undefined-ui/second-brain-os
890 stars · Last commit 2026-09-29
An AI second brain that maintains itself. Full guide, starter vault, agent skills and scripts for a self-organizing knowledge base in Claude Code and Obsidian.
README preview
# AI Second Brain A knowledge base that an AI agent builds and maintains for you, in plain markdown files you own. Everything you read, watch and save gets turned into linked wiki pages, connected to everything already there, and you can ask it questions. This repo is the full version of the guide: the concepts, the setup, the vault template, the agent skills, the scripts, and the resources. Free, no signup, nothing to install beyond Obsidian and an agent. **Read it on the web:** [undefined-ui.github.io/second-brain-os](https://undefined-ui.github.io/second-brain-os/) — the full guide with search and navigation, plus [every vetted link](https://undefined-ui.github.io/second-brain-os/resources.html) in one filterable page. Three things live here — pick your entrance: - **[The second-brain guide](#the-guide)** — a path you follow once: build a knowledge base an agent maintains for you. 65 pages, a starter vault, 18 skills. - **[The agents course](#the-agents-course)** — a path you read in order: seven modules from a single prompt to a production agent, with [tools you install in two commands](plugins/README.md). - **[The handbooks](#the-handbooks)** — not a path, references: the full menu of techniques, tools and builds for one layer. Open one when that layer starts hurting. ## The problem it solves