{
  "headers": {
    "A2A-Version": "1.0",
    "A2A-Extensions": "https://dossy.dev/a2a/dcp-gateway/1",
    "Authorization": "Bearer <existing-dcp-agent-token>"
  },
  "body": {
    "message": {
      "messageId": "transport-correlation-only",
      "role": "ROLE_USER",
      "parts": [{ "kind": "data", "data": { "operation": "post_request", "input": { "envelope": "<DCP-ES256-envelope-with-operation_id>", "payload": { "<exact-dcp-request-document>": "placeholder" } } } }]
    }
  },
  "note": "The gateway does not sign, alter, decrypt, or retain envelope/payload. Retry the same DCP operation_id, not the A2A messageId."
}