WebSocket Handshake Response

{
  "$id": "websocket-handshake-response.json",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "title": "WebSocket Handshake Response",
  "description": "Schema describing the HTTP 101 Switching Protocols response that completes the WebSocket opening handshake as defined in RFC 6455 Section 4.2.2.",
  "type": "object",
  "required": [
    "statusCode",
    "headers"
  ],
  "properties": {
    "statusCode": {
      "type": "integer",
      "const": 101,
      "description": "HTTP status code 101 Switching Protocols, indicating the server agrees to upgrade the connection."
    },
    "statusMessage": {
      "type": "string",
      "const": "Switching Protocols",
      "description": "The HTTP reason phrase for the 101 status code."
    },
    "headers": {
      "type": "object",
      "description": "HTTP headers in the server's handshake response.",
      "required": [
        "Upgrade",
        "Connection",
        "Sec-WebSocket-Accept"
      ],
      "properties": {
        "Upgrade": {
          "type": "string",
          "const": "websocket",
          "description": "Confirms the protocol upgrade to WebSocket."
        },
        "Connection": {
          "type": "string",
          "const": "Upgrade",
          "description": "Confirms the connection is being upgraded."
        },
        "Sec-WebSocket-Accept": {
          "type": "string",
          "description": "A base64-encoded SHA-1 hash of the client's Sec-WebSocket-Key concatenated with the GUID '258EAFA5-E914-47DA-95CA-C5AB0DC85B11'. Used to prove the server received the client's handshake.",
          "pattern": "^[A-Za-z0-9+/]{27}=$"
        },
        "Sec-WebSocket-Protocol": {
          "type": "string",
          "description": "The subprotocol selected by the server from the client's list.",
          "examples": [
            "chat",
            "graphql-ws"
          ]
        },
        "Sec-WebSocket-Extensions": {
          "type": "string",
          "description": "The extensions selected by the server.",
          "examples": [
            "permessage-deflate"
          ]
        }
      },
      "additionalProperties": {
        "type": "string"
      }
    }
  },
  "additionalProperties": false
}