refactor(chronik): remove client-side filter; add aria-live/aria-busy

- Delete feedFilters.ts and its 9 tests (dead code: server now filters)
- Remove activeFilter $state + $effect — read data.filter directly
- fuer-dich stays client-side via youMentioned/youParticipated predicate
- aria-live="polite" + aria-busy={!!navigating.type} on timeline region

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

frontend/src/routes/chronik/+page.svelte

@@ -1,7 +1,7 @@
 <script lang="ts">
 import { onMount, onDestroy } from 'svelte';
 import { goto } from '$app/navigation';
-import { page } from '$app/state';
+import { page, navigating } from '$app/state';
 import * as m from '$lib/paraglide/messages.js';
 import { notificationStore, type NotificationItem } from '$lib/stores/notifications.svelte';
 import ChronikFuerDichBox from '$lib/components/chronik/ChronikFuerDichBox.svelte';
@@ -11,7 +11,6 @@ import ChronikEmptyState from '$lib/components/chronik/ChronikEmptyState.svelte'
 import ChronikErrorCard from '$lib/components/chronik/ChronikErrorCard.svelte';
 import type { components } from '$lib/generated/api';
 import type { FilterValue } from './+page.server';
-import { filterFeed } from './feedFilters';
 
 type ActivityFeedItemDTO = components['schemas']['ActivityFeedItemDTO'];
 
@@ -26,14 +25,6 @@ interface Props {
 
 const { data }: Props = $props();
 
-// Mirror the current filter into a local state we can update on pill change.
-// The effect syncs whenever the server-loaded filter changes (e.g. after goto).
-// eslint-disable-next-line svelte/prefer-writable-derived -- we need this mutable for onFilterChange optimism before goto() resolves
-let activeFilter = $state<FilterValue>('alle');
-$effect(() => {
-	activeFilter = data.filter;
-});
-
 // Prefer the live SSE singleton for unread items so newly arriving mentions
 // prepend without a reload. On first mount, seed from the server-loaded unread
 // set if the singleton hasn't populated yet.
@@ -74,7 +65,6 @@ const unread = $derived<NotificationItem[]>(
 );
 
 async function onFilterChange(v: FilterValue) {
-	activeFilter = v;
 	const url = new URL(page.url);
 	if (v === 'alle') url.searchParams.delete('filter');
 	else url.searchParams.set('filter', v);
@@ -93,7 +83,13 @@ async function onMarkAllRead() {
 	await notificationStore.markAllRead();
 }
 
-const displayFeed = $derived(filterFeed(data.activityFeed, activeFilter));
+// fuer-dich cannot be expressed as a server-side kinds filter — youMentioned/youParticipated
+// are user-scoped flags that require client-side narrowing
+const displayFeed = $derived(
+	data.filter === 'fuer-dich'
+		? data.activityFeed.filter((item) => item.youMentioned || item.youParticipated)
+		: data.activityFeed
+);
 
 const isEmpty = $derived(displayFeed.length === 0);
 const emptyVariant = $derived<'first-run' | 'filter-empty' | 'inbox-zero'>(
@@ -120,15 +116,17 @@ function retry() {
 		<ChronikFuerDichBox unread={unread} onMarkRead={onMarkRead} onMarkAllRead={onMarkAllRead} />
 
 		<div class="mt-6">
-			<ChronikFilterPills value={activeFilter} onChange={onFilterChange} />
+			<ChronikFilterPills value={data.filter} onChange={onFilterChange} />
 		</div>
 
-		{#if isEmpty}
-			<div class="mt-8">
-				<ChronikEmptyState variant={emptyVariant} />
-			</div>
-		{:else}
-			<ChronikTimeline items={displayFeed} />
-		{/if}
+		<div aria-live="polite" aria-atomic="false" aria-busy={!!navigating.type}>
+			{#if isEmpty}
+				<div class="mt-8">
+					<ChronikEmptyState variant={emptyVariant} />
+				</div>
+			{:else}
+				<ChronikTimeline items={displayFeed} />
+			{/if}
+		</div>
 	{/if}
 </main>

frontend/src/routes/chronik/feedFilters.test.ts

@@ -1,94 +0,0 @@
-import { describe, expect, it } from 'vitest';
-import { filterFeed } from './feedFilters';
-import type { components } from '$lib/generated/api';
-
-type Item = components['schemas']['ActivityFeedItemDTO'];
-
-function makeItem(overrides: Partial<Item> = {}): Item {
-	return {
-		kind: 'FILE_UPLOADED',
-		documentId: 'd1',
-		documentTitle: 'Brief A',
-		happenedAt: '2026-04-20T10:00:00Z',
-		youMentioned: false,
-		youParticipated: false,
-		count: 1,
-		actor: null,
-		happenedAtUntil: null,
-		...overrides
-	};
-}
-
-describe('filterFeed', () => {
-	describe('alle', () => {
-		it('returns all items regardless of kind', () => {
-			const items = [
-				makeItem({ kind: 'FILE_UPLOADED' }),
-				makeItem({ kind: 'COMMENT_ADDED' }),
-				makeItem({ kind: 'MENTION_CREATED' })
-			];
-			expect(filterFeed(items, 'alle')).toHaveLength(3);
-		});
-	});
-
-	describe('fuer-dich', () => {
-		it('includes MENTION_CREATED items', () => {
-			const items = [makeItem({ kind: 'MENTION_CREATED' })];
-			expect(filterFeed(items, 'fuer-dich')).toHaveLength(1);
-		});
-
-		it('includes items where youMentioned is true', () => {
-			const items = [makeItem({ kind: 'COMMENT_ADDED', youMentioned: true })];
-			expect(filterFeed(items, 'fuer-dich')).toHaveLength(1);
-		});
-
-		it('includes items where youParticipated is true', () => {
-			const items = [makeItem({ kind: 'COMMENT_ADDED', youParticipated: true })];
-			expect(filterFeed(items, 'fuer-dich')).toHaveLength(1);
-		});
-
-		it('excludes FILE_UPLOADED with no participation', () => {
-			const items = [makeItem({ kind: 'FILE_UPLOADED' })];
-			expect(filterFeed(items, 'fuer-dich')).toHaveLength(0);
-		});
-
-		it('excludes COMMENT_ADDED with no mention and no participation', () => {
-			const items = [makeItem({ kind: 'COMMENT_ADDED' })];
-			expect(filterFeed(items, 'fuer-dich')).toHaveLength(0);
-		});
-	});
-
-	describe('hochgeladen', () => {
-		it('includes only FILE_UPLOADED items', () => {
-			const items = [
-				makeItem({ kind: 'FILE_UPLOADED' }),
-				makeItem({ kind: 'COMMENT_ADDED', youParticipated: true })
-			];
-			expect(filterFeed(items, 'hochgeladen')).toHaveLength(1);
-			expect(filterFeed(items, 'hochgeladen')[0].kind).toBe('FILE_UPLOADED');
-		});
-	});
-
-	describe('transkription', () => {
-		it('includes TEXT_SAVED, BLOCK_REVIEWED, ANNOTATION_CREATED', () => {
-			const items = [
-				makeItem({ kind: 'TEXT_SAVED' }),
-				makeItem({ kind: 'BLOCK_REVIEWED' }),
-				makeItem({ kind: 'ANNOTATION_CREATED' }),
-				makeItem({ kind: 'FILE_UPLOADED' })
-			];
-			expect(filterFeed(items, 'transkription')).toHaveLength(3);
-		});
-	});
-
-	describe('kommentare', () => {
-		it('includes COMMENT_ADDED and MENTION_CREATED', () => {
-			const items = [
-				makeItem({ kind: 'COMMENT_ADDED' }),
-				makeItem({ kind: 'MENTION_CREATED' }),
-				makeItem({ kind: 'FILE_UPLOADED' })
-			];
-			expect(filterFeed(items, 'kommentare')).toHaveLength(2);
-		});
-	});
-});

frontend/src/routes/chronik/feedFilters.ts

@@ -1,27 +0,0 @@
-import type { components } from '$lib/generated/api';
-import type { FilterValue } from './+page.server';
-
-type ActivityFeedItemDTO = components['schemas']['ActivityFeedItemDTO'];
-
-export function filterFeed(
-	items: ActivityFeedItemDTO[],
-	filter: FilterValue
-): ActivityFeedItemDTO[] {
-	switch (filter) {
-		case 'alle':
-			return items;
-		case 'fuer-dich':
-			return items.filter(
-				(i) => i.kind === 'MENTION_CREATED' || i.youMentioned || i.youParticipated
-			);
-		case 'hochgeladen':
-			return items.filter((i) => i.kind === 'FILE_UPLOADED');
-		case 'transkription':
-			return items.filter(
-				(i) =>
-					i.kind === 'TEXT_SAVED' || i.kind === 'BLOCK_REVIEWED' || i.kind === 'ANNOTATION_CREATED'
-			);
-		case 'kommentare':
-			return items.filter((i) => i.kind === 'COMMENT_ADDED' || i.kind === 'MENTION_CREATED');
-	}
-}