{
  "schema_id": "VegetationStress",
  "version": "0.1",
  "description": "Detect agricultural or forest vegetation changes — planting, harvest, drought, irrigation shift — between before/after Sentinel-2 tiles via NDVI.",
  "class_match": "AG",
  "bands_required": ["B04", "B08"],
  "band_rationale": "NDVI = (B08 - B04) / (B08 + B04). Healthy vegetation has high NDVI; stressed / harvested / replanted land drops.",
  "predicate": "Has agricultural or vegetated land changed — planting, harvest, irrigation change, drought, or field pattern shift — between the before and after tiles?",
  "fields": {
    "severity": {"type": "enum", "values": ["low", "moderate", "high", "extreme"]},
    "change_type": {"type": "enum", "values": ["planting", "harvest", "drought_stress", "irrigation_shift", "replanting", "mixed"]},
    "area_fraction": {"type": "number", "range": [0.0, 1.0]},
    "vlm_explanation": {"type": "string"},
    "confidence": {"type": "number", "range": [0.0, 1.0]}
  },
  "negative_output": null,
  "negative_instruction": "If vegetation signature is unchanged, return null."
}