pub fn post(store: &Talks, talk_id: &str, body: &str, by: &str) -> Result<()>Expand description
Append an agent-authored message to the transcript without starting a
turn (magi talk post). by is the posting seat’s run id. No draft, no
lease, no agent call: it only writes under the store guard, onto the
freshest record, so it cannot lose a concurrent reply.