Notecast is a local note engine i've been building to help me with that. it runs a three stage LLM pipeline (Classify -> Organize -> Consolidate) that automatically builds and maintain a knowledge graph from the notes. the theme hierarchy emerges by subdivision as notes accumulate. Any change generates a proposal that can be edited and commited by the user.

It is early stage and a lot of architectural and domain logic decisions might change but the core is working and is already useful.

It has Obsidian vault integration. I recommend using it (just set vaultPath on configurations)

I'm actively developing it this year and would love feedback.