feat: do final stress tests

apps/api/src/tabs/tab-state.spec.ts

@@ -124,6 +124,18 @@ describe('findLine', () => {
   });
 });
 
+describe('VenueTabs.removable', () => {
+  it('counts only drinks still on the line, so a removal after a settlement returns nothing to the stock', () => {
+    const tabs = withCola(3);
+    const removal = event({ type: 'line_removed', lineId: 'line-1', quantity: 5, ...cola });
+    expect(tabs.removable(removal)).toBe(3);
+
+    tabs.apply(event({ type: 'settled', amountInCents: 750, paymentMethod: 'cash', items: [{ ...cola, quantity: 3 }] }), time);
+    expect(tabs.removable(removal)).toBe(0);
+    expect(tabs.removable(event({ type: 'line_removed', tabId: 'gone', quantity: 1, ...cola }))).toBe(0);
+  });
+});
+
 describe('seedTabs and tabSummary', () => {
   it("turns a terminal's snapshot into tabs the dashboard sums up the same", () => {
     const [seeded] = seedTabs([{

apps/api/src/tabs/tab-state.ts

@@ -171,6 +171,16 @@ export class VenueTabs {
     }
   }
 
+  /**
+   * How many drinks a line_removed event can actually take off: none when the tab or line is gone (settled or
+   * deleted elsewhere while the terminal was offline).
+   */
+  removable(event: TabEventDto): number {
+    const tab = event.tabId ? this.tabs.get(event.tabId) : undefined;
+    const line = tab && findLine(tab, event);
+    return line ? Math.min(event.quantity ?? 0, lineQuantity(line)) : 0;
+  }
+
   /** Settles everything still on the tab, as the dashboard does. Null when there is nothing to settle. */
   settleAll(tabId: string, settlement: { id: string; settledAt: Date; paymentMethod: string }): SettlementDraft | null {
     const tab = this.tabs.get(tabId);