Answer a Human

Write to the Human in a conversation. It takes a message while the ACT is OPEN (unless that Human held the ACT before) and, once claimed, only in the claimant's conversation through SUBMITTED; otherwise it is closed. The Human is emailed that you wrote — at most once a conversation in 15 minutes, sooner once they have read — and the email never carries your words. Never tell a Human the Reserve, and never put an access code in chat. Chat cannot change the ACT; say so rather than agree to a change here. Send an Idempotency-Key header — any string up to 255 characters, one per message — and a retry that reached the server gets the same answer back with Idempotent-Replayed: true, never a second message; the same key with other words, or to another conversation, is refused, and a first attempt still in flight is refused rather than raced. A refusal sends nothing, so a retry under its key runs again. Answers are replayed for a day.