{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "title": "WS chat.send response",
  "type": "object",
  "required": ["message_id", "content", "role"],
  "properties": {
    "message_id": { "type": "string" },
    "content": { "type": "string" },
    "role": { "type": "string", "enum": ["assistant", "user", "system"] }
  }
}