fix

Author: Rich-Harris

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

@@ -15,22 +15,24 @@ export function async(node, expressions, fn) {
 
 	var batch = /** @type {Batch} */ (current_batch);
 	var effect = /** @type {Effect} */ (active_effect);
+
 	var boundary = get_pending_boundary(effect);
+	var ran = boundary.ran;
 
 	var restore = capture();
 
 	boundary.increment();
 
 	Promise.all(expressions.map((fn) => async_derived(fn))).then((result) => {
-		batch?.restore();
+		if (ran) batch.restore();
 
 		restore();
 		fn(node, ...result);
 
 		// TODO is this necessary?
 		schedule_effect(effect);
 
-		batch?.flush();
+		if (ran) batch.flush();
 		boundary.decrement();
 	});
 }

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

@@ -74,6 +74,8 @@ export class Batch {
 		}
 
 		for (const [source, current] of this.#current) {
+			current_values.set(source, source.v);
+
 			// TODO this shouldn't be necessary, but tests fail otherwise,
 			// presumably because we need a try-finally somewhere, and the
 			// source wasn't correctly reverted after the previous batch
@@ -214,16 +216,16 @@ export class Batch {
 				raf.tick(update_pending);
 			}
 
-			current_batch = new Batch();
+			const batch = (current_batch = new Batch());
 			batches.add(current_batch);
 
 			queueMicrotask(() => {
-				if (current_batch === null) {
+				if (current_batch !== batch) {
 					// a flushSync happened in the meantime
 					return;
 				}
 
-				current_batch.flush();
+				batch.flush();
 			});
 		}
 

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

@@ -162,9 +162,9 @@ export function async_derived(fn, location) {
 					}
 				}
 
-				batch?.restore();
+				if (ran) batch.restore();
 				internal_set(signal, v);
-				batch?.flush();
+				if (ran) batch.flush();
 
 				if (DEV && location !== undefined) {
 					recent_async_deriveds.add(signal);

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

@@ -40,7 +40,7 @@ import { DEV } from 'esm-env';
 import { define_property } from '../../shared/utils.js';
 import { get_next_sibling } from '../dom/operations.js';
 import { async_derived, derived } from './deriveds.js';
-import { capture } from '../dom/blocks/boundary.js';
+import { capture, get_pending_boundary } from '../dom/blocks/boundary.js';
 import { component_context, dev_current_component_function } from '../context.js';
 import { current_batch, Batch } from './batch.js';
 
@@ -348,6 +348,9 @@ export function template_effect(fn, sync = [], async = [], d = derived) {
 		var batch = /** @type {Batch} */ (current_batch);
 		var restore = capture();
 
+		var boundary = get_pending_boundary(parent);
+		var ran = boundary.ran;
+
 		Promise.all(async.map((expression) => async_derived(expression))).then((result) => {
 			restore();
 
@@ -357,9 +360,9 @@ export function template_effect(fn, sync = [], async = [], d = derived) {
 
 			var effect = create_template_effect(fn, [...sync.map(d), ...result]);
 
-			batch?.restore();
+			if (ran) batch.restore();
 			schedule_effect(effect);
-			batch?.flush();
+			if (ran) batch.flush();
 		});
 	} else {
 		create_template_effect(fn, sync.map(d));