Comma-separated list of websocket protocols in priority order. Valid protocol values are:
v1.exec-interactive.supd: protocol uses binary frames
Websocket frames sent by the server contain chunks of raw merged standard output and standard error streams.
Websocket frames sent by the client can be of two types: data frames and control frames. Each data frame consists of a single 0x10 byte followed by a chunk of application's standard input stream. Each control frame consists of a single 0x11 byte followed by a json object containing two keys: h and w, denoting the number of lines and columns in the terminal correspondingly. Such control frame should be sent every time the terminal size changes.