Second Brain Os plugin for Grok Build

Name: Second Brain Os
Author: undefined-ui

Community Claude Code plugin, installs in GrokPluginProductivity

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.

How to install Second Brain Os in Grok Build

1. Add this repo as a plugin marketplace in Grok Build (once per computer):

grok plugin marketplace add undefined-ui/second-brain-os

2. Install the plugin:

grok plugin install agents-course@undefined-ui/second-brain-os --trust

✓ Install-checked in Grok Buildchecked Oct 18, 2026

Review before you trust it. --trust lets this plugin's hooks, MCP servers and scripts run code on your computer. It's a community repo that neither xAI nor GrokStacks has reviewed, so read its code first.

Then start a new Grok session, or press r in /plugins, to load it.

Inside Grok Build: type /plugins, open the Marketplace tab, press a and add undefined-ui/second-brain-os, then select agents-course and press i.

Command format: Grok Build's plugin guide

What we checked: on Oct 18, 2026 it installed with grok 1.0.62 and Grok found 5 skills, 1 subagent. That's an install check only: we haven't run it in a live Grok session.

What it contains

Skills (5)

context-audit — Audit an agent's context layout against the four places: system prompt, tools, history, tail. Use when the user asks to audit, review or fix their agent's context, prompt caching, token spend per turn, or CLAUDE.md / AGENTS.md layout. Read-
evals-bootstrap — Scaffold a first eval suite for an agent: mine real failures into cases, write behavioural checks over traces, and generate the runner. Use when the user wants evals, regression tests for an agent, a golden set, or asks how to know a prompt
gate-check — Find the decisions in a pipeline that do not need the expensive model and propose the gate for each: a rule, a classic classifier, or a small model, with fail-closed routing. Use when the user asks to cut model costs or latency, says the bi
goal-test — Turn a vague task into a testable definition of done and generate an executable goal-test script for it, optionally with a bounded retry loop around a headless agent. Use when the user wants to run an agent in a loop, asks how to know when
harness-audit — Audit an agent's harness against the four rings: containment, guides, sensors, permissions. Use when the user asks whether their agent setup is safe, wants a review of sandboxing / permissions / hooks / AGENTS.md guardrails, or asks what a

Subagents (1)

agents-course:loop-critic — Reviews the result of an agent loop iteration in a clean context: checks the claimed work against the goal, hunts for shortcuts and untested paths, returns a verdict with specific defects. Use after a

About this listing

Second Brain Os is a community plugin on GitHub by undefined-ui, written as a Claude Code plugin that Grok Build installs. We install-checked it in Grok; we haven't run it in a live session or reviewed its code. When we installed it, Grok found 5 skills, 1 subagent. Its license is MIT. We checked commit 9173e03d4c40. It's one of 162 listings in the Productivity category on GrokStacks.

Second Brain Os FAQ

How do I install Second Brain Os in Grok Build?

Add the repo as a marketplace with grok plugin marketplace add undefined-ui/second-brain-os, then run grok plugin install agents-course@undefined-ui/second-brain-os --trust. Then start a new Grok session, or press r in /plugins, to load it.

Is Second Brain Os an official Grok Build plugin?

No. Second Brain Os is a community plugin on GitHub by undefined-ui, not in xAI's official Grok Build marketplace. We checked that it installs and what Grok loads from it, but haven't run it in a live Grok session or reviewed its code.

What does Second Brain Os include?

According to what Grok loaded in our install check, Second Brain Os includes 5 skills, 1 subagent: context-audit, evals-bootstrap, gate-check, goal-test, harness-audit, agents-course:loop-critic.

Details

Type: Plugin
Category: Productivity
Source: Community Claude Code plugin, installs in Grok
License: MIT
Author: undefined-ui
Keywords: agent-skills, ai-agents, claude, claude-code, claude-skills, knowledge-graph, knowledge-management, llm, mcp, obsidian, personal-knowledge-base, pkm
Source repo: https://github.com/undefined-ui/second-brain-os
Checked commit: 9173e03d4c40
Homepage: https://x.com/undefinedKi/status/2068306794116501544
Checked by GrokStacks: Install-checked in Grok Build on Oct 18, 2026; not run in a live session

Something wrong or missing? Submit or improve this listing. Marketplace listings also refresh automatically every night.

For maintainers: badge and embeds

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Markdown

[![Listed on GrokStacks](https://grokstacks.com/badge.svg)](https://grokstacks.com/p/second-brain-os/)

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<a href="https://grokstacks.com/p/second-brain-os/"><img src="https://grokstacks.com/badge.svg" alt="Listed on GrokStacks" width="164" height="28"></a>

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Second Brain OsCommunity plugin for Grok Build · 5 skills, 1 subagentAn AI second brain that maintains itself. Full guide, starter vault, agent skills and scripts for a self-organizing…View on GrokStacks →

<a href="https://grokstacks.com/p/second-brain-os/" style="display:block;max-width:380px;box-sizing:border-box;padding:14px 16px;border:1px solid #2a2e3c;border-radius:12px;background:#0a0b0f;color:#e8eaf0;font:14px/1.45 -apple-system,Segoe UI,Roboto,Helvetica,Arial,sans-serif;text-decoration:none"><span style="display:block;font-size:16px;font-weight:700;color:#e8eaf0">Second Brain Os</span><span style="display:block;margin:2px 0 8px;font-size:12px;color:#9aa0b1">Community plugin for Grok Build · 5 skills, 1 subagent</span><span style="display:block;margin:0 0 10px;color:#c9cdd8">An AI second brain that maintains itself. Full guide, starter vault, agent skills and scripts for a self-organizing…</span><span style="font-size:12px;font-weight:600;color:#7c9cff">View on GrokStacks →</span></a>

Markdown summary

**[Second Brain Os on GrokStacks](https://grokstacks.com/p/second-brain-os/)**: Community plugin for Grok Build with 5 skills, 1 subagent. Install: `grok plugin install agents-course@undefined-ui/second-brain-os --trust` (after `grok plugin marketplace add undefined-ui/second-brain-os`)

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