The review found that busretry could ask a delivered call again: Conn.request turned a callee's error answer into errors.New(words), and Undelivered matched the words "no responders" and "jetstream not enabled", so a callee that answered so during a blackout ran its work twice. A callee's answer is now *busretry.Answered, which Undelivered never counts: only the transport's own no responders makes a call undelivered. The other busretry sites read or write through JetStream's API (State, Ask) or the runtime's state verbs, where the words are the transport's.