{
  "schema_id": "ConstructionProgress",
  "version": "0.1",
  "description": "Detect newly cleared greenfield land, earthworks, or progressing construction sites between before/after Sentinel-2 tiles.",
  "class_match": "GF",
  "bands_required": ["B02", "B03", "B04", "B08"],
  "band_rationale": "RGB for bare earth / construction surfaces; NIR to track vegetation loss on cleared plots.",
  "predicate": "Has previously vegetated or greenfield land been cleared, graded, or begun construction between the before and after tiles?",
  "fields": {
    "severity": {"type": "enum", "values": ["low", "moderate", "high", "extreme"]},
    "stage": {"type": "enum", "values": ["clearing", "grading", "foundation", "vertical_build", "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 no land clearing or construction activity is visible, return null."
}