fix #17024

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

@@ -610,6 +610,10 @@ export function get(signal) {
 	} else if (is_derived) {
 		derived = /** @type {Derived} */ (signal);
 
+		if (is_updating_effect && effect_tracking() && (derived.f & CONNECTED) === 0) {
+			reconnect(derived);
+		}
+
 		if (batch_values?.has(derived)) {
 			return batch_values.get(derived);
 		}
@@ -617,10 +621,6 @@ export function get(signal) {
 		if (is_dirty(derived)) {
 			update_derived(derived);
 		}
-
-		if (is_updating_effect && effect_tracking() && (derived.f & CONNECTED) === 0) {
-			reconnect(derived);
-		}
 	}
 
 	if (batch_values?.has(signal)) {

packages/svelte/tests/runtime-runes/samples/async-derived-unowned/Component.svelte

@@ -0,0 +1,6 @@
+<script>
+	let { double } = $props();
+	double; // forces derived into UNOWNED mode
+</script>
+
+<p>{double}</p>

packages/svelte/tests/runtime-runes/samples/async-derived-unowned/_config.js

@@ -0,0 +1,30 @@
+import { tick } from 'svelte';
+import { test } from '../../test';
+
+export default test({
+	async test({ assert, target }) {
+		const button = target.querySelector('button');
+
+		button?.click();
+		await tick();
+
+		assert.htmlEqual(
+			target.innerHTML,
+			`
+				<button>1</button>
+				<p>2</p>
+			`
+		);
+
+		button?.click();
+		await tick();
+
+		assert.htmlEqual(
+			target.innerHTML,
+			`
+				<button>2</button>
+				<p>4</p>
+			`
+		);
+	}
+});

packages/svelte/tests/runtime-runes/samples/async-derived-unowned/main.svelte

@@ -0,0 +1,19 @@
+<script>
+	import Component from './Component.svelte';
+	let count = $state(0);
+	const double = $derived(count * 2);
+</script>
+
+<svelte:boundary>
+	{await new Promise((r) => {
+		// long enough for the test to do all its other stuff while this is pending
+		setTimeout(r, 10);
+	})}
+	{#snippet pending()}{/snippet}
+</svelte:boundary>
+
+<button onclick={() => count += 1}>{count}</button>
+
+{#if count > 0}
+	<Component {double} />
+{/if}