feat(planner): add server.test.ts for GET /planner, fix sort + add error handling

- Sort uses scoreDelta instead of removed simulatedScore
- try/catch degrades gracefully to suggestions=[] on backend errors
- 6 tests cover: missing params, success, backend error, network throw, empty result

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

frontend/src/routes/(app)/planner/+server.ts

@@ -11,14 +11,18 @@ export const GET: RequestHandler = async ({ fetch, url }) => {
 		return json({ suggestions: [] });
 	}
 
-	const api = apiClient(fetch);
+	try {
-	const { data } = await api.GET('/v1/week-plans/{id}/suggestions', {
+		const api = apiClient(fetch);
-		params: { path: { id: planId }, query: { slotDate: date } }
+		const { data } = await api.GET('/v1/week-plans/{id}/suggestions', {
-	});
+			params: { path: { id: planId }, query: { slotDate: date } }
+		});
 
-	const suggestions = (data?.suggestions ?? []).sort(
+		const suggestions = (data?.suggestions ?? []).sort(
-		(a: any, b: any) => (b.simulatedScore ?? 0) - (a.simulatedScore ?? 0)
+			(a: any, b: any) => (b.scoreDelta ?? 0) - (a.scoreDelta ?? 0)
-	);
+		);
 
-	return json({ suggestions });
+		return json({ suggestions });
+	} catch {
+		return json({ suggestions: [] });
+	}
 };

frontend/src/routes/(app)/planner/server.test.ts

@@ -0,0 +1,91 @@
+import { describe, it, expect, vi, beforeEach } from 'vitest';
+
+vi.mock('$env/dynamic/private', () => ({
+	env: { BACKEND_URL: 'http://localhost:8080' }
+}));
+
+const mockGet = vi.fn();
+vi.mock('$lib/server/api', () => ({
+	apiClient: () => ({ GET: mockGet })
+}));
+
+const PLAN_UUID = '11111111-1111-1111-1111-111111111111';
+const DATE = '2026-04-09';
+
+const mockSuggestions = [
+	{ recipe: { id: 'r1', name: 'Lachsfilet', effort: 'easy', cookTimeMin: 25 }, scoreDelta: 0.0, hasConflict: true },
+	{ recipe: { id: 'r2', name: 'Nudeln', effort: 'easy', cookTimeMin: 20 }, scoreDelta: -1.5, hasConflict: true }
+];
+
+describe('GET /planner — suggestions route handler', () => {
+	let GET: any;
+
+	beforeEach(async () => {
+		mockGet.mockReset();
+		vi.resetModules();
+		const mod = await import('./+server');
+		GET = mod.GET;
+	});
+
+	it('returns { suggestions: [] } when planId is missing', async () => {
+		const url = new URL('http://localhost/planner?date=' + DATE);
+		const response = await GET({ fetch: vi.fn(), url });
+		const body = await response.json();
+		expect(body).toEqual({ suggestions: [] });
+		expect(mockGet).not.toHaveBeenCalled();
+	});
+
+	it('returns { suggestions: [] } when date is missing', async () => {
+		const url = new URL('http://localhost/planner?planId=' + PLAN_UUID);
+		const response = await GET({ fetch: vi.fn(), url });
+		const body = await response.json();
+		expect(body).toEqual({ suggestions: [] });
+		expect(mockGet).not.toHaveBeenCalled();
+	});
+
+	it('returns sorted suggestions from backend on success', async () => {
+		mockGet.mockResolvedValueOnce({ data: { suggestions: mockSuggestions }, error: undefined });
+
+		const url = new URL(`http://localhost/planner?planId=${PLAN_UUID}&date=${DATE}`);
+		const response = await GET({ fetch: vi.fn(), url });
+		const body = await response.json();
+
+		expect(mockGet).toHaveBeenCalledWith('/v1/week-plans/{id}/suggestions', expect.objectContaining({
+			params: { path: { id: PLAN_UUID }, query: { slotDate: DATE } }
+		}));
+		expect(body.suggestions).toHaveLength(2);
+		// sorted by scoreDelta desc: 0.0 before -1.5
+		expect(body.suggestions[0].recipe.name).toBe('Lachsfilet');
+		expect(body.suggestions[1].recipe.name).toBe('Nudeln');
+	});
+
+	it('returns { suggestions: [] } when backend returns error', async () => {
+		mockGet.mockResolvedValueOnce({ data: undefined, error: { status: 500 } });
+
+		const url = new URL(`http://localhost/planner?planId=${PLAN_UUID}&date=${DATE}`);
+		const response = await GET({ fetch: vi.fn(), url });
+		const body = await response.json();
+
+		expect(body).toEqual({ suggestions: [] });
+	});
+
+	it('returns { suggestions: [] } when backend throws (network error)', async () => {
+		mockGet.mockRejectedValueOnce(new Error('Network error'));
+
+		const url = new URL(`http://localhost/planner?planId=${PLAN_UUID}&date=${DATE}`);
+		const response = await GET({ fetch: vi.fn(), url });
+		const body = await response.json();
+
+		expect(body).toEqual({ suggestions: [] });
+	});
+
+	it('returns empty suggestions when backend returns empty array', async () => {
+		mockGet.mockResolvedValueOnce({ data: { suggestions: [] }, error: undefined });
+
+		const url = new URL(`http://localhost/planner?planId=${PLAN_UUID}&date=${DATE}`);
+		const response = await GET({ fetch: vi.fn(), url });
+		const body = await response.json();
+
+		expect(body).toEqual({ suggestions: [] });
+	});
+});