expo-native-ui

Files (9)

• SKILL.md
• openai.yaml · agents/
• controls.md · references/
• gradients.md · references/
• icons.md · references/
• media.md · references/
• storage.md · references/
• visual-effects.md · references/
• webgpu-three.md · references/

SKILL.md (first lines)

# Expo Native UI Guidelines

For routes, links, stacks, tabs, modals, sheets, and headers, use the `expo-router` skill. For any motion — entering/exiting, gestures, springs, keyboard-driven UI — use the `expo-animation` skill.

> **Before picking any UI component, check `expo-ui` first.** `@expo/ui` provides native equivalents — BottomSheet, Button, Picker, Slider, Menu, Section, Switch, SegmentedControl, and more — rendered as real SwiftUI on iOS and Jetpack Compose on Android, available in Expo Go on SDK 56+ with no custom build. Load the **`expo-ui`** skill to find the right component before falling back to React Native built-ins or community libraries. This skill (`expo-native-ui`) covers the surrounding structure: Expo Router navigation, layout, styling, and visual effects.

## References

Consult these resources as needed:

```
references/
  controls.md            Native iOS: Switch, Slider, SegmentedControl, DateTimePicker, Picker
  gradients.md           CSS gradients via experimental_backgroundImage (New Arch only)
  icons.md               SF Symbols via expo-symbols SymbolView: names, weights, animations; Material icons on Android
  media.md               Camera, audio, video, and file saving
  storage.md             SQLite, AsyncStorage, SecureStore
  visual-effects.md      Blur (expo-blur) and liquid glass (expo-glass-effect)
  webgpu-three.md        3D graphics, games, GPU visualizations with WebGPU and Three.js
```

## Running the App

**CRITICAL: Always try Expo Go first before creating custom builds.**

Most Expo apps work in Expo Go without any custom native code. Before running `npx expo run:ios` or `npx expo run:android`:

1. **Start with Expo Go**: Run `npx expo start` and scan the QR code with Expo Go
2. **Check if features work**: Test your app thoroughly in Expo Go
3. **Only create custom builds when required** - see below

### When Custom Builds Are Required

You need `npx expo run:ios/android` or `eas build` ONLY when using:

- **Local Expo modules** (custom native code in `modules/`)
- **Apple targets** (widgets, app clips, extensions via `@bacons/apple-targets`)
- **Third-party native modules** not included in Expo Go
- **Custom native configuration** that can't be expressed in `app.json`

### When Expo Go Works

Expo Go supports a wide range of features out of the box:

- Most `expo-*` packages (camera, location, sensors, sqlite, etc.) — but not all: remote push notifications don't work in Expo Go on Android since SDK 53, and some packages need native capabilities Expo Go doesn't bundle (e.g. WebGPU — see `references/webgpu-three.md`)
- Expo Router navigation and deep links
- Most UI libraries (reanimated, gesture handler, etc.)

**If you're unsure, try Expo Go first.** Creating custom builds adds complexity, slower iteration, and requires Xcode/Android Studio setup.

## Code Style

- Be cautious of unterminated strings. Ensure nested backticks are escaped; never forget to escape quotes correctly.
- Always use import statements at the top of the file.
- Always use kebab-case for file names, e.g. `comment-card.tsx`
- Never use special characters in file names
- Configure tsconfig.json with path aliases, and prefer aliases over relative imports for refactors.

## Library Preferences

- **For any sheet, picker, slider, toggle, menu, or grouped-form section: use `@expo/ui` (see `expo-ui` skill) before reaching for a React Native built-in or community library** — it renders native SwiftUI/Compose and works in Expo Go on SDK 56+. For grouped/settings-style rows (short, fixed-length), use `@expo/ui`'s `List` + `ListItem`. For large or unknown-length scrolling lists (feeds, search results, catalogs), use `FlatList` or `FlashList` — `@expo/ui`'s `List` is not virtualized.
- Never use modules removed from React Native such as Picker, WebView, SafeAreaView, or AsyncStorage
- Never use legacy expo-permissions
- `expo-audio` not `expo-av`
- `expo-video` not `expo-av`
- `expo-symbols` (`SymbolView`) for SF Symbols on iOS, not `@expo/vector-icons` — see `references/icons.md`. SF Symbols are Apple-only: on Android every icon needs a Material source (`md` prop on NativeTabs triggers; in-screen options under "Android: Material Icons" in icons.md), never SF-only iconography
- `react-native-safe-area-context` not react-native SafeAreaView
- `process.env.EXPO_OS` not `Platform.OS`
- `React.use` not `React.useContext`
- `expo-image` Image component instead of intrinsic element `img`
- `expo-glass-effect` for liquid glass backdrops
- `Color` from `expo-router` for native semantic colors, not raw `PlatformColor` (type-safe, auto-adapts to light/dark)
- In SDK 56+, never import from `@react-navigation/*` directly — use `expo-router/react-navigation` instead (covers `@react-navigation/native`, `/core`, `/elements`, `/routers`)

## Responsiveness

- Wrap screens with scrollable content in a ScrollView. Screens whose root is a FlatList/FlashList must not add an outer ScrollView (the list is the scroll container), and full-bleed screens (camera, map, canvas) need neither
- Use `<ScrollView contentInsetAdjustmentBehavior="automatic" />` instead of `<SafeAreaView>` for smarter safe area insets
- `contentInsetAdjustmentBehavior="automatic"` should be applied to FlatList and SectionList as well
- Use flexbox instead of Dimensions API
- ALWAYS prefer `useWindowDimensions` over `Dimensions.get()` to measure screen size

## Behavior

- Use expo-haptics conditionally on iOS to make more delightful experiences
- Use views with built-in haptics like `<Switch />` from React Native and `@react-native-community/datetimepicker`
- When a Stack route has scrollable content, make the ScrollView (or FlatList) the first component inside the route, with `contentInsetAdjustmentBehavior="automatic"` set
- Use the `<Text selectable />` prop on text containing data that could be copied
- Consider formatting large numbers like 1.4M or 38k
- Never use intrinsic elements like 'img' or 'div' unless in a webview or Expo DOM component
- Every screen that loads data has four states (loading, error, empty, content) - never show the empty state while the first load is still resolving; the rules live in the `expo-data-fetching` skill
- On scrollable forms and search results, use `keyboardShouldPersistTaps="handled"` so controls receive the first tap and unhandled taps can dismiss the keyboard. Use `"always"` only when unhandled taps should also keep it open
- A form's primary action must never sit under the keyboard. For UI that tracks the keyboard's real frame, load the `expo-animation` skill's keyboard recipe (`react-native-keyboard-controller`) - never `Keyboard.addListener` plus a timing animation
- Every enabled control must perform its advertised action: search filters results, Save commits edits, and settings affect behavior. Empty handlers and success alerts are not implementations; local state is enough when the user requested a prototype
- For async saves, preserve drafts and handle pending/failure states per `expo-data-fetching`; do not dismiss a form before its save succeeds

Before calling a screen complete, walk through its primary task, including one failure and recovery when it loads or saves data. Check keyboard access and back/dismiss behavior. Try long titles, missing images, no search results, and large system text; required actions must remain reachable. Report what you exercised and what you could not run.

# Styling

Follow each platform's own design language: Apple Human Interface Guidelines on iOS, Material Design 3 on Android. Never dress one platform in the other's uniform - no FAB or ripple in iOS layouts; no hand-built iOS chrome (back-chevrons, large-title text, iOS-styled switches) on Android.

## General Styling Rules

- Prefer flex gap over margin and padding styles
- Prefer padding over margin where possible
- Always account for safe area, either with stack headers, tabs, or ScrollView/FlatList `contentInsetAdjustmentBehavior="automatic"`
- Ensure both top and bottom safe area insets are accounted for
- Inline styles not StyleSheet.create unless reusing styles is faster
- For any motion or animation work, load the `expo-animation` skill — it owns the animate-or-not decision, timing values, and interruption rules
- Use `{ borderCurve: 'continuous' }` for rounded corners unless creating a capsule shape
- ALWAYS use a navigation stack title instead of a custom text element on the page
- When padding a ScrollView, use `contentContainerStyle` padding and gap instead of padding on the ScrollView itself (reduces clipping)
- CSS and Tailwind are not supported - use inline styles

## Colors

Use the `Color` API from `expo-router` for native semantic colors. It is a type-safe wrapper over `PlatformColor` that exposes iOS UIKit colors through `Color.ios.*` and Android Material 3 colors through `Color.android.material.*` (static) or `Color.android.dynamic.*` (adapts to the user's wallpaper on Android 12+). These resolve on-device and automatically adapt to light/dark mode and accessibility settings, so you no longer maintain separate light/dark hex tables or a `colors.web.ts` file.

From expo/skills, MIT.

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