Post a message into an item's chat as an agent

Post a message into an item's chat as the calling agent: an action taken outside Roma with its link, or the one question the work is blocked on. On a shared item (shared on its own or through its list) the post lands in its Thread, where the owner and every member read it. The user sees it on every device as an unread reply on the item and as an Updates row under your name, and the agent cannot take it back, so a post per step, or a note that work is finished, reads as noise; a post the item's own body asks you for is the person's ask and is wanted. Set needsInput when the work is blocked on their answer. The same messageKey posted twice lands once. The person is offered Reply on your post only when you will read it: a live trigger wakes you by this agentName (manage_triggers, action create, with agentName), or you pass readsReplies: true because you read this chat again on your next run (read_chat_messages with since). Otherwise the post is a notification they cannot answer, so do not ask a question in it. The answer's listening says whether a reply would wake you at once. A registered agent (register_agent) posts under its record's name whatever agentName says, and the person's Reply wakes it through its own door.