Commands have no implicit handler-wide transaction. Each standalone database operation commits before its promise resolves or rolls back on failure.

Use db.transaction(callback) for an explicit Command transaction. Only calls through the callback tx handle join that transaction.

Steps are different. A Step has one kernel-owned transaction for database effects plus durable completion. Application-authored db.transaction is unavailable inside Steps.

This keeps immediate Command effects explicit while preserving exactly-once database effects for committed Step boundaries.