Bumping this instead of starting a new (redundant) thread as official electrum plugin documentation is either severely out of date or non-existent (I know there's a very old readthedocs page on it somewhere, but I can't find it now). The fact that we have to rely on things like Wayback Machine to view old plugin docs - which probably don't apply to newer versions anyway - is woeful.
Regardless, we already have complete protocol documentation here
https://electrumx-spesmilo.readthedocs.io/en/latest/protocol.html. Nevermind that it's on the ElectrumX page, they're standard and applicable to other servers as well.
The main issue is that because there's almost no documentation for developing Electrum plugins, Electrum plugin development is stinted, and adding custom protocol methods for a private server is a moot point when you can't use them.
Anyone volunteer to, like, dig around in the source code and find the extensibility areas so I can try to work out what they do and submit (relatively complete) plugin docs as a pull request?
