t3-code-android-nightly/docs/user/remote-access.md

Remote access

Connect a phone, browser, or another desktop app to T3 Code running on a different machine. That machine must stay running and reachable while you work.

T3 Connect

T3 Connect makes an environment available to your other devices without setting up router forwarding. In the desktop app on the host, open Settings → Connections, sign in, and enable T3 Connect for that environment.

For a command-line host, run:

t3 connect

Follow the sign-in instructions. Setup offers a background service; if you decline it, start the server with t3 serve. Saving your sign-in alone does not make the machine reachable.

On your other device, sign in to the same T3 Connect account and choose the environment. Over SSH, the CLI prints a browser link and a short code. Open the link on any device, confirm the code matches, and approve. The CLI continues on its own, so you do not need to forward an OAuth callback port.

T3 Connect renews access credentials when needed without disconnecting a healthy connection. Pull request diffs and provider settings keep working after the previous credential expires. A failed renewal affects that request; it does not disconnect an otherwise healthy conversation.

Pair over a LAN or private network

Use direct pairing when the other device can reach the host's network address.

On a desktop host, open Settings → Connections, enable Network access, then create a pairing link using an address the other device can reach. Changing network access restarts the desktop app. You can turn it off in the same place.

For a command-line host, replace <private-ip> with the host's LAN or tailnet address:

t3 serve --host <private-ip>

If a server is already running, generate a fresh link without restarting it:

t3 pair

Scan the QR code on your phone or paste the pairing URL into Add environment in the receiving app. Connection settings are under Settings → Connections on web and desktop and Settings → Environments on mobile. A loopback address such as 127.0.0.1 reaches only the device opening the link.

Pairing authorizes that device for future connections. Use a fresh one-time link for each new device; you do not need the original token to reconnect. Links created in Settings can only be copied from the client that created them while its Connections page stays open. If you leave or reload that page, create another link to share.

Reach one machine several ways

A machine can have more than one route: LAN, Tailscale, a public URL, SSH, or T3 Connect. To add one, choose Add route in the machine's route list, or next to it in the T3 Connect list. Pairing the same machine again over another address also adds a route instead of a second machine. A new route is placed by speed, in that order, and you can reorder routes at any time.

While connected through T3 Connect or a paired address, T3 Code also learns the machine's current LAN and Tailscale addresses and adds them as routes, so pairing once through T3 Connect is enough to use the LAN at home. When the machine's LAN address changes, for example after it joins another Wi-Fi network, the learned route follows it. The machine must allow network access for its LAN address to be learned. You can reorder a learned route, but not remove it; it goes away with the route it was learned through, or when the machine stops reporting that address.

T3 Code connects over the first route that answers. Away from home, a LAN address that does not answer is checked briefly and skipped. It is only tried again, after the other routes, if none of them connect. While connected over a later route, T3 Code checks the earlier ones when your network changes, when you return to the app, and every minute, and moves back as soon as one works.

On web and desktop, select the route count under the machine's name in Settings → Connections to see its routes. Drag a route to change the order, or remove it. On mobile, open the machine under Settings → Environments and choose Edit. Signing out of T3 Connect removes only that route; a machine you can still reach another way stays saved.

Balance new threads across machines

Auto balance is off by default. On web and desktop, enable it in Settings → Connections → Load balancing to automatically choose a machine for new threads in projects grouped across connected environments. The section appears once two or more machines are switched on. Each machine starts at Normal. Choose Prefer to favor it when it has CPU and memory available, Less often to reduce its share, or Manual only to exclude it from automatic selection. These are preferences, not fixed traffic percentages. Preferences are saved separately in each client.

The composer checks eligible machines when choosing a draft's environment, then keeps that choice stable. Choose Auto balance again to check current resources, or choose a specific machine to override it. Choosing a branch or worktree also keeps the draft on that machine. Existing threads stay where they started. If resource checks are unavailable or all eligible machines are full, choose a machine manually to continue. Mobile keeps its manual environment selection.

Tailscale HTTPS

Join both devices to the same tailnet. In the desktop app, enable Tailscale HTTPS in Settings → Connections. Turn it off there to remove that route.

To start a command-line server with Tailscale HTTPS:

t3 serve --tailscale-serve

For an already-running server:

t3 pair --tailscale

The pairing link uses an address such as https://machine.tailnet.ts.net/. The mapping created by pair --tailscale persists across restarts. Remove its default-port mapping with:

tailscale serve --https=443 off

If that port is already in use, choose another with --tailscale-serve-port. See t3 pair --help for other pairing options.

Hosted web app

app.t3.codes needs an HTTPS endpoint. It connects directly to your server; a hosted pairing link does not make an unreachable backend reachable or convert HTTP to HTTPS.

For a plain HTTP LAN endpoint, use the direct pairing URL in a browser that can open it, or pair from the desktop app. On mobile, an IP address entered without a scheme uses HTTP, so include https:// when your server uses HTTPS.

Desktop-managed SSH

In the desktop app, open Settings → Connections → Add environment, choose SSH, and enter a host or SSH alias such as user@example.com. T3 Code starts or reuses a server there and opens the port forward for you. Projects, provider credentials, and agent work stay on the remote machine.

The remote host must be Linux or an Apple Silicon Mac with curl or wget, tar, sha256sum or shasum, and provider setup. The first launch downloads T3 Code's server to ~/.t3/runtime on the host, so it takes longer than later ones. Provider CLIs must be on the PATH of a non-interactive login shell there; check with:

ssh user@example.com 'sh -lc "command -v claude codex"'

If SSH reconnecting fails after an app update, retry the launch once. Removing the connection stops a server that T3 Code launched; a server that was already running is left alone.

For Antigravity's Google callback on a remote host, see remote sign-in.

Browser on a remote environment

Browser tabs belong to the environment, so you and your agents see the same tabs from any device. The desktop app shows its own environment's tabs directly. Every other device, and the desktop app for other environments, streams them from the host. Agents keep using them while no device is connected, and localhost addresses reach servers on the host.

The first tab downloads a headless Chrome, about 120 MB, into the T3 home. It is the same browser HTML renders use, so a host downloads it only once. Some Linux hosts need setup before it can start.

Agent tabs have separate storage and share a Chromium process. Take control before typing into an agent's tab, then release control when you want the agent to continue. Read-only connections can watch without changing the page.

While you have control, the tab works with your device: text the page copies or cuts goes to your clipboard, a file picker on the page opens your device's picker, and a finished download is offered for you to save. Popups such as sign-in windows open as their own tabs. Downloads stay on the host until the tab closes. Audio does not play on your device.

On a phone, tap the floating preview's corner dot to show its controls, then Pop into separate window to keep watching in picture-in-picture over other apps.

Browser host setup

macOS, Windows, and Linux desktops run the browser as is. Some Linux hosts need one-time setup: Ubuntu 23.10 and later block the sandbox the browser runs in, and minimal images and containers lack libraries it loads. When that happens, the server says so at startup, and browser tabs and HTML previews show the command to run on the host:

sudo t3 browser setup

The server shows the exact line for how you started it, such as sudo npx t3 browser setup, and keeps your PATH when Node is installed only for your user. Where t3 is not on your PATH, such as with only the desktop app installed, it names the full path of the app's own t3 instead. It allows Chrome's sandbox with an AppArmor profile and installs any missing libraries with apt. It is safe to run again. Without sudo, it only reports what it would change.

The browser always runs in Chrome's sandbox. Where you cannot change the host, set T3CODE_SERVER_BROWSER_SANDBOX=0 for the environment to run without it.

Connect an outside agent

Claude Code, Codex, ChatGPT and other agents T3 Code did not start can drive threads on an environment through its MCP server. See outside agents for setup.

Manage or revoke access

On the host, Settings → Connections lets authorized administrators create pairing links and revoke client sessions. Revoking an unused link prevents new pairings; revoke a device's session to remove its existing access. Command-line management is available through t3 auth --help.

A session with an open connection stays listed after its access credential expires.

To choose a token's permissions, pass --scope once for each scope you want:

npx t3 pair --scope orchestration:read --scope relay:read

The selected scopes replace the default permissions. The same option works with npx t3 auth pairing create and npx t3 auth session issue; each command's --help lists the available scopes. Without --scope, pairing tokens retain standard client permissions and issued bearer sessions retain administrative permissions.

To change an existing client's permissions, create a fresh pairing link with the scopes it needs. In a browser opened directly on the environment, open that link to replace the browser's current grant. For mobile or a saved remote environment in web or desktop, use Add Environment with the fresh link or code; pairing the same environment replaces its saved grant. Reconnecting alone does not change permissions.

Grouping checkouts does not combine their permissions. Shared project settings require orchestration:operate on every member environment; actions on one checkout use that checkout's permissions.

source-control:write covers direct Git and pull request changes made from the client: pushing, switching or creating branches, cloning, and removing worktrees. It does not restrict what a task does. Starting a task in a new worktree still creates that branch and worktree with orchestration:operate, and the agent it runs can use Git however the environment allows.

Settings changes, provider management, and environment maintenance can be granted separately from access administration. New standard pairings include these permissions. Existing clients can stay connected after an update, but newly separated features may require pairing again with the permissions they need. Older clients may show controls that the server denies. Create a fresh pairing link to change a client's permissions.

filesystem:read allows browsing host files, opening workspace files, and viewing local changes. Add filesystem:write to allow editing files or saving plans to the workspace. These scopes control direct file access from the client.

To remove an environment from T3 Connect, open your account menu's T3 Connect page, or Settings → T3 Connect on mobile, and choose Deregister. This revokes its cloud access and frees its host space even when the environment is offline or has been wiped. Removing an environment from a device's connection settings only forgets it on that device; it stays registered to your account.

When idle tunnel cleanup is enabled, T3 Connect removes a linked environment's tunnel after it stays offline for several minutes. The environment stays linked and keeps the same address. When the host starts again or wakes, T3 Connect creates a replacement tunnel on its own. You do not need to pair again. Cleanup usually runs five to ten minutes after the tunnel goes down.

T3 Connect also removes the tunnel of an environment running an older version of T3 Code once it has been offline for seven days. That environment shows a message asking you to update. Start T3 Code on that computer and update it to the latest version; it reconnects at the same address without pairing again.

On a command-line host, t3 connect unlink disables exposure while retaining your login; t3 connect logout also clears that login. Background-service removal is separate.

Treat pairing URLs and authorization codes as passwords. Do not include them in screenshots, logs, or bug reports.

T3 Connect troubleshooting

Run t3 connect status on the host to inspect saved authorization and link configuration. It is not a live reachability check. If the environment appears offline, run t3 service status and read the displayed log. If it disappears when SSH closes, see background-service troubleshooting.

Error	Recovery
environment_link_limit_exceeded or managed tunnel limit	Deregister an unused environment, then restart T3 Code on the host.
auth_invalid or invalid_bearer	Run t3 connect login. If credentials were revoked, run t3 connect logout, then t3 connect again. Restart the server after signing in.
Expired or invalid link proof	Check the host's date and time, update T3 Code, then restart it.
HTTP 403 without a recognized error	Check relay access, proxies, and firewall rules. Keep any Cloudflare Ray ID for a bug report.
HTTP 408, 429, or 5xx	Check network and relay availability. Startup retries temporary failures for up to ten minutes.

After fixing a permanent rejection, restart the host's server. On Linux, use systemctl --user restart t3code.service for the background service. For a foreground server, stop it and run t3 serve again with your usual options. Include the diagnostic message and trace ID when reporting a persistent failure.

For a connection that still fails after linking, check the date and time on both devices. For server version warnings, follow Updating T3 Code.

Using the Desktop App as a Remote Only

If a computer should only drive work running elsewhere, turn off its local environment. In the desktop app, open Settings → Connections and switch off Local environment. T3 Code restarts without a local server: no local agents or terminals run, WSL backends stay off, and other devices can no longer connect to this computer. Your projects, history, and saved connections are kept, and you keep working through pairing, T3 Connect, or SSH.

Switch Local environment back on in the same place to restart with your previous local settings.