m-s-sripati

Have you tried obsidian? It seems to address some points that you are looking for (graph, linked notes, etc).

It is the right thought, aligned to the spirit of open source.

I use tagging heavily with any note taking application (like One Note / evernote). I use voice recorder to record any useful ideas / lessons that my subconscious brain tells me. I then push it to my note taking application with appropriate tag and push it to my cloud drive. I review them once in a while.