Pay-per-Proof: one post-quantum ML-DSA-65 / Dilithium-3 (NIST FIPS 204) signature over you

[
  {
    "scheme": "exact",
    "network": "eip155:8453",
    "payTo": "0xC13789e82661635d9Cea38a53A0390CF9939ef4f",
    "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "amount": "20000",
    "maxTimeoutSeconds": 300
  },
  {
    "scheme": "exact",
    "network": "eip155:8453",
    "payTo": "0xC13789e82661635d9Cea38a53A0390CF9939ef4f",
    "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "amount": "20000",
    "maxTimeoutSeconds": 300
  }
]

{
  "bazaar": {
    "body": {
      "message": "hello agent economy"
    },
    "bodyType": "json",
    "description": "Pay-per-Proof: one post-quantum ML-DSA-65 / Dilithium-3 (NIST FIPS 204) signature over your message/hash, x402-native.",
    "info": {
      "input": {
        "body": {
          "message": "hello agent economy"
        },
        "bodyType": "json",
        "method": "POST",
        "type": "http"
      },
      "output": {
        "example": {
          "algorithm": "ml-dsa-65",
          "digest": "9f86…",
          "public_key": "BASE64_ML_DSA65_1952B",
          "signature": "BASE64_ML_DSA65_3309B"
        },
        "type": "json"
      }
    },
    "method": "POST",
    "output": {
      "example": {
        "algorithm": "ml-dsa-65",
        "digest": "9f86…",
        "public_key": "BASE64_ML_DSA65_1952B",
        "signature": "BASE64_ML_DSA65_3309B"
      },
      "schema": {
        "properties": {
          "algorithm": {
            "description": "ml-dsa-65",
            "type": "string"
          },
          "digest": {
            "description": "The hex digest that was signed.",
            "type": "string"
          },
          "payment": {
            "description": "Settlement receipt (scheme, network, asset, txHash, payer, settled).",
            "type": "object"
          },
          "public_key": {
            "description": "Base64 ML-DSA-65 public key (1952 bytes) that verifies the signature.",
            "type": "string"
          },
          "signature": {
            "description": "Base64 ML-DSA-65 / Dilithium-3 (NIST FIPS 204) signature (3309 bytes) over FRACTALAI-x402-served-v1\\nx402-sign\\n<digest>.",
            "type": "string"
          }
        },
        "required": [
          "digest",
          "signature",
          "algorithm",
          "public_key"
        ],
        "type": "object"
      },
      "type": "json"
    },
    "route_key": "POST /api/x402/sign",
    "schema": {
      "$schema": "https://json-schema.org/draft/2020-12/schema",
      "properties": {
        "input": {
          "additionalProperties": false,
          "properties": {
            "body": {
              "type": "object"
            },
            "bodyType": {
              "enum": [
                "json",
                "form-data",
                "text"
              ],
              "type": "string"
            },
            "headers": {
              "additionalProperties": {
                "type": "string"
              },
              "type": "object"
            },
            "method": {
              "enum": [
                "POST",
                "PUT",
                "PATCH"
              ],
              "type": "string"
            },
            "queryParams": {
              "additionalProperties": {
                "type": "string"
              },
              "type": "object"
            },
            "type": {
              "const": "http",
              "type": "string"
            }
          },
          "required": [
            "type",
            "method",
            "bodyType",
            "body"
          ],
          "type": "object"
        },
        "output": {
          "properties": {
            "example": {
              "type": "object"
            },
            "type": {
              "type": "string"
            }
          },
          "required": [
            "type"
          ],
          "type": "object"
        }
      },
      "required": [
        "input"
      ],
      "type": "object"
    },
    "serviceName": "FractalAI Pay-per-Proof",
    "tags": [
      "signature",
      "post-quantum",
      "ml-dsa-65",
      "ai-agent",
      "fips-204"
    ],
    "type": "http"
  }
}

curl "https://fractalai.net.co/api/x402/sign"
# -> 402 Payment Required, accepts[] lists how to pay
# retry with a PAYMENT-SIGNATURE (or PAYMENT header) once paid

const res = await fetch("https://fractalai.net.co/api/x402/sign");
if (res.status === 402) {
  const { accepts } = await res.json();
  // pay one of accepts[] via an x402 client, then retry with the payment header
}

import httpx
res = httpx.get("https://fractalai.net.co/api/x402/sign")
if res.status_code == 402:
    accepts = res.json()["accepts"]
    # pay one of accepts[] via an x402 client, then retry with the payment header