[rmkr-dev]

Adds a Skillbook entry and a matching Promptbook entry for publishing events reliably from Spring Boot services with a transactional outbox.

Skill: transactional-outbox-guardrails

• Outbox row written in the same transaction as the business change, no broker calls inside it
• Relay choice: polling with FOR UPDATE SKIP LOCKED, Debezium CDC, or a framework registry, with trade-offs
• Per-aggregate ordering across relay replicas (single relay, key ownership, or head-of-line claim) and aggregate versions
• Kafka key + idempotent producer vs Service Bus MessageId, sessions and duplicate detection; at-least-once with consumer inbox dedupe
• Message id and traceparent headers, backoff and parked poison rows, retention, oldest-pending-age metrics, Testcontainers failure tests
• Flyway table, write path, claim SQL, inbox table, checklist, anti-patterns, SKILL.md stub

Prompt: add-transactional-outbox

• Publish-point inventory first, then migration, write path, relay, broker mapping, consumer dedupe, metrics and alerts
• Tests for rollback, broker outage, crash between send and mark, ordering and poison rows; consumers dedupe before the relay goes live

Catalogs go to 50 skills / 50 prompts. node scripts/site-check.mjs passes locally.