pub async fn probe_other_instances(uid: &str) -> Option<LegacyHolder>Expand description
Ask every other live AgentMux instance on this host (from the
host-global cross-channel registry) whether it has uid registered.
Matched by UID, never by name (display names are not unique — Codex P2
on #3730). An instance too old to report UIDs, or one that doesn’t
answer, is not evidence either way and is skipped (logged).