outbox-handler-add

To add a new outbox handler for asynchronous saga dispatches, you scaffold a coroutine implementing the handler contract, wire lifecycle registration into the OutboxWorker, and emit OutboxIntent from forward or compensating steps instead of inline calls.

The outbox pattern for replay-safe asynchronous dispatch uses commit-then-enqueue semantics and idempotency keys to ensure external integrations receive exactly-once delivery, preventing unsafe non-atomic dispatches even during worker retries or dead-letter scenarios.

Wiring a new external integration into an OutboxWorker registry using FastAPI lifespan requires adding a client wrapper, configuring the outbox dispatch builder, and registering the handler during application startup to emit OutboxIntent events safely.

Yes, idempotency keys are required for outbox pattern saga dispatch testing to guarantee replay-safety. You must create a focused worker dispatch unit test verifying failure, retry, and dead-letter behavior for the new external target handler.

Saga outbox dispatches fail without commit-then-enqueue guarantees because inline external calls are non-atomic, causing data inconsistency. You must emit OutboxIntent after database commit and rely on the OutboxWorker for asynchronous delivery.

The best way to scaffold a dead-letter retry handler for an outbox target is to implement the required coroutine signature with explicit idempotency-key usage, ensuring the OutboxWorker safely handles failures and retries without duplicate dispatches.