Transactional outbox

Intent

Avoid dual-write bugs by writing domain state + an outbox record in the same DB transaction, then publishing asynchronously.

Use when

• You need reliable event publication tied to a database transaction.
• You integrate via async events and can accept at-least-once delivery.

Avoid / watch-outs

• Requires idempotent consumers; duplicates will happen.
• Needs monitoring for outbox backlog and publisher failures.

Skill mapping

• architecture: choose outbox vs CDC (transaction log tailing) and define event ownership.
• resilience: publisher retry/backoff; consumer idempotency/dedupe.
• observability: lag metrics and correlation across publish/consume.
• spec: event schemas, ordering/duplication expectations, and compatibility.
• platform: shared outbox publisher when 2+ services need it.