{
  "allOf": [
    {
      "$ref": "#/components/schemas/PaymentRequiredResponse",
      "description": "Protocol response (x402 v2)"
    },
    {
      "type": "object",
      "properties": {
        "seren": {
          "oneOf": [
            {
              "type": "null"
            },
            {
              "$ref": "#/components/schemas/PaymentRequestInfo",
              "description": "Seren-specific payment request info"
            }
          ]
        }
      }
    }
  ],
  "description": "402 Payment Required response body (x402 v2) with Seren-specific extensions."
}