groceries: mobile-first tracker redesign — compact rows per product group (cheapest store badge, unit price, spread, promo), tap to compare stores; category tree (23 tops, subcategories, icons/colours) with chips, store tiles, sort and non-food toggle; owner shelf prices (manual source with date, photo, note)

src/lib/groceries.test.ts

@@ -1,5 +1,14 @@
 import { describe, expect, it } from 'vitest';
-import { cheapest, formatAmount, formatUnitPrice, sortByPrice, type PricedItem } from './groceries';
+import {
+	bestPerStore,
+	cheapest,
+	formatAmount,
+	formatUnitPrice,
+	parseEuros,
+	sortByPrice,
+	toOffers,
+	type PricedItem
+} from './groceries';
 
 const it_ = (
 	id: number,
@@ -42,3 +51,69 @@ describe('grocery price helpers', () => {
 		expect(formatUnitPrice(null, 'kg')).toBeNull();
 	});
 });
+
+describe('parseEuros', () => {
+	it('reads Dutch and English prices', () => {
+		expect(parseEuros('1,29')).toBe(129);
+		expect(parseEuros('€ 2.5')).toBe(250);
+		expect(parseEuros('3')).toBe(300);
+	});
+	it('rejects nonsense', () => {
+		expect(parseEuros('')).toBeNull();
+		expect(parseEuros('0')).toBeNull();
+		expect(parseEuros('1,299')).toBeNull();
+		expect(parseEuros('abc')).toBeNull();
+	});
+});
+
+describe('bestPerStore', () => {
+	const item = (
+		id: number,
+		storeId: number,
+		price: number,
+		unit: number | null,
+		promo?: number
+	) => ({
+		id,
+		storeId,
+		name: `p${id}`,
+		sizeText: null,
+		unit: 'kg',
+		unitAmount: 1,
+		promoLabel: promo ? '1+1' : null,
+		url: null,
+		available: true,
+		priceCents: price,
+		promoPriceCents: promo ?? null,
+		unitPriceCents: unit,
+		promoUnitPriceCents: promo ?? null
+	});
+	it('keeps the cheapest offer per store, cheapest store first, with the spread', () => {
+		const offers = toOffers(
+			[item(1, 1, 300, 300), item(2, 1, 250, 250), item(3, 2, 400, 400, 200), item(4, 3, 500, 500)],
+			[
+				{
+					id: 9,
+					itemId: null,
+					storeId: 4,
+					priceCents: 180,
+					promo: false,
+					sizeText: '1 kg',
+					unit: 'kg',
+					unitPriceCents: 180,
+					observedOn: '2026-10-20',
+					photoUrl: null,
+					note: null
+				}
+			]
+		);
+		const r = bestPerStore(offers, 'unit');
+		expect(r.stores.map((o) => o.key)).toEqual(['m9', 'i3', 'i2', 'i4']);
+		expect(r.best?.manual?.id).toBe(9);
+		expect(r.stores[1].regularCents).toBe(400);
+		expect(r.spread).toEqual({ min: 180, max: 500, pct: 178 });
+	});
+	it('has no spread for one store', () => {
+		expect(bestPerStore(toOffers([item(1, 1, 100, 100)], []), 'pack').spread).toBeNull();
+	});
+});