From facf528cb8a7289c8b3eaf036949a515f5ad2108 Mon Sep 17 00:00:00 2001
From: brunnerh <brunnerh@users.noreply.github.com>
Date: Wed, 25 Jun 2025 20:35:48 +0200
Subject: [PATCH 1/8] docs: Simplify TS config docs (#16236)

* Simplify TypeScript config requirements

Assignments are allowed in the constructor from 5.31.0 onward, so retaining the classes via ES2015 should be enough.

* Add  back a little bit of detail.
---
 documentation/docs/07-misc/03-typescript.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/documentation/docs/07-misc/03-typescript.md b/documentation/docs/07-misc/03-typescript.md
index fbf8817069..ff33885fb8 100644
--- a/documentation/docs/07-misc/03-typescript.md
+++ b/documentation/docs/07-misc/03-typescript.md
@@ -83,7 +83,7 @@ If you're using tools like Rollup or Webpack instead, install their respective S
 
 When using TypeScript, make sure your `tsconfig.json` is setup correctly.
 
-- Use a [`target`](https://www.typescriptlang.org/tsconfig/#target) of at least `ES2022`, or a `target` of at least `ES2015` alongside [`useDefineForClassFields`](https://www.typescriptlang.org/tsconfig/#useDefineForClassFields). This ensures that rune declarations on class fields are not messed with, which would break the Svelte compiler
+- Use a [`target`](https://www.typescriptlang.org/tsconfig/#target) of at least `ES2015` so classes are not compiled to functions
 - Set [`verbatimModuleSyntax`](https://www.typescriptlang.org/tsconfig/#verbatimModuleSyntax) to `true` so that imports are left as-is
 - Set [`isolatedModules`](https://www.typescriptlang.org/tsconfig/#isolatedModules) to `true` so that each file is looked at in isolation. TypeScript has a few features which require cross-file analysis and compilation, which the Svelte compiler and tooling like Vite don't do. 
 

From 0b2b9c724fef657af9371089e468d5c49c209e36 Mon Sep 17 00:00:00 2001
From: 7nik <kifiranet@gmail.com>
Date: Wed, 25 Jun 2025 21:38:26 +0300
Subject: [PATCH 2/8] chore: adjust linting (#16231)

* chore: adjust linting

* more nice treeshaking failure message

* lint
---
 .prettierignore                               |  4 +-
 eslint.config.js                              |  1 +
 .../svelte/scripts/check-treeshakeability.js  | 50 ++++++++++---------
 3 files changed, 30 insertions(+), 25 deletions(-)

diff --git a/.prettierignore b/.prettierignore
index d5c124353c..72cd10aca8 100644
--- a/.prettierignore
+++ b/.prettierignore
@@ -7,6 +7,7 @@ packages/**/config/*.js
 
 # packages/svelte
 packages/svelte/messages/**/*.md
+packages/svelte/scripts/_bundle.js
 packages/svelte/src/compiler/errors.js
 packages/svelte/src/compiler/warnings.js
 packages/svelte/src/internal/client/errors.js
@@ -25,8 +26,7 @@ packages/svelte/tests/hydration/samples/*/_expected.html
 packages/svelte/tests/hydration/samples/*/_override.html
 packages/svelte/types
 packages/svelte/compiler/index.js
-playgrounds/sandbox/input/**.svelte
-playgrounds/sandbox/output
+playgrounds/sandbox/src/*
 
 # sites/svelte.dev
 sites/svelte.dev/static/svelte-app.json
diff --git a/eslint.config.js b/eslint.config.js
index d6c977a36a..d7044fc9f1 100644
--- a/eslint.config.js
+++ b/eslint.config.js
@@ -87,6 +87,7 @@ export default [
 			'**/*.d.ts',
 			'**/tests',
 			'packages/svelte/scripts/process-messages/templates/*.js',
+			'packages/svelte/scripts/_bundle.js',
 			'packages/svelte/src/compiler/errors.js',
 			'packages/svelte/src/internal/client/errors.js',
 			'packages/svelte/src/internal/client/warnings.js',
diff --git a/packages/svelte/scripts/check-treeshakeability.js b/packages/svelte/scripts/check-treeshakeability.js
index 1501ee6954..e883496fe2 100644
--- a/packages/svelte/scripts/check-treeshakeability.js
+++ b/packages/svelte/scripts/check-treeshakeability.js
@@ -118,36 +118,40 @@ const bundle = await bundle_code(
 	).js.code
 );
 
-if (!bundle.includes('hydrate_node') && !bundle.includes('hydrate_next')) {
-	// eslint-disable-next-line no-console
-	console.error(`✅ Hydration code treeshakeable`);
-} else {
-	failed = true;
-	// eslint-disable-next-line no-console
-	console.error(`❌ Hydration code not treeshakeable`);
-}
+/**
+ * @param {string} case_name
+ * @param {string[]} strings
+ */
+function check_bundle(case_name, ...strings) {
+	for (const string of strings) {
+		const index = bundle.indexOf(string);
+		if (index >= 0) {
+			// eslint-disable-next-line no-console
+			console.error(`❌ ${case_name} not treeshakeable`);
+			failed = true;
 
-if (!bundle.includes('component_context.l')) {
-	// eslint-disable-next-line no-console
-	console.error(`✅ Legacy code treeshakeable`);
-} else {
-	failed = true;
+			let lines = bundle.slice(index - 500, index + 500).split('\n');
+			const target_line = lines.findIndex((line) => line.includes(string));
+			// mark the failed line
+			lines = lines
+				.map((line, i) => (i === target_line ? `> ${line}` : `| ${line}`))
+				.slice(target_line - 5, target_line + 6);
+			// eslint-disable-next-line no-console
+			console.error('The first failed line:\n' + lines.join('\n'));
+			return;
+		}
+	}
 	// eslint-disable-next-line no-console
-	console.error(`❌ Legacy code not treeshakeable`);
+	console.error(`✅ ${case_name} treeshakeable`);
 }
 
-if (!bundle.includes(`'CreatedAt'`)) {
-	// eslint-disable-next-line no-console
-	console.error(`✅ $inspect.trace code treeshakeable`);
-} else {
-	failed = true;
-	// eslint-disable-next-line no-console
-	console.error(`❌ $inspect.trace code not treeshakeable`);
-}
+check_bundle('Hydration code', 'hydrate_node', 'hydrate_next');
+check_bundle('Legacy code', 'component_context.l');
+check_bundle('$inspect.trace', `'CreatedAt'`);
 
 if (failed) {
 	// eslint-disable-next-line no-console
-	console.error(bundle);
+	console.error('Full bundle at', path.resolve('scripts/_bundle.js'));
 	fs.writeFileSync('scripts/_bundle.js', bundle);
 }
 

From da2feafe6765d2278ff053f62e6603a60b06833e Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Wed, 25 Jun 2025 14:40:52 -0400
Subject: [PATCH 3/8] chore: silence some pesky logs (#16241)

---
 .../samples/inspect-state-unsafe-mutation/_config.js        | 6 +++++-
 .../legacy-runes-ambiguous-export-labeled/_config.js        | 2 +-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/packages/svelte/tests/runtime-runes/samples/inspect-state-unsafe-mutation/_config.js b/packages/svelte/tests/runtime-runes/samples/inspect-state-unsafe-mutation/_config.js
index 7e8fcd2d48..dcf3a8bc3d 100644
--- a/packages/svelte/tests/runtime-runes/samples/inspect-state-unsafe-mutation/_config.js
+++ b/packages/svelte/tests/runtime-runes/samples/inspect-state-unsafe-mutation/_config.js
@@ -5,5 +5,9 @@ export default test({
 	compileOptions: {
 		dev: true
 	},
-	error: 'state_unsafe_mutation'
+
+	error: 'state_unsafe_mutation',
+
+	// silence the logs
+	test({ logs }) {}
 });
diff --git a/packages/svelte/tests/runtime-runes/samples/legacy-runes-ambiguous-export-labeled/_config.js b/packages/svelte/tests/runtime-runes/samples/legacy-runes-ambiguous-export-labeled/_config.js
index 904fea3f65..c4cff665d2 100644
--- a/packages/svelte/tests/runtime-runes/samples/legacy-runes-ambiguous-export-labeled/_config.js
+++ b/packages/svelte/tests/runtime-runes/samples/legacy-runes-ambiguous-export-labeled/_config.js
@@ -6,7 +6,7 @@ export default test({
 	compileOptions: {
 		runes: undefined
 	},
-	async test({ assert, target }) {
+	async test({ assert, target, logs }) {
 		const p = target.querySelector('p');
 		const btn = target.querySelector('button');
 		flushSync(() => {

From 213274a75ecc71dd86a31ba2dab4f594fc2cd265 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Thu, 26 Jun 2025 18:23:10 -0400
Subject: [PATCH 4/8] chore: reduce some select.value indirection (#16250)

---
 .../client/visitors/RegularElement.js         | 21 ++++++++-----------
 .../client/visitors/shared/utils.js           | 14 -------------
 2 files changed, 9 insertions(+), 26 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/RegularElement.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/RegularElement.js
index 1aefff0db0..b0f285eb41 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/RegularElement.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/RegularElement.js
@@ -25,7 +25,6 @@ import { process_children } from './shared/fragment.js';
 import {
 	build_render_statement,
 	build_template_chunk,
-	build_update_assignment,
 	get_expression_id,
 	memoize_expression
 } from './shared/utils.js';
@@ -657,17 +656,15 @@ function build_element_special_value_attribute(element, node_id, attribute, cont
 	}
 
 	if (has_state) {
-		const id = state.scope.generate(`${node_id.name}_value`);
-		build_update_assignment(
-			state,
-			id,
-			// `<option>` is a special case: The value property reflects to the DOM. If the value is set to undefined,
-			// that means the value should be set to the empty string. To be able to do that when the value is
-			// initially undefined, we need to set a value that is guaranteed to be different.
-			element === 'option' ? b.object([]) : undefined,
-			value,
-			update
-		);
+		const id = b.id(state.scope.generate(`${node_id.name}_value`));
+
+		// `<option>` is a special case: The value property reflects to the DOM. If the value is set to undefined,
+		// that means the value should be set to the empty string. To be able to do that when the value is
+		// initially undefined, we need to set a value that is guaranteed to be different.
+		const init = element === 'option' ? b.object([]) : undefined;
+
+		state.init.push(b.var(id, init));
+		state.update.push(b.if(b.binary('!==', id, b.assignment('=', id, value)), b.block([update])));
 	} else {
 		state.init.push(update);
 	}
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 c861a51b7d..0bd9bfb128 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
@@ -165,20 +165,6 @@ export function parse_directive_name(name) {
 	return expression;
 }
 
-/**
- * @param {ComponentClientTransformState} state
- * @param {string} id
- * @param {Expression | undefined} init
- * @param {Expression} value
- * @param {ExpressionStatement} update
- */
-export function build_update_assignment(state, id, init, value, update) {
-	state.init.push(b.var(id, init));
-	state.update.push(
-		b.if(b.binary('!==', b.id(id), b.assignment('=', b.id(id), value)), b.block([update]))
-	);
-}
-
 /**
  * Serializes `bind:this` for components and elements.
  * @param {Identifier | MemberExpression | SequenceExpression} expression

From 32481bece6018887bd6291b80a4133ebc0a601eb Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Thu, 26 Jun 2025 19:59:30 -0400
Subject: [PATCH 5/8] chore: simplify `<select>` initialization (#16251)

* initialize option values before initing select values

* simplify init_select

* simplify

* tweak

* tidy up

* tweak

* on second thoughts just simplify it here
---
 .../client/visitors/RegularElement.js         | 46 ++++++++--------
 .../client/dom/elements/attributes.js         | 12 ++--
 .../client/dom/elements/bindings/select.js    | 55 +++++++------------
 3 files changed, 50 insertions(+), 63 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/RegularElement.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/RegularElement.js
index b0f285eb41..ae8680f594 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/RegularElement.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/RegularElement.js
@@ -22,12 +22,7 @@ import {
 	build_set_style
 } from './shared/element.js';
 import { process_children } from './shared/fragment.js';
-import {
-	build_render_statement,
-	build_template_chunk,
-	get_expression_id,
-	memoize_expression
-} from './shared/utils.js';
+import { build_render_statement, build_template_chunk, get_expression_id } from './shared/utils.js';
 import { visit_event_attribute } from './shared/events.js';
 
 /**
@@ -199,16 +194,16 @@ export function RegularElement(node, context) {
 
 	const node_id = context.state.node;
 
+	/** If true, needs `__value` for inputs */
+	const needs_special_value_handling =
+		node.name === 'option' ||
+		node.name === 'select' ||
+		bindings.has('group') ||
+		bindings.has('checked');
+
 	if (has_spread) {
 		build_attribute_effect(attributes, class_directives, style_directives, context, node, node_id);
 	} else {
-		/** If true, needs `__value` for inputs */
-		const needs_special_value_handling =
-			node.name === 'option' ||
-			node.name === 'select' ||
-			bindings.has('group') ||
-			bindings.has('checked');
-
 		for (const attribute of /** @type {AST.Attribute[]} */ (attributes)) {
 			if (is_event_attribute(attribute)) {
 				visit_event_attribute(attribute, context);
@@ -216,7 +211,6 @@ export function RegularElement(node, context) {
 			}
 
 			if (needs_special_value_handling && attribute.name === 'value') {
-				build_element_special_value_attribute(node.name, node_id, attribute, context);
 				continue;
 			}
 
@@ -391,6 +385,15 @@ export function RegularElement(node, context) {
 		context.state.update.push(b.stmt(b.assignment('=', dir, dir)));
 	}
 
+	if (!has_spread && needs_special_value_handling) {
+		for (const attribute of /** @type {AST.Attribute[]} */ (attributes)) {
+			if (attribute.name === 'value') {
+				build_element_special_value_attribute(node.name, node_id, attribute, context);
+				break;
+			}
+		}
+	}
+
 	context.state.template.pop_element();
 }
 
@@ -621,12 +624,7 @@ function build_element_special_value_attribute(element, node_id, attribute, cont
 		element === 'select' && attribute.value !== true && !is_text_attribute(attribute);
 
 	const { value, has_state } = build_attribute_value(attribute.value, context, (value, metadata) =>
-		metadata.has_call
-			? // if is a select with value we will also invoke `init_select` which need a reference before the template effect so we memoize separately
-				is_select_with_value
-				? memoize_expression(state, value)
-				: get_expression_id(state.expressions, value)
-			: value
+		metadata.has_call ? get_expression_id(state.expressions, value) : value
 	);
 
 	const evaluated = context.state.scope.evaluate(value);
@@ -651,10 +649,6 @@ function build_element_special_value_attribute(element, node_id, attribute, cont
 			: inner_assignment
 	);
 
-	if (is_select_with_value) {
-		state.init.push(b.stmt(b.call('$.init_select', node_id, b.thunk(value))));
-	}
-
 	if (has_state) {
 		const id = b.id(state.scope.generate(`${node_id.name}_value`));
 
@@ -668,4 +662,8 @@ function build_element_special_value_attribute(element, node_id, attribute, cont
 	} else {
 		state.init.push(update);
 	}
+
+	if (is_select_with_value) {
+		state.init.push(b.stmt(b.call('$.init_select', node_id)));
+	}
 }
diff --git a/packages/svelte/src/internal/client/dom/elements/attributes.js b/packages/svelte/src/internal/client/dom/elements/attributes.js
index 2d3d6a921d..5db685cf3e 100644
--- a/packages/svelte/src/internal/client/dom/elements/attributes.js
+++ b/packages/svelte/src/internal/client/dom/elements/attributes.js
@@ -20,7 +20,7 @@ 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 { block, branch, destroy_effect } from '../../reactivity/effects.js';
+import { block, branch, destroy_effect, effect } from '../../reactivity/effects.js';
 import { derived } from '../../reactivity/deriveds.js';
 import { init_select, select_option } from './bindings/select.js';
 
@@ -513,10 +513,12 @@ export function attribute_effect(
 	});
 
 	if (is_select) {
-		init_select(
-			/** @type {HTMLSelectElement} */ (element),
-			() => /** @type {Record<string | symbol, any>} */ (prev).value
-		);
+		var select = /** @type {HTMLSelectElement} */ (element);
+
+		effect(() => {
+			select_option(select, /** @type {Record<string | symbol, any>} */ (prev).value);
+			init_select(select);
+		});
 	}
 
 	inited = true;
diff --git a/packages/svelte/src/internal/client/dom/elements/bindings/select.js b/packages/svelte/src/internal/client/dom/elements/bindings/select.js
index e3263c65af..5e89686d86 100644
--- a/packages/svelte/src/internal/client/dom/elements/bindings/select.js
+++ b/packages/svelte/src/internal/client/dom/elements/bindings/select.js
@@ -1,6 +1,5 @@
-import { effect } from '../../../reactivity/effects.js';
+import { effect, teardown } from '../../../reactivity/effects.js';
 import { listen_to_event_and_reset_event } from './shared.js';
-import { untrack } from '../../../runtime.js';
 import { is } from '../../../proxy.js';
 import { is_array } from '../../../../shared/utils.js';
 import * as w from '../../../warnings.js';
@@ -51,40 +50,29 @@ export function select_option(select, value, mounting) {
  * current selection to the dom when it changes. Such
  * changes could for example occur when options are
  * inside an `#each` block.
- * @template V
  * @param {HTMLSelectElement} select
- * @param {() => V} [get_value]
  */
-export function init_select(select, get_value) {
-	let mounting = true;
-	effect(() => {
-		if (get_value) {
-			select_option(select, untrack(get_value), mounting);
-		}
-		mounting = false;
+export function init_select(select) {
+	var observer = new MutationObserver(() => {
+		// @ts-ignore
+		select_option(select, select.__value);
+		// Deliberately don't update the potential binding value,
+		// the model should be preserved unless explicitly changed
+	});
+
+	observer.observe(select, {
+		// Listen to option element changes
+		childList: true,
+		subtree: true, // because of <optgroup>
+		// Listen to option element value attribute changes
+		// (doesn't get notified of select value changes,
+		// because that property is not reflected as an attribute)
+		attributes: true,
+		attributeFilter: ['value']
+	});
 
-		var observer = new MutationObserver(() => {
-			// @ts-ignore
-			var value = select.__value;
-			select_option(select, value);
-			// Deliberately don't update the potential binding value,
-			// the model should be preserved unless explicitly changed
-		});
-
-		observer.observe(select, {
-			// Listen to option element changes
-			childList: true,
-			subtree: true, // because of <optgroup>
-			// Listen to option element value attribute changes
-			// (doesn't get notified of select value changes,
-			// because that property is not reflected as an attribute)
-			attributes: true,
-			attributeFilter: ['value']
-		});
-
-		return () => {
-			observer.disconnect();
-		};
+	teardown(() => {
+		observer.disconnect();
 	});
 }
 
@@ -136,7 +124,6 @@ export function bind_select_value(select, get, set = get) {
 		mounting = false;
 	});
 
-	// don't pass get_value, we already initialize it in the effect above
 	init_select(select);
 }
 

From 7019894fd9231cefcc0b4bbd13b6a2d8bb90ccb3 Mon Sep 17 00:00:00 2001
From: Simon H <5968653+dummdidumm@users.noreply.github.com>
Date: Sat, 28 Jun 2025 01:37:23 +0200
Subject: [PATCH 6/8] fix: ensure unowned deriveds can add themselves as
 reactions while connected (#16249)

an unowned derived should still add itself as a reaction while it is properly connected, which means it can be cleaned up correctly - and this connection is indicated by it having reactions.

Fixes #15829 and potentially #15853
---
 .changeset/little-kings-smoke.md              |  5 +++
 .../svelte/src/internal/client/runtime.js     |  7 +++-
 packages/svelte/tests/signals/test.ts         | 39 +++++++++++++++++++
 3 files changed, 50 insertions(+), 1 deletion(-)
 create mode 100644 .changeset/little-kings-smoke.md

diff --git a/.changeset/little-kings-smoke.md b/.changeset/little-kings-smoke.md
new file mode 100644
index 0000000000..1e7f82352a
--- /dev/null
+++ b/.changeset/little-kings-smoke.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: ensure unowned deriveds can add themselves as reactions while connected
diff --git a/packages/svelte/src/internal/client/runtime.js b/packages/svelte/src/internal/client/runtime.js
index 56bc157f33..d057bfdf0d 100644
--- a/packages/svelte/src/internal/client/runtime.js
+++ b/packages/svelte/src/internal/client/runtime.js
@@ -294,7 +294,12 @@ export function update_reaction(reaction) {
 				reaction.deps = deps = new_deps;
 			}
 
-			if (!skip_reaction) {
+			if (
+				!skip_reaction ||
+				// Deriveds that already have reactions can cleanup, so we still add them as reactions
+				((flags & DERIVED) !== 0 &&
+					/** @type {import('#client').Derived} */ (reaction).reactions !== null)
+			) {
 				for (i = skipped_deps; i < deps.length; i++) {
 					(deps[i].reactions ??= []).push(reaction);
 				}
diff --git a/packages/svelte/tests/signals/test.ts b/packages/svelte/tests/signals/test.ts
index 78d7919e0f..719c936df0 100644
--- a/packages/svelte/tests/signals/test.ts
+++ b/packages/svelte/tests/signals/test.ts
@@ -112,6 +112,45 @@ describe('signals', () => {
 		};
 	});
 
+	test('unowned deriveds are not added as reactions but trigger effects', () => {
+		var obj = state<any>(undefined);
+
+		class C1 {
+			#v = state(0);
+			get v() {
+				return $.get(this.#v);
+			}
+			set v(v: number) {
+				set(this.#v, v);
+			}
+		}
+
+		return () => {
+			let d = derived(() => $.get(obj)?.v || '-');
+
+			const log: number[] = [];
+			assert.equal($.get(d), '-');
+
+			let destroy = effect_root(() => {
+				render_effect(() => {
+					log.push($.get(d));
+				});
+			});
+
+			set(obj, new C1());
+			flushSync();
+			assert.equal($.get(d), '-');
+			$.get(obj).v = 1;
+			flushSync();
+			assert.equal($.get(d), 1);
+			assert.deepEqual(log, ['-', 1]);
+			destroy();
+			// ensure we're not leaking reactions
+			assert.equal(obj.reactions, null);
+			assert.equal(d.reactions, null);
+		};
+	});
+
 	test('derived from state', () => {
 		const log: number[] = [];
 

From cf9f8c9c6b59544e0106634606d09a5e1a93375b Mon Sep 17 00:00:00 2001
From: "github-actions[bot]"
 <41898282+github-actions[bot]@users.noreply.github.com>
Date: Sat, 28 Jun 2025 10:35:51 +0200
Subject: [PATCH 7/8] Version Packages (#16257)

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
---
 .changeset/little-kings-smoke.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/little-kings-smoke.md

diff --git a/.changeset/little-kings-smoke.md b/.changeset/little-kings-smoke.md
deleted file mode 100644
index 1e7f82352a..0000000000
--- a/.changeset/little-kings-smoke.md
+++ /dev/null
@@ -1,5 +0,0 @@
----
-'svelte': patch
----
-
-fix: ensure unowned deriveds can add themselves as reactions while connected
diff --git a/packages/svelte/CHANGELOG.md b/packages/svelte/CHANGELOG.md
index e254be754f..ef64091ca3 100644
--- a/packages/svelte/CHANGELOG.md
+++ b/packages/svelte/CHANGELOG.md
@@ -1,5 +1,11 @@
 # svelte
 
+## 5.34.9
+
+### Patch Changes
+
+- fix: ensure unowned deriveds can add themselves as reactions while connected ([#16249](https://github.com/sveltejs/svelte/pull/16249))
+
 ## 5.34.8
 
 ### Patch Changes
diff --git a/packages/svelte/package.json b/packages/svelte/package.json
index 17a3e980c4..1d26663143 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": "5.34.8",
+  "version": "5.34.9",
   "type": "module",
   "types": "./types/index.d.ts",
   "engines": {
diff --git a/packages/svelte/src/version.js b/packages/svelte/src/version.js
index ec0126b17d..1c0aed6e87 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 = '5.34.8';
+export const VERSION = '5.34.9';
 export const PUBLIC_VERSION = '5';

From e896c55b6cc1ec9064cd32ec097ea31d717e29e4 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Mon, 30 Jun 2025 08:59:35 -0400
Subject: [PATCH 8/8] chore: bump esrap (#16240)

* chore: bump esrap

* regenerate
---
 packages/svelte/package.json                  |   4 +-
 .../svelte/scripts/process-messages/index.js  | 318 +++++++++---------
 packages/svelte/src/compiler/errors.js        |   6 +-
 packages/svelte/src/compiler/index.js         |   3 +-
 packages/svelte/src/compiler/legacy.js        |   1 +
 .../src/compiler/phases/1-parse/acorn.js      |  61 +++-
 .../src/compiler/phases/1-parse/index.js      |   2 +
 .../compiler/phases/1-parse/read/context.js   |  11 +-
 .../phases/1-parse/read/expression.js         |  24 +-
 .../compiler/phases/1-parse/read/script.js    |   2 +-
 .../src/compiler/phases/1-parse/state/tag.js  |   7 +-
 .../src/compiler/phases/2-analyze/index.js    |  14 +-
 .../3-transform/client/transform-client.js    |   3 +
 .../src/compiler/phases/3-transform/index.js  |  22 +-
 .../3-transform/server/transform-server.js    |   3 +
 .../svelte/src/compiler/phases/types.d.ts     |   2 +
 .../svelte/src/compiler/types/template.d.ts   |  15 +-
 .../svelte/src/compiler/utils/mapped_code.js  |   9 +-
 packages/svelte/src/compiler/warnings.js      |  21 +-
 packages/svelte/src/internal/client/errors.js |  24 +-
 .../svelte/src/internal/client/warnings.js    |  24 +-
 packages/svelte/src/internal/server/errors.js |   3 +
 packages/svelte/src/internal/shared/errors.js |   6 +
 .../svelte/src/internal/shared/warnings.js    |  10 +-
 packages/svelte/tests/parser-modern/test.ts   |   2 +
 .../_expected/client/index.svelte.js          |   1 +
 .../_expected/server/index.svelte.js          |   1 +
 .../_expected/client/main.svelte.js           |   1 +
 .../_expected/server/main.svelte.js           |   1 +
 .../_expected/client/index.svelte.js          |   2 +
 .../_expected/server/index.svelte.js          |   2 +
 .../_expected/client/index.svelte.js          |   1 +
 .../_expected/client/index.svelte.js          |   4 +-
 .../_expected/server/index.svelte.js          |   4 +-
 packages/svelte/types/index.d.ts              |  15 +-
 pnpm-lock.yaml                                |  10 +-
 36 files changed, 398 insertions(+), 241 deletions(-)

diff --git a/packages/svelte/package.json b/packages/svelte/package.json
index 1d26663143..2d88d2a051 100644
--- a/packages/svelte/package.json
+++ b/packages/svelte/package.json
@@ -164,14 +164,14 @@
   "dependencies": {
     "@ampproject/remapping": "^2.3.0",
     "@jridgewell/sourcemap-codec": "^1.5.0",
+    "@sveltejs/acorn-typescript": "^1.0.5",
     "@types/estree": "^1.0.5",
     "acorn": "^8.12.1",
-    "@sveltejs/acorn-typescript": "^1.0.5",
     "aria-query": "^5.3.1",
     "axobject-query": "^4.1.0",
     "clsx": "^2.1.1",
     "esm-env": "^1.2.1",
-    "esrap": "^1.4.8",
+    "esrap": "^2.0.0",
     "is-reference": "^3.0.3",
     "locate-character": "^3.0.0",
     "magic-string": "^0.30.11",
diff --git a/packages/svelte/scripts/process-messages/index.js b/packages/svelte/scripts/process-messages/index.js
index 81c59271de..e705a1c921 100644
--- a/packages/svelte/scripts/process-messages/index.js
+++ b/packages/svelte/scripts/process-messages/index.js
@@ -1,9 +1,14 @@
+/** @import { Node } from 'esrap/languages/ts' */
+/** @import * as ESTree from 'estree' */
+/** @import { AST } from 'svelte/compiler' */
+
 // @ts-check
 import process from 'node:process';
 import fs from 'node:fs';
 import * as acorn from 'acorn';
 import { walk } from 'zimmerframe';
 import * as esrap from 'esrap';
+import ts from 'esrap/languages/ts';
 
 const DIR = '../../documentation/docs/98-reference/.generated';
 
@@ -97,79 +102,49 @@ function run() {
 			.readFileSync(new URL(`./templates/${name}.js`, import.meta.url), 'utf-8')
 			.replace(/\r\n/g, '\n');
 
-		/**
-		 * @type {Array<{
-		 * 	type: string;
-		 * 	value: string;
-		 * 	start: number;
-		 * 	end: number
-		 * }>}
-		 */
+		/** @type {AST.JSComment[]} */
 		const comments = [];
 
-		let ast = acorn.parse(source, {
-			ecmaVersion: 'latest',
-			sourceType: 'module',
-			onComment: (block, value, start, end) => {
-				if (block && /\n/.test(value)) {
-					let a = start;
-					while (a > 0 && source[a - 1] !== '\n') a -= 1;
-
-					let b = a;
-					while (/[ \t]/.test(source[b])) b += 1;
-
-					const indentation = source.slice(a, b);
-					value = value.replace(new RegExp(`^${indentation}`, 'gm'), '');
-				}
+		let ast = /** @type {ESTree.Node} */ (
+			/** @type {unknown} */ (
+				acorn.parse(source, {
+					ecmaVersion: 'latest',
+					sourceType: 'module',
+					locations: true,
+					onComment: comments
+				})
+			)
+		);
 
-				comments.push({ type: block ? 'Block' : 'Line', value, start, end });
+		comments.forEach((comment) => {
+			if (comment.type === 'Block') {
+				comment.value = comment.value.replace(/^\t+/gm, '');
 			}
 		});
 
 		ast = walk(ast, null, {
-			_(node, { next }) {
-				let comment;
-
-				while (comments[0] && comments[0].start < node.start) {
-					comment = comments.shift();
-					// @ts-expect-error
-					(node.leadingComments ||= []).push(comment);
-				}
-
-				next();
-
-				if (comments[0]) {
-					const slice = source.slice(node.end, comments[0].start);
-
-					if (/^[,) \t]*$/.test(slice)) {
-						// @ts-expect-error
-						node.trailingComments = [comments.shift()];
-					}
-				}
-			},
-			// @ts-expect-error
 			Identifier(node, context) {
 				if (node.name === 'CODES') {
-					return {
+					/** @type {ESTree.ArrayExpression} */
+					const array = {
 						type: 'ArrayExpression',
 						elements: Object.keys(messages[name]).map((code) => ({
 							type: 'Literal',
 							value: code
 						}))
 					};
+
+					return array;
 				}
 			}
 		});
 
-		if (comments.length > 0) {
-			// @ts-expect-error
-			(ast.trailingComments ||= []).push(...comments);
-		}
+		const body = /** @type {ESTree.Program} */ (ast).body;
 
 		const category = messages[name];
 
 		// find the `export function CODE` node
-		const index = ast.body.findIndex((node) => {
+		const index = body.findIndex((node) => {
 			if (
 				node.type === 'ExportNamedDeclaration' &&
 				node.declaration &&
@@ -181,8 +156,19 @@ function run() {
 
 		if (index === -1) throw new Error(`missing export function CODE in ${name}.js`);
 
-		const template_node = ast.body[index];
-		ast.body.splice(index, 1);
+		const template_node = body[index];
+		body.splice(index, 1);
+
+		const jsdoc = /** @type {AST.JSComment} */ (
+			comments.findLast((comment) => comment.start < /** @type {number} */ (template_node.start))
+		);
+
+		const printed = esrap.print(
+			/** @type {Node} */ (ast),
+			ts({
+				comments: comments.filter((comment) => comment !== jsdoc)
+			})
+		);
 
 		for (const code in category) {
 			const { messages } = category[code];
@@ -203,7 +189,7 @@ function run() {
 				};
 			});
 
-			/** @type {import('estree').Expression} */
+			/** @type {ESTree.Expression} */
 			let message = { type: 'Literal', value: '' };
 			let prev_vars;
 
@@ -221,10 +207,10 @@ function run() {
 
 				const parts = text.split(/(%\w+%)/);
 
-				/** @type {import('estree').Expression[]} */
+				/** @type {ESTree.Expression[]} */
 				const expressions = [];
 
-				/** @type {import('estree').TemplateElement[]} */
+				/** @type {ESTree.TemplateElement[]} */
 				const quasis = [];
 
 				for (let i = 0; i < parts.length; i += 1) {
@@ -244,7 +230,7 @@ function run() {
 					}
 				}
 
-				/** @type {import('estree').Expression} */
+				/** @type {ESTree.Expression} */
 				const expression = {
 					type: 'TemplateLiteral',
 					expressions,
@@ -272,138 +258,140 @@ function run() {
 				prev_vars = vars;
 			}
 
-			const clone = walk(/** @type {import('estree').Node} */ (template_node), null, {
-				// @ts-expect-error Block is a block comment, which is not recognised
-				Block(node, context) {
-					if (!node.value.includes('PARAMETER')) return;
-
-					const value = /** @type {string} */ (node.value)
-						.split('\n')
-						.map((line) => {
-							if (line === ' * MESSAGE') {
-								return messages[messages.length - 1]
-									.split('\n')
-									.map((line) => ` * ${line}`)
-									.join('\n');
-							}
+			const clone = /** @type {ESTree.Statement} */ (
+				walk(/** @type {ESTree.Node} */ (template_node), null, {
+					FunctionDeclaration(node, context) {
+						if (node.id.name !== 'CODE') return;
 
-							if (line.includes('PARAMETER')) {
-								return vars
-									.map((name, i) => {
-										const optional = i >= group[0].vars.length;
+						const params = [];
 
-										return optional
-											? ` * @param {string | undefined | null} [${name}]`
-											: ` * @param {string} ${name}`;
-									})
-									.join('\n');
+						for (const param of node.params) {
+							if (param.type === 'Identifier' && param.name === 'PARAMETER') {
+								params.push(...vars.map((name) => ({ type: 'Identifier', name })));
+							} else {
+								params.push(param);
 							}
+						}
 
-							return line;
-						})
-						.filter((x) => x !== '')
-						.join('\n');
+						return /** @type {ESTree.FunctionDeclaration} */ ({
+							.../** @type {ESTree.FunctionDeclaration} */ (context.next()),
+							params,
+							id: {
+								...node.id,
+								name: code
+							}
+						});
+					},
+					TemplateLiteral(node, context) {
+						/** @type {ESTree.TemplateElement} */
+						let quasi = {
+							type: 'TemplateElement',
+							value: {
+								...node.quasis[0].value
+							},
+							tail: node.quasis[0].tail
+						};
 
-					if (value !== node.value) {
-						return { ...node, value };
-					}
-				},
-				FunctionDeclaration(node, context) {
-					if (node.id.name !== 'CODE') return;
+						/** @type {ESTree.TemplateLiteral} */
+						let out = {
+							type: 'TemplateLiteral',
+							quasis: [quasi],
+							expressions: []
+						};
 
-					const params = [];
+						for (let i = 0; i < node.expressions.length; i += 1) {
+							const q = structuredClone(node.quasis[i + 1]);
+							const e = node.expressions[i];
 
-					for (const param of node.params) {
-						if (param.type === 'Identifier' && param.name === 'PARAMETER') {
-							params.push(...vars.map((name) => ({ type: 'Identifier', name })));
-						} else {
-							params.push(param);
-						}
-					}
+							if (e.type === 'Literal' && e.value === 'CODE') {
+								quasi.value.raw += code + q.value.raw;
+								continue;
+							}
 
-					return /** @type {import('estree').FunctionDeclaration} */ ({
-						.../** @type {import('estree').FunctionDeclaration} */ (context.next()),
-						params,
-						id: {
-							...node.id,
-							name: code
-						}
-					});
-				},
-				TemplateLiteral(node, context) {
-					/** @type {import('estree').TemplateElement} */
-					let quasi = {
-						type: 'TemplateElement',
-						value: {
-							...node.quasis[0].value
-						},
-						tail: node.quasis[0].tail
-					};
+							if (e.type === 'Identifier' && e.name === 'MESSAGE') {
+								if (message.type === 'Literal') {
+									const str = /** @type {string} */ (message.value).replace(/(`|\${)/g, '\\$1');
+									quasi.value.raw += str + q.value.raw;
+									continue;
+								}
+
+								if (message.type === 'TemplateLiteral') {
+									const m = structuredClone(message);
+									quasi.value.raw += m.quasis[0].value.raw;
+									out.quasis.push(...m.quasis.slice(1));
+									out.expressions.push(...m.expressions);
+									quasi = m.quasis[m.quasis.length - 1];
+									quasi.value.raw += q.value.raw;
+									continue;
+								}
+							}
 
-					/** @type {import('estree').TemplateLiteral} */
-					let out = {
-						type: 'TemplateLiteral',
-						quasis: [quasi],
-						expressions: []
-					};
+							out.quasis.push((quasi = q));
+							out.expressions.push(/** @type {ESTree.Expression} */ (context.visit(e)));
+						}
 
-					for (let i = 0; i < node.expressions.length; i += 1) {
-						const q = structuredClone(node.quasis[i + 1]);
-						const e = node.expressions[i];
+						return out;
+					},
+					Literal(node) {
+						if (node.value === 'CODE') {
+							return {
+								type: 'Literal',
+								value: code
+							};
+						}
+					},
+					Identifier(node) {
+						if (node.name !== 'MESSAGE') return;
+						return message;
+					}
+				})
+			);
 
-						if (e.type === 'Literal' && e.value === 'CODE') {
-							quasi.value.raw += code + q.value.raw;
-							continue;
+			const jsdoc_clone = {
+				...jsdoc,
+				value: /** @type {string} */ (jsdoc.value)
+					.split('\n')
+					.map((line) => {
+						if (line === ' * MESSAGE') {
+							return messages[messages.length - 1]
+								.split('\n')
+								.map((line) => ` * ${line}`)
+								.join('\n');
 						}
 
-						if (e.type === 'Identifier' && e.name === 'MESSAGE') {
-							if (message.type === 'Literal') {
-								const str = /** @type {string} */ (message.value).replace(/(`|\${)/g, '\\$1');
-								quasi.value.raw += str + q.value.raw;
-								continue;
-							}
+						if (line.includes('PARAMETER')) {
+							return vars
+								.map((name, i) => {
+									const optional = i >= group[0].vars.length;
 
-							if (message.type === 'TemplateLiteral') {
-								const m = structuredClone(message);
-								quasi.value.raw += m.quasis[0].value.raw;
-								out.quasis.push(...m.quasis.slice(1));
-								out.expressions.push(...m.expressions);
-								quasi = m.quasis[m.quasis.length - 1];
-								quasi.value.raw += q.value.raw;
-								continue;
-							}
+									return optional
+										? ` * @param {string | undefined | null} [${name}]`
+										: ` * @param {string} ${name}`;
+								})
+								.join('\n');
 						}
 
-						out.quasis.push((quasi = q));
-						out.expressions.push(/** @type {import('estree').Expression} */ (context.visit(e)));
-					}
+						return line;
+					})
+					.filter((x) => x !== '')
+					.join('\n')
+			};
 
-					return out;
-				},
-				Literal(node) {
-					if (node.value === 'CODE') {
-						return {
-							type: 'Literal',
-							value: code
-						};
-					}
-				},
-				Identifier(node) {
-					if (node.name !== 'MESSAGE') return;
-					return message;
-				}
-			});
+			const block = esrap.print(
+				// @ts-expect-error some bullshit
+				/** @type {ESTree.Program} */ ({ ...ast, body: [clone] }),
+				ts({ comments: [jsdoc_clone] })
+			).code;
 
-			// @ts-expect-error
-			ast.body.push(clone);
-		}
+			printed.code += `\n\n${block}`;
 
-		const module = esrap.print(ast);
+			body.push(clone);
+		}
 
 		fs.writeFileSync(
 			dest,
 			`/* This file is generated by scripts/process-messages/index.js. Do not edit! */\n\n` +
-				module.code,
+				printed.code,
 			'utf-8'
 		);
 	}
diff --git a/packages/svelte/src/compiler/errors.js b/packages/svelte/src/compiler/errors.js
index 25e72340c6..e9fa33b054 100644
--- a/packages/svelte/src/compiler/errors.js
+++ b/packages/svelte/src/compiler/errors.js
@@ -15,10 +15,12 @@ class InternalCompileError extends Error {
 	constructor(code, message, position) {
 		super(message);
 		this.stack = ''; // avoid unnecessary noise; don't set it as a class property or it becomes enumerable
+
 		// We want to extend from Error so that various bundler plugins properly handle it.
 		// But we also want to share the same object shape with that of warnings, therefore
 		// we create an instance of the shared class an copy over its properties.
 		this.#diagnostic = new CompileDiagnostic(code, message, position);
+
 		Object.assign(this, this.#diagnostic);
 		this.name = 'CompileError';
 	}
@@ -816,7 +818,9 @@ export function bind_invalid_expression(node) {
  * @returns {never}
  */
 export function bind_invalid_name(node, name, explanation) {
-	e(node, 'bind_invalid_name', `${explanation ? `\`bind:${name}\` is not a valid binding. ${explanation}` : `\`bind:${name}\` is not a valid binding`}\nhttps://svelte.dev/e/bind_invalid_name`);
+	e(node, 'bind_invalid_name', `${explanation
+		? `\`bind:${name}\` is not a valid binding. ${explanation}`
+		: `\`bind:${name}\` is not a valid binding`}\nhttps://svelte.dev/e/bind_invalid_name`);
 }
 
 /**
diff --git a/packages/svelte/src/compiler/index.js b/packages/svelte/src/compiler/index.js
index 756a88a824..429c6b4a6f 100644
--- a/packages/svelte/src/compiler/index.js
+++ b/packages/svelte/src/compiler/index.js
@@ -3,7 +3,6 @@
 /** @import { AST } from './public.js' */
 import { walk as zimmerframe_walk } from 'zimmerframe';
 import { convert } from './legacy.js';
-import { parse as parse_acorn } from './phases/1-parse/acorn.js';
 import { parse as _parse } from './phases/1-parse/index.js';
 import { remove_typescript_nodes } from './phases/1-parse/remove_typescript_nodes.js';
 import { analyze_component, analyze_module } from './phases/2-analyze/index.js';
@@ -69,7 +68,7 @@ export function compileModule(source, options) {
 	const validated = validate_module_options(options, '');
 	state.reset(source, validated);
 
-	const analysis = analyze_module(parse_acorn(source, false), validated);
+	const analysis = analyze_module(source, validated);
 	return transform_module(analysis, source, validated);
 }
 
diff --git a/packages/svelte/src/compiler/legacy.js b/packages/svelte/src/compiler/legacy.js
index f6b7e4b054..85345bca4a 100644
--- a/packages/svelte/src/compiler/legacy.js
+++ b/packages/svelte/src/compiler/legacy.js
@@ -451,6 +451,7 @@ export function convert(source, ast) {
 			SpreadAttribute(node) {
 				return { ...node, type: 'Spread' };
 			},
+			// @ts-ignore
 			StyleSheet(node, context) {
 				return {
 					...node,
diff --git a/packages/svelte/src/compiler/phases/1-parse/acorn.js b/packages/svelte/src/compiler/phases/1-parse/acorn.js
index 26a09abb66..77ce4a461c 100644
--- a/packages/svelte/src/compiler/phases/1-parse/acorn.js
+++ b/packages/svelte/src/compiler/phases/1-parse/acorn.js
@@ -1,18 +1,32 @@
 /** @import { Comment, Program } from 'estree' */
+/** @import { AST } from '#compiler' */
 import * as acorn from 'acorn';
 import { walk } from 'zimmerframe';
 import { tsPlugin } from '@sveltejs/acorn-typescript';
 
 const ParserWithTS = acorn.Parser.extend(tsPlugin());
 
+/**
+ * @typedef {Comment & {
+ *   start: number;
+ *   end: number;
+ * }} CommentWithLocation
+ */
+
 /**
  * @param {string} source
+ * @param {AST.JSComment[]} comments
  * @param {boolean} typescript
  * @param {boolean} [is_script]
  */
-export function parse(source, typescript, is_script) {
+export function parse(source, comments, typescript, is_script) {
 	const parser = typescript ? ParserWithTS : acorn.Parser;
-	const { onComment, add_comments } = get_comment_handlers(source);
+
+	const { onComment, add_comments } = get_comment_handlers(
+		source,
+		/** @type {CommentWithLocation[]} */ (comments)
+	);
+
 	// @ts-ignore
 	const parse_statement = parser.prototype.parseStatement;
 
@@ -53,13 +67,19 @@ export function parse(source, typescript, is_script) {
 
 /**
  * @param {string} source
+ * @param {Comment[]} comments
  * @param {boolean} typescript
  * @param {number} index
  * @returns {acorn.Expression & { leadingComments?: CommentWithLocation[]; trailingComments?: CommentWithLocation[]; }}
  */
-export function parse_expression_at(source, typescript, index) {
+export function parse_expression_at(source, comments, typescript, index) {
 	const parser = typescript ? ParserWithTS : acorn.Parser;
-	const { onComment, add_comments } = get_comment_handlers(source);
+
+	const { onComment, add_comments } = get_comment_handlers(
+		source,
+		/** @type {CommentWithLocation[]} */ (comments),
+		index
+	);
 
 	const ast = parser.parseExpressionAt(source, index, {
 		onComment,
@@ -78,26 +98,20 @@ export function parse_expression_at(source, typescript, index) {
  * to add them after the fact. They are needed in order to support `svelte-ignore` comments
  * in JS code and so that `prettier-plugin-svelte` doesn't remove all comments when formatting.
  * @param {string} source
+ * @param {CommentWithLocation[]} comments
+ * @param {number} index
  */
-function get_comment_handlers(source) {
-	/**
-	 * @typedef {Comment & {
-	 *   start: number;
-	 *   end: number;
-	 * }} CommentWithLocation
-	 */
-
-	/** @type {CommentWithLocation[]} */
-	const comments = [];
-
+function get_comment_handlers(source, comments, index = 0) {
 	return {
 		/**
 		 * @param {boolean} block
 		 * @param {string} value
 		 * @param {number} start
 		 * @param {number} end
+		 * @param {import('acorn').Position} [start_loc]
+		 * @param {import('acorn').Position} [end_loc]
 		 */
-		onComment: (block, value, start, end) => {
+		onComment: (block, value, start, end, start_loc, end_loc) => {
 			if (block && /\n/.test(value)) {
 				let a = start;
 				while (a > 0 && source[a - 1] !== '\n') a -= 1;
@@ -109,13 +123,26 @@ function get_comment_handlers(source) {
 				value = value.replace(new RegExp(`^${indentation}`, 'gm'), '');
 			}
 
-			comments.push({ type: block ? 'Block' : 'Line', value, start, end });
+			comments.push({
+				type: block ? 'Block' : 'Line',
+				value,
+				start,
+				end,
+				loc: {
+					start: /** @type {import('acorn').Position} */ (start_loc),
+					end: /** @type {import('acorn').Position} */ (end_loc)
+				}
+			});
 		},
 
 		/** @param {acorn.Node & { leadingComments?: CommentWithLocation[]; trailingComments?: CommentWithLocation[]; }} ast */
 		add_comments(ast) {
 			if (comments.length === 0) return;
 
+			comments = comments
+				.filter((comment) => comment.start >= index)
+				.map(({ type, value, start, end }) => ({ type, value, start, end }));
+
 			walk(ast, null, {
 				_(node, { next, path }) {
 					let comment;
diff --git a/packages/svelte/src/compiler/phases/1-parse/index.js b/packages/svelte/src/compiler/phases/1-parse/index.js
index 6cc5b58aa6..b8ae8199eb 100644
--- a/packages/svelte/src/compiler/phases/1-parse/index.js
+++ b/packages/svelte/src/compiler/phases/1-parse/index.js
@@ -1,4 +1,5 @@
 /** @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';
@@ -87,6 +88,7 @@ export class Parser {
 			type: 'Root',
 			fragment: create_fragment(),
 			options: null,
+			comments: [],
 			metadata: {
 				ts: this.ts
 			}
diff --git a/packages/svelte/src/compiler/phases/1-parse/read/context.js b/packages/svelte/src/compiler/phases/1-parse/read/context.js
index b118901830..282288e2a2 100644
--- a/packages/svelte/src/compiler/phases/1-parse/read/context.js
+++ b/packages/svelte/src/compiler/phases/1-parse/read/context.js
@@ -59,7 +59,12 @@ export default function read_pattern(parser) {
 			space_with_newline.slice(0, first_space) + space_with_newline.slice(first_space + 1);
 
 		const expression = /** @type {any} */ (
-			parse_expression_at(`${space_with_newline}(${pattern_string} = 1)`, parser.ts, start - 1)
+			parse_expression_at(
+				`${space_with_newline}(${pattern_string} = 1)`,
+				parser.root.comments,
+				parser.ts,
+				start - 1
+			)
 		).left;
 
 		expression.typeAnnotation = read_type_annotation(parser);
@@ -96,13 +101,13 @@ function read_type_annotation(parser) {
 		// parameters as part of a sequence expression instead, and will then error on optional
 		// parameters (`?:`). Therefore replace that sequence with something that will not error.
 		parser.template.slice(parser.index).replace(/\?\s*:/g, ':');
-	let expression = parse_expression_at(template, parser.ts, a);
+	let expression = parse_expression_at(template, parser.root.comments, parser.ts, a);
 
 	// `foo: bar = baz` gets mangled — fix it
 	if (expression.type === 'AssignmentExpression') {
 		let b = expression.right.start;
 		while (template[b] !== '=') b -= 1;
-		expression = parse_expression_at(template.slice(0, b), parser.ts, a);
+		expression = parse_expression_at(template.slice(0, b), parser.root.comments, parser.ts, a);
 	}
 
 	// `array as item: string, index` becomes `string, index`, which is mistaken as a sequence expression - fix that
diff --git a/packages/svelte/src/compiler/phases/1-parse/read/expression.js b/packages/svelte/src/compiler/phases/1-parse/read/expression.js
index a596cdf572..5d21f85792 100644
--- a/packages/svelte/src/compiler/phases/1-parse/read/expression.js
+++ b/packages/svelte/src/compiler/phases/1-parse/read/expression.js
@@ -34,12 +34,24 @@ export function get_loose_identifier(parser, opening_token) {
  */
 export default function read_expression(parser, opening_token, disallow_loose) {
 	try {
-		const node = parse_expression_at(parser.template, parser.ts, parser.index);
+		let comment_index = parser.root.comments.length;
+
+		const node = parse_expression_at(
+			parser.template,
+			parser.root.comments,
+			parser.ts,
+			parser.index
+		);
 
 		let num_parens = 0;
 
-		if (node.leadingComments !== undefined && node.leadingComments.length > 0) {
-			parser.index = node.leadingComments.at(-1).end;
+		let i = parser.root.comments.length;
+		while (i-- > comment_index) {
+			const comment = parser.root.comments[i];
+			if (comment.end < node.start) {
+				parser.index = comment.end;
+				break;
+			}
 		}
 
 		for (let i = parser.index; i < /** @type {number} */ (node.start); i += 1) {
@@ -47,9 +59,9 @@ export default function read_expression(parser, opening_token, disallow_loose) {
 		}
 
 		let index = /** @type {number} */ (node.end);
-		if (node.trailingComments !== undefined && node.trailingComments.length > 0) {
-			index = node.trailingComments.at(-1).end;
-		}
+
+		const last_comment = parser.root.comments.at(-1);
+		if (last_comment && last_comment.end > index) index = last_comment.end;
 
 		while (num_parens > 0) {
 			const char = parser.template[index];
diff --git a/packages/svelte/src/compiler/phases/1-parse/read/script.js b/packages/svelte/src/compiler/phases/1-parse/read/script.js
index 6290127811..9ce449f200 100644
--- a/packages/svelte/src/compiler/phases/1-parse/read/script.js
+++ b/packages/svelte/src/compiler/phases/1-parse/read/script.js
@@ -34,7 +34,7 @@ export function read_script(parser, start, attributes) {
 	let ast;
 
 	try {
-		ast = acorn.parse(source, parser.ts, true);
+		ast = acorn.parse(source, parser.root.comments, parser.ts, true);
 	} catch (err) {
 		parser.acorn_error(err);
 	}
diff --git a/packages/svelte/src/compiler/phases/1-parse/state/tag.js b/packages/svelte/src/compiler/phases/1-parse/state/tag.js
index 5d77d6a8f4..ba091ef7ec 100644
--- a/packages/svelte/src/compiler/phases/1-parse/state/tag.js
+++ b/packages/svelte/src/compiler/phases/1-parse/state/tag.js
@@ -398,7 +398,12 @@ function open(parser) {
 
 		let function_expression = matched
 			? /** @type {ArrowFunctionExpression} */ (
-					parse_expression_at(prelude + `${params} => {}`, parser.ts, params_start)
+					parse_expression_at(
+						prelude + `${params} => {}`,
+						parser.root.comments,
+						parser.ts,
+						params_start
+					)
 				)
 			: { params: [] };
 
diff --git a/packages/svelte/src/compiler/phases/2-analyze/index.js b/packages/svelte/src/compiler/phases/2-analyze/index.js
index 80adc10c1a..be1f1ee5bb 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/index.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/index.js
@@ -1,8 +1,9 @@
-/** @import { Expression, Node, Program } from 'estree' */
+/** @import { Comment, Expression, Node, Program } from 'estree' */
 /** @import { Binding, AST, ValidatedCompileOptions, ValidatedModuleCompileOptions } from '#compiler' */
 /** @import { AnalysisState, Visitors } from './types' */
 /** @import { Analysis, ComponentAnalysis, Js, ReactiveStatement, Template } from '../types' */
 import { walk } from 'zimmerframe';
+import { parse } from '../1-parse/acorn.js';
 import * as e from '../../errors.js';
 import * as w from '../../warnings.js';
 import { extract_identifiers } from '../../utils/ast.js';
@@ -231,11 +232,16 @@ function get_component_name(filename) {
 const RESERVED = ['$$props', '$$restProps', '$$slots'];
 
 /**
- * @param {Program} ast
+ * @param {string} source
  * @param {ValidatedModuleCompileOptions} options
  * @returns {Analysis}
  */
-export function analyze_module(ast, options) {
+export function analyze_module(source, options) {
+	/** @type {AST.JSComment[]} */
+	const comments = [];
+
+	const ast = parse(source, comments, false, false);
+
 	const { scope, scopes } = create_scopes(ast, new ScopeRoot(), false, null);
 
 	for (const [name, references] of scope.references) {
@@ -259,6 +265,7 @@ export function analyze_module(ast, options) {
 		runes: true,
 		immutable: true,
 		tracing: false,
+		comments,
 		classes: new Map()
 	};
 
@@ -429,6 +436,7 @@ export function analyze_component(root, source, options) {
 		module,
 		instance,
 		template,
+		comments: root.comments,
 		elements: [],
 		runes,
 		// if we are not in runes mode but we have no reserved references ($$props, $$restProps)
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 e2e006c14b..e85a35cf8e 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
@@ -362,6 +362,9 @@ export function client_component(analysis, options) {
 		.../** @type {ESTree.Statement[]} */ (template.body)
 	]);
 
+	// trick esrap into including comments
+	component_block.loc = instance.loc;
+
 	if (!analysis.runes) {
 		// Bind static exports to props so that people can access them with bind:x
 		for (const { name, alias } of analysis.exports) {
diff --git a/packages/svelte/src/compiler/phases/3-transform/index.js b/packages/svelte/src/compiler/phases/3-transform/index.js
index f96fd64ec7..33665097ab 100644
--- a/packages/svelte/src/compiler/phases/3-transform/index.js
+++ b/packages/svelte/src/compiler/phases/3-transform/index.js
@@ -1,6 +1,8 @@
+/** @import { Node } from 'esrap/languages/ts' */
 /** @import { ValidatedCompileOptions, CompileResult, ValidatedModuleCompileOptions } from '#compiler' */
 /** @import { ComponentAnalysis, Analysis } from '../types' */
 import { print } from 'esrap';
+import ts from 'esrap/languages/ts';
 import { VERSION } from '../../../version.js';
 import { server_component, server_module } from './server/transform-server.js';
 import { client_component, client_module } from './client/transform-client.js';
@@ -34,7 +36,7 @@ export function transform_component(analysis, source, options) {
 
 	const js_source_name = get_source_name(options.filename, options.outputFilename, 'input.svelte');
 
-	const js = print(program, {
+	const js = print(/** @type {Node} */ (program), ts({ comments: analysis.comments }), {
 		// include source content; makes it easier/more robust looking up the source map code
 		// (else esrap does return null for source and sourceMapContent which may trip up tooling)
 		sourceMapContent: source,
@@ -93,13 +95,19 @@ export function transform_module(analysis, source, options) {
 		];
 	}
 
+	const js = print(/** @type {Node} */ (program), ts({ comments: analysis.comments }), {
+		// include source content; makes it easier/more robust looking up the source map code
+		// (else esrap does return null for source and sourceMapContent which may trip up tooling)
+		sourceMapContent: source,
+		sourceMapSource: get_source_name(options.filename, undefined, 'input.svelte.js')
+	});
+
+	// prepend comment
+	js.code = `/* ${basename} generated by Svelte v${VERSION} */\n${js.code}`;
+	js.map.mappings = ';' + js.map.mappings;
+
 	return {
-		js: print(program, {
-			// include source content; makes it easier/more robust looking up the source map code
-			// (else esrap does return null for source and sourceMapContent which may trip up tooling)
-			sourceMapContent: source,
-			sourceMapSource: get_source_name(options.filename, undefined, 'input.svelte.js')
-		}),
+		js,
 		css: null,
 		metadata: {
 			runes: true
diff --git a/packages/svelte/src/compiler/phases/3-transform/server/transform-server.js b/packages/svelte/src/compiler/phases/3-transform/server/transform-server.js
index 7a3d6bef6c..86346b864c 100644
--- a/packages/svelte/src/compiler/phases/3-transform/server/transform-server.js
+++ b/packages/svelte/src/compiler/phases/3-transform/server/transform-server.js
@@ -242,6 +242,9 @@ export function server_component(analysis, options) {
 		.../** @type {Statement[]} */ (template.body)
 	]);
 
+	// trick esrap into including comments
+	component_block.loc = instance.loc;
+
 	if (analysis.props_id) {
 		// need to be placed on first line of the component for hydration
 		component_block.body.unshift(
diff --git a/packages/svelte/src/compiler/phases/types.d.ts b/packages/svelte/src/compiler/phases/types.d.ts
index 8fa4bff619..661f363991 100644
--- a/packages/svelte/src/compiler/phases/types.d.ts
+++ b/packages/svelte/src/compiler/phases/types.d.ts
@@ -2,6 +2,7 @@ import type { AST, Binding, StateField } from '#compiler';
 import type {
 	AssignmentExpression,
 	ClassBody,
+	Comment,
 	Identifier,
 	LabeledStatement,
 	Node,
@@ -37,6 +38,7 @@ export interface Analysis {
 	runes: boolean;
 	immutable: boolean;
 	tracing: boolean;
+	comments: AST.JSComment[];
 
 	classes: Map<ClassBody, Map<string, StateField>>;
 
diff --git a/packages/svelte/src/compiler/types/template.d.ts b/packages/svelte/src/compiler/types/template.d.ts
index 2a7ec7b5c6..c9841e9d4e 100644
--- a/packages/svelte/src/compiler/types/template.d.ts
+++ b/packages/svelte/src/compiler/types/template.d.ts
@@ -72,6 +72,8 @@ export namespace AST {
 		instance: Script | null;
 		/** The parsed `<script module>` element, if exists */
 		module: Script | null;
+		/** Comments found in <script> and {expressions} */
+		comments: JSComment[];
 		/** @internal */
 		metadata: {
 			/** Whether the component was parsed with typescript */
@@ -537,6 +539,17 @@ export namespace AST {
 		attributes: Attribute[];
 	}
 
+	export interface JSComment {
+		type: 'Line' | 'Block';
+		value: string;
+		start: number;
+		end: number;
+		loc: {
+			start: { line: number; column: number };
+			end: { line: number; column: number };
+		};
+	}
+
 	export type AttributeLike = Attribute | SpreadAttribute | Directive;
 
 	export type Directive =
@@ -593,7 +606,7 @@ export namespace AST {
 		| AST.Comment
 		| Block;
 
-	export type SvelteNode = Node | TemplateNode | AST.Fragment | _CSS.Node;
+	export type SvelteNode = Node | TemplateNode | AST.Fragment | _CSS.Node | Script;
 
 	export type { _CSS as CSS };
 }
diff --git a/packages/svelte/src/compiler/utils/mapped_code.js b/packages/svelte/src/compiler/utils/mapped_code.js
index 089078af7f..f23e3be245 100644
--- a/packages/svelte/src/compiler/utils/mapped_code.js
+++ b/packages/svelte/src/compiler/utils/mapped_code.js
@@ -398,10 +398,13 @@ export function merge_with_preprocessor_map(result, options, source_name) {
 		// map may contain a different file name. Patch our map beforehand to align sources so merging
 		// with the preprocessor map works correctly.
 		result.map.sources = [file_basename];
-		result.map = apply_preprocessor_sourcemap(
-			file_basename,
+		Object.assign(
 			result.map,
-			/** @type {any} */ (options.sourcemap)
+			apply_preprocessor_sourcemap(
+				file_basename,
+				result.map,
+				/** @type {any} */ (options.sourcemap)
+			)
 		);
 		// After applying the preprocessor map, we need to do the inverse and make the sources
 		// relative to the input file again in case the output code is in a different directory.
diff --git a/packages/svelte/src/compiler/warnings.js b/packages/svelte/src/compiler/warnings.js
index 1226190891..8c03e12e71 100644
--- a/packages/svelte/src/compiler/warnings.js
+++ b/packages/svelte/src/compiler/warnings.js
@@ -1,12 +1,6 @@
 /* This file is generated by scripts/process-messages/index.js. Do not edit! */
 
-import {
-	warnings,
-	ignore_stack,
-	ignore_map,
-	warning_filter
-} from './state.js';
-
+import { warnings, ignore_stack, ignore_map, warning_filter } from './state.js';
 import { CompileDiagnostic } from './utils/compile_diagnostic.js';
 
 /** @typedef {{ start?: number, end?: number }} NodeLike */
@@ -40,6 +34,7 @@ function w(node, code, message) {
 	const warning = new InternalCompileWarning(code, message, node && node.start !== undefined ? [node.start, node.end ?? node.start] : undefined);
 
 	if (!warning_filter(warning)) return;
+
 	warnings.push(warning);
 }
 
@@ -496,7 +491,9 @@ export function a11y_role_supports_aria_props_implicit(node, attribute, role, na
  * @param {string | undefined | null} [suggestion]
  */
 export function a11y_unknown_aria_attribute(node, attribute, suggestion) {
-	w(node, 'a11y_unknown_aria_attribute', `${suggestion ? `Unknown aria attribute 'aria-${attribute}'. Did you mean '${suggestion}'?` : `Unknown aria attribute 'aria-${attribute}'`}\nhttps://svelte.dev/e/a11y_unknown_aria_attribute`);
+	w(node, 'a11y_unknown_aria_attribute', `${suggestion
+		? `Unknown aria attribute 'aria-${attribute}'. Did you mean '${suggestion}'?`
+		: `Unknown aria attribute 'aria-${attribute}'`}\nhttps://svelte.dev/e/a11y_unknown_aria_attribute`);
 }
 
 /**
@@ -506,7 +503,9 @@ export function a11y_unknown_aria_attribute(node, attribute, suggestion) {
  * @param {string | undefined | null} [suggestion]
  */
 export function a11y_unknown_role(node, role, suggestion) {
-	w(node, 'a11y_unknown_role', `${suggestion ? `Unknown role '${role}'. Did you mean '${suggestion}'?` : `Unknown role '${role}'`}\nhttps://svelte.dev/e/a11y_unknown_role`);
+	w(node, 'a11y_unknown_role', `${suggestion
+		? `Unknown role '${role}'. Did you mean '${suggestion}'?`
+		: `Unknown role '${role}'`}\nhttps://svelte.dev/e/a11y_unknown_role`);
 }
 
 /**
@@ -534,7 +533,9 @@ export function legacy_code(node, code, suggestion) {
  * @param {string | undefined | null} [suggestion]
  */
 export function unknown_code(node, code, suggestion) {
-	w(node, 'unknown_code', `${suggestion ? `\`${code}\` is not a recognised code (did you mean \`${suggestion}\`?)` : `\`${code}\` is not a recognised code`}\nhttps://svelte.dev/e/unknown_code`);
+	w(node, 'unknown_code', `${suggestion
+		? `\`${code}\` is not a recognised code (did you mean \`${suggestion}\`?)`
+		: `\`${code}\` is not a recognised code`}\nhttps://svelte.dev/e/unknown_code`);
 }
 
 /**
diff --git a/packages/svelte/src/internal/client/errors.js b/packages/svelte/src/internal/client/errors.js
index 962593b48d..a0ac021c03 100644
--- a/packages/svelte/src/internal/client/errors.js
+++ b/packages/svelte/src/internal/client/errors.js
@@ -11,6 +11,7 @@ export function bind_invalid_checkbox_value() {
 		const error = new Error(`bind_invalid_checkbox_value\nUsing \`bind:value\` together with a checkbox input is not allowed. Use \`bind:checked\` instead\nhttps://svelte.dev/e/bind_invalid_checkbox_value`);
 
 		error.name = 'Svelte error';
+
 		throw error;
 	} else {
 		throw new Error(`https://svelte.dev/e/bind_invalid_checkbox_value`);
@@ -29,6 +30,7 @@ export function bind_invalid_export(component, key, name) {
 		const error = new Error(`bind_invalid_export\nComponent ${component} has an export named \`${key}\` that a consumer component is trying to access using \`bind:${key}\`, which is disallowed. Instead, use \`bind:this\` (e.g. \`<${name} bind:this={component} />\`) and then access the property on the bound component instance (e.g. \`component.${key}\`)\nhttps://svelte.dev/e/bind_invalid_export`);
 
 		error.name = 'Svelte error';
+
 		throw error;
 	} else {
 		throw new Error(`https://svelte.dev/e/bind_invalid_export`);
@@ -47,6 +49,7 @@ export function bind_not_bindable(key, component, name) {
 		const error = new Error(`bind_not_bindable\nA component is attempting to bind to a non-bindable property \`${key}\` belonging to ${component} (i.e. \`<${name} bind:${key}={...}>\`). To mark a property as bindable: \`let { ${key} = $bindable() } = $props()\`\nhttps://svelte.dev/e/bind_not_bindable`);
 
 		error.name = 'Svelte error';
+
 		throw error;
 	} else {
 		throw new Error(`https://svelte.dev/e/bind_not_bindable`);
@@ -64,6 +67,7 @@ export function component_api_changed(method, component) {
 		const error = new Error(`component_api_changed\nCalling \`${method}\` on a component instance (of ${component}) is no longer valid in Svelte 5\nhttps://svelte.dev/e/component_api_changed`);
 
 		error.name = 'Svelte error';
+
 		throw error;
 	} else {
 		throw new Error(`https://svelte.dev/e/component_api_changed`);
@@ -81,6 +85,7 @@ export function component_api_invalid_new(component, name) {
 		const error = new Error(`component_api_invalid_new\nAttempted to instantiate ${component} with \`new ${name}\`, which is no longer valid in Svelte 5. If this component is not under your control, set the \`compatibility.componentApi\` compiler option to \`4\` to keep it working.\nhttps://svelte.dev/e/component_api_invalid_new`);
 
 		error.name = 'Svelte error';
+
 		throw error;
 	} else {
 		throw new Error(`https://svelte.dev/e/component_api_invalid_new`);
@@ -96,6 +101,7 @@ export function derived_references_self() {
 		const error = new Error(`derived_references_self\nA derived value cannot reference itself recursively\nhttps://svelte.dev/e/derived_references_self`);
 
 		error.name = 'Svelte error';
+
 		throw error;
 	} else {
 		throw new Error(`https://svelte.dev/e/derived_references_self`);
@@ -111,9 +117,12 @@ export function derived_references_self() {
  */
 export function each_key_duplicate(a, b, value) {
 	if (DEV) {
-		const error = new Error(`each_key_duplicate\n${value ? `Keyed each block has duplicate key \`${value}\` at indexes ${a} and ${b}` : `Keyed each block has duplicate key at indexes ${a} and ${b}`}\nhttps://svelte.dev/e/each_key_duplicate`);
+		const error = new Error(`each_key_duplicate\n${value
+			? `Keyed each block has duplicate key \`${value}\` at indexes ${a} and ${b}`
+			: `Keyed each block has duplicate key at indexes ${a} and ${b}`}\nhttps://svelte.dev/e/each_key_duplicate`);
 
 		error.name = 'Svelte error';
+
 		throw error;
 	} else {
 		throw new Error(`https://svelte.dev/e/each_key_duplicate`);
@@ -130,6 +139,7 @@ export function effect_in_teardown(rune) {
 		const error = new Error(`effect_in_teardown\n\`${rune}\` cannot be used inside an effect cleanup function\nhttps://svelte.dev/e/effect_in_teardown`);
 
 		error.name = 'Svelte error';
+
 		throw error;
 	} else {
 		throw new Error(`https://svelte.dev/e/effect_in_teardown`);
@@ -145,6 +155,7 @@ export function effect_in_unowned_derived() {
 		const error = new Error(`effect_in_unowned_derived\nEffect cannot be created inside a \`$derived\` value that was not itself created inside an effect\nhttps://svelte.dev/e/effect_in_unowned_derived`);
 
 		error.name = 'Svelte error';
+
 		throw error;
 	} else {
 		throw new Error(`https://svelte.dev/e/effect_in_unowned_derived`);
@@ -161,6 +172,7 @@ export function effect_orphan(rune) {
 		const error = new Error(`effect_orphan\n\`${rune}\` can only be used inside an effect (e.g. during component initialisation)\nhttps://svelte.dev/e/effect_orphan`);
 
 		error.name = 'Svelte error';
+
 		throw error;
 	} else {
 		throw new Error(`https://svelte.dev/e/effect_orphan`);
@@ -176,6 +188,7 @@ export function effect_update_depth_exceeded() {
 		const error = new Error(`effect_update_depth_exceeded\nMaximum update depth exceeded. This can happen when a reactive block or effect repeatedly sets a new value. Svelte limits the number of nested updates to prevent infinite loops\nhttps://svelte.dev/e/effect_update_depth_exceeded`);
 
 		error.name = 'Svelte error';
+
 		throw error;
 	} else {
 		throw new Error(`https://svelte.dev/e/effect_update_depth_exceeded`);
@@ -191,6 +204,7 @@ export function hydration_failed() {
 		const error = new Error(`hydration_failed\nFailed to hydrate the application\nhttps://svelte.dev/e/hydration_failed`);
 
 		error.name = 'Svelte error';
+
 		throw error;
 	} else {
 		throw new Error(`https://svelte.dev/e/hydration_failed`);
@@ -206,6 +220,7 @@ export function invalid_snippet() {
 		const error = new Error(`invalid_snippet\nCould not \`{@render}\` snippet due to the expression being \`null\` or \`undefined\`. Consider using optional chaining \`{@render snippet?.()}\`\nhttps://svelte.dev/e/invalid_snippet`);
 
 		error.name = 'Svelte error';
+
 		throw error;
 	} else {
 		throw new Error(`https://svelte.dev/e/invalid_snippet`);
@@ -222,6 +237,7 @@ export function lifecycle_legacy_only(name) {
 		const error = new Error(`lifecycle_legacy_only\n\`${name}(...)\` cannot be used in runes mode\nhttps://svelte.dev/e/lifecycle_legacy_only`);
 
 		error.name = 'Svelte error';
+
 		throw error;
 	} else {
 		throw new Error(`https://svelte.dev/e/lifecycle_legacy_only`);
@@ -238,6 +254,7 @@ export function props_invalid_value(key) {
 		const error = new Error(`props_invalid_value\nCannot do \`bind:${key}={undefined}\` when \`${key}\` has a fallback value\nhttps://svelte.dev/e/props_invalid_value`);
 
 		error.name = 'Svelte error';
+
 		throw error;
 	} else {
 		throw new Error(`https://svelte.dev/e/props_invalid_value`);
@@ -254,6 +271,7 @@ export function props_rest_readonly(property) {
 		const error = new Error(`props_rest_readonly\nRest element properties of \`$props()\` such as \`${property}\` are readonly\nhttps://svelte.dev/e/props_rest_readonly`);
 
 		error.name = 'Svelte error';
+
 		throw error;
 	} else {
 		throw new Error(`https://svelte.dev/e/props_rest_readonly`);
@@ -270,6 +288,7 @@ export function rune_outside_svelte(rune) {
 		const error = new Error(`rune_outside_svelte\nThe \`${rune}\` rune is only available inside \`.svelte\` and \`.svelte.js/ts\` files\nhttps://svelte.dev/e/rune_outside_svelte`);
 
 		error.name = 'Svelte error';
+
 		throw error;
 	} else {
 		throw new Error(`https://svelte.dev/e/rune_outside_svelte`);
@@ -285,6 +304,7 @@ export function state_descriptors_fixed() {
 		const error = new Error(`state_descriptors_fixed\nProperty descriptors defined on \`$state\` objects must contain \`value\` and always be \`enumerable\`, \`configurable\` and \`writable\`.\nhttps://svelte.dev/e/state_descriptors_fixed`);
 
 		error.name = 'Svelte error';
+
 		throw error;
 	} else {
 		throw new Error(`https://svelte.dev/e/state_descriptors_fixed`);
@@ -300,6 +320,7 @@ export function state_prototype_fixed() {
 		const error = new Error(`state_prototype_fixed\nCannot set prototype of \`$state\` object\nhttps://svelte.dev/e/state_prototype_fixed`);
 
 		error.name = 'Svelte error';
+
 		throw error;
 	} else {
 		throw new Error(`https://svelte.dev/e/state_prototype_fixed`);
@@ -315,6 +336,7 @@ export function state_unsafe_mutation() {
 		const error = new Error(`state_unsafe_mutation\nUpdating state inside \`$derived(...)\`, \`$inspect(...)\` or a template expression is forbidden. If the value should not be reactive, declare it without \`$state\`\nhttps://svelte.dev/e/state_unsafe_mutation`);
 
 		error.name = 'Svelte error';
+
 		throw error;
 	} else {
 		throw new Error(`https://svelte.dev/e/state_unsafe_mutation`);
diff --git a/packages/svelte/src/internal/client/warnings.js b/packages/svelte/src/internal/client/warnings.js
index e07892a4b0..74f9041b91 100644
--- a/packages/svelte/src/internal/client/warnings.js
+++ b/packages/svelte/src/internal/client/warnings.js
@@ -25,7 +25,13 @@ export function assignment_value_stale(property, location) {
  */
 export function binding_property_non_reactive(binding, location) {
 	if (DEV) {
-		console.warn(`%c[svelte] binding_property_non_reactive\n%c${location ? `\`${binding}\` (${location}) is binding to a non-reactive property` : `\`${binding}\` is binding to a non-reactive property`}\nhttps://svelte.dev/e/binding_property_non_reactive`, bold, normal);
+		console.warn(
+			`%c[svelte] binding_property_non_reactive\n%c${location
+				? `\`${binding}\` (${location}) is binding to a non-reactive property`
+				: `\`${binding}\` is binding to a non-reactive property`}\nhttps://svelte.dev/e/binding_property_non_reactive`,
+			bold,
+			normal
+		);
 	} else {
 		console.warn(`https://svelte.dev/e/binding_property_non_reactive`);
 	}
@@ -76,7 +82,13 @@ export function hydration_attribute_changed(attribute, html, value) {
  */
 export function hydration_html_changed(location) {
 	if (DEV) {
-		console.warn(`%c[svelte] hydration_html_changed\n%c${location ? `The value of an \`{@html ...}\` block ${location} changed between server and client renders. The client value will be ignored in favour of the server value` : 'The value of an `{@html ...}` block changed between server and client renders. The client value will be ignored in favour of the server value'}\nhttps://svelte.dev/e/hydration_html_changed`, bold, normal);
+		console.warn(
+			`%c[svelte] hydration_html_changed\n%c${location
+				? `The value of an \`{@html ...}\` block ${location} changed between server and client renders. The client value will be ignored in favour of the server value`
+				: 'The value of an `{@html ...}` block changed between server and client renders. The client value will be ignored in favour of the server value'}\nhttps://svelte.dev/e/hydration_html_changed`,
+			bold,
+			normal
+		);
 	} else {
 		console.warn(`https://svelte.dev/e/hydration_html_changed`);
 	}
@@ -88,7 +100,13 @@ export function hydration_html_changed(location) {
  */
 export function hydration_mismatch(location) {
 	if (DEV) {
-		console.warn(`%c[svelte] hydration_mismatch\n%c${location ? `Hydration failed because the initial UI does not match what was rendered on the server. The error occurred near ${location}` : 'Hydration failed because the initial UI does not match what was rendered on the server'}\nhttps://svelte.dev/e/hydration_mismatch`, bold, normal);
+		console.warn(
+			`%c[svelte] hydration_mismatch\n%c${location
+				? `Hydration failed because the initial UI does not match what was rendered on the server. The error occurred near ${location}`
+				: 'Hydration failed because the initial UI does not match what was rendered on the server'}\nhttps://svelte.dev/e/hydration_mismatch`,
+			bold,
+			normal
+		);
 	} else {
 		console.warn(`https://svelte.dev/e/hydration_mismatch`);
 	}
diff --git a/packages/svelte/src/internal/server/errors.js b/packages/svelte/src/internal/server/errors.js
index 38c545c84e..e47530c9aa 100644
--- a/packages/svelte/src/internal/server/errors.js
+++ b/packages/svelte/src/internal/server/errors.js
@@ -1,5 +1,7 @@
 /* This file is generated by scripts/process-messages/index.js. Do not edit! */
 
+
+
 /**
  * `%name%(...)` is not available on the server
  * @param {string} name
@@ -9,5 +11,6 @@ export function lifecycle_function_unavailable(name) {
 	const error = new Error(`lifecycle_function_unavailable\n\`${name}(...)\` is not available on the server\nhttps://svelte.dev/e/lifecycle_function_unavailable`);
 
 	error.name = 'Svelte error';
+
 	throw error;
 }
\ No newline at end of file
diff --git a/packages/svelte/src/internal/shared/errors.js b/packages/svelte/src/internal/shared/errors.js
index b8606fbf6f..6bcc35016a 100644
--- a/packages/svelte/src/internal/shared/errors.js
+++ b/packages/svelte/src/internal/shared/errors.js
@@ -11,6 +11,7 @@ export function invalid_default_snippet() {
 		const error = new Error(`invalid_default_snippet\nCannot use \`{@render children(...)}\` if the parent component uses \`let:\` directives. Consider using a named snippet instead\nhttps://svelte.dev/e/invalid_default_snippet`);
 
 		error.name = 'Svelte error';
+
 		throw error;
 	} else {
 		throw new Error(`https://svelte.dev/e/invalid_default_snippet`);
@@ -26,6 +27,7 @@ export function invalid_snippet_arguments() {
 		const error = new Error(`invalid_snippet_arguments\nA snippet function was passed invalid arguments. Snippets should only be instantiated via \`{@render ...}\`\nhttps://svelte.dev/e/invalid_snippet_arguments`);
 
 		error.name = 'Svelte error';
+
 		throw error;
 	} else {
 		throw new Error(`https://svelte.dev/e/invalid_snippet_arguments`);
@@ -42,6 +44,7 @@ export function lifecycle_outside_component(name) {
 		const error = new Error(`lifecycle_outside_component\n\`${name}(...)\` can only be used during component initialisation\nhttps://svelte.dev/e/lifecycle_outside_component`);
 
 		error.name = 'Svelte error';
+
 		throw error;
 	} else {
 		throw new Error(`https://svelte.dev/e/lifecycle_outside_component`);
@@ -57,6 +60,7 @@ export function snippet_without_render_tag() {
 		const error = new Error(`snippet_without_render_tag\nAttempted to render a snippet without a \`{@render}\` block. This would cause the snippet code to be stringified instead of its content being rendered to the DOM. To fix this, change \`{snippet}\` to \`{@render snippet()}\`.\nhttps://svelte.dev/e/snippet_without_render_tag`);
 
 		error.name = 'Svelte error';
+
 		throw error;
 	} else {
 		throw new Error(`https://svelte.dev/e/snippet_without_render_tag`);
@@ -73,6 +77,7 @@ export function store_invalid_shape(name) {
 		const error = new Error(`store_invalid_shape\n\`${name}\` is not a store with a \`subscribe\` method\nhttps://svelte.dev/e/store_invalid_shape`);
 
 		error.name = 'Svelte error';
+
 		throw error;
 	} else {
 		throw new Error(`https://svelte.dev/e/store_invalid_shape`);
@@ -88,6 +93,7 @@ export function svelte_element_invalid_this_value() {
 		const error = new Error(`svelte_element_invalid_this_value\nThe \`this\` prop on \`<svelte:element>\` must be a string, if defined\nhttps://svelte.dev/e/svelte_element_invalid_this_value`);
 
 		error.name = 'Svelte error';
+
 		throw error;
 	} else {
 		throw new Error(`https://svelte.dev/e/svelte_element_invalid_this_value`);
diff --git a/packages/svelte/src/internal/shared/warnings.js b/packages/svelte/src/internal/shared/warnings.js
index 281be08382..0acca44184 100644
--- a/packages/svelte/src/internal/shared/warnings.js
+++ b/packages/svelte/src/internal/shared/warnings.js
@@ -25,11 +25,15 @@ export function dynamic_void_element_content(tag) {
  */
 export function state_snapshot_uncloneable(properties) {
 	if (DEV) {
-		console.warn(`%c[svelte] state_snapshot_uncloneable\n%c${properties
-			? `The following properties cannot be cloned with \`$state.snapshot\` — the return value contains the originals:
+		console.warn(
+			`%c[svelte] state_snapshot_uncloneable\n%c${properties
+				? `The following properties cannot be cloned with \`$state.snapshot\` — the return value contains the originals:
 
 ${properties}`
-			: 'Value cannot be cloned with `$state.snapshot` — the original value was returned'}\nhttps://svelte.dev/e/state_snapshot_uncloneable`, bold, normal);
+				: 'Value cannot be cloned with `$state.snapshot` — the original value was returned'}\nhttps://svelte.dev/e/state_snapshot_uncloneable`,
+			bold,
+			normal
+		);
 	} else {
 		console.warn(`https://svelte.dev/e/state_snapshot_uncloneable`);
 	}
diff --git a/packages/svelte/tests/parser-modern/test.ts b/packages/svelte/tests/parser-modern/test.ts
index b47d4a4879..279ba7bc08 100644
--- a/packages/svelte/tests/parser-modern/test.ts
+++ b/packages/svelte/tests/parser-modern/test.ts
@@ -21,6 +21,8 @@ const { test, run } = suite<ParserTest>(async (config, cwd) => {
 		)
 	);
 
+	delete actual.comments;
+
 	// run `UPDATE_SNAPSHOTS=true pnpm test parser` to update parser tests
 	if (process.env.UPDATE_SNAPSHOTS) {
 		fs.writeFileSync(`${cwd}/output.json`, JSON.stringify(actual, null, '\t'));
diff --git a/packages/svelte/tests/snapshot/samples/bind-component-snippet/_expected/client/index.svelte.js b/packages/svelte/tests/snapshot/samples/bind-component-snippet/_expected/client/index.svelte.js
index ba3f4b155a..a87a356d58 100644
--- a/packages/svelte/tests/snapshot/samples/bind-component-snippet/_expected/client/index.svelte.js
+++ b/packages/svelte/tests/snapshot/samples/bind-component-snippet/_expected/client/index.svelte.js
@@ -22,6 +22,7 @@ export default function Bind_component_snippet($$anchor) {
 		get value() {
 			return $.get(value);
 		},
+
 		set value($$value) {
 			$.set(value, $$value, true);
 		}
diff --git a/packages/svelte/tests/snapshot/samples/bind-component-snippet/_expected/server/index.svelte.js b/packages/svelte/tests/snapshot/samples/bind-component-snippet/_expected/server/index.svelte.js
index cadae2cf15..e2c0ee29a5 100644
--- a/packages/svelte/tests/snapshot/samples/bind-component-snippet/_expected/server/index.svelte.js
+++ b/packages/svelte/tests/snapshot/samples/bind-component-snippet/_expected/server/index.svelte.js
@@ -16,6 +16,7 @@ export default function Bind_component_snippet($$payload) {
 			get value() {
 				return value;
 			},
+
 			set value($$value) {
 				value = $$value;
 				$$settled = false;
diff --git a/packages/svelte/tests/snapshot/samples/dynamic-attributes-casing/_expected/client/main.svelte.js b/packages/svelte/tests/snapshot/samples/dynamic-attributes-casing/_expected/client/main.svelte.js
index 28bb01fb18..d84b674f88 100644
--- a/packages/svelte/tests/snapshot/samples/dynamic-attributes-casing/_expected/client/main.svelte.js
+++ b/packages/svelte/tests/snapshot/samples/dynamic-attributes-casing/_expected/client/main.svelte.js
@@ -6,6 +6,7 @@ var root = $.from_html(`<div></div> <svg></svg> <custom-element></custom-element
 export default function Main($$anchor) {
 	// needs to be a snapshot test because jsdom does auto-correct the attribute casing
 	let x = 'test';
+
 	let y = () => 'test';
 	var fragment = root();
 	var div = $.first_child(fragment);
diff --git a/packages/svelte/tests/snapshot/samples/dynamic-attributes-casing/_expected/server/main.svelte.js b/packages/svelte/tests/snapshot/samples/dynamic-attributes-casing/_expected/server/main.svelte.js
index 4ea5edb6a0..cf731d8187 100644
--- a/packages/svelte/tests/snapshot/samples/dynamic-attributes-casing/_expected/server/main.svelte.js
+++ b/packages/svelte/tests/snapshot/samples/dynamic-attributes-casing/_expected/server/main.svelte.js
@@ -3,6 +3,7 @@ import * as $ from 'svelte/internal/server';
 export default function Main($$payload) {
 	// needs to be a snapshot test because jsdom does auto-correct the attribute casing
 	let x = 'test';
+
 	let y = () => 'test';
 
 	$$payload.out += `<div${$.attr('foobar', x)}></div> <svg${$.attr('viewBox', x)}></svg> <custom-element${$.attr('foobar', x)}></custom-element> <div${$.attr('foobar', y())}></div> <svg${$.attr('viewBox', y())}></svg> <custom-element${$.attr('foobar', y())}></custom-element>`;
diff --git a/packages/svelte/tests/snapshot/samples/function-prop-no-getter/_expected/client/index.svelte.js b/packages/svelte/tests/snapshot/samples/function-prop-no-getter/_expected/client/index.svelte.js
index 762a23754c..218951b836 100644
--- a/packages/svelte/tests/snapshot/samples/function-prop-no-getter/_expected/client/index.svelte.js
+++ b/packages/svelte/tests/snapshot/samples/function-prop-no-getter/_expected/client/index.svelte.js
@@ -14,6 +14,7 @@ export default function Function_prop_no_getter($$anchor) {
 		onmousedown: () => $.set(count, $.get(count) + 1),
 		onmouseup,
 		onmouseenter: () => $.set(count, plusOne($.get(count)), true),
+
 		children: ($$anchor, $$slotProps) => {
 			$.next();
 
@@ -22,6 +23,7 @@ export default function Function_prop_no_getter($$anchor) {
 			$.template_effect(() => $.set_text(text, `clicks: ${$.get(count) ?? ''}`));
 			$.append($$anchor, text);
 		},
+
 		$$slots: { default: true }
 	});
 }
\ No newline at end of file
diff --git a/packages/svelte/tests/snapshot/samples/function-prop-no-getter/_expected/server/index.svelte.js b/packages/svelte/tests/snapshot/samples/function-prop-no-getter/_expected/server/index.svelte.js
index 88f6f55ee7..7d37abd97b 100644
--- a/packages/svelte/tests/snapshot/samples/function-prop-no-getter/_expected/server/index.svelte.js
+++ b/packages/svelte/tests/snapshot/samples/function-prop-no-getter/_expected/server/index.svelte.js
@@ -13,9 +13,11 @@ export default function Function_prop_no_getter($$payload) {
 		onmousedown: () => count += 1,
 		onmouseup,
 		onmouseenter: () => count = plusOne(count),
+
 		children: ($$payload) => {
 			$$payload.out += `<!---->clicks: ${$.escape(count)}`;
 		},
+
 		$$slots: { default: true }
 	});
 }
\ No newline at end of file
diff --git a/packages/svelte/tests/snapshot/samples/functional-templating/_expected/client/index.svelte.js b/packages/svelte/tests/snapshot/samples/functional-templating/_expected/client/index.svelte.js
index 792d5421e1..d4034dc55d 100644
--- a/packages/svelte/tests/snapshot/samples/functional-templating/_expected/client/index.svelte.js
+++ b/packages/svelte/tests/snapshot/samples/functional-templating/_expected/client/index.svelte.js
@@ -6,6 +6,7 @@ var root = $.from_tree(
 	[
 		['h1', null, 'hello'],
 		' ',
+
 		[
 			'div',
 			{ class: 'potato' },
diff --git a/packages/svelte/tests/snapshot/samples/imports-in-modules/_expected/client/index.svelte.js b/packages/svelte/tests/snapshot/samples/imports-in-modules/_expected/client/index.svelte.js
index ebbe191dcb..0eab38919c 100644
--- a/packages/svelte/tests/snapshot/samples/imports-in-modules/_expected/client/index.svelte.js
+++ b/packages/svelte/tests/snapshot/samples/imports-in-modules/_expected/client/index.svelte.js
@@ -3,6 +3,4 @@ import 'svelte/internal/flags/legacy';
 import * as $ from 'svelte/internal/client';
 import { random } from './module.svelte';
 
-export default function Imports_in_modules($$anchor) {
-	
-}
\ No newline at end of file
+export default function Imports_in_modules($$anchor) {}
\ No newline at end of file
diff --git a/packages/svelte/tests/snapshot/samples/imports-in-modules/_expected/server/index.svelte.js b/packages/svelte/tests/snapshot/samples/imports-in-modules/_expected/server/index.svelte.js
index 4cd6bc59d7..2ed863d68f 100644
--- a/packages/svelte/tests/snapshot/samples/imports-in-modules/_expected/server/index.svelte.js
+++ b/packages/svelte/tests/snapshot/samples/imports-in-modules/_expected/server/index.svelte.js
@@ -1,6 +1,4 @@
 import * as $ from 'svelte/internal/server';
 import { random } from './module.svelte';
 
-export default function Imports_in_modules($$payload) {
-	
-}
\ No newline at end of file
+export default function Imports_in_modules($$payload) {}
\ No newline at end of file
diff --git a/packages/svelte/types/index.d.ts b/packages/svelte/types/index.d.ts
index 1a83e0d0f1..3401efac04 100644
--- a/packages/svelte/types/index.d.ts
+++ b/packages/svelte/types/index.d.ts
@@ -1120,6 +1120,8 @@ declare module 'svelte/compiler' {
 			instance: Script | null;
 			/** The parsed `<script module>` element, if exists */
 			module: Script | null;
+			/** Comments found in <script> and {expressions} */
+			comments: JSComment[];
 		}
 
 		export interface SvelteOptions {
@@ -1437,6 +1439,17 @@ declare module 'svelte/compiler' {
 			attributes: Attribute[];
 		}
 
+		export interface JSComment {
+			type: 'Line' | 'Block';
+			value: string;
+			start: number;
+			end: number;
+			loc: {
+				start: { line: number; column: number };
+				end: { line: number; column: number };
+			};
+		}
+
 		export type AttributeLike = Attribute | SpreadAttribute | Directive;
 
 		export type Directive =
@@ -1493,7 +1506,7 @@ declare module 'svelte/compiler' {
 			| AST.Comment
 			| Block;
 
-		export type SvelteNode = Node | TemplateNode | AST.Fragment | _CSS.Node;
+		export type SvelteNode = Node | TemplateNode | AST.Fragment | _CSS.Node | Script;
 
 		export type { _CSS as CSS };
 	}
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index cfbc54df33..b7fb655b2d 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -87,8 +87,8 @@ importers:
         specifier: ^1.2.1
         version: 1.2.1
       esrap:
-        specifier: ^1.4.8
-        version: 1.4.8
+        specifier: ^2.0.0
+        version: 2.0.0
       is-reference:
         specifier: ^3.0.3
         version: 3.0.3
@@ -1261,8 +1261,8 @@ packages:
     resolution: {integrity: sha512-YQLXUplAwJgCydQ78IMJywZCceoqk1oH01OERdSAJc/7U2AylwjhSCLDEtqwg811idIS/9fIU5GjG73IgjKMVg==}
     engines: {node: '>=0.10'}
 
-  esrap@1.4.8:
-    resolution: {integrity: sha512-jlENbjZ7lqgJV9/OmgAtVqrFFMwsl70ctOgPIg5oTdQVGC13RSkMdtvAmu7ZTLax92c9ljnIG0xleEkdL69hwg==}
+  esrap@2.0.0:
+    resolution: {integrity: sha512-zhw1TDqno99Ld5wOpe0t47rzVyxfGc1fvxNzPsqk4idUf5dcAePkAyfTceLJaSTytjiWDu26S5tI+grjvymXJA==}
 
   esrecurse@4.3.0:
     resolution: {integrity: sha512-KmfKL3b6G+RXvP8N1vr3Tq1kL/oCFgn2NYXEtqP8/L3pKapUA4G8cFVaoF3SU323CD4XypR/ffioHmkti6/Tag==}
@@ -3622,7 +3622,7 @@ snapshots:
     dependencies:
       estraverse: 5.3.0
 
-  esrap@1.4.8:
+  esrap@2.0.0:
     dependencies:
       '@jridgewell/sourcemap-codec': 1.5.0