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: secondbrainos.dev — the full guide with search and navigation, plus every vetted link in one filterable page.

Three things live here — pick your entrance:

• The second-brain 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 — a path you read in order: seven modules from a single prompt to a production agent, with tools you install in two commands.
• 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

You save things with the intention of coming back. You never do. Bookmarks, screenshots, read-later queues and half-filled Notion pages accumulate without compounding, because filing and linking them is boring work that humans stop doing after two weeks.

Hand that work to an agent and the system stays alive. That is the whole idea.

Quickstart

One evening. Nine steps, each with a full page behind it.

# copy the starter vault, skills, commands and agents
git clone https://github.com/undefined-ui/second-brain-os.git
cp -r second-brain-os/vault-template ~/brain

mkdir -p ~/brain/.claude
cp -r second-brain-os/skills   ~/brain/.claude/skills
cp -r second-brain-os/commands ~/brain/.claude/commands
cp -r second-brain-os/agents   ~/brain/.claude/agents
cp -r second-brain-os/scripts  ~/brain/scripts

# the folder READMEs are for reading on GitHub, not for the agent
rm ~/brain/.claude/*/README.md ~/brain/scripts/README.md

cd ~/brain && claude

The scripts/ copy is what lets /metrics, /health and /graph-export run scripts/vault_stats.py and friends from inside the vault. On Windows, use python where this guide says python3: the python3 name usually resolves to the Microsoft Store stub and does nothing.