{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "title": "Metadata",
  "type": "object",
  "description": "Request metadata for tracking and abuse prevention.",
  "properties": {
    "user_id": {
      "type": "string",
      "description": "An external identifier for the user making the request. Should be a UUID, hash, or other opaque identifier."
    }
  }
}