Function assert_sticky_routing 

pub async fn assert_sticky_routing(
    store: Arc<dyn Store>,
    backend: &str,
) -> String

Shared live-backend proof for strict sticky routing. A 5,000-job high-priority backlog pinned to another worker must not fill the bounded candidate draw and hide the caller’s pinned or ordinary work. Rate-limited requeue then proves the route is durable lifecycle state rather than lease metadata.