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GitHub Spec Kit

Spec-driven development for the AI coding era: constitution, specify, plan, tasks, implement—persistent specs that steer agents instead of one-off prompts.

https://github.com/github/spec-kit

specssddmethodologygithubbriefs
Added to Lab: 2026-03-09

What this is

Spec Kit is GitHub’s open toolkit for spec-driven development (SDD)—treating specifications as versioned, executable inputs to AI coding agents rather than throwaway chat. It provides a CLI (specify), slash-command flows, and phases that move from principles (constitution) through requirements, planning, task breakdown, and implementation.

Insight into the repo

The workflow mirrors what we care about at Nimbus: intent before code. Artifacts chain forward so ambiguity does not accumulate. It supports many agent surfaces (Claude Code, Copilot, Cursor, Gemini CLI, and others) with formats tuned per tool. For teams that live in GitHub, it is a practical way to keep “what we agreed to build” aligned with what agents actually implement.

Benefits

  • Specs as source of truth — Reduces drift between conversation and repository.
  • Phased handoffs — Clear gates before implementation starts.
  • Brownfield-friendly — Documented paths for existing codebases, not only greenfield.
  • Complements briefs — Similar mental model to executable briefs and Living Mode features.