Expire disconnected presence without rewriting incident history
Closing a laptop leaves its user shown as In room for hours. Presence currently uses the same durable event path as incident notes, making heartbeat traffic dominate replay.
- Focused work estimate
- 1h 45m + prerequisites
- Priority in the scenario
- Medium
- Engineering practice
- Leases · Ephemeral state · Resource cleanup
Estimated field mix
- Real-time systems70%
- Distributed systems30%
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
The fictional Harbor operations team coordinates synthetic incidents in a shared room. Engineers post status notes and claim response tasks while connections come and go. Scope is one application gateway, a durable room event store, and fixture clients; alert paging and external chat delivery are excluded.
Setup prerequisites
- Room membership and command contracts
- Synthetic incident events and a controllable transport harness
Preceding work
Complete these dependencies, or supply their agreed outputs before taking this ticket.
Acceptance criteria
- Presence expires from a bounded lease using server-observed heartbeats.
- Multiple tabs collapse to one visible member while preserving presence if one tab remains connected.
- Presence expiration never removes authored notes or changes task ownership.
Implementation constraints
- Presence is advisory activity state, not proof that someone read or understood an incident.
Verification to include
- Open two tabs, close one, and verify the member remains until the final lease expires.
- Delay heartbeats and restart the presence store; stale members expire without changing durable timeline or ownership.
Deliverables
- Ephemeral presence lease model and multi-tab expiry tests
Rollout and recovery
Release advisory presence independently; hide it when its store is unavailable rather than retaining indefinite online claims.
Value of the work
For the engineer: Practice event identity, ordering, replay, authorization, and bounded backpressure in one understandable system.
For the team: Inspect how an engineer keeps collaborative state trustworthy during failures without relying on optimistic success messages.
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.