{
  "id": "001-pdf-prefix",
  "category": "file-checksum",
  "description": "SHA-256 of a minimal PDF file prefix (10 bytes). Demonstrates how the file-checksum layer is computed over the file bytes excluding the XMP packet.",
  "spec_section": "LRFS v1.0 §4.3",
  "inputs": {
    "file_bytes_hex": "255044462d312e340a25",
    "file_bytes_description": "10 bytes: %PDF-1.4\\n% — the first bytes of a typical PDF file before any XMP packet is embedded."
  },
  "expected": {
    "sha256_hex": "1620e31e152332bd7cde6230997c5462dbca64eba72d832bb46c04d3af022250",
    "llmind_filechecksum_value": "1620e31e152332bd7cde6230997c5462dbca64eba72d832bb46c04d3af022250"
  },
  "notes": "Implementations computing the file-checksum layer MUST hash only the file bytes NOT including the XMP packet. For formats where the XMP packet is at a known offset, strip it before hashing. For formats where the XMP location varies, the implementer documents the strip rule."
}