gstack
gstack turns Claude Code (and other coding agents) into a virtual engineering team: a CEO who rethinks the product, an eng manager who locks architecture, a designer who catches AI slop, a reviewer who finds production bugs, a QA lead who opens a real browser, a security officer who runs OWASP + STRIDE audits, and a release engineer who ships the PR. All slash commands, all Markdown, all free, MIT license.
I'm Garry Tan, President & CEO of Y Combinator. This is the open source software factory I use every day, and I'm sharing it because these tools should be available to everyone. The story, the productivity numbers and how I run ten sprints at once are in Why gstack.
Fork it. Improve it. Make it yours. And if you want to hate on free open source software — you're welcome to, but I'd rather you just try it first.
Who this is for:
- Founders and CEOs — especially technical ones who still want to ship
- First-time Claude Code users — structured roles instead of a blank prompt
- Tech leads and staff engineers — rigorous review, QA, and release automation on every PR
Quick start
- Install gstack (two pastes, about 30 seconds of setup; see below).
- Run
/office-hours and describe what you're building. It pushes back on your framing and writes a design doc the other skills read.
- Run
/review on any branch with changes. It finds the bugs that pass CI but break in production, and fixes the obvious ones.
- Run
/qa on your staging URL, or on an isolated local API, CLI, job or webhook. It opens a real browser, reproduces bugs and fixes them.
Stop there. You'll know if this is for you. When you want the whole sprint, /autoplan reviews a plan end to end and /ship runs tests, review and the PR.
Install — about 30 seconds
Requirements: Claude Code, Git, Bun v1.4.2+ (the tested version; setup refuses Bun older than 1.3.3, which would let compiled tools read a project's .env), and Node.js on Windows. Recommended on macOS: the Aside browser (macOS 15+), which the browser skills, /make-pdf and /diagram drive first with your real logged-in sessions; without it, ./setup builds gstack's own bundled browser. /cso needs a native toolchain as well; setup says so and leaves it unavailable when the toolchain is absent. Timing, the /cso prerequisites and the hooks setup registers: docs/install.md.
Step 1: Install on your machine
Open Claude Code and paste this. Claude does the rest.
Install gstack: run git clone --single-branch --depth 1 https://github.com/garrytan/gstack.git ~/.claude/skills/gstack && cd ~/.claude/skills/gstack && ./setup then add a "gstack" section to CLAUDE.md that says to use the /browse skill from gstack for all web browsing and never use mcp__claude-in-chrome__* tools. Claude Code lists the installed skills itself, so the section needs no skill list. Then ask the user if they also want to add gstack to the current project so teammates get it.
Step 2: Team mode — auto-update for shared repos (recommended)
From inside your repo, paste this. Switches you to team mode, bootstraps the repo so teammates get gstack automatically, and commits the change:
(cd ~/.claude/skills/gstack && ./setup --team) && ~/.claude/skills/gstack/bin/gstack-team-init required && git add .claude/ CLAUDE.md && git commit -m "require gstack for AI-assisted work"
No vendored files in your repo, no version drift, no manual upgrades. Every Claude Code session starts with a fast auto-update check (throttled to once/hour, network-failure-safe, completely silent). Team mode follows the stable channel: the twice-weekly tagged release (Monday and Thursday, at most once every 72 hours, plus verified security and regression fixes), not every merge to main. gstack-config set update_channel main follows every merge instead; see docs/releases.md.
Swap required for optional if you'd rather nudge teammates than block them.
Team mode's required hook runs on Node.js, so every teammate needs Node.js on PATH (details). To remove gstack later: docs/uninstall.md.
Other AI Agents
gstack runs on more agents than Claude. Bare ./setup installs for Claude
Code only (run inside OpenClaw, Hermes or a Dot, it also registers gstack's
skills with that harness: docs/hosts.md).
Pick another agent with --host <name>, or install for every agent setup
detects on this machine with --host auto:
git clone --single-branch --depth 1 https://github.com/garrytan/gstack.git ~/gstack
cd ~/gstack && ./setup --host auto # or: ./setup --host codex
./setup --status # one row per install: host, tier, scope, version, path
An explicit --host X installs for X only and never changes another agent's
install. /gstack-upgrade refreshes every install it registered, one row per
host, and says which ones failed.
Tiers: full is certified by a real workflow run (see
Certify your host); experimental
installs and passes the conformance tests but has no certification run yet;
instruction-only installs nothing: setup prints what to copy.
| Agent | Tier | Install | First invocation | Safety skills | Outside review needs | Repair |
|---|
| Claude Code | full | --host claude (default) | /office-hours | enforced (hooks block) | Codex CLI, signed in | ./setup --host claude |
| OpenAI Codex CLI | experimental | --host codex → ${CODEX_HOME:-~/.codex}/skills/gstack-*/ | ask for gstack-office-hours | advisory, not blocked | Claude Code CLI, signed in | ./setup --host codex |
| OpenCode | experimental | --host opencode → ~/.config/opencode/skills/gstack-*/ + /gstack-* commands | /gstack-office-hours | advisory, not blocked | Codex CLI, signed in | ./setup --host opencode |
| Cursor | experimental | --host cursor → ~/.cursor/skills/gstack-*/ | ask for gstack-office-hours | advisory, not blocked | Codex CLI, signed in | ./setup --host cursor |
| Factory Droid | experimental | --host factory → ~/.factory/skills/gstack-*/ | ask for gstack-office-hours | advisory, not blocked | Codex CLI, signed in | ./setup --host factory |
| Kiro | experimental | --host kiro → ~/.kiro/skills/gstack-*/ | ask for gstack-office-hours | advisory, not blocked | Codex CLI, signed in | ./setup --host kiro |
| GitHub Copilot CLI | experimental | --host copilot → ~/.copilot/skills/gstack-*/ | /gstack-office-hours | advisory, not blocked | Codex CLI, signed in | ./setup --host copilot |
| Antigravity CLI | experimental | --host agy (or ) → |
Per-host notes (agent harnesses, Copilot, Antigravity, Gemini CLI, OpenClaw and ClawHub, the Codex behavioral profile and model tiers, outside-review providers, the design binary's models) are in docs/hosts.md. Any rules-reading agent (Zed, Amp, Jules) can use the 2KB agents digest with no install. Adding a host: docs/ADDING_A_HOST.md.
See it work
You: I want to build a daily briefing app for my calendar.
You: /office-hours
Claude: [asks about the pain — specific examples, not hypotheticals]
You: Multiple Google calendars, events with stale info, wrong locations.
Prep takes forever and the results aren't good enough...
Claude: I'm going to push back on the framing. You said "daily briefing
app." But what you actually described is a personal chief of
staff AI.
[extracts 5 capabilities you didn't realize you were describing]
[challenges 4 premises — you agree, disagree, or adjust]
[generates 3 implementation approaches with effort estimates]
RECOMMENDATION: Ship the narrowest wedge tomorrow, learn from
real usage. The full vision is a 3-month project — start with
the daily briefing that actually works.
[writes design doc → feeds into downstream skills automatically]
You: /plan-ceo-review
[reads the design doc, challenges scope, runs 10-section review]
You: /plan-eng-review
[ASCII diagrams for data flow, state machines, error paths]
[test matrix, failure modes, security concerns]
You: Approve plan. Exit plan mode.
[writes 2,400 lines across 11 files. ~8 minutes.]
You: /review
[AUTO-FIXED] 2 issues. [ASK] Race condition → you approve fix.
You: /qa https://staging.myapp.com
[opens real browser, clicks through flows, finds and fixes a bug]
You: /ship
Tests: 42 → 51 (+9 new). PR: github.com/you/app/pull/42
You said "daily briefing app." The agent said "you're building a chief of staff AI" — because it listened to your pain, not your feature request. Eight commands, end to end. That is not a copilot. That is a team.
The sprint
gstack is a process, not a collection of tools. The skills run in the order a sprint runs:
Think → Plan → Build → Review → Test → Ship → Reflect
Each skill feeds into the next. /office-hours writes a design doc that /plan-ceo-review reads. /plan-eng-review writes a test plan that /qa picks up. /review catches bugs that /ship verifies are fixed. Nothing falls through the cracks because every step knows what came before it.
| Skill | Your specialist | What they do |
|---|
/office-hours | YC Office Hours | Start here. Six forcing questions that reframe your product before you write code. Pushes back on your framing, challenges premises, generates implementation alternatives. Design doc feeds into every downstream skill. |
/plan-ceo-review | CEO / Founder | Rethink the problem. Find the 10-star product hiding inside the request. Four modes: Expansion, Selective Expansion, Hold Scope, Reduction. |
/plan-eng-review | Eng Manager | Lock in architecture, data flow, diagrams, edge cases, and tests. Forces hidden assumptions into the open. |
/plan-design-review | Senior Designer | Rates each design dimension 0-10, explains what a 10 looks like, then edits the plan to get there. AI Slop detection. Interactive — one AskUserQuestion per design choice. |
/plan-devex-review | Developer Experience Lead | Interactive DX review: explores developer personas, benchmarks against competitors' TTHW, designs your magical moment, traces friction points step by step. Scores error messages for the agents that read them (agent-ready errors). Three modes: DX EXPANSION, DX POLISH, DX TRIAGE. 20-45 forcing questions. |
/design-consultation | Design Partner | Build a complete design system from scratch. Researches the landscape, proposes creative risks, generates realistic product mockups. Writes DESIGN.md in the open DESIGN.md format, so impeccable, Google Stitch, and any tool that reads it share one file. |
/review | Staff Engineer | Find the bugs that pass CI but blow up in production. Auto-fixes the obvious ones. Flags completeness gaps and gate integrity: every weakened test, timeout, snapshot or suppression reaches a human by name. Advisory simplification lens flags over-built code — never blocks, never auto-applies. |
/deslop-shared-libs | Shared Code Reviewer | Find worthwhile shared-code extractions in recent work. Compares up to five opportunities and recommends the best three, with source evidence, reliability gains, and total code savings. Recommendations only. |
The same /qa and /qa-only commands test CLIs, APIs, jobs, workers and webhooks with no browser: QA without a webpage.
Which review should I use?
| Building for... | Plan stage (before code) | Live audit (after shipping) |
|---|
| End users (UI, web app, mobile) | /plan-design-review | /design-review |
| Developers (API, CLI, SDK, docs) | /plan-devex-review | /devex-review |
| Architecture (data flow, perf, tests) | /plan-eng-review | /review |
| All of the above | /autoplan (runs CEO → design → DX → eng, auto-detects which apply; eng always last) | — |
Power tools
| Skill | What it does |
|---|
/codex | Second Opinion — independent code review from OpenAI Codex CLI. Review, challenge, and consult modes. Available on every harness except Codex. |
/claude-code | Second Opinion — independent code review from Claude Code. Review, challenge, and consult modes, with session continuity for consultation. Available on every harness except Claude Code. |
/careful | Safety Guardrails — warns before destructive commands (rm -rf, DROP TABLE, force-push). Say "be careful" to activate. Override any MEDIUM warning; root/home recursive deletes and default-branch force-pushes are hard-denied. |
/freeze | Edit Lock — restrict file edits to one directory. Prevents accidental changes outside scope while debugging. |
/guard | Full Safety — /careful + /freeze in one command. Maximum safety for prod work. |
/unfreeze | Unlock — remove the /freeze boundary. |
/open-gstack-browser | GStack Browser — launch gstack's own browser headed, with sidebar, anti-bot stealth, auto model routing (Sonnet for actions, Opus for analysis), one-click cookie import, and Claude Code integration. Clean up pages, take smart screenshots, edit CSS, and pass info back to your terminal. The visible face of the fallback engine; with Aside open you watch the agent's tabs there instead. |
/setup-deploy | Deploy Configurator — one-time setup for /land-and-deploy. Detects your platform, production URL, and deploy commands. |
/setup-gbrain | GBrain Onboarding — from zero to running gbrain in under 5 minutes. PGLite local, Supabase existing URL, or auto-provision a new Supabase project via Management API. MCP registration for Claude Code + per-repo trust triad (read-write/read-only/deny). Full guide. |
/sync-gbrain | Keep Brain Current — re-index this repo's code into gbrain via gbrain sources add + , refresh the block in CLAUDE.md, and auto-remove guidance when the capability check fails. (default), , . Idempotent; safe to re-run. |
Beyond the slash commands, gstack ships standalone CLIs (gstack-egress, gstack-context-bill, gstack-model-benchmark, gstack-pr-wait, the review and evidence ledgers, the iOS QA daemon): docs/standalone-binaries.md. The fallback browser's per-site domain skills and raw CDP escape hatch, and the voice-input aliases many skills carry, have their own pages.
Deep dives with examples and philosophy for every skill →
GBrain — persistent knowledge for your coding agent
GBrain is a persistent knowledge base for AI agents — think of it as the memory your agent actually keeps between sessions. GStack gives you a one-command path from zero to "it's running, my agent can call it."
/setup-gbrain
The four setup paths, the per-repo trust policy and memory sync, in brief: docs/gbrain-quick-tour.md. Full monty — every scenario, every flag, every bin helper, every troubleshooting step: USING_GBRAIN_WITH_GSTACK.md
Other references: docs/gbrain-sync.md (sync-specific guide) • docs/gbrain-sync-errors.md (error index)
Platform notes
macOS and Linux get full support. Windows and Gemini models get minimal support: install and the core skills work, and nothing more is promised. See support tiers.
macOS: everything runs. With the Aside browser (macOS 15+) open and signed in, the browser skills, /make-pdf and /diagram use it and your real sessions; otherwise they use the bundled browser ./setup builds. gstack never installs Aside.
Linux: everything runs on the bundled browser; Aside is macOS-only, so the readiness probe says NEEDS_ASIDE: Linux once and the skills use gstack's own Chromium. If Chromium installs but cannot launch because the host blocks unprivileged user namespaces (Ubuntu 24.04+ AppArmor default), set GSTACK_CHROMIUM_NO_SANDBOX=1.
Windows users: gstack works on Windows 11 via Git Bash or WSL. Aside is macOS-only, so on Windows (and Linux) the browser skills, /make-pdf, and /diagram always use gstack's bundled browser. Node.js is required in addition to Bun — Bun has a known bug with Playwright's pipe transport on Windows (bun#4253). The browse server automatically falls back to Node.js. Make sure both bun and node are on your PATH. Native /cso additionally requires PowerShell (PowerShell 7 pwsh is preferred; Windows PowerShell 5.1 is the fallback) and Visual Studio 2022 Build Tools with the Desktop development with C++ workload; setup leaves that skill explicitly unavailable when they are absent. /cso is optional: if its native helper fails to build or publish, setup still finishes, says which step failed with the log path and retry command, and keeps an earlier helper when it has one (GSTACK_STRICT_BUILD=1 makes that failure fatal, as CI does).
Known issue: Windows Smart App Control (#2595). gstack's compiled binaries (browse, find-browse, design, pdf, gstack-global-discover) are built on your machine and unsigned, so Windows 11 with Smart App Control on refuses to start them; Git Bash shows Permission denied. setup detects this, names the blocked binaries and the skills that need them, and gstack-doctor reports them as blocked. Today's workarounds are running gstack inside WSL, or turning Smart App Control off. Details: troubleshooting. The sidebar terminal uses Consolas on Windows, so its text no longer renders spaced out.
From PowerShell, .\setup.ps1 (same arguments as ./setup) checks that Git for Windows, Bun and Node.js are on PATH, prints the winget command for any that are missing, and otherwise runs ./setup in Git Bash.
On Windows without Developer Mode (MSYS2 / Git Bash), setup falls back to file copies instead of symlinks because ln -snf produces frozen copies that don't refresh on git pull. Re-run cd ~/.claude/skills/gstack && ./setup after every git pull so your skill files match the repo. setup prints a one-line note reminding you. Unix and WSL keep symlinks and don't need the re-run.
Docs
| Doc | What it covers |
|---|
| Skill Deep Dives | Philosophy, examples, and workflow for every skill (includes review-bot triage for Greptile, CodeRabbit and other bots) |
| The recommended harness | gstack + Capy from zero to the first merged train: install, the Captain and its Drive, trains, the daily flaky pass, the twice-weekly release, the factory scorecard, what is Capy-specific, known Capy limits |
| gstack + Capy: the software factory | What we built with Capy Captains and gstack, how the pieces fit, the measured before/after, tips, and how Garry uses it |
| Why gstack | The story, the productivity numbers and their caveats, Karpathy's failure modes, parallel sprints |
| Install details | Setup timing, requirements in detail, team mode, the hooks setup registers, agent harness registration |
| Other agents | Agent harnesses (OpenClaw, Hermes, dots, QM, Muse Code, Grok, any other), OpenClaw and ClawHub, per-host notes, the Codex profile and model tiers, outside-review providers, the design binary's models |
| QA without a webpage | /qa and /qa-only on CLIs, APIs, jobs, workers and webhooks |
| Standalone binaries | The standalone gstack-* CLIs (egress auditor, context bill, model benchmark, the review and evidence ledgers, the iOS QA daemon), and the CSO evaluation producer contract |
Privacy & Telemetry
gstack sends nothing about how you use it unless you opt in. Telemetry is off by default and asked about once; the update check (two or three GitHub requests: a git ls-remote, a fetch of VERSION and, when that version equals yours but main has moved, a compare-API call; with telemetry on it also reports your gstack version and OS; on by default) turns off with gstack-config set update_check false; outside reviews (on by default; the first one prints a notice) send code to Codex or Claude Code under your own login and turn off with gstack-config set codex_reviews disabled. Every off-machine send writes a receipt you can audit with gstack-egress list. The full account, including the exact fields telemetry carries and the local state that is not telemetry: docs/privacy.md.
Troubleshooting
Not sure what's wrong? Run the doctor: ~/.claude/skills/gstack/bin/gstack-doctor
(on other hosts, ./setup --status in your gstack checkout ends with the
doctor's absolute path). Without starting a skill or spending anything, it
prints one row per check (install, state root, Bun, hooks, Codex and its cached
model probe, artifacts sync, the browse bundle, the other compiled binaries,
the /cso native helper, Claude Code, your largest session journal and recent
/autoplan guard codes), each ok, warn,
not configured or fail with the command that fixes it. It exits non-zero
only on fail. --live also runs the paid Codex model check (one short call).
Paste its output into bug reports.
A message says not run, unavailable or names a fix? Look it up in
docs/troubleshooting.md: every gate message gstack
prints, what it means, what was kept, and the command that fixes it.
Claude says it can't see the skills? Check that they are installed (ls ~/.claude/skills) and restart Claude Code; it lists every installed skill with its description, so CLAUDE.md does not need to enumerate them (a pasted list goes stale with each release). Your project's CLAUDE.md only needs the browsing rule:
## gstack
Use /browse from gstack for all web browsing. Never use mcp__claude-in-chrome__* tools.
If an older install prompt left an "Available skills:" line in your CLAUDE.md, delete it.
Skill not showing up, stale install, Codex skill descriptions, prefix modes, disabling skills, Chromium install problems: quick answers.
Free, MIT licensed, open source. No premium tier, no waitlist.
I open sourced how I build software. You can fork it and make it your own.
We're hiring. Want to ship real products at AI-coding speed and help harden gstack?
Come work at YC — ycombinator.com/software
Extremely competitive salary and equity. San Francisco, Dogpatch District.
License
MIT. Free forever. Go build something.
