Systems / Software repair
The reservation shop
Repair a busy shop where reservations expire and customers try again.
Six customer requests expose three interacting bugs. Repair the rules so four units of stock are never oversold, expired holds disappear, and retries preserve their original receipts.
A reservation expires when its deadline is reached. A repeated request must return its original answer even after its hold has expired.
Patch the service
Explore the controls, then check your result.
Need a hint?
These rules interact: a successful old receipt is not a new reservation. A retry still advances time, so expired holds must be swept before returning that receipt.
Customer replay
1234
Held3
Available1
Minute0
Rose’s reply: Reserved until 3
| Live reservation | Units | Expires |
|---|---|---|
| Rose | 3 | 3 |
This replay shows the last run. Change a rule and run again to compare its effects.