Model notification intent and dispatch in one durable transaction
A collaboration action commits but crashes before queue publication, so some recipients never receive an alert.
- Focused work estimate
- 4h + prerequisites
- Priority in the scenario
- Medium
- Engineering practice
- Transactional outbox · Idempotency
Estimated field mix
- System design40%
- Distributed systems40%
- 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
A fictional collaboration tool sends email and in-app notifications. Duplicate alerts and preference changes reveal that the design has no single definition of delivery.
Setup prerequisites
- Create synthetic recipients, events and fake delivery providers.
- Do not send real email or messages.
Preceding work
Complete these dependencies, or supply their agreed outputs before taking this ticket.
Acceptance criteria
- Persist domain reference and notification intent atomically.
- Use an outbox fact with deterministic intent identity.
- Make repeated event delivery resolve the same logical intent.
Implementation constraints
- Keep intent creation inside the existing modular application boundary.
Verification to include
- Crash after action commit and replay the outbox to one intent.
- Repeat the originating event and verify no duplicate recipient intent.
Deliverables
- Intent/outbox model and interruption probe
Rollout and recovery
Use a local provider fake initially; pause originating notifications if intent persistence fails.
Value of the work
For the engineer: Practice asynchronous contracts, preference timing and delivery uncertainty.
For the team: Review a notification design that controls nuisance, disclosure 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.