# Antigravity in Scient Scient runs Google's official Antigravity ACP agent and connects it to the account or credential method you select. The runtime, credentials, files, and conversation state stay on the environment that runs your project. Scient never asks for your Google password or silently substitutes another sign-in method. For behavior shared by assisted providers, see [Providers in Scient](./providers.md). ## Assisted setup Open **Settings > Providers**, select Antigravity, and choose **Manage**. The model picker can open the same compact setup flow. On mobile, open **Settings > Environments** and choose **Set up Antigravity** for the host environment. Once the runtime is installed, you can also sign in from **Settings > Providers** in the mobile app. 1. If Antigravity is missing, choose **Install Antigravity**. Scient downloads the qualified official runtime into private app storage, checks the archive and executable, and activates it only after validation succeeds. 2. Choose **Sign in with Google** or **Connect**, according to the configured authentication method. 3. Complete the provider-owned flow. Scient then checks the account and loads the models available to it. Installation and sign-in continue if you leave the setup surface. Background status checks never open a browser or start a sign-in flow. With the Google account method, **Sign in** on the provider's row in **Settings > Providers** starts sign-in directly. Antigravity prepares itself each time it starts, so sign-in can take up to a minute before the Google page opens; Scient shows that it is starting. The page opens once, on the device where you started sign-in, even if you leave the setup surface meanwhile. Other windows and devices show the sign-in in progress and offer **Open Google sign-in** without opening it themselves. If the browser cannot open, the setup card says so, or a notification offers **Open sign-in page** when the card is closed. Google sign-in allows five minutes for runtime startup, browser authorization, and account verification. If Scient cannot open the browser, choose **Reopen Google sign-in** to retry the same attempt. Once the attempt expires, start a new one rather than reusing its old link. ### Sign in from another device Google returns to a `127.0.0.1` URL on the device running the browser. When the browser and provider environment are on different devices, that final page may not load. Expand **Signing in on another computer?**, copy the complete URL from the browser address bar, and paste it into Scient. Keep the query string and do not replace the host with the server address. The response must match the current sign-in attempt. Other connected clients can see that setup is in progress. If the attempt expires, start a new one and use its new URL. ### Authentication methods The Antigravity provider settings select one of the methods exposed by the official agent: | Method | Configuration | Connection flow | | -------------------------- | ------------------------------------ | ----------------------- | | Google account | None | Google sign-in page | | Gemini Enterprise | GCP project and location | Google sign-in page | | Gemini API key | API key | **Connect**, no browser | | Agent Platform (Vertex AI) | API key, or GCP project and location | **Connect**, no browser | Gemini Enterprise resolves access for its configured project and location. Agent Platform can use Application Default Credentials on the environment. The environment stores the Antigravity API key outside its settings file, and clients only see whether one is saved. 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 ownership and updates Scient supports both app-managed and existing installations: - With **Binary path** empty, Scient prefers its verified managed ACP runtime, then looks for the official ACP executable on the environment's `PATH`. - An explicit ACP binary path takes priority. Its `localharness_external` helper must be beside it. Scient does not update or remove explicit or system installations. - Existing legacy `agy` paths and conversations remain supported through the legacy transport. They are not reinterpreted as ACP sessions. Managed ACP downloads are available on Apple Silicon macOS, x64 and ARM64 Linux, and x64 and ARM64 Windows. Intel macOS is not yet an approved target for Scient-managed ACP installation; existing legacy `agy` installations remain usable there, or the Mac can connect to a supported remote environment. Scient's update catalog treats official ACP and legacy `agy` as separate release families. When a newer ACP release has passed download, archive, native-startup, activation, and removal qualification on its supported target, **Update Antigravity** appears for managed ACP installations. An update keeps the previous generation available while active sessions finish. It never mutates a system or custom installation. **Repair Antigravity** stages and validates a complete replacement before it touches a damaged managed generation. A failed download or verification leaves the existing copy and active pointer unchanged. Scient refuses to replace or remove a runtime while it is in use. ## Models, files, and permissions The official agent reports the models available to the selected account, including Claude and GPT models when your plan has them. Pick a thinking level beside the model list in the model picker; it shows only the levels the selected model supports. Scient keeps the thread's selected model when it resumes and asks for another selection if that model disappears. Older model generations remain available under **Legacy models** when the provider still offers them. Before a conversation starts, desktop/web can update an older saved Gemini family selection to its matching available reasoning variant. Existing conversations are not switched automatically. If the matching variant is unavailable, select an available model rather than reinstalling the provider. Use Antigravity's native `/plan` command for planning. Tool approvals follow [Permission modes](./permission-modes.md). Questions with fixed choices still need one of the offered answers, even in **Full access**. The model picker also refreshes when a running session reports new model choices. Models available in other Antigravity apps may not be available through the ACP agent. For supported Gemini variants, choose the model once and use **Reasoning** to select an available level. On mobile, open **Model and reasoning settings**. Changing the level selects Google's corresponding model variant; it does not change your account or installation. Saved favorites keep their exact model and reasoning level, so their labels still include the level. 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 creates empty `.gemini/skills` and `.agents/skills` folders in the workspace when a session starts. Git does not track empty folders, so they never appear in commits. Antigravity receives images and audio directly, and reads PDFs and text files as documents. With the managed runtime on macOS and Linux, an MP4 video up to 20 MiB is sent as video to Gemini models. Other attachments, and videos for other models, are passed as a saved file path for the agent to inspect with its tools. Use Antigravity's native `/plan` command to request a plan. Scient's separate Plan mode control is unavailable when the protocol cannot support it. Antigravity groups subagent activity into batches. Open a batch and select **Subagent work** (**Work** on mobile) to read each child's role, prompt, and recent steps. This view is read only: you cannot message or control individual subagents, and an idle batch does not confirm that every child succeeded. If Antigravity did not record which children a batch started, the view says so. See [agent work](./thread-sidebar.md#inspect-agent-work) for where to inspect activity. File edits, shell commands, and web actions use Scient's normal permission surfaces. Provider questions with fixed choices remain interactive even in **Full access**. See [Permission modes](./permission-modes.md). Antigravity does not support conversation rewind. Reverting a thread or editing and resubmitting an earlier turn is therefore unavailable; send a follow-up or start a new thread instead. Manual context compaction is unavailable through Antigravity's ACP runtime, even though its CLI has `/compact`. Send `/clear` when you need a fresh context. ## Skills and subagents Project skills should use `.agents/skills`. Scient also discovers `.gemini/skills` and the legacy `.agent/skills` directory. For duplicate skill names, precedence is `.gemini/skills`, then `.agents/skills`, then `.agent/skills`. Subagent launches appear as **Antigravity subagent batch** in **Agents** on web and desktop, and in the mobile work log. A launch can start several agents. The batch stays active while its parent turn runs, then becomes idle; launch errors remain visible. Google does not expose individual child status, names, models, usage, or reply ownership through ACP. A batch is not a separate controllable thread, and its launch description is not a child result. ## Accounts, disabling, and removal Each official ACP provider instance has a private profile, so multiple instances can use different accounts on one environment. | Action | Result | | --------------------------- | ------------------------------------------------------------------------------------------------------------------ | | Disable Antigravity | Stops that instance's sessions; keeps credentials, runtime, threads, and files. | | Sign out or disconnect | Stops that instance's sessions and clears its official ACP profile credentials; keeps runtime, threads, and files. | | Remove managed installation | Removes only Scient's shared ACP runtime; keeps account profiles, threads, files, and external installations. | Open **Usage > Limits** to see the remaining Gemini and shared Claude/GPT allowances for Google sign-ins. Each group has separate five-hour and weekly limits and reset times. Limits refresh with provider status and include usage outside Scient. 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 **Settings > Providers** on mobile. Legacy `agy` credentials use the older provider-owned credential store and are kept for legacy-session compatibility. Removing the ACP runtime does not erase that external credential store. Disconnect does not erase API keys saved for the instance or Application Default Credentials managed outside Scient. Remove those separately if you no longer want that credential method available. ## Troubleshooting Installation checks, model refresh, and sign-out allow up to 5 minutes for the official runtime to start, which can be slow on some computers. Explicit refresh uses saved credentials and does not launch a login page. Automatic checks verify installation only. Google controls account eligibility and limits; Scient does not silently switch authentication methods to bypass an account restriction. - **Antigravity is missing:** install the managed runtime, use an official system installation, or set its absolute binary path. - **Sign-in did not open:** use **Reopen Google sign-in** while the attempt is waiting. Helper preparation, runtime startup, and link-capture failures show which stage stopped; these failures require a new attempt. Passive refreshes intentionally do not launch a browser. - **Signed in, but Antigravity couldn't start:** Google accepted the sign-in, but the agent could not start a session or load models with it. Try again; if it keeps failing, the server log records the agent's reason. - **Remote sign-in stopped at localhost:** paste the full return URL through the collapsed remote-device control. - **Credentials are incomplete:** return to provider configuration and supply the key, project, or location required by the selected method. - **Connected but no models:** refresh provider status. Google controls account eligibility, models, subscriptions, and limits. - **Managed runtime is damaged:** choose **Repair Antigravity**. If sessions are active, stop them first and retry. The official ACP registry is available at [agentclientprotocol/registry](https://github.com/agentclientprotocol/registry/blob/main/antigravity-acp/agent.json).