feat(ui): collapsible date filter with sort + filter toggle on person row

Move sort button and filter toggle to the person row, matching the
document search page pattern (sort + filter + count inline). Date
range inputs are now a collapsible section behind the filter toggle,
using slide transition and the same grid layout as the document
search advanced filters. Fix date input padding (add px-3).

Refs: #179

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

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

@@ -28,6 +28,7 @@ $effect(() => {
 });
 
 const isSinglePerson = $derived(!!senderId && !receiverId);
+let showAdvanced = $state(false);
 
 const RECENT_STORAGE_KEY = 'korrespondenz_recent_persons';
 const MAX_RECENT = 5;
@@ -107,20 +108,23 @@ function selectPerson(id: string) {
 				bind:receiverId={receiverId}
 				initialSenderName={data.initialValues.senderName}
 				initialReceiverName={data.initialValues.receiverName}
-				onapplyFilters={applyFilters}
+				sortDir={sortDir}
-				onswapPersons={swapPersons}
+				showAdvanced={showAdvanced}
-			/>
-
-			<CorrespondenzFilterControls
-				senderId={senderId}
-				bind:fromDate={fromDate}
-				bind:toDate={toDate}
-				bind:sortDir={sortDir}
 				documentCount={data.documents.length}
 				onapplyFilters={applyFilters}
+				onswapPersons={swapPersons}
 				ontoggleSort={toggleSort}
+				ontoggleAdvanced={() => (showAdvanced = !showAdvanced)}
 			/>
 
+			{#if showAdvanced}
+				<CorrespondenzFilterControls
+					bind:fromDate={fromDate}
+					bind:toDate={toDate}
+					onapplyFilters={applyFilters}
+				/>
+			{/if}
+
 			{#if isSinglePerson}
 				<SinglePersonHintBar
 					senderName={senderName}

frontend/src/routes/briefwechsel/CorrespondenzFilterControls.svelte

@@ -1,116 +1,50 @@
 <script lang="ts">
+import { slide } from 'svelte/transition';
 import { m } from '$lib/paraglide/messages.js';
 import DateInput from '$lib/components/DateInput.svelte';
 
 interface Props {
-	senderId: string;
 	fromDate?: string;
 	toDate?: string;
-	sortDir?: string;
-	documentCount?: number;
 	onapplyFilters: () => void;
-	ontoggleSort: () => void;
 }
 
-let {
+let { fromDate = $bindable(''), toDate = $bindable(''), onapplyFilters }: Props = $props();
-	senderId,
-	fromDate = $bindable(''),
-	toDate = $bindable(''),
-	sortDir = $bindable('DESC'),
-	documentCount,
-	onapplyFilters,
-	ontoggleSort
-}: Props = $props();
-
-let hasDateFilter = $derived(!!(fromDate || toDate));
-let isActive = $derived(!!(fromDate || toDate || sortDir !== 'DESC'));
 </script>
 
 <div
 	data-testid="conv-filter-controls"
-	class="mt-6 flex items-center gap-4 border-t border-line-2 pt-6 transition-opacity"
+	transition:slide
-	class:opacity-40={!senderId}
+	class="mt-6 grid grid-cols-1 gap-6 border-t border-line-2 pt-6 md:grid-cols-12"
-	class:pointer-events-none={!senderId}
-	aria-disabled={!senderId}
 >
-	<!-- Period label -->
-	<span class="text-xs font-bold tracking-widest text-ink-2 uppercase">
-		{m.conv_strip_period()}
-	</span>
-
 	<!-- From date -->
-	<DateInput
+	<div class="md:col-span-3">
-		bind:value={fromDate}
+		<label
-		onchange={() => onapplyFilters()}
+			for="conv-from"
-		placeholder={m.conv_strip_from_placeholder()}
+			class="mb-2 block text-xs font-bold tracking-widest text-ink-2 uppercase"
-		class="w-[120px] border-line py-2.5 text-sm text-ink shadow-sm focus:outline-none focus-visible:ring-2 focus-visible:ring-focus-ring {fromDate ? 'border-primary' : 'border-line'}"
+		>
-	/>
+			{m.conv_label_from()}
-
+		</label>
-	<span class="text-sm text-ink-3">–</span>
+		<DateInput
+			id="conv-from"
+			bind:value={fromDate}
+			onchange={() => onapplyFilters()}
+			placeholder={m.conv_strip_from_placeholder()}
+			class="block w-full border-line px-3 py-2.5 text-sm text-ink shadow-sm focus:outline-none focus-visible:ring-2 focus-visible:ring-focus-ring"
+		/>
+	</div>
 
 	<!-- To date -->
-	<DateInput
+	<div class="md:col-span-3">
-		bind:value={toDate}
+		<label for="conv-to" class="mb-2 block text-xs font-bold tracking-widest text-ink-2 uppercase">
-		onchange={() => onapplyFilters()}
+			{m.conv_label_to()}
-		placeholder={m.conv_strip_to_placeholder()}
+		</label>
-		class="w-[120px] border-line py-2.5 text-sm text-ink shadow-sm focus:outline-none focus-visible:ring-2 focus-visible:ring-focus-ring {toDate ? 'border-primary' : 'border-line'}"
+		<DateInput
-	/>
+			id="conv-to"
-
+			bind:value={toDate}
-	<!-- Document count -->
+			onchange={() => onapplyFilters()}
-	<span
+			placeholder={m.conv_strip_to_placeholder()}
-		data-testid="conv-strip-count"
+			class="block w-full border-line px-3 py-2.5 text-sm text-ink shadow-sm focus:outline-none focus-visible:ring-2 focus-visible:ring-focus-ring"
-		class="ml-auto text-sm font-bold"
+		/>
-		class:text-primary={hasDateFilter}
+	</div>
-		class:text-ink-3={!hasDateFilter}
-	>
-		{m.conv_letters_count({ count: documentCount ?? 0 })}
-	</span>
-
-	<!-- Sort button -->
-	<button
-		data-testid="conv-sort-btn"
-		type="button"
-		aria-label="Sortierung umkehren"
-		aria-pressed={sortDir === 'ASC'}
-		onclick={ontoggleSort}
-		class="flex items-center gap-2 border px-4 py-2.5 text-sm font-bold tracking-wide uppercase transition hover:bg-muted hover:text-ink"
-		class:border-primary={isActive}
-		class:text-primary={isActive}
-		class:border-line={!isActive}
-		class:text-ink-2={!isActive}
-	>
-		{#if sortDir === 'ASC'}
-			{m.conv_strip_sort_oldest()}
-			<svg
-				xmlns="http://www.w3.org/2000/svg"
-				width="12"
-				height="12"
-				viewBox="0 0 24 24"
-				fill="none"
-				stroke="currentColor"
-				stroke-width="2.5"
-				stroke-linecap="round"
-				stroke-linejoin="round"
-				aria-hidden="true"
-			>
-				<polyline points="18 15 12 9 6 15" />
-			</svg>
-		{:else}
-			{m.conv_strip_sort_newest()}
-			<svg
-				xmlns="http://www.w3.org/2000/svg"
-				width="12"
-				height="12"
-				viewBox="0 0 24 24"
-				fill="none"
-				stroke="currentColor"
-				stroke-width="2.5"
-				stroke-linecap="round"
-				stroke-linejoin="round"
-				aria-hidden="true"
-			>
-				<polyline points="6 9 12 15 18 9" />
-			</svg>
-		{/if}
-	</button>
 </div>

frontend/src/routes/briefwechsel/CorrespondenzPersonBar.svelte

@@ -1,14 +1,20 @@
 <script lang="ts">
 import PersonTypeahead from '$lib/components/PersonTypeahead.svelte';
 import CorrespondentSuggestionsDropdown from './CorrespondentSuggestionsDropdown.svelte';
+import { m } from '$lib/paraglide/messages.js';
 
 interface Props {
 	senderId?: string;
 	receiverId?: string;
 	initialSenderName?: string;
 	initialReceiverName?: string;
+	sortDir?: string;
+	showAdvanced?: boolean;
+	documentCount?: number;
 	onapplyFilters: () => void;
 	onswapPersons: () => void;
+	ontoggleSort: () => void;
+	ontoggleAdvanced: () => void;
 }
 
 let {
@@ -16,8 +22,13 @@ let {
 	receiverId = $bindable(''),
 	initialSenderName = '',
 	initialReceiverName = '',
+	sortDir = 'DESC',
+	showAdvanced = false,
+	documentCount = 0,
 	onapplyFilters,
-	onswapPersons
+	onswapPersons,
+	ontoggleSort,
+	ontoggleAdvanced
 }: Props = $props();
 
 interface Correspondent {
@@ -53,6 +64,7 @@ function handleSuggestionSelect(id: string) {
 }
 </script>
 
+<!-- Row 1: Person inputs -->
 <div data-testid="conv-person-bar" class="flex items-end gap-4">
 	<!-- Person A -->
 	<div
@@ -127,3 +139,67 @@ function handleSuggestionSelect(id: string) {
 		{/if}
 	</div>
 </div>
+
+<!-- Row 2: Sort + Filter toggle + Count (mirrors document search bar pattern) -->
+<div class="mt-4 flex items-center gap-4">
+	<!-- Sort button -->
+	<button
+		data-testid="conv-sort-btn"
+		type="button"
+		aria-label="Sortierung umkehren"
+		aria-pressed={sortDir === 'ASC'}
+		onclick={ontoggleSort}
+		class="flex items-center gap-2 border border-line bg-muted px-4 py-2.5 text-sm font-bold tracking-wide text-ink-2 uppercase transition hover:bg-muted hover:text-ink"
+	>
+		{#if sortDir === 'ASC'}
+			<svg
+				xmlns="http://www.w3.org/2000/svg"
+				width="14"
+				height="14"
+				viewBox="0 0 24 24"
+				fill="none"
+				stroke="currentColor"
+				stroke-width="2.5"
+				stroke-linecap="round"
+				stroke-linejoin="round"
+				aria-hidden="true"
+				class="h-4 w-4"><polyline points="18 15 12 9 6 15" /></svg
+			>
+			{m.conv_strip_sort_oldest()}
+		{:else}
+			<svg
+				xmlns="http://www.w3.org/2000/svg"
+				width="14"
+				height="14"
+				viewBox="0 0 24 24"
+				fill="none"
+				stroke="currentColor"
+				stroke-width="2.5"
+				stroke-linecap="round"
+				stroke-linejoin="round"
+				aria-hidden="true"
+				class="h-4 w-4"><polyline points="6 9 12 15 18 9" /></svg
+			>
+			{m.conv_strip_sort_newest()}
+		{/if}
+	</button>
+
+	<!-- Filter toggle button -->
+	<button
+		onclick={ontoggleAdvanced}
+		class="flex items-center gap-2 border border-line bg-muted px-4 py-2.5 text-sm font-bold tracking-wide text-ink-2 uppercase transition hover:bg-muted hover:text-ink"
+	>
+		<img
+			src="/degruyter-icons/Simple/Small-16px/SVG/Action/Chevron/Chevron-Down-SM.svg"
+			alt=""
+			aria-hidden="true"
+			class="h-4 w-4 transform transition-transform duration-200 {showAdvanced ? 'rotate-180' : ''}"
+		/>
+		{m.docs_btn_filter()}
+	</button>
+
+	<!-- Document count -->
+	<span data-testid="conv-strip-count" class="ml-auto text-sm font-bold text-ink-3">
+		{m.conv_letters_count({ count: documentCount })}
+	</span>
+</div>

frontend/src/routes/briefwechsel/page.svelte.spec.ts

@@ -103,9 +103,10 @@ describe('Briefwechsel page – results state', () => {
 		await expect.element(page.getByTestId('conv-person-bar')).toBeInTheDocument();
 	});
 
-	it('shows filter controls when senderId is set', async () => {
+	it('hides filter controls by default (collapsible)', async () => {
 		render(Page, { data: withSender });
-		await expect.element(page.getByTestId('conv-filter-controls')).toBeInTheDocument();
+		await expect.element(page.getByTestId('conv-person-bar')).toBeInTheDocument();
+		await expect.element(page.getByTestId('conv-filter-controls')).not.toBeInTheDocument();
 	});
 });
 
@@ -149,16 +150,6 @@ describe('Briefwechsel page – single-person hint bar', () => {
 	});
 });
 
-// ─── Filter controls disabled state ──────────────────────────────────────────
-
-describe('Briefwechsel page – filter strip Row 2 disabled state', () => {
-	it('filter controls are not aria-disabled when senderId is set', async () => {
-		render(Page, { data: withSender });
-		const strip = document.querySelector('[aria-disabled="false"]');
-		expect(strip).not.toBeNull();
-	});
-});
-
 // ─── Strip letter count ───────────────────────────────────────────────────────
 
 describe('Briefwechsel page – strip letter count', () => {