Claude Code System Prompts

Client uuid of the user message that triggered this turn (submitMessage options.uuid), echoed back so a consumer can link this error result to the send it answers — the same join key the success variant echoes, carried alone (error turns have no request_sent_wall_ms to report). A delivery-failure result from the remote-session client echoes the failed send's queue key, which is client-minted when the host sent no uuid of its own. A synthetic/scheduled (meta) turn's own uuid is echoed only when the host vouches it is the client event's own (delivered content such as a Slack owner ping or a Slack-bot observation); a meta turn that folded queued user messages in mid-turn, vouched or not, echoes the LAST of them. Absent on turns that neither had a client uuid nor folded a user message in, on session-scoped failures with no single triggering send (a crashed worker's zeroed result), and from older producers.