Claude Code System Prompts

Tells the other side that the sender no longer needs the answer to one of its own in-flight control_requests (for example a pending can_use_tool prompt after the turn was interrupted, or one that another client already answered). Either side may send it for a request it originated. The sender stops waiting at once and ignores any control_response that still arrives for that request_id; a receiver that can abort the work does so and may still reply (typically with an error), otherwise it simply completes the request. There is no reply to the cancel itself.