{
  "query": "What changed, and where?",
  "answer": "Based on the provided measurements and visual evidence, here’s what changed between Image 1 (earlier) and Image 2 (later):\n\nWhat Changed:\n- Water/Flooding Increased: The most significant change is a large area of new or increased water coverage, likely due to flooding. This is confirmed by:\n  - A negative NDVI delta (-0.981), indicating loss of vegetation cover (likely submerged crops).\n  - A positive NDWI delta (+0.838), which typically indicates increased water content in the canopy.\n  - The tool explicitly flags this as \"likely new water / flooding.\"\n\nWhere:\n- The change occurred primarily along the river channel and its immediate floodplain, extending into adjacent agricultural fields.\n- In Image 1, the river appears as a dark blue line with some green/brown patches on either side (vegetated banks).\n- In Image 2, this same area is",
  "evidence": [
    "change_cva: changed_pct=9.16, threshold=1.666, ndvi_delta_in_changed=-0.981, ndwi_delta_in_changed=0.838, likely=new water / flooding"
  ],
  "confidence": 0.582,
  "trace": {
    "task": "change",
    "input_config": "bitemporal",
    "plan": [
      "change_cva",
      "vlm_change"
    ],
    "inputs": [
      {
        "name": "river_t1.tif",
        "modality": "optical",
        "bands": 4,
        "size": [
          1024,
          1024
        ],
        "crs": null
      },
      {
        "name": "river_t2.tif",
        "modality": "optical",
        "bands": 4,
        "size": [
          1024,
          1024
        ],
        "crs": null
      }
    ],
    "steps": [
      {
        "tool": "change_cva",
        "params": {
          "threshold": null,
          "noise_k": 2.0
        },
        "status": "ok",
        "ms": 88,
        "stats": {
          "changed_pct": 9.16,
          "threshold": 1.666,
          "ndvi_delta_in_changed": -0.981,
          "ndwi_delta_in_changed": 0.838,
          "likely": "new water / flooding"
        },
        "conf": null,
        "output": null
      },
      {
        "tool": "vlm_change",
        "params": {
          "max_tokens": 200
        },
        "status": "ok",
        "ms": 11067,
        "stats": null,
        "conf": 0.582,
        "output": "Based on the provided measurements and visual evidence, here’s what changed between Image 1 (earlier) and Image 2 (later):\n\nWhat Changed:\n- Water/Flooding Increased: The most significant change is a large area of new or increased water coverage, likely due to flooding. This is confirmed by:\n  - A negative NDVI delta (-0.981), indicating loss of vegetation cover (likely submerged crops).\n  - A positive NDWI delta (+0.838), which typically indicates increased water content in the canopy.\n  - The tool explicitly flags this as \"likely new water / flooding.\"\n\nWhere:\n- The change occurred primarily along the river channel and its immediate floodplain, extending into adjacent agricultural fields.\n- In Image 1, the river appears as a dark blue line with some green/brown patches on either side (vegetated banks).\n- In Image 2, this same area is"
      }
    ]
  }
}