{
  "tested_date": "2026-10-13",
  "browser": "Codex in-app desktop browser; engine version not recorded",
  "independent_decoder": "Pillow 11.3.0, ICO directory parsed with Python struct, actual browser downloads",
  "encoding_algorithm": "Existing one-entry 256x256 PNG-in-ICO; unchanged for this update",
  "outputs": [
    {
      "input": "alpha-bands.png",
      "input_width": 256,
      "input_height": 256,
      "input_bytes": 868,
      "input_sha256": "56aae8b4d96674765fad8ac3eef609d83dd359ab765b15060d0b1cad9a0b4c65",
      "output": "alpha-bands.ico",
      "output_bytes": 2412,
      "output_sha256": "1b8177ef112ed32b385aa09945d04697b08390b27a62e2c2c05176ba4ecb11a3",
      "width": 256,
      "height": 256,
      "directory_entries": 1,
      "directory_dimension_bytes": [
        0,
        0
      ],
      "payload": "PNG RGBA",
      "payload_offset": 22,
      "payload_bytes": 2390,
      "nontransparent_bbox_exclusive": [
        64,
        0,
        256,
        256
      ],
      "center_pixel": [
        32,
        151,
        112,
        128
      ],
      "alpha_band_centers": [
        0,
        64,
        128,
        255
      ]
    },
    {
      "input": "fine-detail.png",
      "input_width": 512,
      "input_height": 512,
      "input_bytes": 3988,
      "input_sha256": "944605a042acde379d2d6ab29863380f7de6cea681f65615e3fce1adfaf1be77",
      "output": "fine-detail.ico",
      "output_bytes": 3445,
      "output_sha256": "68b2e0892fb5a63ef78d679f068c2a51f9796c5a0a09f8e80dee13a86b3bec34",
      "width": 256,
      "height": 256,
      "directory_entries": 1,
      "directory_dimension_bytes": [
        0,
        0
      ],
      "payload": "PNG RGBA",
      "payload_offset": 22,
      "payload_bytes": 3423,
      "nontransparent_bbox_exclusive": [
        0,
        0,
        256,
        256
      ],
      "center_pixel": [
        34,
        166,
        113,
        255
      ],
      "row_32_unique_rgb": [
        [
          127,
          127,
          127
        ]
      ]
    },
    {
      "input": "tall-marker.png",
      "input_width": 128,
      "input_height": 512,
      "input_bytes": 1332,
      "input_sha256": "be65a6712bb021cfe87110df8aa3efa692e563e4f279bef1a4710a2ffe422c9d",
      "output": "tall-marker.ico",
      "output_bytes": 2442,
      "output_sha256": "2ac8287c5b7eb7f0bc7a5c01da902cf7affc3a66b959f7c80addca0bb19e3c33",
      "width": 256,
      "height": 256,
      "directory_entries": 1,
      "directory_dimension_bytes": [
        0,
        0
      ],
      "payload": "PNG RGBA",
      "payload_offset": 22,
      "payload_bytes": 2420,
      "nontransparent_bbox_exclusive": [
        96,
        0,
        160,
        256
      ],
      "center_pixel": [
        34,
        166,
        113,
        255
      ]
    },
    {
      "input": "tiny-16.png",
      "input_width": 16,
      "input_height": 16,
      "input_bytes": 175,
      "input_sha256": "c1b366f5efff633a567294103f2f614e3dbf38caf164ccb01276b62690d80ec4",
      "output": "tiny-16.ico",
      "output_bytes": 19505,
      "output_sha256": "9ad298f03f6055f9a9a60f0b2ab8494d0845f5efdc284b46382cbfdb15c9df3d",
      "width": 256,
      "height": 256,
      "directory_entries": 1,
      "directory_dimension_bytes": [
        0,
        0
      ],
      "payload": "PNG RGBA",
      "payload_offset": 22,
      "payload_bytes": 19483,
      "nontransparent_bbox_exclusive": [
        0,
        0,
        256,
        256
      ],
      "center_pixel": [
        137,
        142,
        82,
        255
      ],
      "row_128_unique_rgb": 33
    },
    {
      "input": "wide-marker.png",
      "input_width": 512,
      "input_height": 128,
      "input_bytes": 646,
      "input_sha256": "80db979d876d6813ca8142d5d41bc3e0609ead04484fc9303f2ba7e1ae9f06f3",
      "output": "wide-marker.ico",
      "output_bytes": 2462,
      "output_sha256": "46fc83b45a6a661851d375de125423c5f55820ea0c56ec78ebd52f8c6a90efca",
      "width": 256,
      "height": 256,
      "directory_entries": 1,
      "directory_dimension_bytes": [
        0,
        0
      ],
      "payload": "PNG RGBA",
      "payload_offset": 22,
      "payload_bytes": 2440,
      "nontransparent_bbox_exclusive": [
        0,
        96,
        256,
        160
      ],
      "center_pixel": [
        34,
        166,
        113,
        255
      ]
    }
  ],
  "limitations": "Synthetic fixtures only; no Windows shell, legacy icon editor, phone hardware, exhaustive ICC/16-bit/APNG validation",
  "updated_tool_outputs_byte_match_baseline": 5,
  "error_cases": [
    {
      "name": "wrong-header",
      "error": "This file is not a valid PNG file.",
      "download_count": 0,
      "preview_count": 0
    },
    {
      "name": "truncated",
      "error": "This image could not be opened in this browser.",
      "download_count": 0,
      "preview_count": 0
    },
    {
      "name": "oversized",
      "error": "Image dimensions must be at most 4096 pixels per side and 16 million pixels total.",
      "download_count": 0,
      "preview_count": 0
    }
  ]
}