Signed composite preflight (payability + sanctions + trust) of one subject address

[
  {
    "scheme": "exact",
    "network": "eip155:8453",
    "payTo": "0xc87a06DEE4c0E85912296002617120BBfd5EF990",
    "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "amount": "15000",
    "maxTimeoutSeconds": 300
  }
]

{
  "bazaar": {
    "info": {
      "input": {
        "method": "GET",
        "queryParams": {
          "address": "0xc87a06DEE4c0E85912296002617120BBfd5EF990",
          "chain": "eip155:8453",
          "role": "payee"
        },
        "type": "http"
      },
      "output": {
        "example": {
          "components_evaluated": 3,
          "envelope": {
            "signature": "0x00",
            "signer": "0x57fF0F084Cba33e6761503f90eEF0Da9F159350c"
          },
          "schema_version": "preflight_v3"
        },
        "type": "json"
      }
    },
    "schema": {
      "$schema": "https://json-schema.org/draft/2020-12/schema",
      "properties": {
        "input": {
          "additionalProperties": false,
          "properties": {
            "method": {
              "enum": [
                "GET",
                "HEAD",
                "DELETE"
              ],
              "type": "string"
            },
            "queryParams": {
              "properties": {
                "address": {
                  "description": "Subject EVM address (0x-hex).",
                  "type": "string"
                },
                "chain": {
                  "description": "CAIP-2 chain of the subject, e.g. eip155:8453.",
                  "type": "string"
                },
                "role": {
                  "description": "One of payer, payee, escrow_destination.",
                  "type": "string"
                }
              },
              "required": [
                "address",
                "chain",
                "role"
              ],
              "type": "object"
            },
            "type": {
              "const": "http",
              "type": "string"
            }
          },
          "required": [
            "type",
            "method"
          ],
          "type": "object"
        },
        "output": {
          "properties": {
            "example": {
              "properties": {
                "components_evaluated": {
                  "type": "integer"
                },
                "envelope": {
                  "type": "object"
                },
                "schema_version": {
                  "type": "string"
                }
              },
              "required": [
                "schema_version",
                "components_evaluated",
                "envelope"
              ],
              "type": "object"
            },
            "type": {
              "type": "string"
            }
          },
          "required": [
            "type"
          ],
          "type": "object"
        }
      },
      "required": [
        "input"
      ],
      "type": "object"
    }
  }
}

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

const res = await fetch("https://x402.nsgoods.org/preflight");
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://x402.nsgoods.org/preflight")
if res.status_code == 402:
    accepts = res.json()["accepts"]
    # pay one of accepts[] via an x402 client, then retry with the payment header