{
  "id": "002-multi-layer",
  "category": "hmac-sha256",
  "description": "HMAC-SHA256 signature over a three-layer payload after canonicalization. Verifies that the signature is stable across writer implementations as long as canonicalization is correct.",
  "spec_section": "LRFS v1.0 §4.1",
  "inputs": {
    "layers": {
      "llmind:text": "Document content here.",
      "llmind:description": "A document.",
      "llmind:generatedBy": "LLMind/0.1.0"
    },
    "key_utf8": "LRFS-test-key-002-v1",
    "key_hex": "4c5246532d746573742d6b65792d3030322d7631"
  },
  "expected": {
    "canonical_bytes_hex": "6c6c6d696e643a6465736372697074696f6e004120646f63756d656e742e006c6c6d696e643a67656e6572617465644279004c4c4d696e642f302e312e30006c6c6d696e643a7465787400446f63756d656e7420636f6e74656e7420686572652e00",
    "signature_base64": "Lu/DNYnXxEmZbxj9H3EhUFhEYtJaFfErVyt+sMBsm/E=",
    "llmind_signature_value": "hmac-sha256:Lu/DNYnXxEmZbxj9H3EhUFhEYtJaFfErVyt+sMBsm/E="
  }
}