THE SONAR reads a ledger of admin-gate accesses. Bearing = geographic origin · range = trust (center clean, rim failure/unknown) · colour = which password · solid = success, hollow = failure · brightness = recency. The sweep period is the window. ONE PERSON HOLDS THE KEYS, so any ping that is not the captain is a contact that should not exist — the instrument is a tripwire, not a traffic monitor. No live ledger yet: this runs on a SAMPLE feed. SENSOR DARK ≠ ALL QUIET — the scope never lets an empty glass be mistaken for a safe one.