Deterministic package existence for PyPI and npm, built from real published artifacts (nev

[
  {
    "scheme": "exact",
    "network": "eip155:8453",
    "payTo": "0x57407D691F755cAa107647718F3582a8A87467dD",
    "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "amount": "2000",
    "maxTimeoutSeconds": 300
  }
]

{
  "bazaar": {
    "category": "ai",
    "discoverable": true,
    "info": {
      "input": {
        "body": {
          "ecosystem": "pypi",
          "name": "requests"
        },
        "bodyType": "json",
        "method": "POST",
        "type": "http"
      },
      "output": {
        "example": {
          "exists": true,
          "latest_version": "2.32.3",
          "proof": {
            "artifact_sha256": "0x…",
            "source_url": "https://pypi.org/project/requests/"
          },
          "typosquat_adjacent": false
        },
        "type": "json"
      }
    },
    "schema": {
      "$schema": "https://json-schema.org/draft/2020-12/schema",
      "properties": {
        "input": {
          "additionalProperties": false,
          "properties": {
            "body": {
              "properties": {
                "ecosystem": {
                  "enum": [
                    "pypi",
                    "npm"
                  ],
                  "type": "string"
                },
                "name": {
                  "description": "Package name",
                  "type": "string"
                }
              },
              "required": [
                "ecosystem",
                "name"
              ],
              "type": "object"
            },
            "bodyType": {
              "enum": [
                "json"
              ],
              "type": "string"
            },
            "method": {
              "enum": [
                "POST"
              ],
              "type": "string"
            },
            "type": {
              "const": "http",
              "type": "string"
            }
          },
          "required": [
            "type",
            "method",
            "bodyType",
            "body"
          ],
          "type": "object"
        },
        "output": {
          "properties": {
            "example": {
              "type": "object"
            }
          },
          "required": [
            "example"
          ],
          "type": "object"
        }
      },
      "required": [
        "input"
      ]
    }
  }
}

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

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