github.com/9seconds/mtg/v2 (go): mtg is just a command-line application that starts a proxy.  Application logic is how to read a config and configure mtglib.Proxy. So, probably you need to read the documentation for mtglib package first.  mtglib is a core of the application. The rest of the packages provide some default implementations for the interfaces, defined in mtglib.
Keywords: mtproto|mtproxy|telegram