End the current turn and go quiet when there is nothing left to do right now: call this alone, with no arguments, once all pending work is finished and you are only waiting for something new — a user message, the result of an async sub-agent run (analyze, or implement/research when available), or a fired alarm. The session is preserved and will be resumed automatically by the next such event; do not use `sleep` to wait inside a turn or together with other tool calls.