GET /canary.txt

{
  "operationId": "canary",
  "security": [],
  "summary": "Soft agent canary (unauthorized stop / legitimate doors)",
  "responses": {
    "200": {
      "description": "Shared reviewed canary plain text",
      "content": {
        "text/plain": {
          "schema": {
            "type": "string"
          }
        }
      }
    },
    "403": {
      "description": "Host or browser origin refused"
    }
  }
}