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What you can do with Second Brain OS

A starter kit and guide for building a knowledge base in plain markdown files that an AI agent builds, links and maintains for you, using Claude Code and Obsidian.

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undefined-ui/second-brain-os on GitHub

Third-party repos we don't own or vouch for. AI-generated use cases can be wrong: review everything and run at your own risk.

What do you want to do?

4 use cases

  • Turn saved articles into a self-linking wiki

    Copy the starter vault, clip an article, and let the agent file it into linked wiki pages.

    View prompt
    Using the second-brain-os repo, copy vault-template to ~/brain and copy skills, commands, agents and scripts into ~/brain/.claude and ~/brain/scripts. Place one article in ~/brain/raw/, run /ingest, and report the wiki pages created. Verify that every new page has at least one wikilink to another page.

  • Run a project through an Inputs, Process, Outputs pipeline

    Give one project its own CLAUDE.md and a four-stage folder pipeline the agent follows.

    View prompt
    In the second-brain-os vault at ~/brain, work inside the <project-folder> project using its CLAUDE.md and its Inputs, Process, Outputs and Feedback folders. Produce the project's output file and note what changed in Feedback. Verify that the output cites at least two existing wiki pages.

  • Audit an agent setup with the agents course plugin

    Install the course's Claude Code plugin in two commands and run its context auditor.

    View prompt
    Install the agents-course plugin from undefined-ui/second-brain-os in Claude Code, then run its context auditor on <target-repo>. Output the auditor's findings as a list of context problems with file paths. Verify that each finding names a specific file.

  • Feed live calendar, email and chat into the vault

    Follow the live-data guide to let the agent read your calendar, email and chat.

    View prompt
    Using the live-data guide in the second-brain-os repo, connect the calendar, email and chat sources for the vault at ~/brain. Report which sources connected and list one item read from each. Verify that no credential is written into any markdown file in the vault.

How to use Second Brain OS

  1. Check you have what it needs: Git, to clone the repo; Obsidian, to open the vault as a folder; Claude Code, the agent the README sets up the vault around.
  2. Open undefined-ui/second-brain-os on GitHub and read the README and license.
  3. git clone https://github.com/undefined-ui/second-brain-os.git
  4. cp -r second-brain-os/vault-template ~/brain
  5. mkdir -p ~/brain/.claude then 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 and cp -r second-brain-os/scripts ~/brain/scripts (inferred, check the README)
  6. rm ~/brain/.claude/*/README.md ~/brain/scripts/README.md

These steps come from our top use case, Turn saved articles into a self-linking wiki, which also has a copy-paste agent prompt.

Second Brain OS alternatives · Best AI repos for Research

About this repo

Requirements

  • Git, to clone the repo
  • Obsidian, to open the vault as a folder
  • Claude Code, the agent the README sets up the vault around
  • A terminal, for the copy commands and for running claude
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Questions about Second Brain OS

What is Second Brain OS?

A starter kit and guide for building a knowledge base in plain markdown files that an AI agent builds, links and maintains for you, using Claude Code and Obsidian. It is an open-source project on GitHub: https://github.com/undefined-ui/second-brain-os.

Who is Second Brain OS for?

Readers who save articles, videos and notes often and never come back to them, and who are comfortable running a few commands in a terminal.

What can I do with Second Brain OS?

4 use cases so far, for example: Turn saved articles into a self-linking wiki; Run a project through an Inputs, Process, Outputs pipeline; Audit an agent setup with the agents course plugin. Each has steps and a copy-paste agent prompt.

What do I need to run Second Brain OS?

Git, to clone the repo; Obsidian, to open the vault as a folder; Claude Code, the agent the README sets up the vault around; A terminal, for the copy commands and for running claude.

What are alternatives to Second Brain OS?

Other hot AI repos in Research: Scientific Agent Skills, Speaker Mem R1, DSH Council, Evo Bot, AI Engineering Course.

Is Second Brain OS safe to run?

Deduped does not own, audit or vouch for it. Read the README and license, run it on your own systems first and review every command before you run it.