Situation
A booking product needs to combine supplier availability with online payment. The difficult cases happen between systems: availability changes during checkout, payment confirmation is delayed, or a webhook is delivered more than once.
Contract milestone
We document reservation states, hold duration, provider contracts and which system owns each decision. A sandbox proof validates authentication, rate limits and representative failure responses.
Implementation milestone
- Create time-bounded inventory holds
- Process payment events idempotently
- Separate payment success from booking confirmation
- Reconcile incomplete or conflicting states
- Add searchable audit events and support procedures
Acceptance evidence
Automated scenarios cover expired holds, repeated webhooks, delayed confirmation, partial provider outages and safe retries. Operations staff receive a recovery checklist for reservations that need manual review.