ReceiptGap — Transaction Truth Lab

A customer places an order. The server records it, but the confirmation disappears on the way back. The customer sees “failed,” tries again, and creates a duplicate. Most testing tools can simulate a network problem. ReceiptGap makes the missing human consequence visible: what did the person believe, what did the system actually do, and what happened next? ReceiptGap is an interactive transaction truth lab for developers. Builders select a failure boundary, then compare a broken implementation with a repaired one. The app shows the customer-facing message, the server ledger, a step-by-step event trace, and a verdict. In the broken flow, a lost response produces a false failure and a second order. In the fixed flow, the client treats the outcome as unknown, checks the original operation ID, and shows the existing receipt instead of creating another order. The event trace can be exported as JSON, and the deterministic engine is covered by focused tests in the public repository. ReceiptGap is aimed at teams building checkout, bookings, applications, and other high-stakes workflows. The prototype uses synthetic orders and makes no real payments. The planned hackathon build will extend the simulator into a developer workflow that imports a synthetic trace, validates invariants, and generates a replayable regression fixture.