Earlier quoted context omitted.
I am impressed. Whenever I try to build a tree of thoughts, I run into the problem that I want things to fall under multiple categories. I might start by classifying them according to subject area (as you have done), but then I might want a collection of those notes to also fall under "could help with project X" or "would be of interest to person Y" or "can be learned from reference Z" or any number of things.
This is a use of AI I've not seen yet, to sift through soups of knowledge, categorise it and make judgements on what else is related and relevant
It doesn't really seem very AI-ish except maybe for some NLP. Otherwise it's very straightforward indexes and catelogues.
I used to work at a company that used Elasticsearch to catelog and group articles and small snippets. I'm currently working at a company that's using Algolia to do something similar.