> ## Documentation Index
> Fetch the complete documentation index at: https://docs.fastshot.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Preview & Testing

> Test your app in the browser and on your phone

## Browser preview

A live preview of your app appears in the right panel of the editor. It updates automatically as the AI makes changes.

The preview shows your app running through a React Native web build. It's a good approximation, but some elements may look slightly different than on a real device.

<Warning>
  The browser preview cannot simulate native device features like camera, biometrics, NFC, Bluetooth, push notifications, or native date pickers. Use a physical device for testing these features.
</Warning>

## Testing on your phone

For the most accurate experience, test on a physical device:

1. Install [Expo Go](https://expo.dev/go) on your iOS or Android device
2. Open the QR code tab in the preview panel
3. Scan the QR code with your device camera (iOS) or the Expo Go app (Android)
4. Your app loads on your device with live updates

<Tip>
  Your phone and computer need to be on the same network for live preview to work.
</Tip>

## What works where

| Feature               | Browser Preview | Physical Device |
| --------------------- | :-------------: | :-------------: |
| UI layout and styling |       Yes       |       Yes       |
| Navigation            |       Yes       |       Yes       |
| State management      |       Yes       |       Yes       |
| Forms and inputs      |       Yes       |       Yes       |
| Camera                |        No       |       Yes       |
| Biometrics            |        No       |       Yes       |
| Push notifications    |        No       |       Yes       |
| Native date pickers   |        No       |       Yes       |
| Platform-specific UI  |   Approximate   |     Accurate    |

## Preview controls

* **Restart Metro** — click the restart button if the preview stops responding
* **Cache reset** — ask the AI to "restart the preview with cache reset" for a clean rebuild
* **Error display** — runtime errors show with a count badge; click "Fix All Errors" to let the AI diagnose and fix them

## Preview states

| State    | What's happening                                   |
| -------- | -------------------------------------------------- |
| Loading  | Setting up the preview environment                 |
| Building | Compiling your app code                            |
| Ready    | App is running and interactive                     |
| Coding   | AI is editing code — preview will update when done |
| Error    | Build failed — check the error message             |