Whether message needs EOF to complete
Current error number
HTTP major version (e.g., 1 for HTTP/1.1)
HTTP minor version (e.g., 1 for HTTP/1.1)
Whether connection should be kept alive
HTTP method enum (requests only)
HTTP status code (responses only)
Parser type: 0=REQUEST, 1=RESPONSE
Whether this is an upgrade request (e.g., WebSocket)
Current parser state snapshot