -0400
Subject: [PATCH 53/60] Revert "fix: do not defer unmount; immediately unmount
 components (#16624)" (#16639)

This reverts commit 95e51755814329d596ced98fb1829d0f797e503d.
---
 .changeset/few-geese-itch.md                        |  5 -----
 .../internal/client/dom/blocks/svelte-component.js  | 10 +++++-----
 .../dynamic-component-destroy-then-create/A.svelte  |  8 --------
 .../dynamic-component-destroy-then-create/B.svelte  |  8 --------
 .../_config.js                                      | 13 -------------
 .../main.svelte                                     | 13 -------------
 6 files changed, 5 insertions(+), 52 deletions(-)
 delete mode 100644 .changeset/few-geese-itch.md
 delete mode 100644 packages/svelte/tests/runtime-runes/samples/dynamic-component-destroy-then-create/A.svelte
 delete mode 100644 packages/svelte/tests/runtime-runes/samples/dynamic-component-destroy-then-create/B.svelte
 delete mode 100644 packages/svelte/tests/runtime-runes/samples/dynamic-component-destroy-then-create/_config.js
 delete mode 100644 packages/svelte/tests/runtime-runes/samples/dynamic-component-destroy-then-create/main.svelte

diff --git a/.changeset/few-geese-itch.md b/.changeset/few-geese-itch.md
deleted file mode 100644
index 737aa01911..0000000000
--- a/.changeset/few-geese-itch.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-'svelte': patch
----
-
-fix: destroy dynamic component instance before creating new one
diff --git a/packages/svelte/src/internal/client/dom/blocks/svelte-component.js b/packages/svelte/src/internal/client/dom/blocks/svelte-component.js
index be6611c96d..2697722b39 100644
--- a/packages/svelte/src/internal/client/dom/blocks/svelte-component.js
+++ b/packages/svelte/src/internal/client/dom/blocks/svelte-component.js
@@ -34,6 +34,11 @@ export function component(node, get_component, render_fn) {
 	var pending_effect = null;
 
 	function commit() {
+		if (effect) {
+			pause_effect(effect);
+			effect = null;
+		}
+
 		if (offscreen_fragment) {
 			// remove the anchor
 			/** @type {Text} */ (offscreen_fragment.lastChild).remove();
@@ -51,11 +56,6 @@ export function component(node, get_component, render_fn) {
 
 		var defer = should_defer_append();
 
-		if (effect) {
-			pause_effect(effect);
-			effect = null;
-		}
-
 		if (component) {
 			var target = anchor;
 
diff --git a/packages/svelte/tests/runtime-runes/samples/dynamic-component-destroy-then-create/A.svelte b/packages/svelte/tests/runtime-runes/samples/dynamic-component-destroy-then-create/A.svelte
deleted file mode 100644
index e73551cc28..0000000000
--- a/packages/svelte/tests/runtime-runes/samples/dynamic-component-destroy-then-create/A.svelte
+++ /dev/null
@@ -1,8 +0,0 @@
-<script>
-	$effect.pre(() => {
-		console.log('create A');
-		return () => console.log('destroy A');
-	});
-</script>
-
-<h1>A</h1>
diff --git a/packages/svelte/tests/runtime-runes/samples/dynamic-component-destroy-then-create/B.svelte b/packages/svelte/tests/runtime-runes/samples/dynamic-component-destroy-then-create/B.svelte
deleted file mode 100644
index 459aa313c4..0000000000
--- a/packages/svelte/tests/runtime-runes/samples/dynamic-component-destroy-then-create/B.svelte
+++ /dev/null
@@ -1,8 +0,0 @@
-<script>
-	$effect.pre(() => {
-		console.log('create B');
-		return () => console.log('destroy B');
-	});
-</script>
-
-<h1>B</h1>
diff --git a/packages/svelte/tests/runtime-runes/samples/dynamic-component-destroy-then-create/_config.js b/packages/svelte/tests/runtime-runes/samples/dynamic-component-destroy-then-create/_config.js
deleted file mode 100644
index e750c48a00..0000000000
--- a/packages/svelte/tests/runtime-runes/samples/dynamic-component-destroy-then-create/_config.js
+++ /dev/null
@@ -1,13 +0,0 @@
-import { test } from '../../test';
-import { flushSync } from 'svelte';
-
-export default test({
-	mode: ['client', 'hydrate'],
-
-	async test({ assert, target, logs }) {
-		const [button] = target.querySelectorAll('button');
-
-		flushSync(() => button.click());
-		assert.deepEqual(logs, ['create A', 'destroy A', 'create B']);
-	}
-});
diff --git a/packages/svelte/tests/runtime-runes/samples/dynamic-component-destroy-then-create/main.svelte b/packages/svelte/tests/runtime-runes/samples/dynamic-component-destroy-then-create/main.svelte
deleted file mode 100644
index c9ef5430a4..0000000000
--- a/packages/svelte/tests/runtime-runes/samples/dynamic-component-destroy-then-create/main.svelte
+++ /dev/null
@@ -1,13 +0,0 @@
-<script>
-	import A from './A.svelte';
-	import B from './B.svelte';
-
-	let condition = $state(true);
-	let Component = $derived(condition ? A : B);
-</script>
-
-<button onclick={() => condition = !condition}>
-	toggle ({condition})
-</button>
-
-<Component />

From 04836a87995f0674ae4f105b7761fd19f7ee3b6a Mon Sep 17 00:00:00 2001
From: "github-actions[bot]"
 <41898282+github-actions[bot]@users.noreply.github.com>
Date: Mon, 18 Aug 2025 08:56:46 -0400
Subject: [PATCH 54/60] Version Packages (#16603)

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
---
 .changeset/clever-months-clap.md |  5 -----
 .changeset/itchy-games-guess.md  |  5 -----
 .changeset/six-shirts-scream.md  |  5 -----
 packages/svelte/CHANGELOG.md     | 10 ++++++++++
 packages/svelte/package.json     |  2 +-
 packages/svelte/src/version.js   |  2 +-
 6 files changed, 12 insertions(+), 17 deletions(-)
 delete mode 100644 .changeset/clever-months-clap.md
 delete mode 100644 .changeset/itchy-games-guess.md
 delete mode 100644 .changeset/six-shirts-scream.md

diff --git a/.changeset/clever-months-clap.md b/.changeset/clever-months-clap.md
deleted file mode 100644
index 4a1b69e824..0000000000
--- a/.changeset/clever-months-clap.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-'svelte': patch
----
-
-perf: run blocks eagerly during flush instead of aborting
diff --git a/.changeset/itchy-games-guess.md b/.changeset/itchy-games-guess.md
deleted file mode 100644
index 44516cfc21..0000000000
--- a/.changeset/itchy-games-guess.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-'svelte': patch
----
-
-fix: don't clone non-proxies in `$inspect`
diff --git a/.changeset/six-shirts-scream.md b/.changeset/six-shirts-scream.md
deleted file mode 100644
index ac4d183474..0000000000
--- a/.changeset/six-shirts-scream.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-'svelte': patch
----
-
-fix: avoid recursion error when tagging circular references
diff --git a/packages/svelte/CHANGELOG.md b/packages/svelte/CHANGELOG.md
index bb61b50dd5..cd6a4a916c 100644
--- a/packages/svelte/CHANGELOG.md
+++ b/packages/svelte/CHANGELOG.md
@@ -1,5 +1,15 @@
 # svelte
 
+## 5.38.2
+
+### Patch Changes
+
+- perf: run blocks eagerly during flush instead of aborting ([#16631](https://github.com/sveltejs/svelte/pull/16631))
+
+- fix: don't clone non-proxies in `$inspect` ([#16617](https://github.com/sveltejs/svelte/pull/16617))
+
+- fix: avoid recursion error when tagging circular references ([#16622](https://github.com/sveltejs/svelte/pull/16622))
+
 ## 5.38.1
 
 ### Patch Changes
diff --git a/packages/svelte/package.json b/packages/svelte/package.json
index 8904c103e3..fc7db9598d 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": "5.38.1",
+  "version": "5.38.2",
   "type": "module",
   "types": "./types/index.d.ts",
   "engines": {
diff --git a/packages/svelte/src/version.js b/packages/svelte/src/version.js
index cf71ae709a..2aa62504a5 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 = '5.38.1';
+export const VERSION = '5.38.2';
 export const PUBLIC_VERSION = '5';

From 1dcced59e79dd04163ce4aa380948ca6eea777af Mon Sep 17 00:00:00 2001
From: Simon H <5968653+dummdidumm@users.noreply.github.com>
Date: Mon, 18 Aug 2025 19:10:08 +0200
Subject: [PATCH 55/60] fix: properly catch top level await errors (#16619)

* fix: properly catch top level await errors

async errors within the template and derived etc are properly handled because they know about the last active effect and invoke the error boundary correctly as a response. This logic was missing for our top level await output.

Fixes #16613

* test

* use helper for async bodies (#16641)

* use helper for async bodies

* unused

* fix

* failing test + fix

---------

Co-authored-by: Simon Holthausen <simon.holthausen@vercel.com>

---------

Co-authored-by: Rich Harris <rich.harris@vercel.com>
---
 .changeset/silent-suns-whisper.md             |  5 ++
 .../3-transform/client/transform-client.js    | 60 +++++++------------
 packages/svelte/src/internal/client/index.js  |  5 +-
 .../src/internal/client/reactivity/async.js   | 21 ++++++-
 .../src/internal/client/reactivity/effects.js |  3 +-
 .../Child.svelte                              |  9 +++
 .../_config.js                                | 15 +++++
 .../main.svelte                               | 18 ++++++
 .../async-top-level-error-nested/Child.svelte |  7 +++
 .../async-top-level-error-nested/_config.js   | 14 +++++
 .../async-top-level-error-nested/main.svelte  | 18 ++++++
 11 files changed, 131 insertions(+), 44 deletions(-)
 create mode 100644 .changeset/silent-suns-whisper.md
 create mode 100644 packages/svelte/tests/runtime-runes/samples/async-top-level-error-nested-obsolete/Child.svelte
 create mode 100644 packages/svelte/tests/runtime-runes/samples/async-top-level-error-nested-obsolete/_config.js
 create mode 100644 packages/svelte/tests/runtime-runes/samples/async-top-level-error-nested-obsolete/main.svelte
 create mode 100644 packages/svelte/tests/runtime-runes/samples/async-top-level-error-nested/Child.svelte
 create mode 100644 packages/svelte/tests/runtime-runes/samples/async-top-level-error-nested/_config.js
 create mode 100644 packages/svelte/tests/runtime-runes/samples/async-top-level-error-nested/main.svelte

diff --git a/.changeset/silent-suns-whisper.md b/.changeset/silent-suns-whisper.md
new file mode 100644
index 0000000000..7ee7d74abc
--- /dev/null
+++ b/.changeset/silent-suns-whisper.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: properly catch top level await errors
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 166207f66a..940d6a9e00 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
@@ -359,16 +359,31 @@ export function client_component(analysis, options) {
 	if (dev) push_args.push(b.id(analysis.name));
 
 	let component_block = b.block([
+		store_init,
 		...store_setup,
 		...legacy_reactive_declarations,
 		...group_binding_declarations,
-		...state.instance_level_snippets,
-		.../** @type {ESTree.Statement[]} */ (instance.body),
-		analysis.runes || !analysis.needs_context
-			? b.empty
-			: b.stmt(b.call('$.init', analysis.immutable ? b.true : undefined))
+		...state.instance_level_snippets
 	]);
 
+	if (analysis.instance.has_await) {
+		const body = b.block([
+			.../** @type {ESTree.Statement[]} */ (instance.body),
+			b.if(b.call('$.aborted'), b.return()),
+			.../** @type {ESTree.Statement[]} */ (template.body)
+		]);
+
+		component_block.body.push(b.stmt(b.call(`$.async_body`, b.arrow([], body, true))));
+	} else {
+		component_block.body.push(.../** @type {ESTree.Statement[]} */ (instance.body));
+
+		if (!analysis.runes && analysis.needs_context) {
+			component_block.body.push(b.stmt(b.call('$.init', analysis.immutable ? b.true : undefined)));
+		}
+
+		component_block.body.push(.../** @type {ESTree.Statement[]} */ (template.body));
+	}
+
 	if (analysis.needs_mutation_validation) {
 		component_block.body.unshift(
 			b.var('$$ownership_validator', b.call('$.create_ownership_validator', b.id('$$props')))
@@ -389,41 +404,6 @@ export function client_component(analysis, options) {
 		analysis.uses_slots ||
 		analysis.slot_names.size > 0;
 
-	if (analysis.instance.has_await) {
-		const params = [b.id('$$anchor')];
-		if (should_inject_props) {
-			params.push(b.id('$$props'));
-		}
-		if (store_setup.length > 0) {
-			params.push(b.id('$$stores'));
-		}
-		const body = b.function_declaration(
-			b.id('$$body'),
-			params,
-			b.block([
-				b.var('$$unsuspend', b.call('$.suspend')),
-				...component_block.body,
-				b.if(b.call('$.aborted'), b.return()),
-				.../** @type {ESTree.Statement[]} */ (template.body),
-				b.stmt(b.call('$$unsuspend'))
-			]),
-			true
-		);
-
-		state.hoisted.push(body);
-
-		component_block = b.block([
-			b.var('fragment', b.call('$.comment')),
-			b.var('node', b.call('$.first_child', b.id('fragment'))),
-			store_init,
-			b.stmt(b.call(body.id, b.id('node'), ...params.slice(1))),
-			b.stmt(b.call('$.append', b.id('$$anchor'), b.id('fragment')))
-		]);
-	} else {
-		component_block.body.unshift(store_init);
-		component_block.body.push(.../** @type {ESTree.Statement[]} */ (template.body));
-	}
-
 	// trick esrap into including comments
 	component_block.loc = instance.loc;
 
diff --git a/packages/svelte/src/internal/client/index.js b/packages/svelte/src/internal/client/index.js
index c094c9e044..c5b7bb845c 100644
--- a/packages/svelte/src/internal/client/index.js
+++ b/packages/svelte/src/internal/client/index.js
@@ -99,6 +99,7 @@ export {
 	with_script
 } from './dom/template.js';
 export {
+	async_body,
 	for_await_track_reactivity_loss,
 	save,
 	track_reactivity_loss
@@ -151,7 +152,8 @@ export {
 	untrack,
 	exclude_from_object,
 	deep_read,
-	deep_read_state
+	deep_read_state,
+	active_effect
 } from './runtime.js';
 export { validate_binding, validate_each_keys } from './validate.js';
 export { raf } from './timing.js';
@@ -176,3 +178,4 @@ export {
 } from '../shared/validate.js';
 export { strict_equals, equals } from './dev/equality.js';
 export { log_if_contains_state } from './dev/console-log.js';
+export { invoke_error_boundary } from './error-handling.js';
diff --git a/packages/svelte/src/internal/client/reactivity/async.js b/packages/svelte/src/internal/client/reactivity/async.js
index 2b133e5f44..1ea1bbe561 100644
--- a/packages/svelte/src/internal/client/reactivity/async.js
+++ b/packages/svelte/src/internal/client/reactivity/async.js
@@ -11,7 +11,7 @@ import {
 	set_active_effect,
 	set_active_reaction
 } from '../runtime.js';
-import { current_batch } from './batch.js';
+import { current_batch, suspend } from './batch.js';
 import {
 	async_derived,
 	current_async_effect,
@@ -19,6 +19,7 @@ import {
 	derived_safe_equal,
 	set_from_async_derived
 } from './deriveds.js';
+import { aborted } from './effects.js';
 
 /**
  *
@@ -170,3 +171,21 @@ export function unset_context() {
 	set_component_context(null);
 	if (DEV) set_from_async_derived(null);
 }
+
+/**
+ * @param {() => Promise<void>} fn
+ */
+export async function async_body(fn) {
+	const unsuspend = suspend();
+	const active = /** @type {Effect} */ (active_effect);
+
+	try {
+		await fn();
+	} catch (error) {
+		if (!aborted(active)) {
+			invoke_error_boundary(error, active);
+		}
+	} finally {
+		unsuspend();
+	}
+}
diff --git a/packages/svelte/src/internal/client/reactivity/effects.js b/packages/svelte/src/internal/client/reactivity/effects.js
index 68a1555032..df3dd75808 100644
--- a/packages/svelte/src/internal/client/reactivity/effects.js
+++ b/packages/svelte/src/internal/client/reactivity/effects.js
@@ -648,7 +648,6 @@ function resume_children(effect, local) {
 	}
 }
 
-export function aborted() {
-	var effect = /** @type {Effect} */ (active_effect);
+export function aborted(effect = /** @type {Effect} */ (active_effect)) {
 	return (effect.f & DESTROYED) !== 0;
 }
diff --git a/packages/svelte/tests/runtime-runes/samples/async-top-level-error-nested-obsolete/Child.svelte b/packages/svelte/tests/runtime-runes/samples/async-top-level-error-nested-obsolete/Child.svelte
new file mode 100644
index 0000000000..f7ba132ace
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/async-top-level-error-nested-obsolete/Child.svelte
@@ -0,0 +1,9 @@
+<script>
+	import { route } from "./main.svelte";
+
+	await new Promise(async (_, reject) => {
+		await Promise.resolve();
+		route.current = 'other'
+		route.reject = reject;
+	});
+</script>
diff --git a/packages/svelte/tests/runtime-runes/samples/async-top-level-error-nested-obsolete/_config.js b/packages/svelte/tests/runtime-runes/samples/async-top-level-error-nested-obsolete/_config.js
new file mode 100644
index 0000000000..298e33e9a2
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/async-top-level-error-nested-obsolete/_config.js
@@ -0,0 +1,15 @@
+import { tick } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+	html: `<button>reject</button> <p>pending</p>`,
+
+	async test({ assert, target }) {
+		const [reject] = target.querySelectorAll('button');
+
+		await tick();
+		reject.click();
+		await tick();
+		assert.htmlEqual(target.innerHTML, '<button>reject</button> <p>route: other</p>');
+	}
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/async-top-level-error-nested-obsolete/main.svelte b/packages/svelte/tests/runtime-runes/samples/async-top-level-error-nested-obsolete/main.svelte
new file mode 100644
index 0000000000..2f461e96c8
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/async-top-level-error-nested-obsolete/main.svelte
@@ -0,0 +1,18 @@
+<script module>
+	import Child from './Child.svelte';
+	export let route = $state({ current: 'home' });
+</script>
+
+<button onclick={() => route.reject()}>reject</button>
+
+<svelte:boundary>
+	{#if route.current === 'home'}
+		<Child />
+	{:else}
+		<p>route: {route.current}</p>
+	{/if}
+
+	{#snippet pending()}
+		<p>pending</p>
+	{/snippet}
+</svelte:boundary>
diff --git a/packages/svelte/tests/runtime-runes/samples/async-top-level-error-nested/Child.svelte b/packages/svelte/tests/runtime-runes/samples/async-top-level-error-nested/Child.svelte
new file mode 100644
index 0000000000..11c9ebd653
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/async-top-level-error-nested/Child.svelte
@@ -0,0 +1,7 @@
+<script>
+	import { route } from "./main.svelte";
+
+	await new Promise(async (_, reject) => {
+		route.reject = reject;
+	});
+</script>
diff --git a/packages/svelte/tests/runtime-runes/samples/async-top-level-error-nested/_config.js b/packages/svelte/tests/runtime-runes/samples/async-top-level-error-nested/_config.js
new file mode 100644
index 0000000000..57005b4112
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/async-top-level-error-nested/_config.js
@@ -0,0 +1,14 @@
+import { tick } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+	html: `<button>reject</button> <p>pending</p>`,
+
+	async test({ assert, target }) {
+		const [reject] = target.querySelectorAll('button');
+
+		reject.click();
+		await tick();
+		assert.htmlEqual(target.innerHTML, '<button>reject</button> <p>failed</p>');
+	}
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/async-top-level-error-nested/main.svelte b/packages/svelte/tests/runtime-runes/samples/async-top-level-error-nested/main.svelte
new file mode 100644
index 0000000000..2fdf4c0d2f
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/async-top-level-error-nested/main.svelte
@@ -0,0 +1,18 @@
+<script module>
+	import Child from './Child.svelte';
+	export let route = $state({});
+</script>
+
+<button onclick={() => route.reject()}>reject</button>
+
+<svelte:boundary>
+	<Child />
+
+	{#snippet pending()}
+		<p>pending</p>
+	{/snippet}
+
+	{#snippet failed()}
+		<p>failed</p>
+	{/snippet}
+</svelte:boundary>

From a60995abefc52a88493580e8b7f390efeb84456c Mon Sep 17 00:00:00 2001
From: Simon H <5968653+dummdidumm@users.noreply.github.com>
Date: Fri, 22 Aug 2025 19:28:43 +0200
Subject: [PATCH 56/60] fix: allow async `{@const}` in more places (#16643)

Implemented by reusing the `async_body` function inside `Fragment.js`. Also removes the ability to reference a `{@const ...}` of an implicit child inside a boundary pending/failed snippet:
- existing duplication of consts can have unintended side effects, e.g. async consts would unexpectedly called multiple times
- what if a const is the reason for the failure of a boundary, but is then referenced in the failed snippet?
- what if an async const is referenced in a pending snippet? deadlock
- inconsistent with how it behaves for components where this already does not work

Implemented via the experimental flag so the behavior change only applies there as this is a breaking change strictly speaking. Also added a compiler error for this.

closes #16462
---
 .changeset/light-camels-push.md               |  5 ++
 .../98-reference/.generated/compile-errors.md | 45 +++++++++++++
 .../messages/compile-errors/template.md       | 43 ++++++++++++
 packages/svelte/src/compiler/errors.js        | 10 +++
 .../phases/2-analyze/visitors/Identifier.js   | 33 ++++++++++
 .../3-transform/client/visitors/Fragment.js   | 11 +---
 .../client/visitors/SvelteBoundary.js         | 66 ++++++++++++-------
 packages/svelte/src/compiler/phases/nodes.js  |  9 +++
 packages/svelte/src/compiler/phases/scope.js  |  3 +-
 .../_config.js                                | 10 +++
 .../main.svelte                               | 32 +++++++++
 .../_config.js                                | 10 +++
 .../main.svelte                               | 27 ++++++++
 packages/svelte/tests/compiler-errors/test.ts |  4 +-
 .../samples/async-const/_config.js            |  2 +-
 .../samples/async-const/main.svelte           | 10 +++
 .../FlakyComponent.svelte                     |  2 +-
 .../_config.js                                | 18 +++++
 .../main.svelte                               | 14 ++++
 .../samples/const-tag-boundary/_config.js     |  2 +-
 .../samples/const-tag-boundary/main.svelte    | 14 ++--
 .../input.svelte                              |  6 +-
 22 files changed, 328 insertions(+), 48 deletions(-)
 create mode 100644 .changeset/light-camels-push.md
 create mode 100644 packages/svelte/tests/compiler-errors/samples/const-tag-snippet-invalid-reference-1/_config.js
 create mode 100644 packages/svelte/tests/compiler-errors/samples/const-tag-snippet-invalid-reference-1/main.svelte
 create mode 100644 packages/svelte/tests/compiler-errors/samples/const-tag-snippet-invalid-reference-2/_config.js
 create mode 100644 packages/svelte/tests/compiler-errors/samples/const-tag-snippet-invalid-reference-2/main.svelte
 rename packages/svelte/tests/runtime-runes/samples/{const-tag-boundary => const-tag-boundary-deprecated-usage}/FlakyComponent.svelte (74%)
 create mode 100644 packages/svelte/tests/runtime-runes/samples/const-tag-boundary-deprecated-usage/_config.js
 create mode 100644 packages/svelte/tests/runtime-runes/samples/const-tag-boundary-deprecated-usage/main.svelte

diff --git a/.changeset/light-camels-push.md b/.changeset/light-camels-push.md
new file mode 100644
index 0000000000..cac7f5a51e
--- /dev/null
+++ b/.changeset/light-camels-push.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: allow async `{@const}` in more places
diff --git a/documentation/docs/98-reference/.generated/compile-errors.md b/documentation/docs/98-reference/.generated/compile-errors.md
index 957a9f67c7..b9c44163c9 100644
--- a/documentation/docs/98-reference/.generated/compile-errors.md
+++ b/documentation/docs/98-reference/.generated/compile-errors.md
@@ -196,6 +196,51 @@ Cyclical dependency detected: %cycle%
 `{@const}` must be the immediate child of `{#snippet}`, `{#if}`, `{:else if}`, `{:else}`, `{#each}`, `{:then}`, `{:catch}`, `<svelte:fragment>`, `<svelte:boundary` or `<Component>`
 ```
 
+### const_tag_invalid_reference
+
+```
+The `{@const %name% = ...}` declaration is not available in this snippet 
+```
+
+The following is an error:
+
+```svelte
+<svelte:boundary>
+    {@const foo = 'bar'}
+
+    {#snippet failed()}
+        {foo}
+    {/snippet}
+</svelte:boundary>
+```
+
+Here, `foo` is not available inside `failed`. The top level code inside `<svelte:boundary>` becomes part of the implicit `children` snippet, in other words the above code is equivalent to this:
+
+```svelte
+<svelte:boundary>
+    {#snippet children()}
+        {@const foo = 'bar'}
+    {/snippet}
+
+    {#snippet failed()}
+        {foo}
+    {/snippet}
+</svelte:boundary>
+```
+
+The same applies to components:
+
+```svelte
+<Component>
+    {@const foo = 'bar'}
+
+    {#snippet someProp()}
+        <!-- error -->
+        {foo}
+    {/snippet}
+</Component>
+```
+
 ### constant_assignment
 
 ```
diff --git a/packages/svelte/messages/compile-errors/template.md b/packages/svelte/messages/compile-errors/template.md
index 0569f63ad3..dc26a02767 100644
--- a/packages/svelte/messages/compile-errors/template.md
+++ b/packages/svelte/messages/compile-errors/template.md
@@ -124,6 +124,49 @@
 
 > `{@const}` must be the immediate child of `{#snippet}`, `{#if}`, `{:else if}`, `{:else}`, `{#each}`, `{:then}`, `{:catch}`, `<svelte:fragment>`, `<svelte:boundary` or `<Component>`
 
+## const_tag_invalid_reference
+
+> The `{@const %name% = ...}` declaration is not available in this snippet 
+
+The following is an error:
+
+```svelte
+<svelte:boundary>
+    {@const foo = 'bar'}
+
+    {#snippet failed()}
+        {foo}
+    {/snippet}
+</svelte:boundary>
+```
+
+Here, `foo` is not available inside `failed`. The top level code inside `<svelte:boundary>` becomes part of the implicit `children` snippet, in other words the above code is equivalent to this:
+
+```svelte
+<svelte:boundary>
+    {#snippet children()}
+        {@const foo = 'bar'}
+    {/snippet}
+
+    {#snippet failed()}
+        {foo}
+    {/snippet}
+</svelte:boundary>
+```
+
+The same applies to components:
+
+```svelte
+<Component>
+    {@const foo = 'bar'}
+
+    {#snippet someProp()}
+        <!-- error -->
+        {foo}
+    {/snippet}
+</Component>
+```
+
 ## debug_tag_invalid_arguments
 
 > {@debug ...} arguments must be identifiers, not arbitrary expressions
diff --git a/packages/svelte/src/compiler/errors.js b/packages/svelte/src/compiler/errors.js
index e763a6e073..44fc641ee5 100644
--- a/packages/svelte/src/compiler/errors.js
+++ b/packages/svelte/src/compiler/errors.js
@@ -985,6 +985,16 @@ export function const_tag_invalid_placement(node) {
 	e(node, 'const_tag_invalid_placement', `\`{@const}\` must be the immediate child of \`{#snippet}\`, \`{#if}\`, \`{:else if}\`, \`{:else}\`, \`{#each}\`, \`{:then}\`, \`{:catch}\`, \`<svelte:fragment>\`, \`<svelte:boundary\` or \`<Component>\`\nhttps://svelte.dev/e/const_tag_invalid_placement`);
 }
 
+/**
+ * The `{@const %name% = ...}` declaration is not available in this snippet 
+ * @param {null | number | NodeLike} node
+ * @param {string} name
+ * @returns {never}
+ */
+export function const_tag_invalid_reference(node, name) {
+	e(node, 'const_tag_invalid_reference', `The \`{@const ${name} = ...}\` declaration is not available in this snippet \nhttps://svelte.dev/e/const_tag_invalid_reference`);
+}
+
 /**
  * {@debug ...} arguments must be identifiers, not arbitrary expressions
  * @param {null | number | NodeLike} node
diff --git a/packages/svelte/src/compiler/phases/2-analyze/visitors/Identifier.js b/packages/svelte/src/compiler/phases/2-analyze/visitors/Identifier.js
index 4dfdfe5af1..1c98a95e63 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/visitors/Identifier.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/visitors/Identifier.js
@@ -7,6 +7,7 @@ import * as w from '../../../warnings.js';
 import { is_rune } from '../../../../utils.js';
 import { mark_subtree_dynamic } from './shared/fragment.js';
 import { get_rune } from '../../scope.js';
+import { is_component_node } from '../../nodes.js';
 
 /**
  * @param {Identifier} node
@@ -155,5 +156,37 @@ export function Identifier(node, context) {
 		) {
 			w.reactive_declaration_module_script_dependency(node);
 		}
+
+		if (binding.metadata?.is_template_declaration && context.state.options.experimental.async) {
+			let snippet_name;
+
+			// Find out if this references a {@const ...} declaration of an implicit children snippet
+			// when it is itself inside a snippet block at the same level. If so, error.
+			for (let i = context.path.length - 1; i >= 0; i--) {
+				const parent = context.path[i];
+				const grand_parent = context.path[i - 1];
+
+				if (parent.type === 'SnippetBlock') {
+					snippet_name = parent.expression.name;
+				} else if (
+					snippet_name &&
+					grand_parent &&
+					parent.type === 'Fragment' &&
+					(is_component_node(grand_parent) ||
+						(grand_parent.type === 'SvelteBoundary' &&
+							(snippet_name === 'failed' || snippet_name === 'pending')))
+				) {
+					if (
+						is_component_node(grand_parent)
+							? grand_parent.metadata.scopes.default === binding.scope
+							: context.state.scopes.get(parent) === binding.scope
+					) {
+						e.const_tag_invalid_reference(node, node.name);
+					} else {
+						break;
+					}
+				}
+			}
+		}
 	}
 }
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 c7c576101e..85d8e3caff 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
@@ -51,7 +51,6 @@ export function Fragment(node, context) {
 	const has_await = context.state.init !== null && (node.metadata.has_await || false);
 
 	const template_name = context.state.scope.root.unique('root'); // TODO infer name from parent
-	const unsuspend = b.id('$$unsuspend');
 
 	/** @type {Statement[]} */
 	const body = [];
@@ -151,10 +150,6 @@ export function Fragment(node, context) {
 		}
 	}
 
-	if (has_await) {
-		body.push(b.var(unsuspend, b.call('$.suspend')));
-	}
-
 	body.push(...state.consts);
 
 	if (has_await) {
@@ -182,8 +177,8 @@ export function Fragment(node, context) {
 	}
 
 	if (has_await) {
-		body.push(b.stmt(b.call(unsuspend)));
+		return b.block([b.stmt(b.call('$.async_body', b.arrow([], b.block(body), true)))]);
+	} else {
+		return b.block(body);
 	}
-
-	return b.block(body);
 }
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/SvelteBoundary.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/SvelteBoundary.js
index 70df022355..49c89bc438 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/SvelteBoundary.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/SvelteBoundary.js
@@ -39,40 +39,60 @@ export function SvelteBoundary(node, context) {
 	/** @type {Statement[]} */
 	const hoisted = [];
 
+	let has_const = false;
+
 	// const tags need to live inside the boundary, but might also be referenced in hoisted snippets.
 	// to resolve this we cheat: we duplicate const tags inside snippets
+	// We'll revert this behavior in the future, it was a mistake to allow this (Component snippets also don't do this).
 	for (const child of node.fragment.nodes) {
 		if (child.type === 'ConstTag') {
-			context.visit(child, { ...context.state, consts: const_tags });
+			has_const = true;
+			if (!context.state.options.experimental.async) {
+				context.visit(child, { ...context.state, consts: const_tags });
+			}
 		}
 	}
 
 	for (const child of node.fragment.nodes) {
 		if (child.type === 'ConstTag') {
+			if (context.state.options.experimental.async) {
+				nodes.push(child);
+			}
 			continue;
 		}
 
 		if (child.type === 'SnippetBlock') {
-			/** @type {Statement[]} */
-			const statements = [];
-
-			context.visit(child, { ...context.state, init: statements });
-
-			const snippet = /** @type {VariableDeclaration} */ (statements[0]);
-
-			const snippet_fn = dev
-				? // @ts-expect-error we know this shape is correct
-					snippet.declarations[0].init.arguments[1]
-				: snippet.declarations[0].init;
-
-			snippet_fn.body.body.unshift(
-				...const_tags.filter((node) => node.type === 'VariableDeclaration')
-			);
-
-			hoisted.push(snippet);
-
-			if (['failed', 'pending'].includes(child.expression.name)) {
-				props.properties.push(b.prop('init', child.expression, child.expression));
+			if (
+				context.state.options.experimental.async &&
+				has_const &&
+				!['failed', 'pending'].includes(child.expression.name)
+			) {
+				// we can't hoist snippets as they may reference const tags, so we just keep them in the fragment
+				nodes.push(child);
+			} else {
+				/** @type {Statement[]} */
+				const statements = [];
+
+				context.visit(child, { ...context.state, init: statements });
+
+				const snippet = /** @type {VariableDeclaration} */ (statements[0]);
+
+				const snippet_fn = dev
+					? // @ts-expect-error we know this shape is correct
+						snippet.declarations[0].init.arguments[1]
+					: snippet.declarations[0].init;
+
+				if (!context.state.options.experimental.async) {
+					snippet_fn.body.body.unshift(
+						...const_tags.filter((node) => node.type === 'VariableDeclaration')
+					);
+				}
+
+				if (['failed', 'pending'].includes(child.expression.name)) {
+					props.properties.push(b.prop('init', child.expression, child.expression));
+				}
+
+				hoisted.push(snippet);
 			}
 
 			continue;
@@ -83,7 +103,9 @@ export function SvelteBoundary(node, context) {
 
 	const block = /** @type {BlockStatement} */ (context.visit({ ...node.fragment, nodes }));
 
-	block.body.unshift(...const_tags);
+	if (!context.state.options.experimental.async) {
+		block.body.unshift(...const_tags);
+	}
 
 	const boundary = b.stmt(
 		b.call('$.boundary', context.state.node, props, b.arrow([b.id('$$anchor')], block))
diff --git a/packages/svelte/src/compiler/phases/nodes.js b/packages/svelte/src/compiler/phases/nodes.js
index 4874554ff0..f4127db359 100644
--- a/packages/svelte/src/compiler/phases/nodes.js
+++ b/packages/svelte/src/compiler/phases/nodes.js
@@ -23,6 +23,15 @@ export function is_element_node(node) {
 	return element_nodes.includes(node.type);
 }
 
+/**
+ * Returns true for all component-like nodes
+ * @param {AST.SvelteNode} node
+ * @returns {node is AST.Component |  AST.SvelteComponent | AST.SvelteSelf}
+ */
+export function is_component_node(node) {
+	return ['Component', 'SvelteComponent', 'SvelteSelf'].includes(node.type);
+}
+
 /**
  * @param {AST.RegularElement | AST.SvelteElement} node
  * @returns {boolean}
diff --git a/packages/svelte/src/compiler/phases/scope.js b/packages/svelte/src/compiler/phases/scope.js
index f88f5ef8b1..76157d406f 100644
--- a/packages/svelte/src/compiler/phases/scope.js
+++ b/packages/svelte/src/compiler/phases/scope.js
@@ -122,7 +122,7 @@ export class Binding {
 
 	/**
 	 * Additional metadata, varies per binding type
-	 * @type {null | { inside_rest?: boolean }}
+	 * @type {null | { inside_rest?: boolean; is_template_declaration?: boolean }}
 	 */
 	metadata = null;
 
@@ -1121,6 +1121,7 @@ export function create_scopes(ast, root, allow_reactive_declarations, parent) {
 						node.kind,
 						declarator.init
 					);
+					binding.metadata = { is_template_declaration: true };
 					bindings.push(binding);
 				}
 			}
diff --git a/packages/svelte/tests/compiler-errors/samples/const-tag-snippet-invalid-reference-1/_config.js b/packages/svelte/tests/compiler-errors/samples/const-tag-snippet-invalid-reference-1/_config.js
new file mode 100644
index 0000000000..7424278180
--- /dev/null
+++ b/packages/svelte/tests/compiler-errors/samples/const-tag-snippet-invalid-reference-1/_config.js
@@ -0,0 +1,10 @@
+import { test } from '../../test';
+
+export default test({
+	async: true,
+	error: {
+		code: 'const_tag_invalid_reference',
+		message: 'The `{@const foo = ...}` declaration is not available in this snippet ',
+		position: [376, 379]
+	}
+});
diff --git a/packages/svelte/tests/compiler-errors/samples/const-tag-snippet-invalid-reference-1/main.svelte b/packages/svelte/tests/compiler-errors/samples/const-tag-snippet-invalid-reference-1/main.svelte
new file mode 100644
index 0000000000..a2533e33b0
--- /dev/null
+++ b/packages/svelte/tests/compiler-errors/samples/const-tag-snippet-invalid-reference-1/main.svelte
@@ -0,0 +1,32 @@
+<svelte:options runes />
+
+<!-- ok -->
+<svelte:boundary>
+	{@const foo = 'bar'}
+
+	{#snippet other()}
+		{foo}
+	{/snippet}
+
+	{foo}
+
+	<svelte:boundary>
+		{#snippet failed()}
+			{foo}
+		{/snippet}
+	</svelte:boundary>
+
+	{#snippet failed()}
+		{@const foo = 'bar'}
+		{foo}
+	{/snippet}
+</svelte:boundary>
+
+<!-- error -->
+<svelte:boundary>
+	{@const foo = 'bar'}
+
+	{#snippet failed()}
+		{foo}
+	{/snippet}
+</svelte:boundary>
diff --git a/packages/svelte/tests/compiler-errors/samples/const-tag-snippet-invalid-reference-2/_config.js b/packages/svelte/tests/compiler-errors/samples/const-tag-snippet-invalid-reference-2/_config.js
new file mode 100644
index 0000000000..7ff71a61f9
--- /dev/null
+++ b/packages/svelte/tests/compiler-errors/samples/const-tag-snippet-invalid-reference-2/_config.js
@@ -0,0 +1,10 @@
+import { test } from '../../test';
+
+export default test({
+	async: true,
+	error: {
+		code: 'const_tag_invalid_reference',
+		message: 'The `{@const foo = ...}` declaration is not available in this snippet ',
+		position: [298, 301]
+	}
+});
diff --git a/packages/svelte/tests/compiler-errors/samples/const-tag-snippet-invalid-reference-2/main.svelte b/packages/svelte/tests/compiler-errors/samples/const-tag-snippet-invalid-reference-2/main.svelte
new file mode 100644
index 0000000000..c59df28ec9
--- /dev/null
+++ b/packages/svelte/tests/compiler-errors/samples/const-tag-snippet-invalid-reference-2/main.svelte
@@ -0,0 +1,27 @@
+<svelte:options runes />
+
+<!-- ok -->
+<Component>
+	{@const foo = 'bar'}
+	{foo}
+
+	<Component>
+		{#snippet prop()}
+			{foo}
+		{/snippet}
+	</Component>
+
+	{#snippet prop()}
+		{@const foo = 'bar'}
+		{foo}
+	{/snippet}
+</Component>
+
+<!-- error -->
+<Component>
+	{@const foo = 'bar'}
+
+	{#snippet prop()}
+		{foo}
+	{/snippet}
+</Component>
diff --git a/packages/svelte/tests/compiler-errors/test.ts b/packages/svelte/tests/compiler-errors/test.ts
index 13b9280dde..b3a2d4af31 100644
--- a/packages/svelte/tests/compiler-errors/test.ts
+++ b/packages/svelte/tests/compiler-errors/test.ts
@@ -5,6 +5,7 @@ import { suite, type BaseTest } from '../suite';
 import { read_file } from '../helpers.js';
 
 interface CompilerErrorTest extends BaseTest {
+	async?: boolean;
 	error: {
 		code: string;
 		message: string;
@@ -29,7 +30,8 @@ const { test, run } = suite<CompilerErrorTest>((config, cwd) => {
 
 		try {
 			compile(read_file(`${cwd}/main.svelte`), {
-				generate: 'client'
+				generate: 'client',
+				experimental: { async: config.async ?? false }
 			});
 		} catch (e) {
 			const error = e as CompileError;
diff --git a/packages/svelte/tests/runtime-runes/samples/async-const/_config.js b/packages/svelte/tests/runtime-runes/samples/async-const/_config.js
index 084d9c3874..8aeca875f3 100644
--- a/packages/svelte/tests/runtime-runes/samples/async-const/_config.js
+++ b/packages/svelte/tests/runtime-runes/samples/async-const/_config.js
@@ -7,6 +7,6 @@ export default test({
 	async test({ assert, target }) {
 		await tick();
 
-		assert.htmlEqual(target.innerHTML, `<h1>Hello, world!</h1>`);
+		assert.htmlEqual(target.innerHTML, `<h1>Hello, world!</h1> 5 01234`);
 	}
 });
diff --git a/packages/svelte/tests/runtime-runes/samples/async-const/main.svelte b/packages/svelte/tests/runtime-runes/samples/async-const/main.svelte
index 9321bd7929..7410ff6a6f 100644
--- a/packages/svelte/tests/runtime-runes/samples/async-const/main.svelte
+++ b/packages/svelte/tests/runtime-runes/samples/async-const/main.svelte
@@ -3,6 +3,8 @@
 </script>
 
 <svelte:boundary>
+	{@const number = await Promise.resolve(5)}
+
 	{#snippet pending()}
 		<h1>Loading...</h1>
 	{/snippet}
@@ -10,6 +12,14 @@
 	{#snippet greet()}
 		{@const greeting = await `Hello, ${name}!`}
 		<h1>{greeting}</h1>
+		{number}
+		{#if number > 4}
+			{@const length = await number}
+			{#each { length }, index}
+				{@const i = await index}
+				{i}
+			{/each}
+		{/if}
 	{/snippet}
 
 	{@render greet()}
diff --git a/packages/svelte/tests/runtime-runes/samples/const-tag-boundary/FlakyComponent.svelte b/packages/svelte/tests/runtime-runes/samples/const-tag-boundary-deprecated-usage/FlakyComponent.svelte
similarity index 74%
rename from packages/svelte/tests/runtime-runes/samples/const-tag-boundary/FlakyComponent.svelte
rename to packages/svelte/tests/runtime-runes/samples/const-tag-boundary-deprecated-usage/FlakyComponent.svelte
index 8bbec90de4..ea60542af9 100644
--- a/packages/svelte/tests/runtime-runes/samples/const-tag-boundary/FlakyComponent.svelte
+++ b/packages/svelte/tests/runtime-runes/samples/const-tag-boundary-deprecated-usage/FlakyComponent.svelte
@@ -1,3 +1,3 @@
 <script>
 	throw new Error();
-</script>
\ No newline at end of file
+</script>
diff --git a/packages/svelte/tests/runtime-runes/samples/const-tag-boundary-deprecated-usage/_config.js b/packages/svelte/tests/runtime-runes/samples/const-tag-boundary-deprecated-usage/_config.js
new file mode 100644
index 0000000000..915bda91f3
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/const-tag-boundary-deprecated-usage/_config.js
@@ -0,0 +1,18 @@
+import { flushSync } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+	skip_async: true,
+	html: '<button></button><p>2</p>',
+	mode: ['client'],
+	test({ target, assert }) {
+		const btn = target.querySelector('button');
+		const p = target.querySelector('p');
+
+		flushSync(() => {
+			btn?.click();
+		});
+
+		assert.equal(p?.innerHTML, '4');
+	}
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/const-tag-boundary-deprecated-usage/main.svelte b/packages/svelte/tests/runtime-runes/samples/const-tag-boundary-deprecated-usage/main.svelte
new file mode 100644
index 0000000000..25ea8a3ffc
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/const-tag-boundary-deprecated-usage/main.svelte
@@ -0,0 +1,14 @@
+<script>
+	import FlakyComponent from "./FlakyComponent.svelte";
+	let test=$state(1);
+</script>
+
+<button onclick={()=>test++}></button>
+
+<svelte:boundary>
+	{@const double = test * 2}
+	{#snippet failed()}
+		<p>{double}</p>
+	{/snippet}
+	<FlakyComponent />
+</svelte:boundary>
\ No newline at end of file
diff --git a/packages/svelte/tests/runtime-runes/samples/const-tag-boundary/_config.js b/packages/svelte/tests/runtime-runes/samples/const-tag-boundary/_config.js
index 4338969a48..e4ffb4a850 100644
--- a/packages/svelte/tests/runtime-runes/samples/const-tag-boundary/_config.js
+++ b/packages/svelte/tests/runtime-runes/samples/const-tag-boundary/_config.js
@@ -2,7 +2,7 @@ import { flushSync } from 'svelte';
 import { test } from '../../test';
 
 export default test({
-	html: '<button></button><p>2</p>',
+	html: '<button>increment</button><p>2</p>',
 	mode: ['client'],
 	test({ target, assert }) {
 		const btn = target.querySelector('button');
diff --git a/packages/svelte/tests/runtime-runes/samples/const-tag-boundary/main.svelte b/packages/svelte/tests/runtime-runes/samples/const-tag-boundary/main.svelte
index 25ea8a3ffc..9605e12070 100644
--- a/packages/svelte/tests/runtime-runes/samples/const-tag-boundary/main.svelte
+++ b/packages/svelte/tests/runtime-runes/samples/const-tag-boundary/main.svelte
@@ -1,14 +1,10 @@
 <script>
-	import FlakyComponent from "./FlakyComponent.svelte";
-	let test=$state(1);
+	let count = $state(1);
 </script>
 
-<button onclick={()=>test++}></button>
+<button onclick={()=>count++}>increment</button>
 
 <svelte:boundary>
-	{@const double = test * 2}
-	{#snippet failed()}
-		<p>{double}</p>
-	{/snippet}
-	<FlakyComponent />
-</svelte:boundary>
\ No newline at end of file
+	{@const double = count * 2}
+	<p>{double}</p>
+</svelte:boundary>
diff --git a/packages/svelte/tests/validator/samples/const-tag-placement-svelte-boundary/input.svelte b/packages/svelte/tests/validator/samples/const-tag-placement-svelte-boundary/input.svelte
index 5708cc36ca..c965a379e5 100644
--- a/packages/svelte/tests/validator/samples/const-tag-placement-svelte-boundary/input.svelte
+++ b/packages/svelte/tests/validator/samples/const-tag-placement-svelte-boundary/input.svelte
@@ -4,8 +4,6 @@
 
 <svelte:boundary>
 	{@const x = a}
-	{#snippet failed()}
-		{x}
-	{/snippet}
+	{x}
 	<FlakyComponent />
-</svelte:boundary>
\ No newline at end of file
+</svelte:boundary>

From 11a2d8e9371b2a1b456f05af7cd4adc0bf212e62 Mon Sep 17 00:00:00 2001
From: ComputerGuy <63362464+Ocean-OS@users.noreply.github.com>
Date: Fri, 22 Aug 2025 11:33:48 -0700
Subject: [PATCH 57/60] fix: only emit `for_await_track_reactivity_loss` in
 async mode (#16644)

Helps with #16610  (but does not fix it yet)
---
 .changeset/tender-masks-bow.md                             | 5 +++++
 .../phases/3-transform/client/visitors/ForOfStatement.js   | 7 ++++++-
 2 files changed, 11 insertions(+), 1 deletion(-)
 create mode 100644 .changeset/tender-masks-bow.md

diff --git a/.changeset/tender-masks-bow.md b/.changeset/tender-masks-bow.md
new file mode 100644
index 0000000000..224db5fc37
--- /dev/null
+++ b/.changeset/tender-masks-bow.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: only emit `for_await_track_reactivity_loss` in async mode
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/ForOfStatement.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/ForOfStatement.js
index a5d2751812..8ae67f49d1 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/ForOfStatement.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/ForOfStatement.js
@@ -8,7 +8,12 @@ import { dev, is_ignored } from '../../../../state.js';
  * @param {ComponentContext} context
  */
 export function ForOfStatement(node, context) {
-	if (node.await && dev && !is_ignored(node, 'await_reactivity_loss')) {
+	if (
+		node.await &&
+		dev &&
+		!is_ignored(node, 'await_reactivity_loss') &&
+		context.state.options.experimental.async
+	) {
 		const left = /** @type {VariableDeclaration | Pattern} */ (context.visit(node.left));
 		const argument = /** @type {Expression} */ (context.visit(node.right));
 		const body = /** @type {Statement} */ (context.visit(node.body));

From acd9eaf2ec8d964fa5770fdbcd76e41809197848 Mon Sep 17 00:00:00 2001
From: Simon H <5968653+dummdidumm@users.noreply.github.com>
Date: Fri, 22 Aug 2025 22:37:57 +0200
Subject: [PATCH 58/60] fix: ensure correct order of template effect values
 (#16655)

Compiler does sync then async but `memoizer.apply` did it the other way around
---
 .changeset/healthy-crabs-marry.md               |  5 +++++
 .../3-transform/client/visitors/shared/utils.js |  2 +-
 .../async-template-async-sync-mixed/_config.js  |  9 +++++++++
 .../async-template-async-sync-mixed/main.svelte | 17 +++++++++++++++++
 4 files changed, 32 insertions(+), 1 deletion(-)
 create mode 100644 .changeset/healthy-crabs-marry.md
 create mode 100644 packages/svelte/tests/runtime-runes/samples/async-template-async-sync-mixed/_config.js
 create mode 100644 packages/svelte/tests/runtime-runes/samples/async-template-async-sync-mixed/main.svelte

diff --git a/.changeset/healthy-crabs-marry.md b/.changeset/healthy-crabs-marry.md
new file mode 100644
index 0000000000..eab29dae4a
--- /dev/null
+++ b/.changeset/healthy-crabs-marry.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: ensure correct order of template effect values
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/utils.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/utils.js
index 014547cf2d..ba140a153e 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/utils.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/shared/utils.js
@@ -34,7 +34,7 @@ export class Memoizer {
 	}
 
 	apply() {
-		return [...this.#async, ...this.#sync].map((memo, i) => {
+		return [...this.#sync, ...this.#async].map((memo, i) => {
 			memo.id.name = `$${i}`;
 			return memo.id;
 		});
diff --git a/packages/svelte/tests/runtime-runes/samples/async-template-async-sync-mixed/_config.js b/packages/svelte/tests/runtime-runes/samples/async-template-async-sync-mixed/_config.js
new file mode 100644
index 0000000000..709b88578f
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/async-template-async-sync-mixed/_config.js
@@ -0,0 +1,9 @@
+import { tick } from 'svelte';
+import { ok, test } from '../../test';
+
+export default test({
+	async test({ assert, target }) {
+		await tick();
+		assert.htmlEqual(target.innerHTML, '<p>foo bar</p>');
+	}
+});
diff --git a/packages/svelte/tests/runtime-runes/samples/async-template-async-sync-mixed/main.svelte b/packages/svelte/tests/runtime-runes/samples/async-template-async-sync-mixed/main.svelte
new file mode 100644
index 0000000000..2e0ae46f1f
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/async-template-async-sync-mixed/main.svelte
@@ -0,0 +1,17 @@
+<script>
+	function foo() {
+		return 'foo';
+	}
+
+	async function bar() {
+		return Promise.resolve('bar');
+	}
+</script>
+
+<svelte:boundary>
+	<p>{foo()} {await bar()}</p>
+
+	{#snippet pending()}
+		<p>pending</p>
+	{/snippet}
+</svelte:boundary>

From d3cb1482fe45a2b80b189856d8ab8a1f2c446bc6 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Sat, 23 Aug 2025 16:29:10 -0400
Subject: [PATCH 59/60] perf: better effect pruning (#16625)

* tweak

* prune effects where possible

* tweak

* simplify

* simplify

* changeset

* reset parent if necessary
---
 .changeset/tasty-lizards-care.md              |  5 ++
 .../src/internal/client/reactivity/effects.js | 57 +++++++++++--------
 2 files changed, 39 insertions(+), 23 deletions(-)
 create mode 100644 .changeset/tasty-lizards-care.md

diff --git a/.changeset/tasty-lizards-care.md b/.changeset/tasty-lizards-care.md
new file mode 100644
index 0000000000..b6aff07ffb
--- /dev/null
+++ b/.changeset/tasty-lizards-care.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+perf: prune effects without dependencies
diff --git a/packages/svelte/src/internal/client/reactivity/effects.js b/packages/svelte/src/internal/client/reactivity/effects.js
index df3dd75808..2c9e4db911 100644
--- a/packages/svelte/src/internal/client/reactivity/effects.js
+++ b/packages/svelte/src/internal/client/reactivity/effects.js
@@ -133,29 +133,40 @@ function create_effect(type, fn, sync, push = true) {
 		schedule_effect(effect);
 	}
 
-	// if an effect has no dependencies, no DOM and no teardown function,
-	// don't bother adding it to the effect tree
-	var inert =
-		sync &&
-		effect.deps === null &&
-		effect.first === null &&
-		effect.nodes_start === null &&
-		effect.teardown === null &&
-		(effect.f & EFFECT_PRESERVED) === 0;
-
-	if (!inert && push) {
-		if (parent !== null) {
-			push_effect(effect, parent);
-		}
+	if (push) {
+		/** @type {Effect | null} */
+		var e = effect;
 
-		// if we're in a derived, add the effect there too
+		// if an effect has already ran and doesn't need to be kept in the tree
+		// (because it won't re-run, has no DOM, and has no teardown etc)
+		// then we skip it and go to its child (if any)
 		if (
-			active_reaction !== null &&
-			(active_reaction.f & DERIVED) !== 0 &&
-			(type & ROOT_EFFECT) === 0
+			sync &&
+			e.deps === null &&
+			e.teardown === null &&
+			e.nodes_start === null &&
+			e.first === e.last && // either `null`, or a singular child
+			(e.f & EFFECT_PRESERVED) === 0
 		) {
-			var derived = /** @type {Derived} */ (active_reaction);
-			(derived.effects ??= []).push(effect);
+			e = e.first;
+		}
+
+		if (e !== null) {
+			e.parent = parent;
+
+			if (parent !== null) {
+				push_effect(e, parent);
+			}
+
+			// if we're in a derived, add the effect there too
+			if (
+				active_reaction !== null &&
+				(active_reaction.f & DERIVED) !== 0 &&
+				(type & ROOT_EFFECT) === 0
+			) {
+				var derived = /** @type {Derived} */ (active_reaction);
+				(derived.effects ??= []).push(e);
+			}
 		}
 	}
 
@@ -242,7 +253,7 @@ export function inspect_effect(fn) {
  */
 export function effect_root(fn) {
 	Batch.ensure();
-	const effect = create_effect(ROOT_EFFECT, fn, true);
+	const effect = create_effect(ROOT_EFFECT | EFFECT_PRESERVED, fn, true);
 
 	return () => {
 		destroy_effect(effect);
@@ -256,7 +267,7 @@ export function effect_root(fn) {
  */
 export function component_root(fn) {
 	Batch.ensure();
-	const effect = create_effect(ROOT_EFFECT, fn, true);
+	const effect = create_effect(ROOT_EFFECT | EFFECT_PRESERVED, fn, true);
 
 	return (options = {}) => {
 		return new Promise((fulfil) => {
@@ -375,7 +386,7 @@ export function block(fn, flags = 0) {
  * @param {boolean} [push]
  */
 export function branch(fn, push = true) {
-	return create_effect(BRANCH_EFFECT, fn, true, push);
+	return create_effect(BRANCH_EFFECT | EFFECT_PRESERVED, fn, true, push);
 }
 
 /**

From e883cd086bd5f93b086220c7f2e2304bcb958eb8 Mon Sep 17 00:00:00 2001
From: "github-actions[bot]"
 <41898282+github-actions[bot]@users.noreply.github.com>
Date: Sat, 23 Aug 2025 14:24:51 -0700
Subject: [PATCH 60/60] Version Packages (#16642)

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
---
 .changeset/healthy-crabs-marry.md |  5 -----
 .changeset/light-camels-push.md   |  5 -----
 .changeset/silent-suns-whisper.md |  5 -----
 .changeset/tasty-lizards-care.md  |  5 -----
 .changeset/tender-masks-bow.md    |  5 -----
 packages/svelte/CHANGELOG.md      | 14 ++++++++++++++
 packages/svelte/package.json      |  2 +-
 packages/svelte/src/version.js    |  2 +-
 8 files changed, 16 insertions(+), 27 deletions(-)
 delete mode 100644 .changeset/healthy-crabs-marry.md
 delete mode 100644 .changeset/light-camels-push.md
 delete mode 100644 .changeset/silent-suns-whisper.md
 delete mode 100644 .changeset/tasty-lizards-care.md
 delete mode 100644 .changeset/tender-masks-bow.md

diff --git a/.changeset/healthy-crabs-marry.md b/.changeset/healthy-crabs-marry.md
deleted file mode 100644
index eab29dae4a..0000000000
--- a/.changeset/healthy-crabs-marry.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-'svelte': patch
----
-
-fix: ensure correct order of template effect values
diff --git a/.changeset/light-camels-push.md b/.changeset/light-camels-push.md
deleted file mode 100644
index cac7f5a51e..0000000000
--- a/.changeset/light-camels-push.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-'svelte': patch
----
-
-fix: allow async `{@const}` in more places
diff --git a/.changeset/silent-suns-whisper.md b/.changeset/silent-suns-whisper.md
deleted file mode 100644
index 7ee7d74abc..0000000000
--- a/.changeset/silent-suns-whisper.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-'svelte': patch
----
-
-fix: properly catch top level await errors
diff --git a/.changeset/tasty-lizards-care.md b/.changeset/tasty-lizards-care.md
deleted file mode 100644
index b6aff07ffb..0000000000
--- a/.changeset/tasty-lizards-care.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-'svelte': patch
----
-
-perf: prune effects without dependencies
diff --git a/.changeset/tender-masks-bow.md b/.changeset/tender-masks-bow.md
deleted file mode 100644
index 224db5fc37..0000000000
--- a/.changeset/tender-masks-bow.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-'svelte': patch
----
-
-fix: only emit `for_await_track_reactivity_loss` in async mode
diff --git a/packages/svelte/CHANGELOG.md b/packages/svelte/CHANGELOG.md
index cd6a4a916c..fb6b20c489 100644
--- a/packages/svelte/CHANGELOG.md
+++ b/packages/svelte/CHANGELOG.md
@@ -1,5 +1,19 @@
 # svelte
 
+## 5.38.3
+
+### Patch Changes
+
+- fix: ensure correct order of template effect values ([#16655](https://github.com/sveltejs/svelte/pull/16655))
+
+- fix: allow async `{@const}` in more places ([#16643](https://github.com/sveltejs/svelte/pull/16643))
+
+- fix: properly catch top level await errors ([#16619](https://github.com/sveltejs/svelte/pull/16619))
+
+- perf: prune effects without dependencies ([#16625](https://github.com/sveltejs/svelte/pull/16625))
+
+- fix: only emit `for_await_track_reactivity_loss` in async mode ([#16644](https://github.com/sveltejs/svelte/pull/16644))
+
 ## 5.38.2
 
 ### Patch Changes
diff --git a/packages/svelte/package.json b/packages/svelte/package.json
index fc7db9598d..b7effe35bd 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": "5.38.2",
+  "version": "5.38.3",
   "type": "module",
   "types": "./types/index.d.ts",
   "engines": {
diff --git a/packages/svelte/src/version.js b/packages/svelte/src/version.js
index 2aa62504a5..815b25bf1f 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 = '5.38.2';
+export const VERSION = '5.38.3';
 export const PUBLIC_VERSION = '5';