Hi. I currently look for Clojure applications which have implemented a plugin system because I might implement one in a application I currently work on. Kocha has one. One of my concerns are classpath problems. I mean having two versions of the same lib, one from my application and one from the plugin in the same classpath. What is Kocha doing about that problem?

Kaocha doesn't do anything about this as such, you just add your plugins to deps.edn or project.clj and they do their regular dependency resolution

You might also want to look into metabase, there plugins are actually uberjars that you drop into a plugin directory, so I would think they are more likely to have this problem.