fix #16477

Author: Rich-Harris

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

@@ -563,7 +563,7 @@ function flush_queued_effects(effects) {
 		var effect = effects[i++];
 
 		if ((effect.f & (DESTROYED | INERT)) === 0 && is_dirty(effect)) {
-			var wv = write_version;
+			var n = current_batch ? current_batch.current.size : 0;
 
 			update_effect(effect);
 
@@ -586,7 +586,11 @@ function flush_queued_effects(effects) {
 
 			// if state is written in a user effect, abort and re-schedule, lest we run
 			// effects that should be removed as a result of the state change
-			if (write_version > wv && (effect.f & USER_EFFECT) !== 0) {
+			if (
+				current_batch !== null &&
+				current_batch.current.size > n &&
+				(effect.f & USER_EFFECT) !== 0
+			) {
 				break;
 			}
 		}

packages/svelte/tests/runtime-runes/samples/1000-reading-derived-effects/Component.svelte

@@ -0,0 +1,7 @@
+<script>
+	const der = $derived(false);
+
+	$effect(() => {
+		der
+	});
+</script>

packages/svelte/tests/runtime-runes/samples/1000-reading-derived-effects/_config.js

@@ -0,0 +1,5 @@
+import { test } from '../../test';
+
+export default test({
+	async test() {}
+});

packages/svelte/tests/runtime-runes/samples/1000-reading-derived-effects/main.svelte

@@ -0,0 +1,8 @@
+<script>
+	import Component from './Component.svelte'	
+	const arr = Array.from({length: 10001});
+</script>
+
+{#each arr}
+	<Component />
+{/each}