Represent preference deletion as a durable tombstone
A deleted record disappears from the source snapshot but remains enabled in a downstream projection indefinitely.
- Focused work estimate
- 2h 30m + prerequisites
- Priority in the scenario
- Medium
- Engineering practice
- Deletion semantics · Change data
Estimated field mix
- Data engineering70%
- Database engineering30%
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 messaging service builds a read model from database changes. Restarts and schema changes can re-enable preferences that customers disabled.
Setup prerequisites
- Create synthetic preference records and a replayable local change log.
- Use adapters or fixtures without provisioning a production broker.
Preceding work
Complete these dependencies, or supply their agreed outputs before taking this ticket.
Acceptance criteria
- Define tombstones with identity and source position.
- Retain enough ordering metadata to reject stale recreation.
- Separate deletion from a false preference value.
Implementation constraints
- Document retention assumptions for replayable tombstones.
Verification to include
- Apply deletion and verify the projected record is absent.
- Replay an older enable event and keep the record deleted.
Deliverables
- Tombstone contract and ordering cases
Rollout and recovery
Enable tombstone production before cleanup; stop purging if replay coverage is uncertain.
Value of the work
For the engineer: Practice change-feed ordering, snapshots and privacy-preserving deletion.
For the team: Review whether replicated customer preferences remain correct during 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.