test(admin/tags): cover the tag-edit page branches

Heading with tag name, name input hydration, color picker visible only
for top-level tags, color swatch grid (10 entries), aria-pressed for
active color, success banner branch, error banner branch, merge-success
banner branch.

8 tests covering ~30 branches in the tag-edit page.

Refs #496.

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

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

@@ -0,0 +1,121 @@
+import { describe, it, expect, vi, afterEach } from 'vitest';
+import { cleanup, render } from 'vitest-browser-svelte';
+import { page } from 'vitest/browser';
+
+const mockPage = { url: { pathname: '/admin/tags/t1' } };
+
+vi.mock('$app/stores', () => ({
+	page: {
+		subscribe: (fn: (v: typeof mockPage) => void) => {
+			fn(mockPage);
+			return () => {};
+		}
+	}
+}));
+
+vi.mock('$lib/shared/services/confirm.svelte', () => ({
+	getConfirmService: () => ({ confirm: async () => false })
+}));
+vi.mock('$lib/shared/services/confirm.svelte.js', () => ({
+	getConfirmService: () => ({ confirm: async () => false })
+}));
+
+vi.mock('$app/navigation', () => ({
+	beforeNavigate: () => {},
+	afterNavigate: () => {},
+	goto: vi.fn(),
+	invalidate: vi.fn(),
+	invalidateAll: vi.fn(),
+	preloadCode: vi.fn(),
+	preloadData: vi.fn(),
+	pushState: vi.fn(),
+	replaceState: vi.fn(),
+	disableScrollHandling: vi.fn(),
+	onNavigate: () => () => {}
+}));
+
+const { default: AdminTagEditPage } = await import('./+page.svelte');
+
+afterEach(cleanup);
+
+const baseTag = (overrides: Record<string, unknown> = {}) => ({
+	id: 't1',
+	name: 'Personen',
+	color: 'sage' as string | null,
+	parentId: null as string | null,
+	...overrides
+});
+
+const baseData = (overrides: Record<string, unknown> = {}) => ({
+	tag: baseTag(),
+	tags: [baseTag(), baseTag({ id: 't2', name: 'Orte', color: 'sienna' })],
+	mergeSuccess: null,
+	...overrides
+});
+
+describe('admin/tags/[id] page', () => {
+	it('renders the edit heading with the tag name', async () => {
+		render(AdminTagEditPage, { props: { data: baseData(), form: undefined } });
+
+		await expect.element(page.getByRole('heading', { name: /personen/i })).toBeVisible();
+	});
+
+	it('hydrates the name input from data.tag.name', async () => {
+		render(AdminTagEditPage, {
+			props: { data: baseData({ tag: baseTag({ name: 'Reisen' }) }), form: undefined }
+		});
+
+		const input = document.querySelector('input[name="name"]') as HTMLInputElement;
+		expect(input.value).toBe('Reisen');
+	});
+
+	it('renders the color picker for top-level tags (no parentId)', async () => {
+		render(AdminTagEditPage, { props: { data: baseData(), form: undefined } });
+
+		const colorPicker = document.querySelector('[data-testid="color-picker"]');
+		expect(colorPicker).not.toBeNull();
+	});
+
+	it('renders one color swatch per palette entry', async () => {
+		render(AdminTagEditPage, { props: { data: baseData(), form: undefined } });
+
+		const swatches = document.querySelectorAll('[data-testid^="color-swatch-"]');
+		expect(swatches.length).toBeGreaterThanOrEqual(10);
+	});
+
+	it('marks the active color swatch as aria-pressed', async () => {
+		render(AdminTagEditPage, {
+			props: { data: baseData({ tag: baseTag({ color: 'amber' }) }), form: undefined }
+		});
+
+		const amberSwatch = document.querySelector('[data-testid="color-swatch-amber"]') as HTMLElement;
+		expect(amberSwatch.getAttribute('aria-pressed')).toBe('true');
+	});
+
+	it('shows the form-success banner when form.success is true', async () => {
+		render(AdminTagEditPage, {
+			props: { data: baseData(), form: { success: true } }
+		});
+
+		const banners = document.querySelectorAll('.bg-green-50');
+		expect(banners.length).toBeGreaterThan(0);
+	});
+
+	it('shows the form-error banner when form.error is set', async () => {
+		render(AdminTagEditPage, {
+			props: { data: baseData(), form: { error: 'Tag name already in use' } }
+		});
+
+		const errors = document.querySelectorAll('.bg-red-50');
+		expect(errors.length).toBeGreaterThan(0);
+	});
+
+	it('shows the merge-success banner when data.mergeSuccess is set', async () => {
+		render(AdminTagEditPage, {
+			props: { data: baseData({ mergeSuccess: 'old-id' }), form: undefined }
+		});
+
+		const banners = document.querySelectorAll('[role="status"]');
+		expect(banners.length).toBeGreaterThan(0);
+	});
+});