Antigravity

T3 Code runs Google's official Antigravity ACP agent. By default it signs in with your personal Google account and uses that account's Antigravity access, including access provided by a Google AI subscription. It never falls back to a different sign-in method than the one you select.

The agent, files, conversation state, and Google credentials stay on the selected environment. Your browser or phone controls that environment. Signing in to the Antigravity IDE or CLI does not sign in this T3 Code provider.

Set up Antigravity

On web or desktop, open Settings > Providers, select the device that runs your project, then select Antigravity. Provider setup is not available in the mobile app.

1. Choose Enable Antigravity. Antigravity is off by default.
2. Choose Install Antigravity. T3 Code downloads the official runtime from Google to that environment. Installation continues if you leave the page or reconnect.
3. Choose Sign in with Google.
4. Choose Open sign-in page. You can use Copy sign-in link to open it in another browser.
5. Complete Google sign-in. Use the account you use for Antigravity.
6. Wait for T3 Code to confirm sign-in and load the model choices. Select an Antigravity model in the thread's model picker.

Setup requires a connection with permission to operate the environment. If setup is unavailable on an older server, update that environment first.

Sign in from a remote device

Google returns to a 127.0.0.1 address on the device running your browser. If that is the same machine as the T3 Code environment, sign-in can finish directly.

On a phone or another computer, the final page will usually fail to load. This is expected. Copy the full address from the browser, including everything after ?, and paste it into the return URL field in the web or desktop client where you started setup. Choose Continue. Do not change the address to your server's hostname.

Return to the same T3 Code client and environment where you started sign-in. Another client can see that sign-in is in progress, but cannot complete that attempt. The setup screen shows the expiry time. If it expires, choose Retry Google sign-in and use the new link.

The return URL contains a temporary sign-in code. Paste it only into the setup field, not into a thread or bug report. T3 Code waits for Google's agent to confirm sign-in. A successful callback page alone does not prove account access.

Other sign-in methods

Sign-in method in the Antigravity provider settings on web or desktop selects how the agent authenticates.

Gemini Enterprise resolves your license for the project and location you enter. Agent Platform with a project and location uses Application Default Credentials on the environment. API keys are stored in plain text in T3 Code settings on that environment and are passed only to the Antigravity agent process. Ambient GEMINI_API_KEY or GOOGLE_* variables on the environment are ignored.

Changing the method stops the instance's sessions. Sign out or disconnect before you switch accounts.

Runtime installation

Managed downloads are available for these environment hosts:

Google does not publish a local Intel Mac runtime. Use an Intel Mac as a client connected to a supported remote environment.

The current Linux x64 runtime downloads about 682 MB and uses about 2.01 GB after extraction. Allow at least 3 GB free for installation. An update keeps the previous runtime too. T3 Code does not download it until you choose to install it.

On web or desktop, Update Antigravity appears when T3 Code has a newer managed release. Running sessions keep their current runtime. New sessions use the installed update.

Use a manual installation

Download the correct archive from the official ACP Registry and extract both the ACP executable and its localharness_external helper into the same directory. Keep both files at the same version and make them executable on macOS or Linux. Windows uses .exe files.

On web or desktop, set Binary path in the Antigravity provider settings to the ACP executable on the selected environment. Do not point it at the helper or the Antigravity IDE.

A nonempty Binary path takes priority. With the field empty, T3 Code uses its managed runtime, then an installation on the environment's PATH. An invalid explicit path reports an error instead of selecting another installation. T3 Code does not update or remove manual installations. Clear Binary path to use managed installation controls.

Models and threads

The current official ACP exposes Gemini models only. T3 Code uses the model IDs and names returned for your account, including any model choices with different thinking levels. Models available in other Antigravity apps might not be available through this agent. The model picker updates when a running session reports new model choices.

New threads use Gemini 3.8 Flash (High) when your account offers it. Older Gemini generations stay available under Legacy models in the picker.

Threads keep their selected model when you resume them. If that model is no longer available, T3 Code asks you to select an available model instead of silently changing it.

Use Antigravity's native /plan command to request a plan. T3 Code's separate Plan mode control is not available for this provider.

Project skills should use .agents/skills. T3 Code also discovers .gemini/skills and the legacy .agent/skills location. When multiple locations define the same skill name, .gemini/skills takes precedence, followed by .agents/skills and then .agent/skills.

Antigravity reads and edits workspace files through T3 Code. Each write shows up as a file change approval with the content, so Supervised and Auto-accept edits behave the same way they do for other providers. Attach images, PDFs, text files, or audio clips to a message and the agent receives them directly.

When the agent offers Allow for this thread on a shell or web tool, T3 Code shows Google's prompt injection warning next to that choice. Untrusted content could re-run the same action without asking again.

Antigravity can ask you to choose from a fixed set of answers. Select one of the offered choices. These questions do not accept custom text and still appear in Full access mode. See Permission modes for tool approvals.

T3 Code keeps thread history and file diffs. Antigravity does not support conversation rewind, so reverting a thread or editing and resubmitting an earlier turn is unavailable. Send a follow-up message or start a new thread instead.

Subagents

Subagent launches appear as Antigravity subagent batch in Agents on web and desktop, and in the work log on mobile. One launch can start several agents. The batch stays active after launch while the parent turn runs. When that turn ends, the entry becomes idle and states that individual agent status is unavailable. Launch errors remain visible. The conversation summary counts launches as batches and shows idle or stopped batches without a completion checkmark.

The official ACP agent does not send individual child status, names, models, token usage, or reply ownership. T3 Code cannot show separate child entries or separate child replies from the parent conversation. The launch description is not a child result. Batch entries cannot be opened or controlled as separate threads.

Accounts and removal

Each Antigravity provider instance has its own Google sign-in on its environment. Use Add provider in web or desktop provider settings to create a separate instance for another account. To replace an instance's account, sign out first, then sign in again.

Send /logout by itself in an Antigravity thread to sign out that provider instance. This has the same effect as Sign out of Google, including stopping its other sessions.

Before removing a managed runtime, disable the instances that use it and cancel any active installation. T3 Code refuses removal while the runtime is in use. An explicit Binary path that points into the managed runtime must be cleared first.

Account access and errors

Google controls account eligibility, models, and usage limits. T3 Code does not report your paid-plan tier or remaining subscription quota. See Google's Antigravity plans and personal Google sign-in guide.

After an environment restarts, Google sign-in can show as not checked until an authenticated session succeeds. You can continue an existing thread. Antigravity checks saved Google sign-in when the session starts. An unchecked status does not require signing in again.

To check account access and reload models on web or desktop, open Settings > Providers and select the circular arrow beside Checked at the top of the page. Its tooltip says Refresh provider status. On mobile, use Refresh models in the model picker. Refresh uses saved Google sign-in and does not open a login page. If sign-in is required, use the provider's setup controls on web or desktop. Automatic status checks verify the installation only.

The packaged runtime can be slow to start, especially on Windows. Health checks, model refresh, and sign-out each allow up to 90 seconds before reporting a timeout.

If Google reports SUBSCRIPTION_REQUIRED, an account restriction, or a usage limit, read the provider's message. A finished turn can contain an upstream error instead of completed work. Use any retry time Google supplies. T3 Code does not switch to an API key to get past the limit.