From d92901edd1184e464bc020b362b78df658041571 Mon Sep 17 00:00:00 2001
From: ComputerGuy <63362464+Ocean-OS@users.noreply.github.com>
Date: Fri, 1 Aug 2025 22:20:56 -0700
Subject: [PATCH 01/18] init

---
 .../src/compiler/phases/2-analyze/index.js    | 14 +++++++++
 .../src/compiler/phases/2-analyze/types.d.ts  |  6 ++++
 .../2-analyze/visitors/AwaitExpression.js     |  3 ++
 .../phases/2-analyze/visitors/Fragment.js     | 29 +++++++++++++++++++
 .../3-transform/client/transform-client.js    |  1 +
 .../phases/3-transform/client/types.d.ts      |  5 +++-
 .../phases/3-transform/client/utils.js        | 16 ++++++++--
 .../client/visitors/AwaitExpression.js        |  6 +++-
 .../3-transform/client/visitors/ConstTag.js   | 28 +++++++++++++-----
 .../3-transform/client/visitors/Fragment.js   | 29 +++++++++++++++----
 .../client/visitors/SnippetBlock.js           | 18 +++++++-----
 .../svelte/src/compiler/types/template.d.ts   |  5 +++-
 12 files changed, 133 insertions(+), 27 deletions(-)
 create mode 100644 packages/svelte/src/compiler/phases/2-analyze/visitors/Fragment.js

diff --git a/packages/svelte/src/compiler/phases/2-analyze/index.js b/packages/svelte/src/compiler/phases/2-analyze/index.js
index cd44fd998aed..7c0943bf7c27 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 +302,10 @@ export function analyze_module(source, options) {
 			function_depth: 0,
 			has_props_rune: false,
 			options: /** @type {ValidatedCompileOptions} */ (options),
+			fragment: {
+				has_await: false,
+				node: null
+			},
 			parent_element: null,
 			reactive_statement: null
 		},
@@ -688,6 +694,10 @@ export function analyze_component(root, source, options) {
 				analysis,
 				options,
 				ast_type: ast === instance.ast ? 'instance' : ast === template.ast ? 'template' : 'module',
+				fragment: {
+					has_await: false,
+					node: ast === template.ast ? template.ast : null
+				},
 				parent_element: null,
 				has_props_rune: false,
 				component_slots: new Set(),
@@ -753,6 +763,10 @@ export function analyze_component(root, source, options) {
 				scopes,
 				analysis,
 				options,
+				fragment: {
+					has_await: false,
+					node: ast === template.ast ? template.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 080239bac063..7f7dfa3c1474 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: FragmentAnalysis;
 	/**
 	 * 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.
@@ -28,6 +29,11 @@ export interface AnalysisState {
 	reactive_statement: null | ReactiveStatement;
 }
 
+export interface FragmentAnalysis {
+	has_await: boolean;
+	node: AST.Fragment | null;
+}
+
 export type Context<State extends AnalysisState = AnalysisState> = import('zimmerframe').Context<
 	AST.SvelteNode,
 	State
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 af7d0307e9dc..6e9052a0286b 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 +11,9 @@ export function AwaitExpression(node, context) {
 
 	if (context.state.expression) {
 		context.state.expression.has_await = true;
+		if (context.state.fragment.node) {
+			context.state.fragment.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 000000000000..4916c8910ea5
--- /dev/null
+++ b/packages/svelte/src/compiler/phases/2-analyze/visitors/Fragment.js
@@ -0,0 +1,29 @@
+/** @import { AST } from '#compiler' */
+/** @import { Context } from '../types.js' */
+
+/**
+ * @param {AST.Fragment} node
+ * @param {Context} context
+ */
+export function Fragment(node, context) {
+	const parent = /** @type {AST.TemplateNode} */ (context.path.at(-1));
+	if (
+		!parent ||
+		parent.type === 'Component' ||
+		parent.type === 'Root' ||
+		parent.type === 'IfBlock' ||
+		parent.type === 'KeyBlock' ||
+		parent.type === 'EachBlock' ||
+		parent.type === 'SnippetBlock' ||
+		parent.type === 'AwaitBlock'
+	) {
+		const fragment_metadata = {
+			has_await: false,
+			node
+		};
+		context.next({ ...context.state, fragment: fragment_metadata });
+		node.metadata.has_await = fragment_metadata.has_await;
+	} else {
+		context.next();
+	}
+}
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 a56aca9c5f0b..560d6c67b743 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
@@ -170,6 +170,7 @@ 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 e691be169b55..30ad2c29e852 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 6d9dac8a33d3..ff3d439d59f4 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/utils.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/utils.js
@@ -290,7 +290,19 @@ 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 {boolean} [async]
  */
-export function create_derived(state, arg) {
-	return b.call(state.analysis.runes ? '$.derived' : '$.derived_safe_equal', arg);
+export function create_derived(state, arg, async = false) {
+	if (async) {
+		return b.call(
+			b.await(
+				b.call(
+					'$.save',
+					b.call('$.async_derived', arg.type === 'ArrowFunctionExpression' ? b.async(arg) : arg)
+				)
+			)
+		);
+	} else {
+		return b.call(state.analysis.runes ? '$.derived' : '$.derived_safe_equal', arg);
+	}
 }
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AwaitExpression.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AwaitExpression.js
index 803d317ad40e..7acd5aaaae12 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AwaitExpression.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AwaitExpression.js
@@ -15,7 +15,11 @@ export function AwaitExpression(node, context) {
 	// preserve context for
 	//   a) top-level await and
 	//   b) awaits that precede other expressions in template or `$derived(...)`
-	if (tla || (is_reactive_expression(context) && !is_last_evaluated_expression(context, node))) {
+	if (
+		tla ||
+		(is_reactive_expression(context) &&
+			(!is_last_evaluated_expression(context, node) || context.path.at(-1)?.type === 'ConstTag'))
+	) {
 		return b.call(b.await(b.call('$.save', argument)));
 	}
 
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 34acdd6bb975..d5c5b2ea41fe 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 +16,29 @@ 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,
+			b.thunk(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 +52,11 @@ 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
@@ -61,18 +73,18 @@ export function ConstTag(node, context) {
 			])
 		);
 
-		let expression = create_derived(context.state, fn);
+		let expression = create_derived(context.state, fn, 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 0b10c02ffbe1..abda1c164480 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(),
@@ -78,7 +81,7 @@ export function Fragment(node, context) {
 
 	if (is_text_first) {
 		// skip over inserted comment
-		body.push(b.stmt(b.call('$.next')));
+		state.init.unshift(b.stmt(b.call('$.next')));
 	}
 
 	if (is_single_element) {
@@ -96,13 +99,13 @@ 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 +123,7 @@ 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 +143,12 @@ 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 +156,16 @@ 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()));
+	}
+
 	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/SnippetBlock.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/SnippetBlock.js
index 203cf62b3792..98894780e1fa 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),
+				has_await ? b.async(b.function(null, args, body)) : b.function(null, args, body)
+			)
+		: b.arrow(args, body, has_await);
 
 	const declaration = b.const(node.expression, snippet);
 
diff --git a/packages/svelte/src/compiler/types/template.d.ts b/packages/svelte/src/compiler/types/template.d.ts
index 058a1a8e66c3..8cb3657a5aeb 100644
--- a/packages/svelte/src/compiler/types/template.d.ts
+++ b/packages/svelte/src/compiler/types/template.d.ts
@@ -19,6 +19,9 @@ import type {
 } from 'estree';
 import type { Scope } from '../phases/scope';
 import type { _CSS } from './css';
+import type { FragmentAnalysis } from '../phases/2-analyze/types';
+
+type FragmentMetadata = Omit<FragmentAnalysis, 'node'>;
 
 /**
  * - `html`    — the default, for e.g. `<div>` or `<span>`
@@ -45,7 +48,7 @@ export namespace AST {
 		type: 'Fragment';
 		nodes: Array<Text | Tag | ElementLike | Block | Comment>;
 		/** @internal */
-		metadata: {
+		metadata: Partial<FragmentMetadata> & {
 			/**
 			 * Fragments declare their own scopes. A transparent fragment is one whose scope
 			 * is not represented by a scope in the resulting JavaScript (e.g. an element scope),

From 7fa57b1b0e370d94b23d4496192c04aa08110f9d Mon Sep 17 00:00:00 2001
From: ComputerGuy <63362464+Ocean-OS@users.noreply.github.com>
Date: Fri, 1 Aug 2025 22:47:45 -0700
Subject: [PATCH 02/18] fix

---
 .../compiler/phases/2-analyze/visitors/AwaitExpression.js    | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

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 6e9052a0286b..1f1c8ca6714d 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/visitors/AwaitExpression.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/visitors/AwaitExpression.js
@@ -11,7 +11,10 @@ export function AwaitExpression(node, context) {
 
 	if (context.state.expression) {
 		context.state.expression.has_await = true;
-		if (context.state.fragment.node) {
+		if (
+			context.state.fragment.node &&
+			!context.path.find((node) => node.type === 'ExpressionTag')
+		) {
 			context.state.fragment.has_await = true;
 		}
 		suspend = true;

From 5787224971eb8cc7b3a071caa8a986e477d1e4ea Mon Sep 17 00:00:00 2001
From: ComputerGuy <63362464+Ocean-OS@users.noreply.github.com>
Date: Fri, 1 Aug 2025 22:49:21 -0700
Subject: [PATCH 03/18] fix

---
 .../src/compiler/phases/2-analyze/visitors/AwaitExpression.js  | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

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 1f1c8ca6714d..bf18358106d8 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/visitors/AwaitExpression.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/visitors/AwaitExpression.js
@@ -13,7 +13,8 @@ export function AwaitExpression(node, context) {
 		context.state.expression.has_await = true;
 		if (
 			context.state.fragment.node &&
-			!context.path.find((node) => node.type === 'ExpressionTag')
+			// TODO there's probably a better way to do this
+			context.path.find((node) => node.type === 'ConstTag')
 		) {
 			context.state.fragment.has_await = true;
 		}

From 4d677151ab7f08e4f718f983f7d706432dc31f59 Mon Sep 17 00:00:00 2001
From: ComputerGuy <63362464+Ocean-OS@users.noreply.github.com>
Date: Fri, 1 Aug 2025 23:13:43 -0700
Subject: [PATCH 04/18] maybe this works?

---
 .../phases/2-analyze/visitors/Fragment.js     | 26 +++++++++----------
 1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/2-analyze/visitors/Fragment.js b/packages/svelte/src/compiler/phases/2-analyze/visitors/Fragment.js
index 4916c8910ea5..4a2d621629af 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/visitors/Fragment.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/visitors/Fragment.js
@@ -7,23 +7,23 @@
  */
 export function Fragment(node, context) {
 	const parent = /** @type {AST.TemplateNode} */ (context.path.at(-1));
-	if (
-		!parent ||
-		parent.type === 'Component' ||
-		parent.type === 'Root' ||
-		parent.type === 'IfBlock' ||
-		parent.type === 'KeyBlock' ||
-		parent.type === 'EachBlock' ||
-		parent.type === 'SnippetBlock' ||
-		parent.type === 'AwaitBlock'
-	) {
+	// if (
+	// 	!parent ||
+	// 	parent.type === 'Component' ||
+	// 	parent.type === 'Root' ||
+	// 	parent.type === 'IfBlock' ||
+	// 	parent.type === 'KeyBlock' ||
+	// 	parent.type === 'EachBlock' ||
+	// 	parent.type === 'SnippetBlock' ||
+	// 	parent.type === 'AwaitBlock'
+	// ) {
 		const fragment_metadata = {
 			has_await: false,
 			node
 		};
 		context.next({ ...context.state, fragment: fragment_metadata });
 		node.metadata.has_await = fragment_metadata.has_await;
-	} else {
-		context.next();
-	}
+	// } else {
+	// 	context.next();
+	// }
 }

From ebca33930cf8c42fe6892736dde8f098e22105d8 Mon Sep 17 00:00:00 2001
From: ComputerGuy <63362464+Ocean-OS@users.noreply.github.com>
Date: Fri, 1 Aug 2025 23:25:12 -0700
Subject: [PATCH 05/18] fix, minor cleanup

---
 .../phases/2-analyze/visitors/Fragment.js     | 26 +++++--------------
 .../client/visitors/SvelteBoundary.js         |  2 +-
 2 files changed, 7 insertions(+), 21 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/2-analyze/visitors/Fragment.js b/packages/svelte/src/compiler/phases/2-analyze/visitors/Fragment.js
index 4a2d621629af..f3442bad49ef 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/visitors/Fragment.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/visitors/Fragment.js
@@ -6,24 +6,10 @@
  * @param {Context} context
  */
 export function Fragment(node, context) {
-	const parent = /** @type {AST.TemplateNode} */ (context.path.at(-1));
-	// if (
-	// 	!parent ||
-	// 	parent.type === 'Component' ||
-	// 	parent.type === 'Root' ||
-	// 	parent.type === 'IfBlock' ||
-	// 	parent.type === 'KeyBlock' ||
-	// 	parent.type === 'EachBlock' ||
-	// 	parent.type === 'SnippetBlock' ||
-	// 	parent.type === 'AwaitBlock'
-	// ) {
-		const fragment_metadata = {
-			has_await: false,
-			node
-		};
-		context.next({ ...context.state, fragment: fragment_metadata });
-		node.metadata.has_await = fragment_metadata.has_await;
-	// } else {
-	// 	context.next();
-	// }
+	const fragment_metadata = {
+		has_await: false,
+		node
+	};
+	context.next({ ...context.state, fragment: fragment_metadata });
+	node.metadata.has_await = fragment_metadata.has_await;
 }
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 d37b990440c7..70df0223557d 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 });
 		}
 	}
 

From d12ee9bf4fd7d3bdb7e12d46e5c95c4dca6e3e6f Mon Sep 17 00:00:00 2001
From: ComputerGuy <63362464+Ocean-OS@users.noreply.github.com>
Date: Sat, 2 Aug 2025 16:02:27 -0700
Subject: [PATCH 06/18] maybe this'll fix hydration issues?

---
 .../compiler/phases/3-transform/client/visitors/Fragment.js | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/Fragment.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/Fragment.js
index abda1c164480..fbad556e09b5 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
@@ -99,13 +99,13 @@ export function Fragment(node, context) {
 		const template = transform_template(state, namespace, flags);
 		state.hoisted.push(b.var(template_name, template));
 
-		state.init.unshift(b.var(id, b.call(template_name)));
+		state.init.push(b.var(id, b.call(template_name)));
 		close = b.stmt(b.call('$.append', b.id('$$anchor'), id));
 	} else if (is_single_child_not_needing_template) {
 		context.visit(trimmed[0], state);
 	} else if (trimmed.length === 1 && trimmed[0].type === 'Text') {
 		const id = b.id(context.state.scope.generate('text'));
-		state.init.unshift(b.var(id, b.call('$.text', b.literal(trimmed[0].data))));
+		state.init.push(b.var(id, b.call('$.text', b.literal(trimmed[0].data))));
 		close = b.stmt(b.call('$.append', b.id('$$anchor'), id));
 	} else if (trimmed.length > 0) {
 		const id = b.id(context.state.scope.generate('fragment'));
@@ -123,7 +123,7 @@ export function Fragment(node, context) {
 				state
 			});
 
-			state.init.unshift(b.var(id, b.call('$.text')));
+			state.init.push(b.var(id, b.call('$.text')));
 			close = b.stmt(b.call('$.append', b.id('$$anchor'), id));
 		} else {
 			if (is_standalone) {

From 58842f5795dde103be99bd1fb0451871a3c280b5 Mon Sep 17 00:00:00 2001
From: ComputerGuy <63362464+Ocean-OS@users.noreply.github.com>
Date: Sat, 2 Aug 2025 16:09:54 -0700
Subject: [PATCH 07/18] apparently not, maybe this'll do it

---
 .../3-transform/client/visitors/Fragment.js      | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/Fragment.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/Fragment.js
index fbad556e09b5..c7c576101e5d 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
@@ -79,11 +79,6 @@ export function Fragment(node, context) {
 		context.visit(node, state);
 	}
 
-	if (is_text_first) {
-		// skip over inserted comment
-		state.init.unshift(b.stmt(b.call('$.next')));
-	}
-
 	if (is_single_element) {
 		const element = /** @type {AST.RegularElement} */ (trimmed[0]);
 
@@ -99,13 +94,13 @@ export function Fragment(node, context) {
 		const template = transform_template(state, namespace, flags);
 		state.hoisted.push(b.var(template_name, template));
 
-		state.init.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('$$anchor'), id));
 	} else if (is_single_child_not_needing_template) {
 		context.visit(trimmed[0], state);
 	} else if (trimmed.length === 1 && trimmed[0].type === 'Text') {
 		const id = b.id(context.state.scope.generate('text'));
-		state.init.push(b.var(id, b.call('$.text', b.literal(trimmed[0].data))));
+		state.init.unshift(b.var(id, b.call('$.text', b.literal(trimmed[0].data))));
 		close = b.stmt(b.call('$.append', b.id('$$anchor'), id));
 	} else if (trimmed.length > 0) {
 		const id = b.id(context.state.scope.generate('fragment'));
@@ -123,7 +118,7 @@ export function Fragment(node, context) {
 				state
 			});
 
-			state.init.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) {
@@ -166,6 +161,11 @@ export function Fragment(node, context) {
 		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) {

From 7b19d12d34de72cb78a8ea4054b98e7eb8e93694 Mon Sep 17 00:00:00 2001
From: ComputerGuy <63362464+Ocean-OS@users.noreply.github.com>
Date: Sat, 2 Aug 2025 16:39:18 -0700
Subject: [PATCH 08/18] add test, changeset

---
 .changeset/brave-baboons-teach.md             |  5 ++++
 .../samples/async-const/_config.js            | 16 +++++++++++++
 .../samples/async-const/main.svelte           | 23 +++++++++++++++++++
 3 files changed, 44 insertions(+)
 create mode 100644 .changeset/brave-baboons-teach.md
 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 000000000000..ca761018437c
--- /dev/null
+++ b/.changeset/brave-baboons-teach.md
@@ -0,0 +1,5 @@
+---
+'svelte': minor
+---
+
+feat: async fragments
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 000000000000..9319bafeb023
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/async-const/_config.js
@@ -0,0 +1,16 @@
+import { test } from '../../test';
+
+export default test({
+	html: `<h1>Loading...</h1>`,
+
+	async test({ assert, target }) {
+		await new Promise((resolve) => setTimeout(resolve, 100));
+		assert.htmlEqual(
+			target.innerHTML,
+			`
+            <h1>Hello, world!</h1>
+            <input type="text"/>
+			`
+		);
+	}
+});
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 000000000000..bbcf82739fbf
--- /dev/null
+++ b/packages/svelte/tests/runtime-runes/samples/async-const/main.svelte
@@ -0,0 +1,23 @@
+<script>
+    let name = $state('world');
+    /**
+     * @template T
+     * @param {T} value
+     * @param {number} ms
+     * @returns {Promise<T>}
+     */
+    function wait(value, ms) {
+        return new Promise(resolve => setTimeout(resolve, ms, value));
+    }
+</script>
+<svelte:boundary>
+    {#snippet pending()}
+        <h1>Loading...</h1>
+    {/snippet}
+    {#snippet greet()}
+        {@const greeting = await wait(`Hello, ${name}!`, 50)}
+        <h1>{greeting}</h1>
+        <input type="text" bind:value={name} />
+    {/snippet}
+    {@render greet()}
+</svelte:boundary>
\ No newline at end of file

From 2522b98a8e567f078b997d19853938d783534911 Mon Sep 17 00:00:00 2001
From: ComputerGuy <63362464+Ocean-OS@users.noreply.github.com>
Date: Sat, 2 Aug 2025 17:01:16 -0700
Subject: [PATCH 09/18] minor tweak

---
 .../svelte/src/compiler/phases/3-transform/client/types.d.ts    | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

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 30ad2c29e852..59c024dfb78b 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
@@ -58,7 +58,7 @@ 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 */
+	/** Transformed `{@const }` declarations */
 	readonly consts: Statement[];
 	/** Memoized expressions */
 	readonly memoizer: Memoizer;

From 1fd17a2ec3347129ebe3ac65fff1421d322d64d3 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Tue, 5 Aug 2025 21:30:00 -0400
Subject: [PATCH 10/18] tabs

---
 .../samples/async-const/_config.js            |  4 +-
 .../samples/async-const/main.svelte           | 40 +++++++++----------
 2 files changed, 22 insertions(+), 22 deletions(-)

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 9319bafeb023..f9ce32506494 100644
--- a/packages/svelte/tests/runtime-runes/samples/async-const/_config.js
+++ b/packages/svelte/tests/runtime-runes/samples/async-const/_config.js
@@ -8,8 +8,8 @@ export default test({
 		assert.htmlEqual(
 			target.innerHTML,
 			`
-            <h1>Hello, world!</h1>
-            <input type="text"/>
+				<h1>Hello, world!</h1>
+				<input type="text"/>
 			`
 		);
 	}
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 bbcf82739fbf..3c13320fa61b 100644
--- a/packages/svelte/tests/runtime-runes/samples/async-const/main.svelte
+++ b/packages/svelte/tests/runtime-runes/samples/async-const/main.svelte
@@ -1,23 +1,23 @@
 <script>
-    let name = $state('world');
-    /**
-     * @template T
-     * @param {T} value
-     * @param {number} ms
-     * @returns {Promise<T>}
-     */
-    function wait(value, ms) {
-        return new Promise(resolve => setTimeout(resolve, ms, value));
-    }
+	let name = $state('world');
+	/**
+	 * @template T
+	 * @param {T} value
+	 * @param {number} ms
+	 * @returns {Promise<T>}
+	 */
+	function wait(value, ms) {
+		return new Promise(resolve => setTimeout(resolve, ms, value));
+	}
 </script>
 <svelte:boundary>
-    {#snippet pending()}
-        <h1>Loading...</h1>
-    {/snippet}
-    {#snippet greet()}
-        {@const greeting = await wait(`Hello, ${name}!`, 50)}
-        <h1>{greeting}</h1>
-        <input type="text" bind:value={name} />
-    {/snippet}
-    {@render greet()}
-</svelte:boundary>
\ No newline at end of file
+	{#snippet pending()}
+		<h1>Loading...</h1>
+	{/snippet}
+	{#snippet greet()}
+		{@const greeting = await wait(`Hello, ${name}!`, 50)}
+		<h1>{greeting}</h1>
+		<input type="text" bind:value={name} />
+	{/snippet}
+	{@render greet()}
+</svelte:boundary>

From 201bf3704bc16cf7fb73c539126d586974f0e2ce Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Tue, 5 Aug 2025 21:32:02 -0400
Subject: [PATCH 11/18] avoid timeouts in tests, they add up quickly

---
 .../runtime-runes/samples/async-const/_config.js  | 12 ++++--------
 .../runtime-runes/samples/async-const/main.svelte | 15 ++++-----------
 2 files changed, 8 insertions(+), 19 deletions(-)

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 f9ce32506494..084d9c3874ef 100644
--- a/packages/svelte/tests/runtime-runes/samples/async-const/_config.js
+++ b/packages/svelte/tests/runtime-runes/samples/async-const/_config.js
@@ -1,16 +1,12 @@
+import { tick } from 'svelte';
 import { test } from '../../test';
 
 export default test({
 	html: `<h1>Loading...</h1>`,
 
 	async test({ assert, target }) {
-		await new Promise((resolve) => setTimeout(resolve, 100));
-		assert.htmlEqual(
-			target.innerHTML,
-			`
-				<h1>Hello, world!</h1>
-				<input type="text"/>
-			`
-		);
+		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
index 3c13320fa61b..9321bd792980 100644
--- a/packages/svelte/tests/runtime-runes/samples/async-const/main.svelte
+++ b/packages/svelte/tests/runtime-runes/samples/async-const/main.svelte
@@ -1,23 +1,16 @@
 <script>
 	let name = $state('world');
-	/**
-	 * @template T
-	 * @param {T} value
-	 * @param {number} ms
-	 * @returns {Promise<T>}
-	 */
-	function wait(value, ms) {
-		return new Promise(resolve => setTimeout(resolve, ms, value));
-	}
 </script>
+
 <svelte:boundary>
 	{#snippet pending()}
 		<h1>Loading...</h1>
 	{/snippet}
+
 	{#snippet greet()}
-		{@const greeting = await wait(`Hello, ${name}!`, 50)}
+		{@const greeting = await `Hello, ${name}!`}
 		<h1>{greeting}</h1>
-		<input type="text" bind:value={name} />
 	{/snippet}
+
 	{@render greet()}
 </svelte:boundary>

From f3daef7947c2c720d9f626cf04d5fbca6262ba6e Mon Sep 17 00:00:00 2001
From: ComputerGuy <63362464+Ocean-OS@users.noreply.github.com>
Date: Tue, 5 Aug 2025 19:15:43 -0700
Subject: [PATCH 12/18] tweak

---
 .../svelte/src/compiler/phases/2-analyze/index.js | 15 +++------------
 .../src/compiler/phases/2-analyze/types.d.ts      |  7 +------
 .../phases/2-analyze/visitors/AwaitExpression.js  |  4 ++--
 .../phases/2-analyze/visitors/Fragment.js         |  8 ++------
 packages/svelte/src/compiler/types/template.d.ts  |  6 ++----
 5 files changed, 10 insertions(+), 30 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/2-analyze/index.js b/packages/svelte/src/compiler/phases/2-analyze/index.js
index 7c0943bf7c27..a64f7048e443 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/index.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/index.js
@@ -302,10 +302,7 @@ export function analyze_module(source, options) {
 			function_depth: 0,
 			has_props_rune: false,
 			options: /** @type {ValidatedCompileOptions} */ (options),
-			fragment: {
-				has_await: false,
-				node: null
-			},
+			fragment: null,
 			parent_element: null,
 			reactive_statement: null
 		},
@@ -694,10 +691,7 @@ export function analyze_component(root, source, options) {
 				analysis,
 				options,
 				ast_type: ast === instance.ast ? 'instance' : ast === template.ast ? 'template' : 'module',
-				fragment: {
-					has_await: false,
-					node: ast === template.ast ? template.ast : null
-				},
+				fragment: ast === template.ast ? ast : null,
 				parent_element: null,
 				has_props_rune: false,
 				component_slots: new Set(),
@@ -763,10 +757,7 @@ export function analyze_component(root, source, options) {
 				scopes,
 				analysis,
 				options,
-				fragment: {
-					has_await: false,
-					node: ast === template.ast ? template.ast : null
-				},
+				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 7f7dfa3c1474..2d99a2e155f6 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/types.d.ts
+++ b/packages/svelte/src/compiler/phases/2-analyze/types.d.ts
@@ -8,7 +8,7 @@ export interface AnalysisState {
 	analysis: ComponentAnalysis;
 	options: ValidatedCompileOptions;
 	ast_type: 'instance' | 'template' | 'module';
-	fragment: FragmentAnalysis;
+	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.
@@ -29,11 +29,6 @@ export interface AnalysisState {
 	reactive_statement: null | ReactiveStatement;
 }
 
-export interface FragmentAnalysis {
-	has_await: boolean;
-	node: AST.Fragment | null;
-}
-
 export type Context<State extends AnalysisState = AnalysisState> = import('zimmerframe').Context<
 	AST.SvelteNode,
 	State
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 bf18358106d8..4e9d0e93da44 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/visitors/AwaitExpression.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/visitors/AwaitExpression.js
@@ -12,11 +12,11 @@ export function AwaitExpression(node, context) {
 	if (context.state.expression) {
 		context.state.expression.has_await = true;
 		if (
-			context.state.fragment.node &&
+			context.state.fragment &&
 			// TODO there's probably a better way to do this
 			context.path.find((node) => node.type === 'ConstTag')
 		) {
-			context.state.fragment.has_await = true;
+			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
index f3442bad49ef..d6e155f2f135 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/visitors/Fragment.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/visitors/Fragment.js
@@ -6,10 +6,6 @@
  * @param {Context} context
  */
 export function Fragment(node, context) {
-	const fragment_metadata = {
-		has_await: false,
-		node
-	};
-	context.next({ ...context.state, fragment: fragment_metadata });
-	node.metadata.has_await = fragment_metadata.has_await;
+	node.metadata.has_await = false;
+	context.next({ ...context.state, fragment: node });
 }
diff --git a/packages/svelte/src/compiler/types/template.d.ts b/packages/svelte/src/compiler/types/template.d.ts
index 8cb3657a5aeb..060df2dcb2a4 100644
--- a/packages/svelte/src/compiler/types/template.d.ts
+++ b/packages/svelte/src/compiler/types/template.d.ts
@@ -19,9 +19,6 @@ import type {
 } from 'estree';
 import type { Scope } from '../phases/scope';
 import type { _CSS } from './css';
-import type { FragmentAnalysis } from '../phases/2-analyze/types';
-
-type FragmentMetadata = Omit<FragmentAnalysis, 'node'>;
 
 /**
  * - `html`    — the default, for e.g. `<div>` or `<span>`
@@ -48,7 +45,7 @@ export namespace AST {
 		type: 'Fragment';
 		nodes: Array<Text | Tag | ElementLike | Block | Comment>;
 		/** @internal */
-		metadata: Partial<FragmentMetadata> & {
+		metadata: {
 			/**
 			 * Fragments declare their own scopes. A transparent fragment is one whose scope
 			 * is not represented by a scope in the resulting JavaScript (e.g. an element scope),
@@ -59,6 +56,7 @@ export namespace AST {
 			 * Whether or not we need to traverse into the fragment during mount/hydrate
 			 */
 			dynamic: boolean;
+			has_await: boolean;
 		};
 	}
 

From b1cc101c085327b412ac10a043737c30e9dc474f Mon Sep 17 00:00:00 2001
From: ComputerGuy <63362464+Ocean-OS@users.noreply.github.com>
Date: Tue, 5 Aug 2025 19:21:41 -0700
Subject: [PATCH 13/18] fix

---
 packages/svelte/src/compiler/phases/1-parse/utils/create.js    | 3 ++-
 .../svelte/src/compiler/phases/2-analyze/visitors/Fragment.js  | 1 -
 2 files changed, 2 insertions(+), 2 deletions(-)

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 6030f1bd7bff..2fba918f20ee 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/visitors/Fragment.js b/packages/svelte/src/compiler/phases/2-analyze/visitors/Fragment.js
index d6e155f2f135..02d780dc0dc7 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/visitors/Fragment.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/visitors/Fragment.js
@@ -6,6 +6,5 @@
  * @param {Context} context
  */
 export function Fragment(node, context) {
-	node.metadata.has_await = false;
 	context.next({ ...context.state, fragment: node });
 }

From e57f09ffe91e1b22a5c3c4147d3b07ad62935f67 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Wed, 6 Aug 2025 09:47:05 -0400
Subject: [PATCH 14/18] some is more 'correct' than find

---
 .../src/compiler/phases/2-analyze/visitors/AwaitExpression.js | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

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 4e9d0e93da44..b2f59b849b42 100644
--- a/packages/svelte/src/compiler/phases/2-analyze/visitors/AwaitExpression.js
+++ b/packages/svelte/src/compiler/phases/2-analyze/visitors/AwaitExpression.js
@@ -11,13 +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.find((node) => node.type === 'ConstTag')
+			context.path.some((node) => node.type === 'ConstTag')
 		) {
 			context.state.fragment.metadata.has_await = true;
 		}
+
 		suspend = true;
 	}
 

From 9587530a32746e8a85d42b0758a0c85cd66d42f2 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Wed, 6 Aug 2025 10:32:31 -0400
Subject: [PATCH 15/18] chore: remove `b.async`

---
 .../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 175b44f4fe29..08537577751a 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 81c4e6b8e0c5..defdb1642e1d 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 529571d18489d895b4e044c8f0d20c15481a1376 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Wed, 6 Aug 2025 12:06:26 -0400
Subject: [PATCH 16/18] simplify

---
 .../phases/3-transform/client/utils.js        | 19 +++++++----------
 .../3-transform/client/visitors/AwaitBlock.js |  4 ++--
 .../3-transform/client/visitors/ConstTag.js   | 21 +++++++------------
 .../client/visitors/LetDirective.js           |  5 +----
 .../client/visitors/SnippetBlock.js           |  2 +-
 .../svelte/src/compiler/utils/builders.js     |  4 ++--
 6 files changed, 21 insertions(+), 34 deletions(-)

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 ff3d439d59f4..19a4342b5eb1 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' */
@@ -289,20 +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, async = false) {
+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', arg.type === 'ArrowFunctionExpression' ? b.async(arg) : arg)
-				)
-			)
-		);
+		return b.call(b.await(b.call('$.save', b.call('$.async_derived', thunk))));
 	} else {
-		return b.call(state.analysis.runes ? '$.derived' : '$.derived_safe_equal', arg);
+		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 4246091bcf88..e2e8e93f768c 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 d5c5b2ea41fe..b550dae890db 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
@@ -21,11 +21,8 @@ export function ConstTag(node, context) {
 			declaration.init,
 			node.metadata.expression
 		);
-		let expression = create_derived(
-			context.state,
-			b.thunk(init),
-			node.metadata.expression.has_await
-		);
+
+		let expression = create_derived(context.state, init, node.metadata.expression.has_await);
 
 		if (dev) {
 			expression = b.call('$.tag', expression, b.literal(declaration.id.name));
@@ -65,15 +62,13 @@ 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, node.metadata.expression.has_await);
+		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('$.tag', expression, b.literal('[@const]'));
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/LetDirective.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/LetDirective.js
index abdbc381d99c..f33febeeb281 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/LetDirective.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/LetDirective.js
@@ -46,9 +46,6 @@ export function LetDirective(node, context) {
 			read: (node) => b.call('$.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 98894780e1fa..895522d47ab2 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
@@ -81,7 +81,7 @@ export function SnippetBlock(node, context) {
 		? b.call(
 				'$.wrap_snippet',
 				b.id(context.state.analysis.name),
-				has_await ? b.async(b.function(null, args, body)) : b.function(null, args, body)
+				b.function(null, args, body, has_await)
 			)
 		: b.arrow(args, body, has_await);
 
diff --git a/packages/svelte/src/compiler/utils/builders.js b/packages/svelte/src/compiler/utils/builders.js
index defdb1642e1d..56a5f31ffe82 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
 	};
 }

From 88e4fb65282decdeb865c52025d240d5bd4f8198 Mon Sep 17 00:00:00 2001
From: ComputerGuy <63362464+Ocean-OS@users.noreply.github.com>
Date: Wed, 6 Aug 2025 10:24:27 -0700
Subject: [PATCH 17/18] apply suggestion from review

Co-authored-by: Rich Harris <rich.harris@vercel.com>
---
 .../phases/3-transform/client/visitors/AwaitExpression.js   | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AwaitExpression.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AwaitExpression.js
index 7acd5aaaae12..803d317ad40e 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/AwaitExpression.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/AwaitExpression.js
@@ -15,11 +15,7 @@ export function AwaitExpression(node, context) {
 	// preserve context for
 	//   a) top-level await and
 	//   b) awaits that precede other expressions in template or `$derived(...)`
-	if (
-		tla ||
-		(is_reactive_expression(context) &&
-			(!is_last_evaluated_expression(context, node) || context.path.at(-1)?.type === 'ConstTag'))
-	) {
+	if (tla || (is_reactive_expression(context) && !is_last_evaluated_expression(context, node))) {
 		return b.call(b.await(b.call('$.save', argument)));
 	}
 

From 15f3508529fd56179464f82f392168370f285204 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Wed, 6 Aug 2025 13:52:56 -0400
Subject: [PATCH 18/18] Update .changeset/brave-baboons-teach.md

---
 .changeset/brave-baboons-teach.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.changeset/brave-baboons-teach.md b/.changeset/brave-baboons-teach.md
index ca761018437c..55d7d2a9884f 100644
--- a/.changeset/brave-baboons-teach.md
+++ b/.changeset/brave-baboons-teach.md
@@ -2,4 +2,4 @@
 'svelte': minor
 ---
 
-feat: async fragments
+feat: allow `await` inside `@const` declarations