Function session_is_idle 

pub async fn session_is_idle(handle: &SessionHandle) -> bool

Whether handle’s actor is between turns. Asks Query{Status} under the reserved crate::session::wire::IDLE_PROBE_QUERY_ID (transports swallow it) and reads streaming. A no-answer inside [IDLE_PROBE_TIMEOUT] — the actor is inside compact()/preflight, or its queue is full — counts as busy: the daemon never exits under a running turn (jcode mistake #1).