t3-code-android-nightly/docs/user/providers-antigravity.md

# Antigravity

T3 Code runs Google's official Antigravity ACP agent on your selected environment.
It has its own sign-in, separate from the Antigravity IDE or CLI. Google controls
which models and account access are available through this agent.

## Set up Antigravity

On web or desktop, open **Settings > Providers**, choose the environment that runs
your project, and enable Antigravity. Install its runtime there, then choose
**Sign in** and complete the browser sign-in. Wait for T3 Code to confirm
account access and load models before starting a thread. Once the runtime is installed,
you can also sign in from **Settings > Provider accounts** in the mobile app.

Installation continues if you leave settings or reconnect. Setup requires
permission to operate the environment; update an older server if it does not offer
Antigravity setup.

### Sign in from a remote device

Google returns to a `127.0.0.1` address. It can finish directly when your browser is
on the environment's machine. From another device, the final page will usually
fail to load because the sign-in listener is on the environment.

Copy the full return address, including everything after `?`, into the return URL
field in the client where you started sign-in, then choose
**Continue**. Keep the original address; do not replace it with the server's
hostname. Only that T3 Code sign-in session can finish the attempt. If it expires,
retry sign-in and use the new link.

The return URL contains a temporary sign-in code. Paste it only into the setup
field. A successful callback page alone does not confirm account access; wait for
T3 Code's confirmation.

### Other sign-in methods

Choose **Sign-in method** in the Antigravity provider settings:

| Method                     | Credentials                                                                                  |
| -------------------------- | -------------------------------------------------------------------------------------------- |
| Google account             | Personal Google sign-in in the browser                                                       |
| Gemini Enterprise          | Browser sign-in, GCP project, and GCP location                                               |
| Gemini API key             | API key; choose Connect without a browser                                                    |
| Agent Platform / Vertex AI | API key, or GCP project and location with Application Default Credentials on the environment |

The Antigravity API key field is stored in plain text in settings on the
environment. The agent uses the method and credentials selected for this instance;
ambient `GEMINI_API_KEY` and Google credential variables do not override them.
Changing the method stops the instance's sessions. Sign out before replacing an
account.

## Runtime installation

Managed installation supports Apple Silicon macOS, Linux x64 or ARM64, and Windows
x64 or ARM64. Intel Macs can connect to a supported remote environment. Allow
several GB of free disk space, especially on Linux.

### Use a manual installation

Download the archive for your environment from the [official ACP Registry][registry].
Extract the ACP executable and its `localharness_external` helper into the same
directory, at the same version. Make both executable on macOS or Linux; Windows
uses `.exe` files.

Set **Binary path** to the ACP executable on the environment and update it yourself.
Leave the field blank to use the managed runtime, or a compatible executable on
`PATH` if no managed runtime is installed.

## Models and threads

The model list comes from your Antigravity account and can differ from other
Antigravity apps. A resumed thread keeps its selected model. If access to that
model ends, select another available model before continuing.

Use Antigravity's native `/plan` command for planning. T3 Code's separate Plan mode
is unavailable. Tool approvals follow [Permission modes](./permission-modes.md).
Questions with fixed choices still need one of the offered answers, even in
**Full access**.

T3 Code keeps conversation history and file diffs, but Antigravity cannot rewind
its conversation. Reverting a thread or editing and resubmitting an earlier turn
is unavailable. Continue with a follow-up message or start a new thread.

### Skills and attachments

Put project skills in `.agents/skills`. T3 Code also reads `.gemini/skills` and the
legacy `.agent/skills` directory. Among these project locations, the first copy
wins in this order: `.gemini/skills`, `.agents/skills`, `.agent/skills`. See
[commands and skills](./composer.md#commands-and-skills) for invoking them.

Skills for every project go in `~/.gemini/config/skills` or
`~/.gemini/antigravity-cli/skills`. Antigravity does not read `~/.agents/skills`,
so a skill there only appears when the project itself is your home directory.

Antigravity receives images directly. Every other attachment, including PDFs,
text, audio, archives, and videos, is passed as a saved file path for the agent
to inspect with its tools. A video path does not enable native video input.

### Subagents

Antigravity groups subagent activity into batches. You cannot open or control
individual subagents, and an idle batch does not confirm that every child
succeeded. See [agent work](./thread-sidebar.md#inspect-agent-work) for where to
inspect activity.

## Accounts and removal

Add an Antigravity provider instance for each Google account in
**Settings > Providers** on web or desktop. Each has its own sign-in; downloaded
runtimes are shared on the environment.

| Action                    | Effect                                                            |
| ------------------------- | ----------------------------------------------------------------- |
| Disable                   | Stops the instance's sessions and keeps its Google sign-in.       |
| Sign out                  | Stops the instance's sessions and removes its saved Google login. |
| Remove downloaded runtime | Removes the shared installation and keeps Google credentials.     |

All three keep thread history and workspace files. Sending `/logout` by itself in
a thread signs out its instance, including stopping that instance's other sessions.
Sign out, then sign in again to replace an account.

Before removing a managed runtime, disable its instances and cancel any active
installation. Clear any explicit binary path pointing into that runtime. Removal
is refused while the runtime is in use.

## Check access and troubleshoot

A server restart keeps your Google sign-in. The provider shows the saved account
until a session, a refresh, or a sign-out reports something new.

To check access and reload models, use **Refresh provider status** in web or desktop
provider settings, or **Refresh models** in mobile thread settings. If asked to
sign in again, use provider settings on web or desktop, or **Provider accounts** on mobile.

If Google reports `SUBSCRIPTION_REQUIRED`, an account restriction, or a usage limit,
follow the provider's message and any retry time. See [Google's account plans][plans]
for eligibility.

[registry]: https://github.com/agentclientprotocol/registry/blob/main/antigravity-acp/agent.json
[plans]: https://antigravity.google/docs/plans