GStack: I Converted Claude Code into a Complete Engineering Team in 5 Minutes

Claude Code
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GStack: Turned Claude Code into a Complete Engineering Team in 5 Minutes

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Every dev who’s worked long enough with Claude Code eventually hits the same ceiling. AI is brilliant but diffuse — it answers what you ask, but doesn’t question your architecture, doesn’t run QA in a real browser, doesn’t review your PR with the paranoia of an experienced senior engineer. GStack solves exactly that.

Launched on March 12, 2026 by Garry Tan — Y Combinator’s CEO — and open-sourced at SXSW, GStack set GitHub Trending on fire within hours. It accumulated over 33,000 stars, trended on Product Hunt, and sparked a real debate about what disciplined agentic development means. The premise: instead of dotting Claude Code with variable context and hoping for consistent results, you give Claude a defined role with explicit responsibilities.

Fifteen specialists. Six power tools. All slash commands. All Markdown. MIT license.

What is GStack?

GStack is a collection of opinionated workflow skills for Claude Code. Each command mutates Claude Code into a specific operating mode — CEO, Engineering Manager, Designer, Paranoid Code Reviewer, QA Lead, Release Manager — each with its own priorities and constraints.

The philosophy is simple: a QA engineer thinks differently from a product lead. A release manager applies different criteria than a dev writing feature code. GStack activates those mental models explicitly, so Claude’s output matches the development phase you’re in.

Under the hood, GStack is two things:

  1. A set of skill files in Markdown (the slash commands themselves)
  2. A persistent headless Chromium daemon — the technically hard part

That browser daemon is what makes QA genuinely useful. Instead of spinning up a fresh browser for each tool call (3–5 seconds of cold start), GStack runs a long-lived Chromium process over localhost HTTP. Subsequent calls run in ~100–200ms. Cookies, tabs, localStorage, login state — everything persists between commands.

Requirements

  • Claude Code (installed and authenticated)
  • Git
  • Bun v1.0+
  • macOS or Linux (x64 or arm64) — Windows users: use WSL

Installation

git clone https://github.com/garrytan/gstack.git ~/.claude/skills/gstack
cd ~/.claude/skills/gstack && ./setup

That’s it. Claude does the rest. First useful run: less than 5 minutes on any repo that already has tests.

To add GStack to a specific project so your teammates have it too:

cp -Rf ~/.claude/skills/gstack .claude/skills/gstack
rm -rf .claude/skills/gstack/.git
cd .claude/skills/gstack && ./setup

Then add a gstack section to your project’s CLAUDE.md listing the available skills.

The 15 Specialists

Planning roles

/office-hours — Describe what you’re building. GStack reformulates the problem before you write a single line of code. Start here with each new feature.

/plan-ceo-review — Founder mode. Tests product direction, hunts for the most ambitious version of a feature, evaluates market fit and user value.

/plan-eng-review — Engineering Manager mode. Locks down architecture, maps data flow, state transitions, failure modes, and generates technical diagrams. Writes a test plan artifact that /qa automatically picks up afterward.

/plan-design-review — Design review before implementation starts.

/design-consultation — Design consultation during development.

Review and shipping

/review — Paranoid Staff Engineer mode. Hunts bugs that break production and slip CI: race conditions, N+1 queries, trust boundary violations, missing invariants. If you run nothing else, run this before every PR.

/ship — Ship in one command. Runs the complete review gate (Eng Review required; CEO and Design are informational), then prepares the PR. Integrates with Greptile for automated triage.

/document-release — Generates release documentation.

QA and browser

/qa — Opens a real browser and clicks through your app. Analyzes branch diffs, identifies affected routes, and tests relevant paths — not a generic smoke test.

/qa-only — Same as /qa but without review gates.

/browse — Persistent browser for any web navigation task. Use this instead of MCP browser tools within GStack sessions.

/setup-browser-cookies — Imports cookies from Chrome, Arc, Brave, and Edge to test authenticated pages without manual login.

/retro — Engineering retrospective with commit analysis, shipping velocity metrics, and feedback per contributor.

Utility

/codex — Multi-AI second opinion. Gets a Codex review alongside Claude’s output.

/investigate — Deep investigation mode for bugs or unclear behavior.

The 6 Power Tools (Safety + Ops)

/careful — Adds warnings before any destructive command.

/freeze [dir] — Restricts edits to a specific directory. Anything outside that boundary gets blocked. Accident prevention when touching production systems.

/guard — Full security mode: /careful + /freeze combined. Use this when debugging production.

/unfreeze — Removes the freeze boundary.

/gstack-upgrade — Keeps GStack up to date. Detects your installation type (global vs. project), syncs both if you have dual installations, and shows what changed.

The Flow in Practice

A typical GStack session for a new feature:

  1. /office-hours — Describe the feature. Let GStack question whether you’re building the right thing.
  2. /plan-eng-review — Lock down the architecture. The test plan artifact writes itself automatically.
  3. Code normally with Claude Code.
  4. /review — Catch bugs before the PR.
  5. /qa — Real browser validation of the affected paths.
  6. /ship — Prepare and push the PR.

For anything touching production or sensitive directories: /guard before you start.

Conductor: Parallel Sessions

GStack is designed to work with Conductor, a companion tool that runs multiple Claude Code sessions in parallel in isolated workspaces — each with its own Chromium instance, cookies, tabs, and logs. One session handles QA, another does review, another implements. Garry Tan reports averaging 10,000 lines of code and 100 PRs per week over a 50-day stretch with this setup.

Install It Now

git clone https://github.com/garrytan/gstack.git ~/.claude/skills/gstack && cd ~/.claude/skills/gstack && ./setup

GitHub: GitHub - garrytan/gstack: Use Garry Tan's exact Claude Code setup: 15 opinionated tools that serve as CEO, Designer, Eng Manager, Release Manager, Doc Engineer, and QA · GitHub

Already installed GStack? Which of the 15 roles seems most useful for your current workflow? Let us know in the comments.