TaskTerminalFailureHandler class abstract interface

Optional durable failure finalization for a TaskHandler.

The worker awaits this after persisting a terminal failed TaskStatus and before acknowledging or dead-lettering the delivery. It is not called for retryable attempts or failures that reject a task before execution. The status contains the persisted error; Envelope is the original failed attempt, not a possibly modified redelivery. It can run again on terminal redelivery, so implementations must be idempotent. Throwing leaves the delivery unacknowledged. Authenticated redelivery retries finalization without executing the handler again, even after expiration or revocation.

Task status persistence and this callback are not one transaction. The worker retains finalization metadata in the status, so successful callbacks can also be repeated on subsequent redelivery.