Live preview, rock-solid — and every device to test on
We tracked down why previews could hang on “Connecting…” and fixed it at the root. Plus a device switcher with real iPhone, iPad, Galaxy and Pixel frames.
The live preview is the heart of Saturn — describe an app, watch it appear. So when a preview could get stuck spinning on “Connecting to cloud sandbox…”, it broke the magic. We went hunting, and the culprit was subtle.
The dev server inside each cloud sandbox was being started with detached, fire-and-forget code that ran after the request had already responded. On serverless infrastructure, the function is frozen the instant it replies — so the server never finished starting, its port never opened, and the panel waited forever. The fix was to keep the work alive until the server truly binds its port. Previews now come up reliably, on every platform.
While we were there, we made testing feel like the real thing. The preview now frames your app in actual devices you can switch between: iPhone 17 Pro and Pro Max, iPhone 16, the smaller iPhone SE, iPad and iPad mini — and for Android, the Samsung Galaxy S25 and Google Pixel 10. Building for the web? There's a MacBook frame and a free-fit mode too.
It means you can eyeball a notch, a tall-screen layout, or a compact phone before you ever ship — right next to the chat, updating live as you build.
Small idea, big feel: preview that just works, on the device your users actually hold.