Currently, there are 2 built-in plugins in Konsole. But there's no documentation on how plugin system works. Using plugin source code is one way to get an idea of how plugin API works, but generally speaking, plugin developers don't (and shouldn't) know how app itsellf works. API should define boundary and be descriptive so people could write plugin without diving too deep into app internals. So, I am suggesting at least adding README file in konsole/src/pluginsystem or konsole/doc/plugins, etc so one could refer to that.