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How to Make Claude Code Your AI Engineering Team

GStack is an open-source toolkit built by YC President & CEO Garry Tan that turns Claude Code into an AI engineering team — with skills for office hours, design, code review, QA, and browser testing. Use it with Claude Code or Codex or Cursor. It's free and open source: https://github.com/garrytan/gstack In this video, Garry walks through how GStack works, starting with Office Hours, a skill modeled after real YC partner sessions that pressure-tests your idea before you write a line of code. He demos it live, going from idea through adversarial review, design mockups, and automated QA in a single session. 00:00 – AI Just Changed Coding Forever 00:09 – From YC to Building With AI 01:07 – Why AI Coding Feels So Different 02:45 – Turning AI Into a Real Team (GStack) 03:45 – Let’s Build an App Live 05:23 – The Question That Kills Most Ideas 07:13 – This Idea Just Got Way Bigger 08:38 – The “Feels Illegal” AI Hack 10:50 – Upgrading the Idea in Real Time 12:44 – Breaking + Fixing the Plan 14:25 – AI Designs the App 16:59 – The Full System Explained 18:00 – Running Multiple AI Engineers 20:00 – Shipping 10x Faster 21:20 – The Only Thing That Matters Now Apply to Y Combinator: https://www.ycombinator.com/apply Work at a startup: https://www.ycombinator.com/jobs https://www.conductor.build/

Garry Tanhost
Apr 23, 202621mWatch on YouTube ↗

At a glance

WHAT IT’S REALLY ABOUT

Garry Tan shows GStack turning Claude Code into engineering teams

  1. GStack is presented as a “thin harness, fat skills” framework that adds process, roles, and reviews so coding agents stop wandering and producing plausibly wrong code.
  2. The “Office Hours” skill emulates YC-style founder advising by forcing evidence, wedge strategy, and business-model clarity before writing code.
  3. A live build example (a 1099 tax-document finder) shows how the tool reframes a small utility into a broader product (browser automation + CPA marketplace) through iterative questioning.
  4. The workflow includes adversarial plan review, UI “design shotgun” generation, staff-level code review, and automated QA via a Playwright/Chromium CLI browser tool.
  5. Tan argues the new bottleneck is no longer model intelligence but engineering scaffolding, execution process, and secure integration—enabling many parallel PRs and much faster shipping.

IDEAS WORTH REMEMBERING

5 ideas

Process, not raw model IQ, is the main limiter in AI coding.

Tan claims models are already “smart enough,” but without roles, checks, and constraints they guess at scale and silently break things; GStack adds the missing structure.

Use forcing questions to kill weak ideas early and expand strong ones fast.

Office Hours starts with evidence-of-demand and competitive reality checks (e.g., TurboTax import, Plaid), then helps reframe toward a wedge and viable business model.

Browser automation can replace brittle integrations and reduce credential risk.

Instead of OAuth/Plaid, the app concept shifts to user-visible local browser control where AI navigates portals and downloads PDFs while the user watches—minimizing stored secrets.

Adversarial plan review catches product and engineering gaps before coding.

The workflow runs multi-step critiques (privacy, failure handling, 2FA handoff, etc.), auto-fixes issues, and only then “locks” a higher-quality design doc.

Generate multiple UI directions quickly, then select and iterate.

“Design shotgun” produces several interface concepts (e.g., command center vs friendly progress), enabling rapid convergence on a chosen direction with lightweight feedback.

WORDS WORTH SAVING

5 quotes

Basically, I've written a lot of code in my career, and I'm here to tell you, we are in a completely new era of building software, the agent era.

Garry Tan

Out of the box, the model wanders. It doesn't know your data well, so it guesses. And guessing at that scale is how you get plausible looking code that silently breaks.

Garry Tan

Here's the question that determines everything else. What's the strongest evidence that you have that someone actually wants this?

Garry Tan

The way to think about Claude Code is that by default it uses Claude, and I think Opus 4.6 is sort of ADHD CEO. He's the guy you want to get a beer with, and he's got a billion ideas. But when the going gets tough, you got to call in your autistic CTO, and that's Codex.

Garry Tan

This is the most incredible time in history to build software. The barrier to building just collapsed. The only question left is what are you gonna build? It's time to let it rip. Go make something people want.

Garry Tan

Agent era of software developmentThin harness / fat skills scaffoldingGStack skills: Office Hours, reviews, Auto PlanLive product ideation: 1099 extraction from GmailBrowser automation with Playwright/ChromiumAdversarial review and issue auto-fixingParallel AI sessions and PR throughputSupply-chain risk and security paranoia

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