Tracks sends the FX lighting cues to the Lighting PC through NA Tracks' network MIDI session. A midi_peer check may now name a "host": the watchdog reads that Mac's sessions over SSH every 5 s, sending this folder's coremidi.py over stdin (nothing installed there). Unreachable = no verdict; the Tracks Mac's own ping check covers that. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>