{
  "description": "Salted fingerprints of the adapter profile (PROTOCOL.md §15.3): SHA-256(salt || JCS(value)), salt the 32 raw bytes of the hex salt, lowercase hex. The input fingerprint covers the arguments as the consumer sent them; the output fingerprint covers the tool result's structuredContent when present, otherwise its content array, never isError, _meta or anything the adapter adds. JCS is RFC 8785.",
  "algorithm": "sha-256(bytes.fromhex(salt) + JCS(value))",
  "cases": [
    {
      "name": "simple object",
      "salt": "00112233445566778899aabbccddeeff00112233445566778899aabbccddeeff",
      "value": {
        "area_ref": "loc:ca:dublin",
        "min_beds": 3
      },
      "jcs": "{\"area_ref\":\"loc:ca:dublin\",\"min_beds\":3}",
      "fingerprint": "46839dcf7511e1b9789e56ccbce9a4e7a562adc9aa9b1088337802fec1018a3c"
    },
    {
      "name": "key order by UTF-16 code units, non-ASCII and a surrogate pair",
      "salt": "00112233445566778899aabbccddeeff00112233445566778899aabbccddeeff",
      "value": {
        "é": 1,
        "z": 2,
        "😀": 3,
        "A": 4,
        "€": 5,
        "aa": 6,
        "a": 7
      },
      "jcs": "{\"A\":4,\"a\":7,\"aa\":6,\"z\":2,\"é\":1,\"€\":5,\"😀\":3}",
      "fingerprint": "ff74d9d98496e4f71a9f305b0ffd4e6c9aebc2f397f7a162d2248e7099876094"
    },
    {
      "name": "numbers: integers, negative zero, exponents, edges",
      "salt": "00112233445566778899aabbccddeeff00112233445566778899aabbccddeeff",
      "value": {
        "int": 9007199254740991,
        "neg": -1,
        "zero": -0.0,
        "small": 1e-07,
        "big": 1e+21,
        "frac": 0.1,
        "exp": 1.23,
        "f": 333333333.3333333
      },
      "jcs": "{\"big\":1e+21,\"exp\":1.23,\"f\":333333333.3333333,\"frac\":0.1,\"int\":9007199254740991,\"neg\":-1,\"small\":1e-7,\"zero\":0}",
      "fingerprint": "4ad0134fceb1f18cf57cee8ff1ecd4572d6f85626f5d663eb9c3721cf190f774"
    },
    {
      "name": "string escaping: control characters and characters left as they are",
      "salt": "00112233445566778899aabbccddeeff00112233445566778899aabbccddeeff",
      "value": {
        "s": "line\nbreak\ttab \u0001 \u001f quote\" backslash\\ slash/ 
 é"
      },
      "jcs": "{\"s\":\"line\\nbreak\\ttab \\u0001 \\u001f quote\\\" backslash\\\\ slash/ 
 é\"}",
      "fingerprint": "335713a24cc174fd34ae2e955dbfea32770a8f22a2b065debffa31be601d0dd2"
    },
    {
      "name": "empty and nested values with null",
      "salt": "00112233445566778899aabbccddeeff00112233445566778899aabbccddeeff",
      "value": {
        "a": [],
        "b": {},
        "c": [
          null,
          {
            "d": [
              1,
              [
                2,
                {}
              ]
            ]
          }
        ],
        "e": null
      },
      "jcs": "{\"a\":[],\"b\":{},\"c\":[null,{\"d\":[1,[2,{}]]}],\"e\":null}",
      "fingerprint": "4e544932a43f0b0a3dbc940f7d111397cf334b7a22848d05949a3dffb4d68f4c"
    },
    {
      "name": "same value, another salt",
      "salt": "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff",
      "value": {
        "area_ref": "loc:ca:dublin",
        "min_beds": 3
      },
      "jcs": "{\"area_ref\":\"loc:ca:dublin\",\"min_beds\":3}",
      "fingerprint": "17dc5d80658c6bcac4a60afec7a13187b73d7de0fb0d765259eac4085b3fbe46"
    },
    {
      "name": "result body: structuredContent",
      "salt": "00112233445566778899aabbccddeeff00112233445566778899aabbccddeeff",
      "value": {
        "listings": [
          {
            "address": "4252 Escudo Ct",
            "price": "1349000.00"
          }
        ],
        "next_cursor": null
      },
      "jcs": "{\"listings\":[{\"address\":\"4252 Escudo Ct\",\"price\":\"1349000.00\"}],\"next_cursor\":null}",
      "fingerprint": "1a22bbbe0546873ae70004bfdd78ba62541b74cfe70744b98f5ce490dbad6858"
    },
    {
      "name": "result body: content array when there is no structuredContent",
      "salt": "00112233445566778899aabbccddeeff00112233445566778899aabbccddeeff",
      "value": [
        {
          "type": "text",
          "text": "No homes match."
        }
      ],
      "jcs": "[{\"text\":\"No homes match.\",\"type\":\"text\"}]",
      "fingerprint": "9e0ff412a7b964ff6f0208b744dc2428b7ef00daab4f83170f95c7b7f9fd09fe"
    }
  ],
  "result_selection": {
    "description": "Which body of an MCP tool result is fingerprinted.",
    "result": {
      "structuredContent": {
        "listings": [
          {
            "address": "4252 Escudo Ct",
            "price": "1349000.00"
          }
        ],
        "next_cursor": null
      },
      "content": [
        {
          "type": "text",
          "text": "{...}"
        }
      ],
      "isError": false,
      "_meta": {
        "ekl": {
          "outcome": "succeeded"
        }
      }
    },
    "fingerprinted": "structuredContent",
    "fingerprint": "1a22bbbe0546873ae70004bfdd78ba62541b74cfe70744b98f5ce490dbad6858"
  },
  "challenge": {
    "description": "The endpoint challenge's proof (PROTOCOL.md §15.2): HMAC-SHA256 keyed with the lowercase hex SHA-256 of the provider credential (as ASCII), over the challenge hex followed by the endpoint URL.",
    "provider_credential": "eklp_example-credential-not-a-real-one",
    "credential_sha256": "9658fb1a63b49233e0779f391763c30f4bc900a92615739fdad96bedcbf95504",
    "challenge": "9f9f9f9f9f9f9f9f9f9f9f9f9f9f9f9f9f9f9f9f9f9f9f9f9f9f9f9f9f9f9f9f",
    "endpoint": "https://mcp.example.com/ekl",
    "proof": "53d2cef6a77ddb2c0c41485276e84217bb9b878ce200fa1e64c321990d91dd8a"
  }
}