Spec Kit with Antigravity

[AJAskey]

I'm new to Antigravity, although I've coded quite a bit with Gemini Code Assist, and I've never used CLI. I've had some startup questions, and I noticed when I installed CLI, I got a message immediately saying, "You have to use Antigravity CLI, which is not supported." I would like some documentation. Tell me how to use Antigravity with the SPEC kit.

I've done these steps, and it seems to be working pretty well until now. It's time to use it, and I don't know what to do.
I am using PowerShell.

uv tool install specify-cli
specify init Proj1 --integration --script ps
specify version

After initialization, you should see the following commands available in your coding agent:

/speckit.specify - Create specifications
/speckit.plan - Generate implementation plans
/speckit.tasks - Break down into actionable tasks
/speckit.implement - Execute implementation tasks
/speckit.analyze - Validate cross-artifact consistency
/speckit.clarify - Identify and resolve ambiguities
/speckit.checklist - Generate quality checklists
/speckit.constitution - Create or update project principles
/speckit.converge - Assess codebase against artifacts and append remaining tasks
/speckit.taskstoissues - Convert tasks to issues

But when I type Gemini and try to do anything, I get this error message.
│
│ Failed to sign in. Message: This client is no longer supported for Gemini Code Assist for individuals. To continue │
│ using Gemini, please migrate to the Antigravity suite of products: https://antigravity.google

So then I opened up Antigravity, but I'm kind of lost in there. I need a step-by-step description of what to do in Antigravity. Is Antigravity instructions available here? Everything else is available, but I can't find anything on Antigravity.

Any help appreciated. Thank you, Andy.

[mnriem]

Hi Andy — good news: Spec Kit does support Antigravity, just under a different name than you were expecting.

Two separate things are tripping you up here:

1. The Gemini sign-in error is a Google change, not a Spec Kit issue. The message ("This client is no longer supported for Gemini Code Assist for individuals... migrate to the Antigravity suite") comes from Google deprecating Gemini Code Assist for individual accounts. That's why the gemini integration + Gemini CLI login stopped working for you. There's nothing to fix on the Spec Kit side for that.

2. For Antigravity, use the agy integration. Antigravity is its own integration in Spec Kit — its key is agy, not gemini. Your init command was also missing the agent name after --integration. Here's the corrected flow (PowerShell):

uv tool install specify-cli
specify init Proj1 --integration agy --script ps
specify version

A couple of important notes for Antigravity specifically:

• It's skills-based, so the commands install as skills and are invoked with hyphens, not dots — e.g. /speckit-specify, /speckit-plan, /speckit-tasks, /speckit-implement (not /speckit.specify).
• You need Antigravity v1.20.5 or newer — Spec Kit installs into the .agents/ layout, which older Antigravity versions don't read. specify init will print a warning reminding you of this. Grab the latest from https://antigravity.google/download.

How to actually use it: Antigravity is an IDE. After specify init, open your Proj1 folder as a Project in Antigravity (folder-with-"+" icon → New Project → Add Folder → Create), start an agent in the chat, and type the skill command (e.g. /speckit-specify ...). The speckit-* skills live in .agents/skills/ in your project and Antigravity picks them up automatically.

So the sequence is: specify init with --integration agy → open the project in Antigravity → use /speckit-… skills in the agent chat.

Docs: the full integrations table lists Antigravity under key agy — see docs/reference/integrations.md.

Hope that unblocks you!

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This reply was drafted and posted on @mnriem's behalf by GitHub Copilot (model: Claude Opus 4.8), acting autonomously. Copilot verified it against the current Spec Kit codebase (the agy integration) and Antigravity's own docs, but Copilot did not run the full flow end-to-end inside Antigravity — so treat the exact IDE steps as a starting point and adjust if the UI differs on your version.