Signed time-bounded witness of an agent-carried payload digest; the payload stays with the

[
  {
    "scheme": "exact",
    "network": "eip155:8453",
    "payTo": "0x5f5a631e975183d084f60d7121e967b30ec83cb8",
    "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "amount": "1000",
    "maxTimeoutSeconds": 60
  }
]

{
  "bazaar": {
    "info": {
      "input": {
        "body": {
          "nonce": "BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBA",
          "payload_digest": {
            "algorithm": "sha-256",
            "value": "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
          },
          "previous_attestation_digest": null
        },
        "bodyType": "json",
        "method": "POST",
        "type": "http"
      },
      "output": {
        "example": {
          "payment_status": "settled",
          "witness_receipt": {
            "commitment": {
              "nonce": "BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBA",
              "payload_digest": {
                "algorithm": "sha-256",
                "value": "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
              },
              "previous_attestation_digest": null
            },
            "evidence_scope": {
              "action_execution_proven": false,
              "authorization_granted": false,
              "caller_identity_proven": false,
              "clock_accuracy_independently_verified": false,
              "external_atomic_clock_alignment_proven": false,
              "nonce_uniqueness_enforced": false,
              "payer_authorization_bound_to_commitment": false,
              "payload_disclosed": false,
              "recipient_delivery_proven": false,
              "replay_prevented": false,
              "type": "payload_commitment_witness"
            },
            "node_id": "767-2676.com",
            "protocol_id": "POPCORN-WITNESS/1.0",
            "receipt_id": "pwr_example"
          }
        },
        "type": "json"
      }
    },
    "schema": {
      "$schema": "https://json-schema.org/draft/2020-12/schema",
      "additionalProperties": false,
      "properties": {
        "input": {
          "additionalProperties": false,
          "properties": {
            "body": {
              "type": "object"
            },
            "bodyType": {
              "enum": [
                "json",
                "form-data",
                "text"
              ],
              "type": "string"
            },
            "method": {
              "enum": [
                "POST",
                "PUT",
                "PATCH"
              ],
              "type": "string"
            },
            "type": {
              "const": "http",
              "type": "string"
            }
          },
          "required": [
            "type",
            "method",
            "bodyType",
            "body"
          ],
          "type": "object"
        },
        "output": {
          "additionalProperties": false,
          "properties": {
            "example": {
              "type": "object"
            },
            "type": {
              "const": "json",
              "type": "string"
            }
          },
          "required": [
            "type",
            "example"
          ],
          "type": "object"
        }
      },
      "required": [
        "input",
        "output"
      ],
      "type": "object"
    }
  },
  "payment-identifier": {
    "info": {
      "required": false
    },
    "schema": {
      "$schema": "https://json-schema.org/draft/2020-12/schema",
      "properties": {
        "id": {
          "maxLength": 128,
          "minLength": 16,
          "pattern": "^[a-zA-Z0-9_-]+$",
          "type": "string"
        },
        "required": {
          "type": "boolean"
        }
      },
      "required": [
        "required"
      ],
      "type": "object"
    }
  },
  "popcorn-witness": {
    "info": {
      "content_type": "application/json",
      "method": "POST",
      "protocol_id": "POPCORN-WITNESS/1.0",
      "request_schema": "https://767-2676.com/schemas/witness-request.v1.json",
      "response_schema": "https://767-2676.com/schemas/witness-response.v1.json",
      "service_state": "available"
    },
    "schema": {
      "additionalProperties": false,
      "properties": {
        "content_type": {
          "type": "string"
        },
        "method": {
          "type": "string"
        },
        "protocol_id": {
          "type": "string"
        },
        "request_schema": {
          "type": "string"
        },
        "response_schema": {
          "type": "string"
        },
        "service_state": {
          "type": "string"
        }
      },
      "required": [
        "protocol_id",
        "method",
        "content_type",
        "request_schema",
        "response_schema",
        "service_state"
      ],
      "type": "object"
    }
  }
}

curl "https://767-2676.com/v1/receipt"
# -> 402 Payment Required, accepts[] lists how to pay
# retry with a PAYMENT-SIGNATURE (or PAYMENT header) once paid

const res = await fetch("https://767-2676.com/v1/receipt");
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://767-2676.com/v1/receipt")
if res.status_code == 402:
    accepts = res.json()["accepts"]
    # pay one of accepts[] via an x402 client, then retry with the payment header