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SpecKit Companion

Install in VS Code

In VS Code, SpecKit Companion is the full workspace: the sidebar, the spec viewer, review comments and the Overview. It works the same in Cursor, Windsurf and other editors built on VS Code.

The path has the same shape everywhere: Spec Kit itself, then the Companion extension for Spec Kit, which is optional but recommended, then the one thing your tool needs. Install where you work has the other two places.

  1. Get Spec Kit

    Spec Kit is GitHub’s toolkit for spec-driven development. Its specify command sets a project up with the /speckit commands your assistant runs.

    uv tool install specify-cli --from git+https://github.com/github/spec-kit.git --force

    This installs the GitHub build. The stock PyPI specify-cli has no extension command, so step 2 would fail with it. The command changes your global uv tools.

    Then set the project up, from its root. Swap claude for your assistant, such as copilot, gemini or codex:

    specify init --here --integration claude

    You can skip that second command. In step 3 the Specs view offers Initialize Workspace, which runs it for the assistant you chose.

    You should see

    specify extension --help lists add and list, and the project has a .specify folder.

  2. Add the Companion extension for Spec Kit (optional, recommended)

    This is the engine half. It records each run, adds the Companion pipeline and Auto, and brings living specs. It needs Spec Kit 0.9.5 or newer.

    specify extension add companion --from https://github.com/alfredoperez/speckit-companion/releases/download/companion-latest/companion.zip --force

    Run it from your project root and copy it whole. The short catalog form does not work.

    Without it the sidebar and the viewer still work with stock Spec Kit. You lose the run record, so the Overview has no step times, decisions or checks to show. You also lose the /speckit.companion.* commands, Auto and the Living Specs view.

    You should see

    A one-time untrusted source prompt, because the archive comes from a URL and not the catalog. Accept it. Then specify extension list has companion in it.

  3. Install the VS Code extension and choose your assistant

    Get it on the Marketplace

    Or open it in VS Code. It is on Open VSX too, for Cursor, Windsurf and other editors. From a terminal:

    code --install-extension alfredoperez.speckit-companion

    The first time it starts, a picker asks which AI assistant runs your steps. Pick the one you use. Choose an AI provider covers the picker and how to change it later.

    You should see

    A SpecKit icon in the activity bar with the Specs and Steering views. With the Companion extension from step 2, a Living Specs view too.

    The three-panel sidebar explainer: Specs, Steering and Living Specs as captioned cards
    The sidebar's three views. Living Specs is the one the Companion extension adds.

  4. Check that it took

    Click + in the Specs view, describe a small change and press Create Spec.

    You should see

    A new spec under Active in the Specs view, and the spec open in the viewer when your assistant finishes. With the Companion extension, your assistant also offers /speckit.companion.* commands next to the stock /speckit.* ones.

    Your first spec walks through it with pictures.

Update it, or fix it

Section titled “Update it, or fix it”

Update later has the command for each piece. If something did not work lists what you might see and what to do.

Section titled “Related”