Using T3 Code from a phone or tablet
No native app, but T3 Code runs in any mobile browser over Tailscale. How to pair by QR code, keep the host awake, and what actually works on a small screen.
Short version: there is no native App Store or Play Store app. T3 Code's front end is a web app, and a mobile browser can connect to a server running on your desktop. In practice that covers most of what people want from a phone.
Why this works at all#
The desktop app and the browser UI are the same React front end talking to the same Node server over WebSocket. Nothing about that requires a desktop browser. Point Safari or Chrome on your phone at a running server and you get the real interface — threads, streaming output, diffs.
The agent runs on the host machine, with the host's repositories and credentials. Your phone is a screen.
Setting it up#
1. Start a server on the machine that has your code.
npx t3 serve --host "$(tailscale ip -4)"Or with Tailscale terminating HTTPS, which is the better experience on mobile:
npx t3 serve --tailscale-serve2. Scan the QR code. t3 serve prints one along with the URL and pairing token. Scanning is substantially less painful than typing a pairing token on a phone keyboard.
3. Add it to your home screen. In Safari, Share → Add to Home Screen; in Chrome, menu → Add to Home screen. You get an icon and a full-screen view without browser chrome, which makes a real difference on a phone-sized viewport.
What's actually usable on a phone#
Honest assessment, based on what a touch screen is good at:
| Task | Verdict |
|---|---|
| Reading agent output | Good |
| Kicking off a thread from a short prompt | Good |
| Checking whether a long run finished | Good — the main use case |
| Approving Supervised prompts | Workable |
| Reviewing a small diff | Workable |
| Reviewing a large diff | Painful |
| Writing a detailed prompt | Painful |
| Resolving conflicts, merging | Don't |
The realistic pattern is monitoring and nudging: you start a long refactor at your desk, walk away, and check on your phone. Recent builds have been polishing exactly this — there's an iOS git progress overlay and thread snoozing, which suggests mobile is getting deliberate attention.
Keeping the host awake#
The most common mobile disappointment isn't the UI, it's coming back to a dead session because the host machine slept.
- macOS — disable sleep, or run
caffeinatealongside the server - Windows — set the power plan to never sleep while plugged in
- Linux — mask the sleep targets, or just use a machine that doesn't suspend
A cheap always-on Linux box or a home server is the setup that makes mobile access genuinely useful.
Looking for the ChatGPT app connecting to Codex Desktop?#
Different product, different mechanism, and it fails in its own distinctive ways — your desktop registers with OpenAI's backend through a headless daemon, and when that daemon can't reach the backend your phone waits forever on "Waiting for desktop".
That has its own page, including a proxy fix that works.
Security, briefly#
Your phone will store a pairing token that grants shell access to your development machine. That raises the stakes on the phone itself: keep a device passcode, and revoke the token with t3 auth if the phone is lost or sold.
Don't pair over hotel or coffee shop Wi-Fi to a server on a public IP. Tailscale, or nothing.
FAQ#
Is there a T3 Code iOS app?#
There is no native App Store app. T3 Code's web interface works in mobile Safari, and you can add it to your home screen for a full-screen, app-like experience. It connects to a server running on your computer.
Can I use T3 Code on Android?#
Yes, through Chrome or any modern mobile browser connected to a T3 Code server on your computer. Add it to your home screen for a standalone window.
How do I connect my phone to T3 Code?#
Run npx t3 serve --tailscale-serve on your computer and scan the QR code it prints. Both devices need to be on the same Tailscale network, or the same LAN if you're using a local address.
Is T3 Code usable on a phone screen?#
For monitoring runs, reading output and sending short follow-ups, yes. Reviewing large diffs and writing detailed prompts are much better on a desktop.