Join incident snapshots and streams at one watermark
An update between snapshot fetch and stream connect disappears. Establish a snapshot watermark for replay.
- Focused work estimate
- 4h + prerequisites
- Priority in the scenario
- High
- Engineering practice
- Consistency · Transactions
Estimated field mix
- Distributed systems50%
- Real-time systems30%
- Database engineering20%
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 internal status team Harbor updates operational incident cards. Build a local event log and SSE adapter; incidents and service names are invented.
Setup prerequisites
- Create synthetic incident revisions and a local append-only event stub.
- Provide controllable disconnect, replay and retention fixtures.
Preceding work
Complete these dependencies, or supply their agreed outputs before taking this ticket.
- CLIVE-101 · Give live incident events stable opaque identifiers
- CLIVE-102 · Render incident status text independently of severity color
- CLIVE-103 · Apply live incident updates only to newer revisions
- CLIVE-104 · Resume incident streams from the last applied event
- CLIVE-105 · Return a reset contract when incident replay history expired
Acceptance criteria
- Snapshot declares its watermark
- Stream replays later events
- Boundary duplicates remain harmless
Implementation constraints
- Define transaction or adapter ordering explicitly.
Verification to include
- Update before snapshot
- Update between snapshot and subscription
Deliverables
- Snapshot-stream handoff and race cases
Rollout and recovery
Use periodic full snapshots while handoff is repaired.
Value of the work
For the engineer: Practice event projection, replay and freshness communication.
For the team: Inspect whether dashboards remain trustworthy through network interruptions.
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.