Building An Ai-powered Notion “second Brain” For School + Long-term Knowledge Management — What Github Projects/tools Should I Look At?

I’m building a long-term personal knowledge system in Notion, starting with my university coursework but designed to eventually support professional knowledge, research, projects, and business.
I’m especially interested in ideas/tools for:
AI-assisted knowledge intake and organization
Automatic tagging, relationships, and cross-linking
Knowledge graphs / connecting related information
Source tracking and citation/evidence trails
Active recall, spaced repetition, flashcards, and study workflows
Turning notes/resources into reusable workflows or “skills”
Semantic/vector search across a knowledge base
Capturing webpages, YouTube resources, PDFs, screenshots, etc.
AI agents that can safely work with Notion
Notion API automations
Backup/export/versioning strategies
Detecting duplicate or outdated information
Maintaining an immutable/raw source layer alongside AI-generated summaries
I’m particularly interested in GitHub repositories, open-source projects, APIs, automations, or architecture examples rather than just aesthetic Notion templates.
The goal is to keep the front end simple enough for everyday use while allowing the system behind it to become much more intelligent over time.
If you were building this today, what projects/repos would you study or incorporate? What am I overlooking?
What would you build differently if you knew this database needed to remain useful for 10+ years?

Mira my AI helped me write this ???? I wasn’t sure exactly what I needed.