diff --git a/frontend/src/lib/shared/discussion/MentionDropdown.svelte.test.ts b/frontend/src/lib/shared/discussion/MentionDropdown.svelte.test.ts
index 5ccc85bb..95124728 100644
--- a/frontend/src/lib/shared/discussion/MentionDropdown.svelte.test.ts
+++ b/frontend/src/lib/shared/discussion/MentionDropdown.svelte.test.ts
@@ -1,7 +1,7 @@
 import { describe, it, expect, vi, afterEach } from 'vitest';
 import { cleanup, render } from 'vitest-browser-svelte';
 import { page, userEvent } from 'vitest/browser';
-import { flushSync, mount, unmount } from 'svelte';
+import { flushSync, mount, tick, unmount } from 'svelte';
 import MentionDropdown from './MentionDropdown.svelte';
 import MentionDropdownFixture from './MentionDropdown.test-fixture.svelte';
 import { m } from '$lib/paraglide/messages.js';
@@ -241,7 +241,10 @@ describe('MentionDropdown — search input', () => {
 		await expect.element(page.getByRole('searchbox')).toHaveValue('Walter');
 
 		setEditorQuery('WdGruyter');
-		await new Promise((r) => setTimeout(r, 50));
+		// Flush pending Svelte reactivity so any (non-)update from the mirror
+		// $effect has landed before we assert. expect.element already polls, so
+		// no fixed-timeout fallback is needed. Sara on PR #629 round 3.
+		await tick();
 
 		await expect.element(page.getByRole('searchbox')).toHaveValue('Walter');
 	});