fix(notifications): move onClose/goto into enhance result callback

onClose() and goto() were firing before the server responded, making it
impossible for a fail() response to cancel navigation. Moved them inside
the result callback behind a result.type !== 'failure' guard.

Updated the $app/forms enhance mock to always invoke the returned async
callback with a configurable mockFormResult, and added three tests:
- success path calls onClose + goto with the correct deep-link URL
- failure path skips onClose and goto
- annotationId is appended to the URL when present

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/lib/notification/NotificationDropdown.svelte

@@ -84,15 +84,17 @@ function handleViewAll() {
 						class="contents"
 						use:enhance={() => {
 							optimisticMarkRead(notification.id);
-							onClose();
-							goto(
-								buildCommentHref(
-									notification.documentId,
-									notification.referenceId,
-									notification.annotationId
-								)
-							);
-							return async ({ update }) => {
+							return async ({ result, update }) => {
+								if (result.type !== 'failure') {
+									onClose();
+									goto(
+										buildCommentHref(
+											notification.documentId,
+											notification.referenceId,
+											notification.annotationId
+										)
+									);
+								}
 								await update({ reset: false, invalidateAll: false });
 							};
 						}}

frontend/src/lib/notification/NotificationDropdown.svelte.test.ts

@@ -6,13 +6,28 @@ import NotificationDropdown from './NotificationDropdown.svelte';
 
 vi.mock('$app/navigation', () => ({ goto: vi.fn() }));
 
-// Invoke the SubmitFunction synchronously on form submit so tests can assert
-// that optimisticMarkRead / optimisticMarkAllRead are called.
+// Configurable result for the enhance mock — tests that need failure set
+// mockFormResult.type = 'failure' before clicking.
+const mockFormResult = vi.hoisted(() => ({ type: 'success' as string }));
+
+// Invoke the SubmitFunction and always call the returned result callback with
+// mockFormResult so tests can exercise both success and failure branches.
 vi.mock('$app/forms', () => ({
-	enhance(node: HTMLFormElement, submit?: (opts: { formData: FormData }) => unknown) {
-		const handler = (e: Event) => {
+	enhance(
+		node: HTMLFormElement,
+		submit?: (opts: {
+			formData: FormData;
+		}) => (opts: {
+			result: { type: string; data?: Record<string, unknown> };
+			update: () => Promise<void>;
+		}) => Promise<void>
+	) {
+		const handler = async (e: Event) => {
 			e.preventDefault();
-			submit?.({ formData: new FormData(node) } as never);
+			const cb = submit?.({ formData: new FormData(node) } as never);
+			if (typeof cb === 'function') {
+				await cb({ result: mockFormResult, update: async () => {} } as never);
+			}
 		};
 		node.addEventListener('submit', handler);
 		return { destroy: () => node.removeEventListener('submit', handler) };
@@ -22,6 +37,7 @@ vi.mock('$app/forms', () => ({
 afterEach(() => {
 	cleanup();
 	vi.clearAllMocks();
+	mockFormResult.type = 'success'; // reset to default after each test
 });
 
 const makeNotification = (overrides: Record<string, unknown> = {}) => ({
@@ -313,4 +329,69 @@ describe('NotificationDropdown', () => {
 		const forms = document.querySelectorAll('form[action="/aktivitaeten?/dismiss-notification"]');
 		expect(forms.length).toBe(2);
 	});
+
+	it('calls onClose and goto with the deep-link URL after a successful dismiss', async () => {
+		const onClose = vi.fn();
+		const n = makeNotification({
+			id: 'n42',
+			documentId: 'd1',
+			referenceId: 'c1',
+			annotationId: null,
+			actorName: 'Anna'
+		});
+		render(NotificationDropdown, {
+			props: {
+				notifications: [n],
+				optimisticMarkRead: () => {},
+				optimisticMarkAllRead: () => {},
+				onClose
+			}
+		});
+
+		await page.getByRole('button', { name: /Anna hat auf deinen/i }).click();
+
+		expect(onClose).toHaveBeenCalledOnce();
+		expect(goto).toHaveBeenCalledWith('/documents/d1?commentId=c1');
+	});
+
+	it('does NOT call onClose or goto when the dismiss action returns a failure', async () => {
+		mockFormResult.type = 'failure';
+		const onClose = vi.fn();
+		const n = makeNotification({ id: 'n99', actorName: 'Bob' });
+		render(NotificationDropdown, {
+			props: {
+				notifications: [n],
+				optimisticMarkRead: () => {},
+				optimisticMarkAllRead: () => {},
+				onClose
+			}
+		});
+
+		await page.getByRole('button', { name: /Bob hat auf deinen/i }).click();
+
+		expect(onClose).not.toHaveBeenCalled();
+		expect(goto).not.toHaveBeenCalled();
+	});
+
+	it('calls goto with annotationId appended when the notification has an annotationId', async () => {
+		const n = makeNotification({
+			id: 'n55',
+			documentId: 'd1',
+			referenceId: 'c1',
+			annotationId: 'a1',
+			actorName: 'Eva'
+		});
+		render(NotificationDropdown, {
+			props: {
+				notifications: [n],
+				optimisticMarkRead: () => {},
+				optimisticMarkAllRead: () => {},
+				onClose: () => {}
+			}
+		});
+
+		await page.getByRole('button', { name: /Eva hat auf deinen/i }).click();
+
+		expect(goto).toHaveBeenCalledWith('/documents/d1?commentId=c1&annotationId=a1');
+	});
 });