Create workshop holds atomically under contention
Two clients see one available seat and both reserve it. Serialize capacity consumption at storage.
- Focused work estimate
- 3h + prerequisites
- Priority in the scenario
- High
- Engineering practice
- Transactions · Concurrency
Estimated field mix
- Database engineering70%
- Backend30%
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
Fictional craft studio Maple offers workshop seats. Implement synthetic reservations without payments or real booking services.
Setup prerequisites
- Create synthetic workshops with small capacities.
- Implement local transactional hold storage and injected clocks.
Preceding work
Complete these dependencies, or supply their agreed outputs before taking this ticket.
Acceptance criteria
- At most capacity is consumed
- Loser receives unavailable result
- No partial hold record remains
Implementation constraints
- A browser availability check is advisory only.
Verification to include
- Create uncontested hold
- Race two requests for one seat
Deliverables
- Transactional hold operation
Rollout and recovery
Pause hold creation if capacity invariant fails.
Value of the work
For the engineer: Practice contention, expiry and truthful realtime projections.
For the team: Inspect whether concurrent clients avoid overselling and recover uncertain results.
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.