VS Code extension for spec-driven development — manage specs, workflows, and steering docs for AI CLI tools (Claude Code, Gemini CLI, Copilot CLI)
SpecKit Companion is a VS Code extension that enables spec-driven development for AI CLI tools including Claude Code, Gemini CLI, and Copilot CLI. It manages specs, workflows, and steering documentation within the editor, allowing developers to coordinate spec creation, planning, tasking, and implementation phases through an integrated pipeline. Built in TypeScript for VS Code, the project includes a separate independently-versioned spec-kit extension and ships with comprehensive documentation covering architecture, state machines, schema definitions, and release processes. The repository also contains benchmarking infrastructure to compare the SpecKit Companion workflow against stock spec-kit across multiple feature sizes, measuring correctness, speed, artifact fidelity, and capture overhead.