Antigravity in Coincide

How Coincide runs Antigravity

Antigravity’s agent runs as Google’s ACP server, a runtime separate from the Antigravity app. Coincide installs it for you: it downloads a pinned release from Google (dl.google.com), checks the archive’s size and SHA-256 checksum and every file’s checksum, verifies Google’s Developer ID signature, and starts the runtime once to check it before using it. Newer runtimes arrive with Coincide updates. If you’d rather use your own copy, Coincide also finds agy_acp_server on your PATH or at a custom path.

Coincide keeps Antigravity’s sign-in in a private profile inside its own data folder, separate from any other Google tools you use.

Set it up

1. Open Settings › Antigravity, read the notice and choose I Understand.
2. Choose Install Antigravity. Coincide shows the download size and progress, and then the installed version. (Google publishes the runtime for Apple silicon and Intel Macs.)
3. Choose Sign in with Google and finish signing in in your browser. If you sign in on another device, you can paste the address the browser ends on back into Coincide.
4. Pick an Antigravity model in the composer, or type /antigravity to continue a thread with it.

To avoid the subscription-account risk, add an account with a Gemini API key instead, in the same pane; each API-key account gets its own profile and the key is kept in your Keychain. Agent accounts has the details.

Models

Coincide asks the runtime which models your account can use, without sending a prompt, and keeps the list for six hours. It offers only models your account lists. Reasoning effort appears only where the runtime offers it for a model.

What works with Antigravity

• Approvals and full access: in approval mode, each request offers Allow once, Allow for this thread, Deny or Cancel, along with Google’s own security warning. Full access uses the runtime’s yolo mode.
• Questions from Antigravity are answered inline.
• Images (PNG, JPEG, WebP and BMP) can be attached.
• Plan mode: Coincide asks for a plan in the prompt, and switches the runtime to a planning mode if it offers one.
• Follow-ups are queued for the next turn; Antigravity can’t be steered mid-turn.
• Stopping cancels the turn, and Coincide replaces the runtime process if it hasn’t stopped after five seconds.
• Resuming: each thread resumes its own Antigravity session.
• Usage limits: for Google sign-ins, the Gemini and shared Claude and GPT quotas, over five hours and a week, read from Google’s Cloud Code service. None for API-key accounts.

Limitations

• The account risk above, for Google subscription sign-ins.
• If Google says your account needs a subscription, or asks you to sign in again in the middle of a turn, the turn stops and Coincide asks you to sign in to Antigravity in Settings.
• Coincide’s data folder can’t contain a colon (:) in its path, because the runtime can’t use it.
• No mid-turn steering.