{
  "investigation_date": "2026-10-23",
  "model": "HP Color Laser MFP 178nw",
  "document": "Two numbered diagnostic pages with three tiny colour squares per page",
  "raster_bytes": 24138,
  "raster_sha256": "90ab9f26cef47359aa874c58970353a4f8b0c966edd174997a865ec852b74ad4",
  "opening_44_bytes_hex": "55 4e 49 52 41 53 54 00 00 00 00 02 18 01 01 00 00 00 00 00 00 00 00 00 00 00 09 b0 00 00 0d b3 00 00 01 2c 00 00 00 00 00 00 00 00",
  "opening_layout": [
    {
      "offset": 0,
      "bytes": 8,
      "field": "UNIRAST identifier plus zero"
    },
    {
      "offset": 8,
      "bytes": 4,
      "field": "page count"
    },
    {
      "offset": 12,
      "bytes": 32,
      "field": "first-page header"
    }
  ],
  "matrix_trials_per_variant": 1,
  "cases": [
    {
      "case": "captured-split",
      "printer_job": 1154,
      "image_chunks": [
        4,
        16384,
        7750
      ],
      "first_header_bytes": 4,
      "physical_result": "Gibberish, confirmed by user",
      "document_sha256": "90ab9f26cef47359aa874c58970353a4f8b0c966edd174997a865ec852b74ad4"
    },
    {
      "case": "complete-header",
      "printer_job": 1155,
      "image_chunks": [
        44,
        16344,
        7750
      ],
      "first_header_bytes": 44,
      "physical_result": "Both numbered pages correct, confirmed by user",
      "document_sha256": "90ab9f26cef47359aa874c58970353a4f8b0c966edd174997a865ec852b74ad4"
    },
    {
      "case": "complete-header-full-block",
      "printer_job": 1156,
      "image_chunks": [
        44,
        16384,
        7710
      ],
      "first_header_bytes": 44,
      "physical_result": "Both numbered pages correct, confirmed by user",
      "document_sha256": "90ab9f26cef47359aa874c58970353a4f8b0c966edd174997a865ec852b74ad4"
    },
    {
      "case": "split-header-short-block",
      "printer_job": 1157,
      "image_chunks": [
        4,
        16344,
        7790
      ],
      "first_header_bytes": 4,
      "physical_result": "Gibberish, confirmed by user",
      "document_sha256": "90ab9f26cef47359aa874c58970353a4f8b0c966edd174997a865ec852b74ad4"
    }
  ],
  "same_document_on_wire": true,
  "same_normalized_ipp_body": true,
  "buffered_preview": {
    "physical_result": "Both numbered pages correct, confirmed by user",
    "raster_bytes": 24138,
    "raster_sha256": "90ab9f26cef47359aa874c58970353a4f8b0c966edd174997a865ec852b74ad4",
    "image_http_chunks": [
      16384,
      7754
    ]
  },
  "limitations": [
    "Long-run reliability and a permanent fix for ordinary macOS printing.",
    "The exact firmware code path, or whether the defect is in HTTP chunk handling, TCP read buffering, language detection or their interaction.",
    "A universal failure for every four-byte first chunk; earlier one-page short-continuation controls succeeded.",
    "A statistical failure rate; each matrix combination has one trial and timing/state are not fixed."
  ],
  "chunk_unit": "HTTP chunks containing raster data, excluding the preceding IPP attributes; not TCP packet sizes",
  "raw_network_capture_published": false
}