feat: add feature

apps/api/src/devices/devices.service.spec.ts

@@ -9,6 +9,7 @@ function createService({ previous = [] as Snapshot[], delivered = 0, expired = 0
     openTabSnapshot: { deleteMany: jest.fn(), upsert: jest.fn(), updateMany: jest.fn() },
     plannedTab: { updateMany: jest.fn().mockResolvedValue({ count: delivered }) },
     device: { update: jest.fn() },
+    tabEvent: { createMany: jest.fn() },
   };
   const prisma = {
     openTabSnapshot: { findMany: jest.fn().mockResolvedValue(previous) },
@@ -154,3 +155,49 @@ describe('DevicesService.sync writes', () => {
     expect(tx.openTabSnapshot.updateMany).not.toHaveBeenCalled();
   });
 });
+
+describe('DevicesService.sync tab events', () => {
+  const event = {
+    id: '6f1c2c0e-6a2b-4c1e-9a4c-1f2a3b4c5d6e',
+    type: 'line_added',
+    tabId: 't1',
+    customerName: 'Jan',
+    occurredAt: new Date().toISOString(),
+    productName: 'Cola',
+    unitPriceInCents: 250,
+    quantity: 2,
+  };
+
+  it('stores events once and acknowledges them', async () => {
+    const { service, tx } = createService();
+
+    const result = await service.sync(device, { deviceId: 'd1', openTabs: [], events: [event] });
+
+    expect(tx.tabEvent.createMany).toHaveBeenCalledWith({
+      data: [expect.objectContaining({ id: event.id, venueId: 'v1', deviceId: 'd1', quantityDelta: 2 })],
+      skipDuplicates: true,
+    });
+    expect(result.acknowledgedEventIds).toEqual([event.id]);
+    expect(result.rejectedEvents).toEqual([]);
+  });
+
+  it('still syncs when an event is invalid, and reports it', async () => {
+    const { service, tx } = createService();
+
+    const result = await service.sync(device, { deviceId: 'd1', openTabs: [], events: [{ ...event, quantity: -1 }] });
+
+    expect(tx.tabEvent.createMany).not.toHaveBeenCalled();
+    expect(tx.device.update).toHaveBeenCalled();
+    expect(result.acknowledgedEventIds).toEqual([]);
+    expect(result.rejectedEvents).toEqual([{ id: event.id, reason: expect.stringMatching(/quantity/) }]);
+  });
+
+  it('works for terminals that send no events', async () => {
+    const { service, tx } = createService();
+
+    const result = await service.sync(device, { deviceId: 'd1', openTabs: [] });
+
+    expect(tx.tabEvent.createMany).not.toHaveBeenCalled();
+    expect(result.acknowledgedEventIds).toEqual([]);
+  });
+});