The gateway now creates a local control socket at startup (Unix domain
socket at $HERMES_HOME/gateway.sock with a pointer-file fallback for
long paths; named pipe on Windows) and answers versioned JSON verbs:
- identify: pid, profile, hermes_home, code_sha/code_version (#91283
stamps, now queryable live), self-declared supervisor kind, start_time
- status: the live runtime-status payload, answered by the process itself
Bound immediately after the PID-file O_EXCL claim (the moment the
process becomes the authoritative gateway for its HERMES_HOME), removed
on clean shutdown; a successor clears any stale socket on bind. Strictly
non-fatal: bind failure only means consumers use the old path.
Consumers migrated (observability only, scan layer demoted to fallback,
never deleted):
- collect_fleet_versions() (post-update fleet matrix): prefers a live
identify answer over gateway_state.json; entries carry source=socket
- collect_runtime_inventory() (hermes update --plan): prefers the
socket, and takes the gateway's own supervisor declaration instead of
inferring it from PID scans
Old gateways mid-upgrade, crashed processes, and bind failures behave
exactly as before. Never a TCP port; filesystem/pipe ACLs are the auth
boundary (0600 socket).
Part of #91277 (fleet-update reliability). Design: #92091.
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