Issue a monotonically increasing assignment generation on every reclaim
A disconnected reviewer reconnects after its job was reassigned and still holds a token that appears current.
- Focused work estimate
- 3h 30m + prerequisites
- Priority in the scenario
- Medium
- Engineering practice
- Fencing · Optimistic concurrency
Estimated field mix
- Database engineering60%
- Distributed systems40%
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 inspection service assigns review jobs to staff. Polling clients sometimes claim the same job and a disconnected client can finish work after reassignment.
Setup prerequisites
- Create synthetic jobs and two independent database clients.
- Use explicit state methods and an injected clock.
Preceding work
Complete these dependencies, or supply their agreed outputs before taking this ticket.
Acceptance criteria
- Every new assignment increments a durable generation.
- Mutation commands require job, assignee and generation.
- A stale generation cannot renew or finish work.
Implementation constraints
- Treat the generation as authority, not a UI-only counter.
Verification to include
- Reclaim a job and complete using the new generation.
- Try completion from the previous generation and reject it.
Deliverables
- Assignment-generation guard
Rollout and recovery
Enable guarded writes before automated reclaim; retain old assignment history.
Value of the work
For the engineer: Practice database concurrency, leases and transactional invariants.
For the team: Review whether assignment authority remains reliable during contention and recovery.
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.