Reject stale presence heartbeats after reconnect
Delayed heartbeat from a replaced socket prolongs a dead session. Bind renewal to session generation.
- Focused work estimate
- 3h + prerequisites
- Priority in the scenario
- High
- Engineering practice
- Concurrency · Fencing
Estimated field mix
- Distributed systems60%
- Real-time 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
Fictional document team Pine shows collaboration presence for synthetic accounts. Build a loopback WebSocket server and injected clocks; no message content or activity surveillance is required.
Setup prerequisites
- Create synthetic memberships and session identifiers.
- Implement controllable sockets and an in-memory TTL adapter.
Preceding work
Complete these dependencies, or supply their agreed outputs before taking this ticket.
Acceptance criteria
- New generation supersedes old
- Old heartbeat cannot renew
- Current heartbeat extends its own lease
Implementation constraints
- Generation changes must be atomic in the adapter.
Verification to include
- Renew current session
- Deliver old heartbeat after reconnect
Deliverables
- Generation guard and race tests
Rollout and recovery
Close superseded sessions and require fresh joins.
Value of the work
For the engineer: Practice ephemeral state, ordering and reconnect semantics.
For the team: Inspect whether online indicators avoid stale or unauthorized claims.
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.