Introduction

Brain OS is a Claude Code plugin that gives you 25 AI-powered skills for managing a second brain in Obsidian — from processing books to running your day to deep thinking.

Brain OS is a Claude Code plugin for Obsidian-based second brain management. It installs as a set of skills that Claude Code can invoke directly, turning your vault into an active thinking and knowledge system rather than a static archive.

You get 25 skills across four categories, all reading from and writing to a structured Obsidian vault.

What you need

• Claude Code installed and running
• An Obsidian vault (or any markdown-based note system) with the expected folder structure

Skill categories

Knowledge Pipeline

Process books end-to-end: extract, validate against NotebookLM, ingest into structured vault notes, and absorb deep insights. Skills include self-learn, audit, chain, ingest, absorb, and book.

Daily Operations

Start and close your day with purpose. Morning review, end-of-day extraction, session handovers, and vault sync. Skills include today, close, handover, pickup, and sync.

Thinking Tools

Deep thinking, idea surfacing, belief pressure-testing, and pattern discovery across your vault. Skills include think, emerge, challenge, drift, connect, trace, ghost, ideas-gen, and graduate.

Configuration

Set your vault path, manage installation modes, configure the eval system, and install dependencies for book learning.

Next step

Follow the Quick Start to install Brain OS and run your first skill in under five minutes.