fix(#145): deep-link notifications; show createdAt in recent docs

- Notification widget builds full link with ?commentId= and
  &annotationId= params, matching the bell notification behaviour
- Recent docs widget shows createdAt (upload date) instead of
  documentDate (the date on the original document)

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

frontend/src/lib/components/DashboardMentions.svelte

@@ -5,6 +5,8 @@ type NotificationDTO = {
 	id: string;
 	type: 'REPLY' | 'MENTION';
 	documentId?: string;
+	referenceId?: string;
+	annotationId?: string;
 	read: boolean;
 	createdAt: string;
 	actorName?: string;
@@ -26,7 +28,9 @@ let { mentions }: Props = $props();
 			<div class="flex items-center gap-3 border-b border-line py-2 last:border-0">
 				{#if mention.documentId}
 					<a
-						href="/documents/{mention.documentId}"
+						href={mention.annotationId
+							? `/documents/${mention.documentId}?commentId=${mention.referenceId}&annotationId=${mention.annotationId}`
+							: `/documents/${mention.documentId}?commentId=${mention.referenceId}`}
 						class="font-serif text-sm text-ink hover:text-ink-2"
 					>
 						{mention.actorName ?? ''}

frontend/src/lib/components/DashboardMentions.svelte.spec.ts

@@ -10,6 +10,8 @@ type NotificationDTO = {
 	id: string;
 	type: 'REPLY' | 'MENTION';
 	documentId?: string;
+	referenceId?: string;
+	annotationId?: string;
 	read: boolean;
 	createdAt: string;
 	actorName?: string;
@@ -20,6 +22,7 @@ function makeMention(overrides: Partial<NotificationDTO> = {}): NotificationDTO
 		id: 'notif-1',
 		type: 'MENTION',
 		documentId: 'doc-abc',
+		referenceId: 'comment-xyz',
 		read: false,
 		createdAt: '2026-01-15T10:00:00Z',
 		actorName: 'Anna Schmidt',
@@ -40,15 +43,22 @@ describe('DashboardMentions', () => {
 		await expect.element(widget).toBeInTheDocument();
 	});
 
-	it('renders one row per mention with link to document', async () => {
-		const mentions = [
-			makeMention({ id: 'n1', documentId: 'doc-1', actorName: 'Anna' }),
-			makeMention({ id: 'n2', documentId: 'doc-2', actorName: 'Bob' })
-		];
-		render(DashboardMentions, { mentions });
-		const links = page.getByRole('link');
-		await expect.element(links.nth(0)).toHaveAttribute('href', '/documents/doc-1');
-		await expect.element(links.nth(1)).toHaveAttribute('href', '/documents/doc-2');
+	it('builds link with commentId param when no annotationId', async () => {
+		render(DashboardMentions, {
+			mentions: [makeMention({ documentId: 'doc-1', referenceId: 'cmt-1' })]
+		});
+		const link = page.getByRole('link');
+		await expect.element(link).toHaveAttribute('href', '/documents/doc-1?commentId=cmt-1');
+	});
+
+	it('builds link with commentId and annotationId when annotationId is present', async () => {
+		render(DashboardMentions, {
+			mentions: [makeMention({ documentId: 'doc-2', referenceId: 'cmt-2', annotationId: 'ann-9' })]
+		});
+		const link = page.getByRole('link');
+		await expect
+			.element(link)
+			.toHaveAttribute('href', '/documents/doc-2?commentId=cmt-2&annotationId=ann-9');
 	});
 
 	it('shows actor name in each row', async () => {

frontend/src/lib/components/DashboardRecentDocuments.svelte

@@ -5,7 +5,7 @@ import { getLocale } from '$lib/paraglide/runtime.js';
 type Document = {
 	id: string;
 	title: string;
-	documentDate?: string;
+	createdAt?: string;
 	sender?: { id: string; firstName: string; lastName: string };
 };
 
@@ -20,7 +20,7 @@ function formatDate(dateStr: string): string {
 		day: 'numeric',
 		month: 'long',
 		year: 'numeric'
-	}).format(new Date(dateStr + 'T12:00:00'));
+	}).format(new Date(dateStr));
 }
 </script>
 
@@ -37,12 +37,12 @@ function formatDate(dateStr: string): string {
 				>
 					{doc.title}
 				</a>
-				{#if doc.documentDate}
+				{#if doc.createdAt}
 					<span
 						data-testid="doc-date-{doc.id}"
 						class="ml-2 shrink-0 font-sans text-xs text-gray-400"
 					>
-						{formatDate(doc.documentDate)}
+						{formatDate(doc.createdAt)}
 					</span>
 				{/if}
 			</div>

frontend/src/lib/components/DashboardRecentDocuments.svelte.spec.ts

@@ -9,12 +9,12 @@ afterEach(cleanup);
 type Document = {
 	id: string;
 	title: string;
-	documentDate?: string;
+	createdAt?: string;
 	sender?: { id: string; firstName: string; lastName: string };
 };
 
-function makeDoc(id: string, title: string, date?: string): Document {
-	return { id, title, documentDate: date };
+function makeDoc(id: string, title: string, createdAt?: string): Document {
+	return { id, title, createdAt };
 }
 
 describe('DashboardRecentDocuments', () => {