Tells a freshly-started stdio proxy (npx local-mcp@latest) whether the tray serving THIS machine is running OLDER code than the bundle staged on disk — the disk-vs-running lag (~half the fleet, 2026-06-13). The tray's own idle self-heal (applyDeferredTrayRestartIfIdle) only ships in 3.0.278+ and only runs once the tray is ALREADY executing 278+ code, so it can't unstick the pre-278 always-on tail. The proxy is the only always-fresh code on a stuck machine; it calls this and, if stale, restarts the tray.

Authoritative signal: the latest heartbeat's running_version (compile-time VERSION = the code actually executing) vs version (disk bundle). ServerCore.version is read from the on-disk Info.plist, so /status/IPC/lmcp_state all report the DISK version — only the heartbeat exposes the true running version. Strict numeric older => stale. Read-only; machine_id is a UUID the caller already owns (no PII, no auth needed).