feat: add SQLite-backed products store

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013gwc3aCiyQxmCWQke8RvEz

test/db.test.js

@@ -0,0 +1,64 @@
+const test = require('node:test');
+const assert = require('node:assert/strict');
+const {
+  openDb, listProducts, getProduct, addProduct, deleteProduct,
+  recordCheckSuccess, recordCheckFailure,
+} = require('../src/db');
+
+function freshDb() {
+  return openDb(':memory:');
+}
+
+test('addProduct inserts a row with defaults and returns it', () => {
+  const db = freshDb();
+  const product = addProduct(db, { name: 'Voorbeeld', url: 'https://example.com' });
+  assert.equal(product.name, 'Voorbeeld');
+  assert.equal(product.url, 'https://example.com');
+  assert.equal(product.last_price, null);
+  assert.equal(product.last_checked_at, null);
+  assert.ok(product.created_at);
+  assert.ok(product.id);
+});
+
+test('listProducts returns all inserted products in insertion order', () => {
+  const db = freshDb();
+  addProduct(db, { name: 'A', url: 'https://a' });
+  addProduct(db, { name: 'B', url: 'https://b' });
+  const products = listProducts(db);
+  assert.equal(products.length, 2);
+  assert.equal(products[0].name, 'A');
+  assert.equal(products[1].name, 'B');
+});
+
+test('getProduct returns undefined for an unknown id', () => {
+  const db = freshDb();
+  assert.equal(getProduct(db, 999), undefined);
+});
+
+test('deleteProduct removes the row', () => {
+  const db = freshDb();
+  const product = addProduct(db, { name: 'A', url: 'https://a' });
+  deleteProduct(db, product.id);
+  assert.equal(getProduct(db, product.id), undefined);
+});
+
+test('recordCheckSuccess updates price, timestamp and status', () => {
+  const db = freshDb();
+  const product = addProduct(db, { name: 'A', url: 'https://a' });
+  recordCheckSuccess(db, product.id, { price: 12.5, checkedAt: '2026-09-05T08:00:00.000Z' });
+  const updated = getProduct(db, product.id);
+  assert.equal(updated.last_price, 12.5);
+  assert.equal(updated.last_checked_at, '2026-09-05T08:00:00.000Z');
+  assert.equal(updated.last_check_status, 'ok');
+});
+
+test('recordCheckFailure only updates the status, leaving price and timestamp untouched', () => {
+  const db = freshDb();
+  const product = addProduct(db, { name: 'A', url: 'https://a' });
+  recordCheckSuccess(db, product.id, { price: 12.5, checkedAt: '2026-09-05T08:00:00.000Z' });
+  recordCheckFailure(db, product.id, 'fetch_error');
+  const updated = getProduct(db, product.id);
+  assert.equal(updated.last_price, 12.5);
+  assert.equal(updated.last_checked_at, '2026-09-05T08:00:00.000Z');
+  assert.equal(updated.last_check_status, 'fetch_error');
+});