fix: run deferred effects in async components

Author: Ocean-OS

.changeset/red-spies-mix.md

@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: run deferred effects in async components

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

@@ -385,7 +385,7 @@ export function client_component(analysis, options) {
 			.../** @type {ESTree.Statement[]} */ (template.body)
 		]);
 
-		component_block.body.push(b.stmt(b.call(`$.async_body`, b.arrow([], body, true))));
+		component_block.body.push(b.stmt(b.call(`$.async_body`, b.arrow([], body, true), b.true)));
 	} else {
 		component_block.body.push(
 			...state.instance_level_snippets,

packages/svelte/src/internal/client/context.js

@@ -147,6 +147,7 @@ export function push(props, runes = false, fn) {
 		p: component_context,
 		c: null,
 		e: null,
+		a: false,
 		s: props,
 		x: null,
 		l: legacy_mode_flag && !runes ? { s: null, u: null, $: [] } : null
@@ -168,7 +169,7 @@ export function pop(component) {
 	var context = /** @type {ComponentContext} */ (component_context);
 	var effects = context.e;
 
-	if (effects !== null) {
+	if (effects !== null && context.a === false) {
 		context.e = null;
 
 		for (var fn of effects) {

packages/svelte/src/internal/client/reactivity/async.js

@@ -19,7 +19,7 @@ import {
 	derived_safe_equal,
 	set_from_async_derived
 } from './deriveds.js';
-import { aborted } from './effects.js';
+import { aborted, create_user_effect } from './effects.js';
 
 /**
  *
@@ -176,10 +176,15 @@ export function unset_context() {
 
 /**
  * @param {() => Promise<void>} fn
+ * @param {boolean} [is_component]
  */
-export async function async_body(fn) {
+export async function async_body(fn, is_component = false) {
 	var unsuspend = suspend();
 	var active = /** @type {Effect} */ (active_effect);
+	var ctx = is_component ? component_context : null;
+	if (ctx !== null) {
+		ctx.a = true;
+	}
 
 	try {
 		await fn();
@@ -189,5 +194,15 @@ export async function async_body(fn) {
 		}
 	} finally {
 		unsuspend();
+		if (ctx !== null && ctx.e !== null) {
+			var prev = component_context;
+			var effects = ctx.e;
+			set_component_context(ctx);
+			for (var effect of effects) {
+				create_user_effect(effect);
+			}
+			set_component_context(prev);
+			ctx = prev = null;
+		}
 	}
 }

packages/svelte/src/internal/client/types.d.ts

@@ -16,6 +16,8 @@ export type ComponentContext = {
 	c: null | Map<unknown, unknown>;
 	/** deferred effects */
 	e: null | Array<() => void | (() => void)>;
+	/** whether the component is suspending */
+	a: boolean;
 	/**
 	 * props — needed for legacy mode lifecycle functions, and for `createEventDispatcher`
 	 * @deprecated remove in 6.0