Expire holds without cancelling a booking confirmed at the boundary
An expiry worker reads an old hold while checkout confirms it; the worker then frees a slot already sold.
- Focused work estimate
- 6h + prerequisites
- Priority in the scenario
- High
- Engineering practice
- State machines · Concurrency
Estimated field mix
- Backend60%
- Database engineering40%
Field percentages are editorial estimates of the ticket's engineering focus. They total 100%; they are not measured time, proficiency scores, or ownership evidence.
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Project context
A fictional equipment service books maintenance visits. Expiring checkout holds and reschedules occasionally double-book a technician.
Setup prerequisites
- Build synthetic technicians, slots and booking records.
- Use an injectable clock and separate clients for concurrency probes.
Preceding work
Complete these dependencies, or supply their agreed outputs before taking this ticket.
Acceptance criteria
- Confirm and expire use guarded state transitions.
- Exactly one terminal outcome wins at the expiry boundary.
- A stale expiry job cannot alter a confirmed booking.
Implementation constraints
- Specify whether confirmation at the exact deadline is rejected.
Verification to include
- Race confirmation and expiry with a controlled clock.
- Retry the stale expiry after confirmation and retain the booking.
Deliverables
- Hold state machine and boundary race reproduction
Rollout and recovery
Canary the guarded worker; stop expiry consumption while preserving stored deadlines.
Value of the work
For the engineer: Practice resource allocation, interval conflicts and durable workflows.
For the team: Review scheduling correctness and recovery before exposing scarce capacity.
Evidence boundaries
Outcome Evidence: Tests, patches, and runbooks are requested deliverables. They become Outcome Evidence only through a qualified Mission and immutable Evidence IDs.
Ownership Evidence: Independent adaptation must be observed under a declared verification policy and cite immutable Evidence IDs. Completing a planning ticket establishes no Ownership Evidence.