Publish workshop availability changes only after commit
Clients see seats disappear for a transaction that later rolls back. Publish committed availability through an outbox.
- Focused work estimate
- 4h + prerequisites
- Priority in the scenario
- High
- Engineering practice
- Outbox · Consistency
Estimated field mix
- Distributed systems50%
- Database engineering30%
- Real-time systems20%
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.
- CAUCT-101 · Specify workshop seat counts without negative availability
- CAUCT-102 · Validate workshop hold quantities before storage
- CAUCT-103 · Create workshop holds atomically under contention
- CAUCT-104 · Scope workshop hold lookup and cancellation to its owner
- CAUCT-105 · Confirm workshop holds only before the expiry boundary
- CAUCT-106 · Replay workshop hold requests with the same idempotency key
Acceptance criteria
- Committed changes enqueue events
- Rollback emits no event
- Replay cannot double-apply availability
Implementation constraints
- Event consumers receive versions, not count deltas alone.
Verification to include
- Commit hold and publish
- Roll back after preparing event
Deliverables
- Outbox handoff and rollback cases
Rollout and recovery
Stop live updates and serve authoritative snapshots.
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.