diff --git a/frontend/src/lib/activity/ChronikFuerDichBox.svelte b/frontend/src/lib/activity/ChronikFuerDichBox.svelte
index 9cb94c24..fccf5892 100644
--- a/frontend/src/lib/activity/ChronikFuerDichBox.svelte
+++ b/frontend/src/lib/activity/ChronikFuerDichBox.svelte
@@ -1,4 +1,5 @@
 <script lang="ts">
+import { enhance } from '$app/forms';
 import * as m from '$lib/paraglide/messages.js';
 import { relativeTime } from '$lib/shared/utils/time';
 import type { NotificationItem } from '$lib/notification/notifications.svelte';
@@ -6,11 +7,11 @@ import { buildCommentHref } from '$lib/shared/discussion/commentDeepLink';
 
 interface Props {
 	unread: NotificationItem[];
-	onMarkRead: (n: NotificationItem) => void;
-	onMarkAllRead: () => void;
+	optimisticMarkRead: (id: string) => void;
+	optimisticMarkAllRead: () => void;
 }
 
-const { unread, onMarkRead, onMarkAllRead }: Props = $props();
+const { unread, optimisticMarkRead, optimisticMarkAllRead }: Props = $props();
 
 function verb(type: NotificationItem['type'], actor: string): string {
 	return type === 'REPLY'
@@ -66,14 +67,24 @@ function href(n: NotificationItem): string {
 					{m.chronik_for_you_count({ count: unread.length })}
 				</span>
 			</div>
-			<button
-				type="button"
-				data-testid="chronik-mark-all-read"
-				onclick={onMarkAllRead}
-				class="font-sans text-xs font-medium text-ink-3 transition-colors hover:text-ink"
+			<form
+				action="/aktivitaeten?/mark-all-read"
+				method="POST"
+				use:enhance={() => {
+					optimisticMarkAllRead();
+					return async ({ update }) => {
+						await update({ reset: false, invalidateAll: false });
+					};
+				}}
 			>
-				{m.chronik_mark_all_read()}
-			</button>
+				<button
+					type="submit"
+					data-testid="chronik-mark-all-read"
+					class="font-sans text-xs font-medium text-ink-3 transition-colors hover:text-ink"
+				>
+					{m.chronik_mark_all_read()}
+				</button>
+			</form>
 		</div>
 
 		<ul role="list" class="flex flex-col gap-2">
@@ -89,7 +100,7 @@ function href(n: NotificationItem): string {
 							aria-hidden="true"
 							class="mt-0.5 inline-flex h-6 w-6 shrink-0 items-center justify-center rounded-full bg-accent-bg font-sans text-xs font-bold text-accent"
 						>
-							{n.type === 'MENTION' ? '@' : '\u21A9'}
+							{n.type === 'MENTION' ? '@' : '↩'}
 						</span>
 						<div class="min-w-0 flex-1">
 							<p class="font-sans text-sm leading-snug text-ink">
@@ -100,25 +111,36 @@ function href(n: NotificationItem): string {
 							</p>
 						</div>
 					</a>
-					<button
-						type="button"
-						data-testid="chronik-fuerdich-dismiss"
-						aria-label={m.chronik_mark_read_aria()}
-						onclick={() => onMarkRead(n)}
-						class="mt-0.5 shrink-0 rounded-sm p-1 text-ink-3 transition-colors hover:bg-muted hover:text-ink focus-visible:ring-2 focus-visible:ring-focus-ring focus-visible:outline-none"
+					<form
+						action="/aktivitaeten?/dismiss-notification"
+						method="POST"
+						use:enhance={() => {
+							optimisticMarkRead(n.id);
+							return async ({ update }) => {
+								await update({ reset: false, invalidateAll: false });
+							};
+						}}
 					>
-						<svg
-							xmlns="http://www.w3.org/2000/svg"
-							class="h-4 w-4"
-							fill="none"
-							viewBox="0 0 24 24"
-							stroke="currentColor"
-							stroke-width="2"
-							aria-hidden="true"
+						<input type="hidden" name="notificationId" value={n.id} />
+						<button
+							type="submit"
+							data-testid="chronik-fuerdich-dismiss"
+							aria-label={m.chronik_mark_read_aria()}
+							class="mt-0.5 shrink-0 rounded-sm p-1 text-ink-3 transition-colors hover:bg-muted hover:text-ink focus-visible:ring-2 focus-visible:ring-focus-ring focus-visible:outline-none"
 						>
-							<path stroke-linecap="round" stroke-linejoin="round" d="M6 18L18 6M6 6l12 12" />
-						</svg>
-					</button>
+							<svg
+								xmlns="http://www.w3.org/2000/svg"
+								class="h-4 w-4"
+								fill="none"
+								viewBox="0 0 24 24"
+								stroke="currentColor"
+								stroke-width="2"
+								aria-hidden="true"
+							>
+								<path stroke-linecap="round" stroke-linejoin="round" d="M6 18L18 6M6 6l12 12" />
+							</svg>
+						</button>
+					</form>
 				</li>
 			{/each}
 		</ul>
diff --git a/frontend/src/lib/activity/ChronikFuerDichBox.svelte.spec.ts b/frontend/src/lib/activity/ChronikFuerDichBox.svelte.spec.ts
index f491dd06..44099b40 100644
--- a/frontend/src/lib/activity/ChronikFuerDichBox.svelte.spec.ts
+++ b/frontend/src/lib/activity/ChronikFuerDichBox.svelte.spec.ts
@@ -5,6 +5,17 @@ import { page, userEvent } from 'vitest/browser';
 import ChronikFuerDichBox from './ChronikFuerDichBox.svelte';
 import type { NotificationItem } from '$lib/notification/notifications.svelte';
 
+vi.mock('$app/forms', () => ({
+	enhance(node: HTMLFormElement, submit?: (opts: { formData: FormData }) => unknown) {
+		const handler = (e: Event) => {
+			e.preventDefault();
+			submit?.({ formData: new FormData(node) } as never);
+		};
+		node.addEventListener('submit', handler);
+		return { destroy: () => node.removeEventListener('submit', handler) };
+	}
+}));
+
 afterEach(cleanup);
 
 function notif(partial: Partial<NotificationItem>): NotificationItem {
@@ -26,8 +37,8 @@ describe('ChronikFuerDichBox', () => {
 	it('renders inbox-zero state when there are no unread items', async () => {
 		render(ChronikFuerDichBox, {
 			unread: [],
-			onMarkRead: vi.fn(),
-			onMarkAllRead: vi.fn()
+			optimisticMarkRead: vi.fn(),
+			optimisticMarkAllRead: vi.fn()
 		});
 		const zero = document.querySelector('[data-testid="chronik-inbox-zero"]');
 		expect(zero).not.toBeNull();
@@ -37,8 +48,8 @@ describe('ChronikFuerDichBox', () => {
 	it('links to the archived mentions in the inbox-zero state', async () => {
 		render(ChronikFuerDichBox, {
 			unread: [],
-			onMarkRead: vi.fn(),
-			onMarkAllRead: vi.fn()
+			optimisticMarkRead: vi.fn(),
+			optimisticMarkAllRead: vi.fn()
 		});
 		const link = document.querySelector('a[href="/aktivitaeten?filter=fuer-dich"]');
 		expect(link).not.toBeNull();
@@ -47,8 +58,8 @@ describe('ChronikFuerDichBox', () => {
 	it('renders the count badge with correct total when unread exists', async () => {
 		render(ChronikFuerDichBox, {
 			unread: [notif({ id: 'a' }), notif({ id: 'b' })],
-			onMarkRead: vi.fn(),
-			onMarkAllRead: vi.fn()
+			optimisticMarkRead: vi.fn(),
+			optimisticMarkAllRead: vi.fn()
 		});
 		await expect.element(page.getByText('2 neu')).toBeInTheDocument();
 	});
@@ -56,8 +67,8 @@ describe('ChronikFuerDichBox', () => {
 	it('count badge has aria-live=polite when unread exists', async () => {
 		render(ChronikFuerDichBox, {
 			unread: [notif({ id: 'a' })],
-			onMarkRead: vi.fn(),
-			onMarkAllRead: vi.fn()
+			optimisticMarkRead: vi.fn(),
+			optimisticMarkAllRead: vi.fn()
 		});
 		// Wait for render
 		await expect.element(page.getByText('1 neu')).toBeInTheDocument();
@@ -69,8 +80,8 @@ describe('ChronikFuerDichBox', () => {
 	it('does not render the "Alle gelesen" button when there are no unread items', async () => {
 		render(ChronikFuerDichBox, {
 			unread: [],
-			onMarkRead: vi.fn(),
-			onMarkAllRead: vi.fn()
+			optimisticMarkRead: vi.fn(),
+			optimisticMarkAllRead: vi.fn()
 		});
 		await expect.element(page.getByText('Keine neuen Erwähnungen')).toBeInTheDocument();
 		const all = document.querySelector('[data-testid="chronik-mark-all-read"]');
@@ -80,38 +91,38 @@ describe('ChronikFuerDichBox', () => {
 	it('renders the "Alle gelesen" button when unread exists', async () => {
 		render(ChronikFuerDichBox, {
 			unread: [notif({ id: 'a' })],
-			onMarkRead: vi.fn(),
-			onMarkAllRead: vi.fn()
+			optimisticMarkRead: vi.fn(),
+			optimisticMarkAllRead: vi.fn()
 		});
 		await expect.element(page.getByText('Alle gelesen')).toBeInTheDocument();
 	});
 
-	it('calls onMarkAllRead when the "Alle gelesen" button is clicked', async () => {
-		const onMarkAllRead = vi.fn();
+	it('calls optimisticMarkAllRead when the "Alle gelesen" button is submitted', async () => {
+		const optimisticMarkAllRead = vi.fn();
 		render(ChronikFuerDichBox, {
 			unread: [notif({ id: 'a' })],
-			onMarkRead: vi.fn(),
-			onMarkAllRead
+			optimisticMarkRead: vi.fn(),
+			optimisticMarkAllRead
 		});
 		await userEvent.click(page.getByText('Alle gelesen'));
-		expect(onMarkAllRead).toHaveBeenCalledTimes(1);
+		expect(optimisticMarkAllRead).toHaveBeenCalledTimes(1);
 	});
 
-	it('calls onMarkRead (and not navigation) when a per-item Dismiss button is clicked', async () => {
-		const onMarkRead = vi.fn();
+	it('calls optimisticMarkRead with the notification id when its dismiss button is submitted', async () => {
+		const optimisticMarkRead = vi.fn();
 		const n = notif({ id: 'xyz' });
 		render(ChronikFuerDichBox, {
 			unread: [n],
-			onMarkRead,
-			onMarkAllRead: vi.fn()
+			optimisticMarkRead,
+			optimisticMarkAllRead: vi.fn()
 		});
 		const dismiss = document.querySelector(
 			'[data-testid="chronik-fuerdich-dismiss"]'
 		) as HTMLButtonElement | null;
 		expect(dismiss).not.toBeNull();
 		dismiss?.click();
-		expect(onMarkRead).toHaveBeenCalledTimes(1);
-		expect(onMarkRead.mock.calls[0][0]).toEqual(n);
+		expect(optimisticMarkRead).toHaveBeenCalledTimes(1);
+		expect(optimisticMarkRead.mock.calls[0][0]).toBe('xyz');
 	});
 
 	it('mention row href includes both commentId and annotationId when annotationId is present', async () => {
@@ -124,8 +135,8 @@ describe('ChronikFuerDichBox', () => {
 					annotationId: 'annot-9'
 				})
 			],
-			onMarkRead: vi.fn(),
-			onMarkAllRead: vi.fn()
+			optimisticMarkRead: vi.fn(),
+			optimisticMarkAllRead: vi.fn()
 		});
 		const link = document.querySelector(
 			'a[href="/documents/doc-42?commentId=comment-7&annotationId=annot-9"]'
@@ -136,8 +147,8 @@ describe('ChronikFuerDichBox', () => {
 	it('Dismiss button is a sibling of the document link, never nested inside <a>', async () => {
 		render(ChronikFuerDichBox, {
 			unread: [notif({ id: 'x' })],
-			onMarkRead: vi.fn(),
-			onMarkAllRead: vi.fn()
+			optimisticMarkRead: vi.fn(),
+			optimisticMarkAllRead: vi.fn()
 		});
 		const dismiss = document.querySelector('[data-testid="chronik-fuerdich-dismiss"]');
 		expect(dismiss).not.toBeNull();
diff --git a/frontend/src/lib/activity/ChronikFuerDichBox.svelte.test.ts b/frontend/src/lib/activity/ChronikFuerDichBox.svelte.test.ts
index 6b887a86..dfc271f6 100644
--- a/frontend/src/lib/activity/ChronikFuerDichBox.svelte.test.ts
+++ b/frontend/src/lib/activity/ChronikFuerDichBox.svelte.test.ts
@@ -4,6 +4,17 @@ import { page } from 'vitest/browser';
 import ChronikFuerDichBox from './ChronikFuerDichBox.svelte';
 import type { NotificationItem } from '$lib/notification/notifications';
 
+vi.mock('$app/forms', () => ({
+	enhance(node: HTMLFormElement, submit?: (opts: { formData: FormData }) => unknown) {
+		const handler = (e: Event) => {
+			e.preventDefault();
+			submit?.({ formData: new FormData(node) } as never);
+		};
+		node.addEventListener('submit', handler);
+		return { destroy: () => node.removeEventListener('submit', handler) };
+	}
+}));
+
 afterEach(cleanup);
 
 const mention = (overrides: Partial<NotificationItem> = {}): NotificationItem => ({
@@ -22,7 +33,7 @@ const mention = (overrides: Partial<NotificationItem> = {}): NotificationItem =>
 describe('ChronikFuerDichBox', () => {
 	it('renders the inbox-zero state when there are no unread', async () => {
 		render(ChronikFuerDichBox, {
-			props: { unread: [], onMarkRead: () => {}, onMarkAllRead: () => {} }
+			props: { unread: [], optimisticMarkRead: () => {}, optimisticMarkAllRead: () => {} }
 		});
 
 		await expect.element(page.getByText(/keine neuen erwähnungen/i)).toBeVisible();
@@ -34,8 +45,8 @@ describe('ChronikFuerDichBox', () => {
 		render(ChronikFuerDichBox, {
 			props: {
 				unread: [mention(), mention({ id: 'n-2' }), mention({ id: 'n-3' })],
-				onMarkRead: () => {},
-				onMarkAllRead: () => {}
+				optimisticMarkRead: () => {},
+				optimisticMarkAllRead: () => {}
 			}
 		});
 
@@ -47,8 +58,8 @@ describe('ChronikFuerDichBox', () => {
 		render(ChronikFuerDichBox, {
 			props: {
 				unread: [mention({ id: 'n-m', type: 'MENTION' }), mention({ id: 'n-r', type: 'REPLY' })],
-				onMarkRead: () => {},
-				onMarkAllRead: () => {}
+				optimisticMarkRead: () => {},
+				optimisticMarkAllRead: () => {}
 			}
 		});
 
@@ -62,8 +73,8 @@ describe('ChronikFuerDichBox', () => {
 		render(ChronikFuerDichBox, {
 			props: {
 				unread: [mention({ actorName: 'Bertha' })],
-				onMarkRead: () => {},
-				onMarkAllRead: () => {}
+				optimisticMarkRead: () => {},
+				optimisticMarkAllRead: () => {}
 			}
 		});
 
@@ -76,8 +87,8 @@ describe('ChronikFuerDichBox', () => {
 		render(ChronikFuerDichBox, {
 			props: {
 				unread: [mention({ type: 'REPLY', actorName: 'Carl' })],
-				onMarkRead: () => {},
-				onMarkAllRead: () => {}
+				optimisticMarkRead: () => {},
+				optimisticMarkAllRead: () => {}
 			}
 		});
 
@@ -86,11 +97,11 @@ describe('ChronikFuerDichBox', () => {
 			.toBeVisible();
 	});
 
-	it('calls onMarkRead with the notification when its dismiss button is clicked', async () => {
-		const onMarkRead = vi.fn();
+	it('calls optimisticMarkRead with the notification id when its dismiss button is clicked', async () => {
+		const optimisticMarkRead = vi.fn();
 		const item = mention({ id: 'n-7' });
 		render(ChronikFuerDichBox, {
-			props: { unread: [item], onMarkRead, onMarkAllRead: () => {} }
+			props: { unread: [item], optimisticMarkRead, optimisticMarkAllRead: () => {} }
 		});
 
 		const dismiss = document.querySelector(
@@ -98,31 +109,31 @@ describe('ChronikFuerDichBox', () => {
 		) as HTMLElement;
 		dismiss.click();
 
-		expect(onMarkRead).toHaveBeenCalledWith(item);
+		expect(optimisticMarkRead).toHaveBeenCalledWith('n-7');
 	});
 
-	it('calls onMarkAllRead when the mark-all-read button is clicked', async () => {
-		const onMarkAllRead = vi.fn();
+	it('calls optimisticMarkAllRead when the mark-all-read button is clicked', async () => {
+		const optimisticMarkAllRead = vi.fn();
 		render(ChronikFuerDichBox, {
 			props: {
 				unread: [mention()],
-				onMarkRead: () => {},
-				onMarkAllRead
+				optimisticMarkRead: () => {},
+				optimisticMarkAllRead
 			}
 		});
 
 		const btn = document.querySelector('[data-testid="chronik-mark-all-read"]') as HTMLElement;
 		btn.click();
 
-		expect(onMarkAllRead).toHaveBeenCalledOnce();
+		expect(optimisticMarkAllRead).toHaveBeenCalledOnce();
 	});
 
 	it('builds a deep-link href to the comment for each notification', async () => {
 		render(ChronikFuerDichBox, {
 			props: {
 				unread: [mention({ documentId: 'doc-x', referenceId: 'ref-y', annotationId: null })],
-				onMarkRead: () => {},
-				onMarkAllRead: () => {}
+				optimisticMarkRead: () => {},
+				optimisticMarkAllRead: () => {}
 			}
 		});
 
diff --git a/frontend/src/routes/aktivitaeten/+page.svelte b/frontend/src/routes/aktivitaeten/+page.svelte
index fa870696..7246e51e 100644
--- a/frontend/src/routes/aktivitaeten/+page.svelte
+++ b/frontend/src/routes/aktivitaeten/+page.svelte
@@ -76,14 +76,6 @@ async function onFilterChange(v: FilterValue) {
 	});
 }
 
-async function onMarkRead(n: NotificationItem) {
-	await notificationStore.markRead(n);
-}
-
-async function onMarkAllRead() {
-	await notificationStore.markAllRead();
-}
-
 const displayFeed = $derived(applyClientFilter(data.activityFeed, data.filter));
 
 const isEmpty = $derived(displayFeed.length === 0);
@@ -108,7 +100,11 @@ function retry() {
 	{#if data.loadError === 'activity'}
 		<ChronikErrorCard onRetry={retry} />
 	{:else}
-		<ChronikFuerDichBox unread={unread} onMarkRead={onMarkRead} onMarkAllRead={onMarkAllRead} />
+		<ChronikFuerDichBox
+			unread={unread}
+			optimisticMarkRead={notificationStore.optimisticMarkRead}
+			optimisticMarkAllRead={notificationStore.optimisticMarkAllRead}
+		/>
 
 		<div class="mt-6">
 			<ChronikFilterPills value={data.filter} onChange={onFilterChange} />