An AI tester shopped a demo store with planted bugs and checked what it saw against the database, logs and payments. It filed: Each paid order is fulfilled twice: buying 1 coffee set drops stock by 2 (12→10) and sends 2 confirmation emails; Double-clicking "Pay" creates 2 orders and 2 Stripe Checkout Sessions for one cart (phantom "Awaiting payment" order); FIVEOFF is applied per unit in Stripe: 3 items are charged $40.69 while the cart and order say $50.69 ($10 undercharge, order still marked Confirmed). Each bug comes with screenshots, logs, a Playwright repro and the full recording.