gstack

gstack is a collection of opinionated workflow skills for Claude Code created by Garry Tan, President and CEO of Y Combinator. Rather than treating Claude Code as a single generic assistant, gstack introduces role-based slash commands that switch the AI into distinct cognitive modes, each with specific priorities and constraints.

The toolkit provides eight specialized skills that map to different engineering roles. The /plan-ceo-review command activates a founder mode that pressure-tests product direction and looks for the most ambitious version of a feature before any code gets written. The /plan-eng-review command shifts into an engineering manager mode focused on architecture, data flow, state transitions, failure modes, and technical diagrams. The /review command operates as a paranoid staff engineer hunting for production-breaking bugs that pass CI, including race conditions, N+1 queries, trust boundary violations, and missing invariants.

For execution, /ship acts as a release engineer that syncs with main, runs tests, resolves review comments, pushes the branch, and opens a pull request. The /browse skill gives the agent browser access through a compiled binary that talks to a persistent Chromium daemon built on Playwright, enabling it to navigate pages, fill forms, take screenshots, and inspect console errors. The /qa command provides systematic QA testing that analyzes git diffs to identify affected routes and tests them automatically, with modes for diff-aware testing, full exploration, quick smoke tests, and regression comparison.

Two additional utilities round out the toolkit. The /setup-browser-cookies command imports cookies from real browsers including Chrome, Arc, Brave, and Edge into the headless session, enabling testing of authenticated pages without manual login. The /retro command generates engineering retrospectives with commit analysis, shipping velocity metrics, and per-contributor feedback.

gstack integrates with Greptile for automated PR review triage. When Greptile comments are present on a pull request, the /review and /ship commands automatically classify each comment as valid, already fixed, or a false positive, then take appropriate action. False positive patterns are tracked and auto-skipped in future runs.

The browser subsystem is the core technical component. Instead of launching a fresh browser for every action, gstack runs a long-lived headless Chromium daemon that communicates over localhost HTTP. The first call starts the browser in roughly three seconds, with subsequent calls completing in 100 to 200 milliseconds. Cookies, tabs, and localStorage persist across commands. Each workspace gets its own isolated browser instance, preventing interference between parallel sessions.

gstack is designed for use with Conductor, a tool that runs multiple Claude Code sessions in parallel across isolated workspaces. This enables workflows where separate sessions handle QA, review, implementation, and other tasks simultaneously on different branches.

The project is written primarily in TypeScript with the browser binary compiled using Bun. It requires Claude Code, Git, and Bun v1.0 or later. The browse binary works on macOS and Linux across x64 and arm64 architectures. Installation clones the repository into the Claude skills directory and runs a setup script that creates symlinks for each slash command.