{
  "event_id": "evt_550e8400...",
  "event_type": "fuel_rate.updated",
  "carrier": "fedex",
  "service": "ground",
  "old_rate": "18.5",
  "new_rate": "19.0",
  "change_percent": "+0.5",
  "detected_at": "2026-07-21T05:30:00Z"
}