v0.21.4 already attaches a second Desktop to the live hermes serve. The release defers curated notes to v0.22.0; this path is in the tag. I looked at backend-discovery.ts and attachToRunningHostBackend in main.ts at peel d337b736; I did not run Desktop or hermes update.

parseSpawnLedger keeps loopback dashboard/serve records with a bound port (0.0.0.0 and :: included). A record without a port is skipped so another usable one can still attach. spawnOrAttach takes the newest of those. Unreadable JSON, or none left, means spawn. HERMES_DESKTOP_ISOLATED_BACKEND still starts a new backend. The ledger is written after the socket binds. Attach still needs the served token, readiness, and a WebSocket probe; a failed discovery falls through to spawn.

Gateway attach is a different wait: host_attach.py uses the rendezvous record only to prove an owner (pid + createTime), then waits for that process’s control-socket identify before ATTACH. I commented on #117999 first.