Kafka Envelope Response Wire Format v0 — Binary Protocol Layout

What is Envelope?

Brokers use this to forward client requests to the KRaft controller while preserving the original client's identity for authorization. When a broker proxies a CreateTopics request to the controller, the ACL check uses the actual client's principal, not the broker's.

Schema
{
  "ResponseData": bytes?,
  "ErrorCode": int16
}

Example
{
  "ResponseData": "<binary>",
  "ErrorCode": 0
}