{
  "metric_id": "soil-water-content",
  "value": 0.25,
  "unit": "m3/m3",
  "observed_at": "2026-11-09T00:00:00Z",
  "quality_flag": "ok",
  "sensor_id": "demo-sensor-01",
  "site_id": "demo-site-01",
  "raw": {"value":250,"unit":"device_count"},
  "provenance": {"source":"teaching_example","algorithm":"demo-linear-v1","calibration":null}
}