Implements 100% exactly-once semantics for CDC events from 1.0 identity-service
(user_accounts table) to auth-service.
Key changes:
- Add ProcessedCdcEvent model with (sourceTopic, offset) unique constraint
- Implement processWithIdempotency() using Serializable transaction isolation
- All database operations now use the transaction client
- Outbox event creation is also within the same transaction
This ensures that:
1. Each CDC event is processed exactly once
2. Idempotency record and business logic are in the same transaction
3. Outbox event publishing is atomic with data sync
4. Any failure causes complete rollback
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
hailin
9037c2da97
