diff --git a/frontend/src/routes/admin/page.server.spec.ts b/frontend/src/routes/admin/page.server.spec.ts
new file mode 100644
index 00000000..a8edb053
--- /dev/null
+++ b/frontend/src/routes/admin/page.server.spec.ts
@@ -0,0 +1,77 @@
+import { describe, expect, it, vi, beforeEach } from 'vitest';
+import { load } from './+page.server';
+
+vi.mock('$lib/api.server', () => ({ createApiClient: vi.fn() }));
+
+import { createApiClient } from '$lib/api.server';
+
+const adminUser = { groups: [{ permissions: ['ADMIN'] }] };
+const readOnlyUser = { groups: [{ permissions: ['READ_ALL'] }] };
+
+function mockApiReturning(users: unknown[], groups: unknown[], tags: unknown[]) {
+	vi.mocked(createApiClient).mockReturnValue({
+		GET: vi
+			.fn()
+			.mockResolvedValueOnce({ response: { ok: true }, data: users })
+			.mockResolvedValueOnce({ response: { ok: true }, data: groups })
+			.mockResolvedValueOnce({ response: { ok: true }, data: tags })
+	} as ReturnType<typeof createApiClient>);
+}
+
+beforeEach(() => vi.clearAllMocks());
+
+// ─── permission check ─────────────────────────────────────────────────────────
+
+describe('admin load — permission check', () => {
+	it('throws 403 when user has no ADMIN permission', async () => {
+		await expect(
+			load({ fetch: vi.fn() as unknown as typeof fetch, locals: { user: readOnlyUser } })
+		).rejects.toMatchObject({ status: 403 });
+	});
+
+	it('throws 403 when user is undefined', async () => {
+		await expect(
+			load({ fetch: vi.fn() as unknown as typeof fetch, locals: { user: undefined } })
+		).rejects.toMatchObject({ status: 403 });
+	});
+
+	it('throws 403 when user has no groups', async () => {
+		await expect(
+			load({ fetch: vi.fn() as unknown as typeof fetch, locals: { user: { groups: [] } } })
+		).rejects.toMatchObject({ status: 403 });
+	});
+});
+
+// ─── happy path ───────────────────────────────────────────────────────────────
+
+describe('admin load — happy path', () => {
+	it('returns users, groups, and tags for an admin user', async () => {
+		mockApiReturning(
+			[{ id: 'u1', username: 'alice' }],
+			[{ id: 'g1', name: 'Editors' }],
+			[{ id: 't1', name: 'Familie' }]
+		);
+
+		const result = await load({
+			fetch: vi.fn() as unknown as typeof fetch,
+			locals: { user: adminUser }
+		});
+
+		expect(result.users).toHaveLength(1);
+		expect(result.groups).toHaveLength(1);
+		expect(result.tags).toHaveLength(1);
+	});
+
+	it('returns empty arrays when API returns no data', async () => {
+		mockApiReturning([], [], []);
+
+		const result = await load({
+			fetch: vi.fn() as unknown as typeof fetch,
+			locals: { user: adminUser }
+		});
+
+		expect(result.users).toEqual([]);
+		expect(result.groups).toEqual([]);
+		expect(result.tags).toEqual([]);
+	});
+});
diff --git a/frontend/src/routes/documents/[id]/page.server.spec.ts b/frontend/src/routes/documents/[id]/page.server.spec.ts
new file mode 100644
index 00000000..2d15c61c
--- /dev/null
+++ b/frontend/src/routes/documents/[id]/page.server.spec.ts
@@ -0,0 +1,126 @@
+import { describe, expect, it, vi, beforeEach } from 'vitest';
+
+vi.mock('$lib/api.server', () => ({ createApiClient: vi.fn() }));
+vi.mock('$env/dynamic/private', () => ({ env: { API_INTERNAL_URL: 'http://test-backend:8080' } }));
+
+import { load } from './+page.server';
+import { createApiClient } from '$lib/api.server';
+
+beforeEach(() => vi.clearAllMocks());
+
+function makeCommentsResponse(comments: unknown[]) {
+	return {
+		ok: true,
+		json: vi.fn().mockResolvedValue(comments)
+	};
+}
+
+// ─── happy path ───────────────────────────────────────────────────────────────
+
+describe('document detail load — happy path', () => {
+	it('returns document and comments on success', async () => {
+		vi.mocked(createApiClient).mockReturnValue({
+			GET: vi.fn().mockResolvedValue({
+				response: { ok: true, status: 200 },
+				data: { id: '123', title: 'Testbrief' }
+			})
+		} as ReturnType<typeof createApiClient>);
+
+		const mockFetch = vi.fn().mockResolvedValue(makeCommentsResponse([{ id: 'c1', body: 'Hi' }]));
+
+		const result = await load({
+			params: { id: '123' },
+			fetch: mockFetch as unknown as typeof fetch
+		});
+
+		expect(result.document.title).toBe('Testbrief');
+		expect(result.comments).toHaveLength(1);
+	});
+
+	it('returns empty comments when the comments fetch fails', async () => {
+		vi.mocked(createApiClient).mockReturnValue({
+			GET: vi.fn().mockResolvedValue({
+				response: { ok: true, status: 200 },
+				data: { id: '123', title: 'Testbrief' }
+			})
+		} as ReturnType<typeof createApiClient>);
+
+		// fetch throws a network error for the comments endpoint
+		const mockFetch = vi.fn().mockRejectedValue(new Error('Network error'));
+
+		const result = await load({
+			params: { id: '123' },
+			fetch: mockFetch as unknown as typeof fetch
+		});
+
+		expect(result.document.title).toBe('Testbrief');
+		expect(result.comments).toEqual([]);
+	});
+
+	it('returns empty comments when the comments response is not ok', async () => {
+		vi.mocked(createApiClient).mockReturnValue({
+			GET: vi.fn().mockResolvedValue({
+				response: { ok: true, status: 200 },
+				data: { id: '123', title: 'Testbrief' }
+			})
+		} as ReturnType<typeof createApiClient>);
+
+		const mockFetch = vi.fn().mockResolvedValue({ ok: false });
+
+		const result = await load({
+			params: { id: '123' },
+			fetch: mockFetch as unknown as typeof fetch
+		});
+
+		expect(result.comments).toEqual([]);
+	});
+});
+
+// ─── error paths ──────────────────────────────────────────────────────────────
+
+describe('document detail load — error paths', () => {
+	it('throws 404 when document does not exist', async () => {
+		vi.mocked(createApiClient).mockReturnValue({
+			GET: vi.fn().mockResolvedValue({
+				response: { ok: false, status: 404 },
+				error: null
+			})
+		} as ReturnType<typeof createApiClient>);
+
+		const mockFetch = vi.fn().mockResolvedValue({ ok: false });
+
+		await expect(
+			load({ params: { id: 'missing' }, fetch: mockFetch as unknown as typeof fetch })
+		).rejects.toMatchObject({ status: 404 });
+	});
+
+	it('throws 403 when document is forbidden', async () => {
+		vi.mocked(createApiClient).mockReturnValue({
+			GET: vi.fn().mockResolvedValue({
+				response: { ok: false, status: 403 },
+				error: null
+			})
+		} as ReturnType<typeof createApiClient>);
+
+		const mockFetch = vi.fn().mockResolvedValue({ ok: false });
+
+		await expect(
+			load({ params: { id: 'secret' }, fetch: mockFetch as unknown as typeof fetch })
+		).rejects.toMatchObject({ status: 403 });
+	});
+
+	it('redirects to /login on 401', async () => {
+		vi.mocked(createApiClient).mockReturnValue({
+			GET: vi.fn().mockResolvedValue({
+				response: { ok: false, status: 401 },
+				error: null
+			})
+		} as ReturnType<typeof createApiClient>);
+
+		const mockFetch = vi.fn().mockResolvedValue({ ok: false });
+
+		await expect(
+			load({ params: { id: 'any' }, fetch: mockFetch as unknown as typeof fetch })
+		).rejects.toMatchObject({ location: '/login' });
+	});
+});
diff --git a/frontend/src/routes/page.server.spec.ts b/frontend/src/routes/page.server.spec.ts
new file mode 100644
index 00000000..e250ee78
--- /dev/null
+++ b/frontend/src/routes/page.server.spec.ts
@@ -0,0 +1,128 @@
+import { describe, expect, it, vi, beforeEach } from 'vitest';
+
+vi.mock('$lib/api.server', () => ({ createApiClient: vi.fn() }));
+
+import { load } from './+page.server';
+import { createApiClient } from '$lib/api.server';
+
+beforeEach(() => vi.clearAllMocks());
+
+function makeUrl(params: Record<string, string | string[]> = {}) {
+	const url = new URL('http://localhost/');
+	for (const [key, value] of Object.entries(params)) {
+		if (Array.isArray(value)) {
+			value.forEach((v) => url.searchParams.append(key, v));
+		} else {
+			url.searchParams.set(key, value);
+		}
+	}
+	return url;
+}
+
+// ─── happy path ───────────────────────────────────────────────────────────────
+
+describe('home page load — happy path', () => {
+	it('returns documents and persons on success', async () => {
+		vi.mocked(createApiClient).mockReturnValue({
+			GET: vi
+				.fn()
+				.mockResolvedValueOnce({
+					response: { ok: true, status: 200 },
+					data: [{ id: 'd1', title: 'Brief' }]
+				})
+				.mockResolvedValueOnce({
+					response: { ok: true, status: 200 },
+					data: [{ id: 'p1', firstName: 'Hans', lastName: 'Müller' }]
+				})
+				.mockResolvedValueOnce({ response: { ok: true }, data: { count: 3 } })
+		} as ReturnType<typeof createApiClient>);
+
+		const result = await load({ url: makeUrl(), fetch: vi.fn() as unknown as typeof fetch });
+
+		expect(result.documents).toHaveLength(1);
+		expect(result.incompleteCount).toBe(3);
+		expect(result.error).toBeNull();
+	});
+
+	it('passes search params from the URL to the API', async () => {
+		const mockGet = vi
+			.fn()
+			.mockResolvedValueOnce({ response: { ok: true, status: 200 }, data: [] })
+			.mockResolvedValueOnce({ response: { ok: true, status: 200 }, data: [] })
+			.mockResolvedValueOnce({ response: { ok: true }, data: { count: 0 } });
+		vi.mocked(createApiClient).mockReturnValue({
+			GET: mockGet
+		} as ReturnType<typeof createApiClient>);
+
+		await load({
+			url: makeUrl({ q: 'Urlaub', from: '2020-01-01' }),
+			fetch: vi.fn() as unknown as typeof fetch
+		});
+
+		const firstCall = mockGet.mock.calls[0];
+		expect(firstCall[1].params.query.q).toBe('Urlaub');
+		expect(firstCall[1].params.query.from).toBe('2020-01-01');
+	});
+
+	it('returns incompleteCount 0 when the incomplete-count API fails', async () => {
+		vi.mocked(createApiClient).mockReturnValue({
+			GET: vi
+				.fn()
+				.mockResolvedValueOnce({ response: { ok: true, status: 200 }, data: [] })
+				.mockResolvedValueOnce({ response: { ok: true, status: 200 }, data: [] })
+				.mockResolvedValueOnce({ response: { ok: false }, data: null })
+		} as ReturnType<typeof createApiClient>);
+
+		const result = await load({ url: makeUrl(), fetch: vi.fn() as unknown as typeof fetch });
+
+		expect(result.incompleteCount).toBe(0);
+	});
+});
+
+// ─── 401 redirect ─────────────────────────────────────────────────────────────
+
+describe('home page load — auth redirect', () => {
+	it('redirects to /login when documents API returns 401', async () => {
+		vi.mocked(createApiClient).mockReturnValue({
+			GET: vi
+				.fn()
+				.mockResolvedValueOnce({ response: { ok: false, status: 401 }, data: null })
+				.mockResolvedValueOnce({ response: { ok: true, status: 200 }, data: [] })
+				.mockResolvedValueOnce({ response: { ok: true }, data: { count: 0 } })
+		} as ReturnType<typeof createApiClient>);
+
+		await expect(
+			load({ url: makeUrl(), fetch: vi.fn() as unknown as typeof fetch })
+		).rejects.toMatchObject({ location: '/login' });
+	});
+
+	it('redirects to /login when persons API returns 401', async () => {
+		vi.mocked(createApiClient).mockReturnValue({
+			GET: vi
+				.fn()
+				.mockResolvedValueOnce({ response: { ok: true, status: 200 }, data: [] })
+				.mockResolvedValueOnce({ response: { ok: false, status: 401 }, data: null })
+				.mockResolvedValueOnce({ response: { ok: true }, data: { count: 0 } })
+		} as ReturnType<typeof createApiClient>);
+
+		await expect(
+			load({ url: makeUrl(), fetch: vi.fn() as unknown as typeof fetch })
+		).rejects.toMatchObject({ location: '/login' });
+	});
+});
+
+// ─── network error fallback ───────────────────────────────────────────────────
+
+describe('home page load — network error fallback', () => {
+	it('returns error string instead of throwing when API call throws', async () => {
+		vi.mocked(createApiClient).mockReturnValue({
+			GET: vi.fn().mockRejectedValue(new Error('Network failure'))
+		} as ReturnType<typeof createApiClient>);
+
+		const result = await load({ url: makeUrl(), fetch: vi.fn() as unknown as typeof fetch });
+
+		expect(result.error).toBe('Daten konnten nicht geladen werden.');
+		expect(result.documents).toEqual([]);
+		expect(result.incompleteCount).toBe(0);
+	});
+});
diff --git a/frontend/src/routes/persons/[id]/page.server.spec.ts b/frontend/src/routes/persons/[id]/page.server.spec.ts
new file mode 100644
index 00000000..e1e8f493
--- /dev/null
+++ b/frontend/src/routes/persons/[id]/page.server.spec.ts
@@ -0,0 +1,83 @@
+import { describe, expect, it, vi, beforeEach } from 'vitest';
+import { load } from './+page.server';
+
+vi.mock('$lib/api.server', () => ({ createApiClient: vi.fn() }));
+
+import { createApiClient } from '$lib/api.server';
+
+const mockFetch = vi.fn() as unknown as typeof fetch;
+
+beforeEach(() => vi.clearAllMocks());
+
+// ─── happy path ───────────────────────────────────────────────────────────────
+
+describe('person detail load — happy path', () => {
+	it('returns person, sentDocuments, and receivedDocuments on success', async () => {
+		vi.mocked(createApiClient).mockReturnValue({
+			GET: vi
+				.fn()
+				.mockResolvedValueOnce({
+					response: { ok: true, status: 200 },
+					data: { id: 'p1', firstName: 'Hans', lastName: 'Müller' }
+				})
+				.mockResolvedValueOnce({ response: { ok: true }, data: [{ id: 'd1', title: 'Brief' }] })
+				.mockResolvedValueOnce({ response: { ok: true }, data: [] })
+		} as ReturnType<typeof createApiClient>);
+
+		const result = await load({ params: { id: 'p1' }, fetch: mockFetch });
+
+		expect(result.person.firstName).toBe('Hans');
+		expect(result.sentDocuments).toHaveLength(1);
+		expect(result.receivedDocuments).toEqual([]);
+	});
+
+	it('returns empty arrays when sent/received document APIs fail', async () => {
+		vi.mocked(createApiClient).mockReturnValue({
+			GET: vi
+				.fn()
+				.mockResolvedValueOnce({
+					response: { ok: true, status: 200 },
+					data: { id: 'p1', firstName: 'Anna', lastName: 'Schmidt' }
+				})
+				.mockResolvedValueOnce({ response: { ok: false }, data: null })
+				.mockResolvedValueOnce({ response: { ok: false }, data: null })
+		} as ReturnType<typeof createApiClient>);
+
+		const result = await load({ params: { id: 'p1' }, fetch: mockFetch });
+
+		expect(result.sentDocuments).toEqual([]);
+		expect(result.receivedDocuments).toEqual([]);
+	});
+});
+
+// ─── error paths ──────────────────────────────────────────────────────────────
+
+describe('person detail load — error paths', () => {
+	it('throws 404 when person does not exist', async () => {
+		vi.mocked(createApiClient).mockReturnValue({
+			GET: vi
+				.fn()
+				.mockResolvedValueOnce({ response: { ok: false, status: 404 }, error: null })
+				.mockResolvedValueOnce({ response: { ok: true }, data: [] })
+				.mockResolvedValueOnce({ response: { ok: true }, data: [] })
+		} as ReturnType<typeof createApiClient>);
+
+		await expect(load({ params: { id: 'missing' }, fetch: mockFetch })).rejects.toMatchObject({
+			status: 404
+		});
+	});
+
+	it('throws 403 when person is not accessible', async () => {
+		vi.mocked(createApiClient).mockReturnValue({
+			GET: vi
+				.fn()
+				.mockResolvedValueOnce({ response: { ok: false, status: 403 }, error: null })
+				.mockResolvedValueOnce({ response: { ok: true }, data: [] })
+				.mockResolvedValueOnce({ response: { ok: true }, data: [] })
+		} as ReturnType<typeof createApiClient>);
+
+		await expect(load({ params: { id: 'forbidden' }, fetch: mockFetch })).rejects.toMatchObject({
+			status: 403
+		});
+	});
+});