saltbo__agent-kanban/docs/adr/0009-post-commit-task-notifications.md

0009: Notify assigned Agents after Task lifecycle commits

Status: accepted

Context

Assignment and later lifecycle decisions must wake or inform an assigned Agent through Inbox. D1 and Inbox do not share a transaction, so a distributed write can partially succeed.

Decision

AK commits the authoritative Task mutation first, then sends an Inbox message for assignment, review rejection, completion, and cancellation. Each message uses the stable key ak:<event>:<taskId>:<taskVersion>. If delivery fails, AK returns a retryable service failure. Retrying the same idempotent lifecycle request retries the notification without applying the Task mutation twice.

Consequences

Task state is never rolled back because Inbox is unavailable. A caller may see an error after the Task changed and must retry the same request. Inbox must deduplicate the stable message key; AK logs the boundary failure without placing credentials or message bodies in logs.