Recover expired worker leases without concurrent duplicate effects
A worker crashes after producing output but before acknowledging completion.
- Focused work estimate
- 3h 30m + prerequisites
- Priority in the scenario
- High
- Engineering practice
- Leases · Idempotency
Estimated field mix
- Distributed systems50%
- Platform engineering30%
- Site reliability20%
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 document service has a rising processing backlog. Operators cannot tell whether arrivals, worker failures, or a slow dependency is responsible.
Setup prerequisites
- Create a bounded local queue simulation with synthetic jobs and controllable worker/dependency failures.
Preceding work
Complete these dependencies, or supply their agreed outputs before taking this ticket.
Acceptance criteria
- Use stable job operation identity.
- Reclaim only expired ownership.
- Adopt existing completed output before repeating effects.
Implementation constraints
- Mock effects must be idempotent and locally scoped.
Verification to include
- Crash after effect acceptance and reclaim.
- Race two reclaimers and observe one terminal outcome.
Deliverables
- Lease recovery behavior.
Rollout and recovery
Reclaim in bounded batches; stop on conflicting output identities.
Value of the work
For the engineer: Practice incident timelines, queue diagnosis, and measured recovery.
For the team: Produce a repeatable response that preserves work integrity and exposes customer delay.
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.