fix

packages/svelte/src/compiler/phases/2-analyze/index.js

@@ -265,7 +265,8 @@ export function analyze_module(ast, options) {
 		runes: true,
 		immutable: true,
 		tracing: analysis.tracing,
-		async_deriveds: new Set()
+		async_deriveds: new Set(),
+		blocking_awaits: new Set()
 	};
 }
 
@@ -453,7 +454,8 @@ export function analyze_component(root, source, options) {
 		snippet_renderers: new Map(),
 		snippets: new Set(),
 		is_async: false,
-		async_deriveds: new Set()
+		async_deriveds: new Set(),
+		blocking_awaits: new Set()
 	};
 
 	if (!runes) {

packages/svelte/src/compiler/phases/2-analyze/visitors/AwaitExpression.js

@@ -6,15 +6,22 @@
  * @param {Context} context
  */
 export function AwaitExpression(node, context) {
+	const tla = context.state.ast_type === 'instance' && context.state.function_depth === 1;
+	const blocking = tla || !!context.state.expression;
+
+	if (blocking) {
 		if (!context.state.analysis.runes) {
 			throw new Error('TODO runes mode only');
 		}
 
+		context.state.analysis.blocking_awaits.add(node);
+	}
+
 	if (context.state.expression) {
 		context.state.expression.is_async = true;
 	}
 
-	if (context.state.ast_type === 'instance' && context.state.scope.function_depth === 1) {
+	if (tla) {
 		context.state.analysis.is_async = true;
 	}
 

packages/svelte/src/compiler/phases/2-analyze/visitors/shared/function.js

@@ -15,6 +15,7 @@ export function visit_function(node, context) {
 
 	context.next({
 		...context.state,
-		function_depth: context.state.function_depth + 1
+		function_depth: context.state.function_depth + 1,
+		expression: null
 	});
 }

packages/svelte/src/compiler/phases/3-transform/client/visitors/AwaitExpression.js

@@ -7,12 +7,19 @@ import * as b from '../../../../utils/builders.js';
  * @param {ComponentContext} context
  */
 export function AwaitExpression(node, context) {
+	if (!context.state.analysis.runes) {
+		return context.next();
+	}
+
+	const block = context.state.analysis.blocking_awaits.has(node);
+
 	return b.call(
 		b.member(
 			b.await(
 				b.call(
 					'$.preserve_context',
-					node.argument && /** @type {Expression} */ (context.visit(node.argument))
+					node.argument && /** @type {Expression} */ (context.visit(node.argument)),
+					block && b.true
 				)
 			),
 			'read'

packages/svelte/src/compiler/phases/types.d.ts

@@ -1,5 +1,12 @@
 import type { AST, Binding } from '#compiler';
-import type { CallExpression, Identifier, LabeledStatement, Node, Program } from 'estree';
+import type {
+	AwaitExpression,
+	CallExpression,
+	Identifier,
+	LabeledStatement,
+	Node,
+	Program
+} from 'estree';
 import type { Scope, ScopeRoot } from './scope.js';
 
 export interface Js {
@@ -34,6 +41,9 @@ export interface Analysis {
 
 	/** A set of deriveds that contain `await` expressions */
 	async_deriveds: Set<CallExpression>;
+
+	/** A set of `await` expressions that should trigger suspense */
+	blocking_awaits: Set<AwaitExpression>;
 }
 
 export interface ComponentAnalysis extends Analysis {

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

@@ -247,14 +247,15 @@ export function trigger_async_boundary(effect, trigger) {
 /**
  * @template T
  * @param {Promise<T>} promise
+ * @param {boolean} block
  * @returns {Promise<{ read: () => T }>}
  */
-export async function preserve_context(promise) {
+export function preserve_context(promise, block = false) {
 	var previous_effect = active_effect;
 	var previous_reaction = active_reaction;
 	var previous_component_context = component_context;
 
-	let boundary = active_effect;
+	let boundary = block ? active_effect : null;
 	while (boundary !== null) {
 		if ((boundary.f & BOUNDARY_EFFECT) !== 0) {
 			break;
@@ -263,15 +264,14 @@ export async function preserve_context(promise) {
 		boundary = boundary.parent;
 	}
 
-	if (boundary === null) {
+	if (block && boundary === null) {
 		throw new Error('cannot suspend outside a boundary');
 	}
 
 	// @ts-ignore
-	boundary.fn(ASYNC_INCREMENT);
+	boundary?.fn(ASYNC_INCREMENT);
-
-	const value = await promise;
 
+	return promise.then((value) => {
 		return {
 			read() {
 				set_active_effect(previous_effect);
@@ -279,9 +279,10 @@ export async function preserve_context(promise) {
 				set_component_context(previous_component_context);
 
 				// @ts-ignore
-			boundary.fn(ASYNC_DECREMENT);
+				boundary?.fn(ASYNC_DECREMENT);
 
 				return value;
 			}
 		};
+	});
 }