🌱 Spec Kit

Build with a spec, fix a bug, or assess an idea — with your coding agent.

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Spec Kit is an open source toolkit that gives AI coding agents structured processes, reusable templates, and documented outcomes. Start with one of the three processes below, customize it, or bring your own.

Choose your process

What you need	Process	Outcome
Build a feature or application	Spec-Driven Development	A specification carried through planning, implementation, and convergence
Diagnose and repair broken behavior	Bug fixing	An assessed cause, scoped fix, and recorded verification
Decide whether an idea deserves investment	Idea assessment	An evidence-backed go, clarify, or stop decision

These are independent entry points, not three mandatory phases. SDD ships in core; bug fixing and assessment are bundled extensions you install when needed.

Get started

You need Python 3.11+, uv, and a supported AI coding agent on Linux, macOS, or Windows. For CLI setup only, run this in your terminal to install Spec Kit and create a project:

uv tool install specify-cli
specify init my-project --integration copilot
cd my-project

The examples use GitHub Copilot's default skills mode. Replace copilot with your integration key to use another supported agent.

Already have code? Follow the existing-project guide. For pinned releases, other installers, CI, or troubleshooting, see Installation. To update an existing installation, see Upgrade.

Now launch your coding agent in the project directory and choose a process below. Invoke each /speckit-* skill in your agent's chat, one at a time, and review the result before continuing. These are agent skills, not terminal commands. Other agents and modes may use different invocation syntax.

Spec-Driven Development

Define what and why before deciding how to build it. SDD turns your requirements into a specification, a technical plan, and actionable tasks, then guides implementation against those artifacts.

Constitution once per project; specify → plan → tasks → implement → converge per feature.

Invoke these skills in your agent's chat:

/speckit-constitution Create principles focused on code quality, testing, and maintainability.
/speckit-specify Build a photo organizer with albums grouped by date and a tile preview of each album.
/speckit-plan Use Vite with vanilla JavaScript. Keep images local and store metadata in SQLite.
/speckit-tasks
/speckit-implement
/speckit-converge

Repeat implement → converge until convergence reports Converged. Add clarification, checklists, and consistency analysis when you need extra quality gates.

SDD walkthrough · Command reference

Bug fixing

Keep diagnosis, repair, and verification separate so the agent fixes the assessed cause and checks the original symptom. No SDD feature workflow is required first.

CLI setup (terminal): install the opt-in extension from the project directory:

specify extension add bug

Then invoke the assess → fix → test skills in your agent's chat:

/speckit-bug-assess "Submitting an empty password crashes the login form." slug=login-crash
/speckit-bug-fix slug=login-crash
/speckit-bug-test slug=login-crash

The reports live in .specify/bugs/login-crash/. Review the final verdict: verified, partial, or failed. Missing verification is not a successful fix.

Bug-fixing walkthrough · Command reference

Idea assessment

Gather evidence before committing to an idea, whether or not it becomes software. This standalone process works even in a project with no source code.

CLI setup (terminal): install the opt-in extension from the project directory:

specify extension add assess

Then invoke the intake → research → define → shape → decide skills in your agent's chat:

/speckit-assess-intake "Let users work offline and sync when they reconnect." slug=offline-mode
/speckit-assess-research slug=offline-mode
/speckit-assess-define slug=offline-mode
/speckit-assess-shape slug=offline-mode
/speckit-assess-decide slug=offline-mode

The artifacts live in .specify/assessments/offline-mode/, ending in a go / needs-clarification / kill decision. Resolve unknowns by refining the existing Markdown artifacts directly or with the agent, rather than regenerating whole stages. A go decision can be handed to /speckit-specify if you choose to build it; stopping with a documented reason is also a useful result.

Assessment walkthrough · Command reference

Customize or bring your own process

Extensions add capabilities, presets adapt existing behavior, workflows automate steps, and bundles package a role-based setup. Use project-local overrides for one-off template changes.

Customization guide · Community extensions, presets, bundles, and walkthroughs

Documentation

• CLI reference and process commands
• SDD philosophy, full methodology, and evolving existing specs
• Video overview and project history
• How Spec Kit uses Spec Kit

Support and contributing

Report a bug or request a feature · Contributing guide · Code of conduct

Spec Kit is MIT licensed.