Garry Tan's `gstack` repository offers a suite of opinionated tools designed to transform the use of Claude Code, an AI coding assistant, from a generic tool into a specialized team of software development experts. The core purpose of `gstack` is to provide consistent, high-rigor workflows for developers who heavily utilize Claude Code, enabling them to switch between different cognitive modes on demand, mimicking the roles of a founder/CEO, engineering manager, release engineer, and QA engineer. This approach aims to move beyond the limitations of a single, generalized AI assistant and instead provide a more structured and efficient way to build software.

The primary feature of `gstack` is its collection of eight distinct "skills," each designed to address a specific stage of the software development lifecycle. These skills are invoked as slash commands within Claude Code, allowing users to seamlessly transition between different perspectives and tasks. The `/plan-ceo-review` skill, for instance, encourages a founder-level perspective, prompting the AI to rethink the problem and identify the core value proposition of a feature. `/plan-eng-review` then shifts the focus to an engineering manager's role, guiding the AI to create architecture diagrams, define data flows, and establish test matrices.

The repository also includes skills for code review (`/review`), release management (`/ship`), and QA testing (`/qa`). The `/review` skill, designed for a "paranoid staff engineer," focuses on identifying potential bugs that might slip through standard testing, such as race conditions or security vulnerabilities. `/ship` streamlines the release process by automating tasks like syncing with the main branch, running tests, and creating pull requests. The `/qa` skill provides systematic QA testing capabilities, including automated analysis of code changes, identification of affected pages, and various testing modes like full exploration, quick smoke tests, and regression testing.

Furthermore, `gstack` incorporates the `/browse` skill, which allows the AI to interact with a web application by simulating a QA engineer. This skill gives the AI "eyes," enabling it to log in, navigate through the application, take screenshots, and catch any breakage. The `/setup-browser-cookies` skill facilitates testing of authenticated pages by importing cookies from the user's browser. Finally, the `/retro` skill provides an engineering manager mode, enabling team-aware retrospectives with praise and growth opportunities for each contributor.

The repository emphasizes that `gstack` is not a prompt pack for beginners but an operating system for experienced developers who want to leverage Claude Code effectively. It is designed for users who already rely heavily on Claude Code and seek to enhance their workflows with consistent, high-quality results. The installation process involves cloning the repository, running a setup script, and adding the skills to the Claude Code environment. The repository also provides instructions for integrating `gstack` into a project, making it accessible to team members.

A key aspect of `gstack` is its integration with Greptile, an automated PR review tool. The `/review` and `/ship` skills are designed to work in conjunction with Greptile, automatically triaging its comments and taking appropriate actions, such as fixing identified issues, acknowledging already-fixed issues, or pushing back on false positives. This integration streamlines the code review process and helps ensure that no issues are overlooked. The repository also highlights the benefits of running multiple Claude Code sessions in parallel, using a tool like Conductor, to maximize productivity. This allows developers to simultaneously perform tasks like QA testing, code review, and feature implementation.