Commit product changes with a durable invalidation fact
The product write commits and then the process dies before deleting shared cache keys.
- Focused work estimate
- 4h + prerequisites
- Priority in the scenario
- High
- Engineering practice
- Transactional outbox · Invalidation
Estimated field mix
- Distributed systems60%
- 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 wholesale portal caches product availability descriptions across several API instances. Delayed invalidations and slow refreshes bring back old content after edits.
Setup prerequisites
- Create two local cache clients and a synthetic authoritative product store.
- Use a fake clock and controllable read/write barriers.
Preceding work
Complete these dependencies, or supply their agreed outputs before taking this ticket.
Acceptance criteria
- Persist the product revision and invalidation outbox fact atomically.
- Bind invalidation identity to product scope and revision.
- Replay invalidation safely after a crash.
Implementation constraints
- Cache failure must not roll back an already committed product change.
Verification to include
- Crash after database commit and dispatch the retained invalidation.
- Replay the same invalidation and retain correct cache state.
Deliverables
- Product/outbox transaction and recovery test
Rollout and recovery
Canary one synthetic product class; monitor pending invalidations and fall back to authoritative reads when stale bounds expire.
Value of the work
For the engineer: Practice cache consistency, version guards and recoverable invalidation.
For the team: Review fast derived reads without losing authoritative state or tenant isolation.
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.