feat(planner): add AbortController to suggestion fetch $effect

Cancels the inflight request when activePickerDate changes or picker
closes, preventing stale responses from overwriting suggestions.
Adds page.test.ts covering fetch trigger, suggestion rendering,
and AbortSignal presence.

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

frontend/src/routes/(app)/planner/+page.svelte

@@ -106,12 +106,14 @@
 			isLoadingSuggestions = false;
 			return;
 		}
+		const controller = new AbortController();
 		isLoadingSuggestions = true;
-		fetch(`/planner?planId=${weekPlan.id}&date=${activePickerDate}`)
+		fetch(`/planner?planId=${weekPlan.id}&date=${activePickerDate}`, { signal: controller.signal })
 			.then((r) => r.json())
 			.then((d) => { suggestions = d.suggestions ?? []; })
-			.catch(() => { suggestions = []; })
+			.catch((e) => { if (e.name !== 'AbortError') suggestions = []; })
 			.finally(() => { isLoadingSuggestions = false; });
+		return () => controller.abort();
 	});
 
 	function handleSelectDay(day: string) {

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

@@ -0,0 +1,84 @@
+import { describe, it, expect, vi, afterEach } from 'vitest';
+import { render, screen, waitFor } from '@testing-library/svelte';
+import userEvent from '@testing-library/user-event';
+import Page from './+page.svelte';
+
+vi.mock('$app/navigation', () => ({ goto: vi.fn(), invalidateAll: vi.fn() }));
+vi.mock('$app/forms', () => ({
+	enhance: () => () => ({ destroy: () => {} })
+}));
+
+const PLAN_ID = 'plan-00000000-0000-0000-0000-000000000001';
+// Use a past week so "today" is never in this range — selectedDay defaults to weekStart (Monday)
+const DATE = '2025-01-06'; // Monday, January 6 2025
+
+const mockData = {
+	weekPlan: { id: PLAN_ID, weekStart: DATE, status: 'draft', slots: [] },
+	varietyScore: null,
+	weekStart: DATE,
+	recipes: [{ id: 'r1', name: 'Beef Bourguignon', effort: 'hard', cookTimeMin: 150 }],
+	benutzer: { rolle: 'planer' }
+};
+
+const mockSuggestions = [
+	{
+		recipe: { id: 's1', name: 'Lachsfilet', effort: 'easy', cookTimeMin: 20 },
+		scoreDelta: 1.5,
+		hasConflict: false
+	}
+];
+
+describe('+page.svelte — $effect suggestion fetch', () => {
+	afterEach(() => {
+		vi.restoreAllMocks();
+	});
+
+	it('calls fetch when picker opens with correct planId and date', async () => {
+		vi.stubGlobal(
+			'fetch',
+			vi.fn().mockResolvedValueOnce({
+				json: () => Promise.resolve({ suggestions: mockSuggestions })
+			})
+		);
+
+		render(Page, { props: { data: mockData } });
+
+		await userEvent.click(screen.getAllByRole('button', { name: /Gericht/i })[0]);
+
+		await waitFor(() => expect(fetch).toHaveBeenCalledTimes(1));
+		expect((fetch as any).mock.calls[0][0]).toContain(`planId=${PLAN_ID}`);
+		expect((fetch as any).mock.calls[0][0]).toContain(`date=${DATE}`);
+	});
+
+	it('shows suggestions in RecipePicker after fetch resolves', async () => {
+		vi.stubGlobal(
+			'fetch',
+			vi.fn().mockResolvedValueOnce({
+				json: () => Promise.resolve({ suggestions: mockSuggestions })
+			})
+		);
+
+		render(Page, { props: { data: mockData } });
+
+		await userEvent.click(screen.getAllByRole('button', { name: /Gericht/i })[0]);
+
+		expect(await screen.findByText('Lachsfilet')).toBeTruthy();
+	});
+
+	it('passes AbortSignal to fetch so inflight requests can be cancelled', async () => {
+		vi.stubGlobal(
+			'fetch',
+			vi.fn().mockResolvedValueOnce({
+				json: () => Promise.resolve({ suggestions: [] })
+			})
+		);
+
+		render(Page, { props: { data: mockData } });
+
+		await userEvent.click(screen.getAllByRole('button', { name: /Gericht/i })[0]);
+
+		await waitFor(() => expect(fetch).toHaveBeenCalledTimes(1));
+		const fetchOptions = (fetch as any).mock.calls[0][1];
+		expect(fetchOptions?.signal).toBeInstanceOf(AbortSignal);
+	});
+});