1# Antigravity
2
3T3 Code runs Google's official Antigravity ACP agent on your selected environment.
4It has its own sign-in, separate from the Antigravity IDE or CLI. Google controls
5which models and account access are available through this agent.
6
7## Set up Antigravity
8
9On web or desktop, open **Settings > Providers**, choose the environment that runs
10your project, and enable Antigravity. Install its runtime there, then choose
11**Sign in** and complete the browser sign-in. Wait for T3 Code to confirm
12account access and load models before starting a thread. Once the runtime is installed,
13you can also sign in from **Settings > Provider accounts** in the mobile app.
14
15Installation continues if you leave settings or reconnect. Setup requires
16permission to operate the environment; update an older server if it does not offer
17Antigravity setup.
18
19### Sign in from a remote device
20
21Google returns to a `127.0.0.1` address. It can finish directly when your browser is
22on the environment's machine. From another device, the final page will usually
23fail to load because the sign-in listener is on the environment.
24
25Copy the full return address, including everything after `?`, into the return URL
26field in the client where you started sign-in, then choose
27**Continue**. Keep the original address; do not replace it with the server's
28hostname. Only that T3 Code sign-in session can finish the attempt. If it expires,
29retry sign-in and use the new link.
30
31The return URL contains a temporary sign-in code. Paste it only into the setup
32field. A successful callback page alone does not confirm account access; wait for
33T3 Code's confirmation.
34
35### Other sign-in methods
36
37Choose **Sign-in method** in the Antigravity provider settings:
38
39| Method | Credentials |
40| -------------------------- | -------------------------------------------------------------------------------------------- |
41| Google account | Personal Google sign-in in the browser |
42| Gemini Enterprise | Browser sign-in, GCP project, and GCP location |
43| Gemini API key | API key; choose Connect without a browser |
44| Agent Platform / Vertex AI | API key, or GCP project and location with Application Default Credentials on the environment |
45
46The Antigravity API key field is stored in plain text in settings on the
47environment. The agent uses the method and credentials selected for this instance;
48ambient `GEMINI_API_KEY` and Google credential variables do not override them.
49Changing the method stops the instance's sessions. Sign out before replacing an
50account.
51
52## Runtime installation
53
54Managed installation supports Apple Silicon macOS, Linux x64 or ARM64, and Windows
55x64 or ARM64. Intel Macs can connect to a supported remote environment. Allow
56several GB of free disk space, especially on Linux.
57
58### Use a manual installation
59
60Download the archive for your environment from the [official ACP Registry][registry].
61Extract the ACP executable and its `localharness_external` helper into the same
62directory, at the same version. Make both executable on macOS or Linux; Windows
63uses `.exe` files.
64
65Set **Binary path** to the ACP executable on the environment and update it yourself.
66Leave the field blank to use the managed runtime, or a compatible executable on
67`PATH` if no managed runtime is installed.
68
69## Models and threads
70
71The model list comes from your Antigravity account and can differ from other
72Antigravity apps. A resumed thread keeps its selected model. If access to that
73model ends, select another available model before continuing.
74
75Use Antigravity's native `/plan` command for planning. T3 Code's separate Plan mode
76is unavailable. Tool approvals follow [Permission modes](./permission-modes.md).
77Questions with fixed choices still need one of the offered answers, even in
78**Full access**.
79
80T3 Code keeps conversation history and file diffs, but Antigravity cannot rewind
81its conversation. Reverting a thread or editing and resubmitting an earlier turn
82is unavailable. Continue with a follow-up message or start a new thread.
83
84### Skills and attachments
85
86Put project skills in `.agents/skills`. T3 Code also reads `.gemini/skills` and the
87legacy `.agent/skills` directory. Among these project locations, the first copy
88wins in this order: `.gemini/skills`, `.agents/skills`, `.agent/skills`. See
89[commands and skills](./composer.md#commands-and-skills) for invoking them.
90
91Skills for every project go in `~/.gemini/config/skills` or
92`~/.gemini/antigravity-cli/skills`. Antigravity does not read `~/.agents/skills`,
93so a skill there only appears when the project itself is your home directory.
94
95Antigravity receives images directly. Every other attachment, including PDFs,
96text, audio, archives, and videos, is passed as a saved file path for the agent
97to inspect with its tools. A video path does not enable native video input.
98
99### Subagents
100
101Antigravity groups subagent activity into batches. You cannot open or control
102individual subagents, and an idle batch does not confirm that every child
103succeeded. See [agent work](./thread-sidebar.md#inspect-agent-work) for where to
104inspect activity.
105
106## Accounts and removal
107
108Add an Antigravity provider instance for each Google account in
109**Settings > Providers** on web or desktop. Each has its own sign-in; downloaded
110runtimes are shared on the environment.
111
112| Action | Effect |
113| ------------------------- | ----------------------------------------------------------------- |
114| Disable | Stops the instance's sessions and keeps its Google sign-in. |
115| Sign out | Stops the instance's sessions and removes its saved Google login. |
116| Remove downloaded runtime | Removes the shared installation and keeps Google credentials. |
117
118All three keep thread history and workspace files. Sending `/logout` by itself in
119a thread signs out its instance, including stopping that instance's other sessions.
120Sign out, then sign in again to replace an account.
121
122Before removing a managed runtime, disable its instances and cancel any active
123installation. Clear any explicit binary path pointing into that runtime. Removal
124is refused while the runtime is in use.
125
126## Check access and troubleshoot
127
128Hover or focus the sidebar **Usage** button on web and desktop, or open **Usage → Limits** on
129mobile, to see the remaining Gemini and shared Claude/GPT allowances
130for Google sign-ins. Each group has separate five-hour and weekly limits and reset
131times. Limits refresh with provider status and include usage outside T3 Code.
132
133A server restart keeps your Google sign-in. The provider shows the saved account
134until a session, a refresh, or a sign-out reports something new.
135
136To check access and reload models, use **Refresh provider status** in web or desktop
137provider settings, or **Refresh models** in mobile thread settings. If asked to
138sign in again, use provider settings on web or desktop, or **Provider accounts** on mobile.
139
140If Google reports `SUBSCRIPTION_REQUIRED`, an account restriction, or a usage limit,
141follow the provider's message and any retry time. See [Google's account plans][plans]
142for eligibility.
143
144[registry]: https://github.com/agentclientprotocol/registry/blob/main/antigravity-acp/agent.json
145[plans]: https://antigravity.google/docs/plans