fix(#248): resolve parent UUID to name in TagParentPicker dropdown subtitle

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

frontend/src/lib/components/TagParentPicker.svelte

@@ -7,14 +7,27 @@ import { createTypeahead } from '$lib/hooks/useTypeahead.svelte';
 
 type Tag = components['schemas']['Tag'];
 
+interface FlatTagRef {
+	id: string;
+	name: string;
+	parentId?: string;
+}
+
 interface Props {
 	name: string;
 	value?: string;
 	excludeIds?: string[];
 	initialName?: string;
+	allTags?: FlatTagRef[];
 }
 
-let { name, value = $bindable(''), excludeIds = [], initialName = '' }: Props = $props();
+let {
+	name,
+	value = $bindable(''),
+	excludeIds = [],
+	initialName = '',
+	allTags = []
+}: Props = $props();
 
 // displayName must be both prop-derived AND locally writable (user typing), so $state +
 // $effect is the correct pattern here — writable $derived is read-only and won't work.
@@ -135,7 +148,8 @@ function handleKeydown(e: KeyboardEvent) {
 				>
 					<span class="block truncate font-medium">{tag.name}</span>
 					{#if tag.parentId}
-						<span class="block truncate text-xs text-ink-3">{tag.parentId}</span>
+						{@const parentName = allTags.find((t) => t.id === tag.parentId)?.name ?? tag.parentId}
+						<span class="block truncate text-xs text-ink-3">{parentName}</span>
 					{/if}
 				</div>
 			{/each}

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

@@ -162,3 +162,35 @@ describe('TagParentPicker – ARIA combobox', () => {
 		expect(option.id).toBe('parentId-option-0');
 	});
 });
+
+// ─── Parent name resolution ───────────────────────────────────────────────────
+
+describe('TagParentPicker – parent name subtitle', () => {
+	it('shows parent name instead of UUID when allTags is provided', async () => {
+		mockFetchWithTags([{ id: 't2', name: 'Keller', parentId: 't1' }]);
+		const allTags = [
+			{ id: 't1', name: 'Haus', documentCount: 5 },
+			{ id: 't2', name: 'Keller', parentId: 't1', documentCount: 2 }
+		];
+		render(TagParentPicker, { name: 'parentId', allTags });
+
+		const input = page.getByRole('combobox');
+		await input.fill('K');
+		await vi.advanceTimersByTimeAsync(300);
+
+		await expect.element(page.getByText('Haus')).toBeInTheDocument();
+	});
+
+	it('shows nothing as subtitle when tag has no parentId', async () => {
+		mockFetchWithTags([{ id: 't1', name: 'Haus' }]);
+		const allTags = [{ id: 't1', name: 'Haus', documentCount: 5 }];
+		render(TagParentPicker, { name: 'parentId', allTags });
+
+		const input = page.getByRole('combobox');
+		await input.fill('H');
+		await vi.advanceTimersByTimeAsync(300);
+
+		// Only the tag name should appear (no subtitle)
+		await expect.element(page.getByRole('option', { name: 'Haus' })).toBeInTheDocument();
+	});
+});

frontend/src/routes/admin/tags/[id]/+page.svelte

@@ -131,6 +131,7 @@ const colors = [
 					bind:value={parentId}
 					excludeIds={[data.tag.id]}
 					initialName={parentName}
+					allTags={data.tags}
 				/>
 			</div>