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 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:
npx t3@latest connectFollow the sign-in instructions. Setup offers a
background service; if you decline it, start the
server with npx 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 accepts the returned authorization code, so you do not need to forward an OAuth callback port.
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:
npx t3 serve --host <private-ip>If a server is already running, generate a fresh link without restarting it:
npx t3 pairScan 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.
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:
npx t3 serve --tailscale-serveFor an already-running server:
npx t3 pair --tailscaleThe 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 offIf that port is already in use, choose another with
--tailscale-serve-port. See npx t3 pair --help for other pairing options.
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.
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 needs a compatible Node.js installation and provider setup. If launch cannot find Node or reports an incompatible version, check it through a non-interactive SSH session:
ssh user@example.com 'sh -lc "command -v node && node --version"'Configure your version manager for non-interactive shells if this differs from
your normal terminal. With nvm, setting a compatible default, such as
nvm alias default 24, can resolve the problem.
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.
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 npx t3 auth --help.
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.
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.
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.