OpenSpec: write the spec first, let AI code after — lightweight spec-driven development
TL;DR
OpenSpec (Fission AI, MIT) is a spec-driven framework for AI coding assistants, supporting 25+ tools including Claude Code, Cursor and Copilot. Install via npm, run openspec init, then /opsx:propose → /opsx:apply → /opsx:archive. No extra API key required.
Install
npm install -g @fission-ai/openspec@latest # Node 20.19+
cd your-project
openspec initLifecycle of a change
| Step | Command | Result |
|---|---|---|
| Propose | /opsx:propose <idea> | Change folder: proposal.md, specs/, design.md, tasks.md |
| Apply | /opsx:apply | Agent works through the tasks |
| Close | /opsx:archive | Moved to archive, main specs updated |
Why PMs should care
- Proposal + tasks are effectively “tickets with acceptance criteria” an agent can read.
- Reviewing a spec (hundreds of lines) is faster than reviewing a diff (thousands).
- Specs live in the repo → docs travel with code, less tribal knowledge.
References: OpenSpec on GitHub · OpenSpec docs summary