GSD Core

What is GSD Core

GSD Core is a context-engineering and spec-driven development framework that drives AI coding agents (Claude Code, Codex, Gemini CLI, Copilot, Cursor, and more) through a disciplined phase loop. It solves context rot — the quality degradation that accumulates as an AI fills its context window — by running all heavy research, planning, and execution work in fresh-context subagents while keeping your main session lean.

This is a fork of open-gsd/gsd-core (MIT), maintained by TheRocketCode and published as @therocketcode/gsd-core. It keeps everything upstream offers and adds the greenfield discovery spine and testing methodology described below.

What this fork adds

On top of gsd-core's phase loop, this fork adds a connected product → domain → architecture → tests discovery spine, plus concrete test-infrastructure know-how.

Greenfield discovery — each step feeds the next:

• /gsd:discover-product — define what to build and why: real demand vs. interest, the narrowest wedge, the four product risks, outcome-framed → PRODUCT-BRIEF.md
• /gsd:model-domain — lightweight DDD: ubiquitous language + core/supporting/generic subdomain distillation → DOMAIN-MODEL.md
• /gsd:recommend-architecture — a two-axis recommendation (domain-logic ladder × deployment topology) that avoids over- and under-engineering, captured as an ADR → ADR-NNNN.md
• /gsd:testing-strategy — derives the test shape from the architecture (rich core → unit tests; CRUD-over-DB → integration tests), with coverage-as-floor + mutation testing → TEST-STRATEGY.md

Testing know-how the agent consults while writing tests: Testcontainers, parallel-safe DB isolation, authenticate-once / multi-role auth, synthetic test data, E2E tiering, and flaky-test avoidance.

The payoff: one complexity assessment made during discovery parameterizes both the architecture and the test strategy — a single thread from "what are we building" to "how do we test it."

How it works

Each milestone repeats the same five-step loop, one phase at a time:

1. Discuss — capture implementation decisions before anything is planned
2. Plan — research, decompose, and verify the plan fits a fresh context window
3. Execute — run plans in parallel waves; each executor starts with a clean 200k-token context
4. Verify — walk through what was built; diagnose and fix before declaring done
5. Ship — create the PR, archive the phase, repeat for the next one

Quickstart

npx @therocketcode/gsd-core@latest

The installer prompts for your runtime (Claude Code, OpenCode, Gemini CLI, Kilo, Codex, Copilot, Cursor, Windsurf, and more) and whether to install globally or locally. The installer is required for cross-runtime compatibility — do not copy files from agents/ or commands/ directly.

On another runtime or without Node.js? See Install on your runtime.

Once installed, start your first project:

/gsd-new-project

New here? Follow Your first project for a guided walkthrough from install to first shipped phase.

Installing & updating

How you get the latest version depends on what you already have installed: