Specify what stale product data the portal may display
The cache uses one TTL for descriptive text and order-critical availability, though they have different correctness needs.
- Focused work estimate
- 2h 30m + prerequisites
- Priority in the scenario
- Medium
- Engineering practice
- Consistency policy · Data semantics
Estimated field mix
- Distributed systems60%
- System design40%
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
- Classify fields by tolerated staleness.
- Keep authoritative order decisions outside stale display data.
- Define fresh, stale-allowed and unusable cache states.
Implementation constraints
- Use explicit hypothetical freshness bounds with product approval noted as pending.
Verification to include
- Serve stale descriptive text within the declared window.
- Reject using stale cached availability to authorize an order.
Deliverables
- Cache consistency matrix
Rollout and recovery
Review the matrix before changing TTLs; leave unresolved critical reads authoritative.
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.