expo-brownfield
expo brownfield
expo-ui
Framework (OSS). Build native UI with the @expo/ui package: real SwiftUI on iOS and Jetpack Compose on Android rendered from React in an Expo or React Native app. Covers universal cross-platform components (Host, Column, Row, Button, Text, List, and more imported from @expo/ui), drop-in replacements for popular React Native community libraries (BottomSheet, DateTimePicker, Slider, Menu, etc.), and platform-specific SwiftUI (@expo/ui/swift-ui, iOS only) and Jetpack Compose (@expo/ui/jetpack-compose, Android only) trees and modifiers. Use when adding or reviewing @expo/ui Host/RNHostView trees, building native-feeling UI where standard React Native components fall short (grouped settings forms with toggles, sections, menus, sheets, pickers, sliders), choosing between universal and platform-specific components, or replacing an RN community UI library with a native @expo/ui equivalent. Not for custom native modules, Expo Router navigation, Reanimated, or data fetching.
Full skill instructions
@expo/ui)@expo/ui renders real native UI from React: SwiftUI on iOS, Jetpack Compose on Android. It also ships drop-in replacements for migrating off RN community UI libraries.
These instructions track the latest Expo SDK. The universal layer requires SDK 56+ and works in Expo Go — no custom build needed. Drop-in replacements and the platform-specific layers also exist on SDK 55. For component details on a specific SDK, refer to the Expo UI docs for that version.
npx expo install @expo/ui
Every @expo/ui tree — universal or platform-specific — must be wrapped in Host.
Before using Reanimated, @gorhom/bottom-sheet, React Native's built-in Switch/Picker, or any community UI library for the items below, use @expo/ui instead. Only fall back to RN built-ins when @expo/ui is missing the component.
| Need | Use |
|---|---|
| Slide-up sheet / bottom sheet | BottomSheet from @expo/ui — not Reanimated or @gorhom/bottom-sheet |
| Grouped native list rows (settings/form-style) | List + ListItem from @expo/ui — not FlatList (see note below) |
| Toggle | Switch from @expo/ui |
| Slider | Slider from @expo/ui |
| Date/time picker | @expo/ui/community/datetimepicker |
| Menu | Menu from @expo/ui |
| Form section with label | FieldGroup from @expo/ui |
| Collapsible section | Collapsible from @expo/ui |
Listis NOT a virtualized scrolling list. It renders native grouped table rows — the visual look of an iOS Settings screen or a form section, with disclosure indicators and native row styling. EachListItemis a native node on the JS thread; rows are not recycled. For any list with large or unknown-length data (feeds, search results, catalogs), useFlatListorFlashListinstead.Listis the right choice for short, fixed-length groups: a settings screen, a detail panel's rows, a fixed menu.
BottomSheet example (use this for map pin details, action sheets, detail panels — not Reanimated):
import { Host, BottomSheet, Column, Text } from '@expo/ui';
import { useState } from 'react';
export default function MapScreen() {
const [isOpen, setIsOpen] = useState(false);
return (
<View style={{ flex: 1 }}>
<MapView onMarkerPress={() => setIsOpen(true)} />
<Host>
<BottomSheet
isPresented={isOpen}
onDismiss={() => setIsOpen(false)}
snapPoints={['half', 'full']}
>
<Column>
<Text>Café name</Text>
<Text>Address</Text>
</Column>
</BottomSheet>
</Host>
</View>
);
}
BottomSheet uses isPresented/onDismiss — not isOpened, isOpen, onIsOpenedChange, or onChange (those are @gorhom/bottom-sheet props and will silently do nothing). snapPoints accepts 'half', 'full', { fraction: 0.5 }, or { height: 400 } and is optional (auto-sizes to content when omitted).
Work down this list and stop at the first layer that meets the need:
Universal components — start here. Import from the @expo/ui root. One component tree runs unmodified on iOS, Android, and web from a single source (Compose on Android, SwiftUI on iOS, react-native-web/react-dom on web). No platform file splits. → ./references/universal.md
Platform-specific (SwiftUI / Jetpack Compose). Import from @expo/ui/swift-ui or @expo/ui/jetpack-compose. Use only when the universal layer is missing a component or modifier you need, or when you need platform-specific behavior or optimization. Downside: you write two trees and split them into .ios.tsx / .android.tsx files (or branch on Platform.OS) — more code to maintain.
@expo/ui/swift-uiis iOS-only.@expo/ui/jetpack-composeis Android-only. Importing either in a file that runs on the other platform will crash at runtime with "Unable to get view config" errors. Isolate platform-specific trees in.ios.tsx/.android.tsxfiles placed incomponents/(never insideapp/— Expo Router does not support platform extensions for route files), or guard withPlatform.OSin a regular route file.Hostmust always be imported from@expo/ui(the universal package root), not from the platform-specific sub-packages. →./references/swift-ui.mdand./references/jetpack-compose.md
Already using an RN community UI library? @expo/ui also ships drop-in replacements — API-compatible swaps for popular libraries (@gorhom/bottom-sheet, @react-native-community/datetimepicker, and more), imported from @expo/ui/community/<name>. This is a migration side-path for replacing an existing dependency, not a step in the universal-vs-platform decision above. → ./references/drop-in-replacements.md
Consult these resources as needed:
references/
universal.md Universal @expo/ui components and when to use them (SDK 56+)
drop-in-replacements.md API-compatible replacements for RN community UI libraries
swift-ui.md Platform-specific iOS UI: @expo/ui/swift-ui components, modifiers, RNHostView, useNativeState
jetpack-compose.md Platform-specific Android UI: @expo/ui/jetpack-compose components, modifiers, LazyColumn caveat, icons, useNativeState
If you encounter errors, misleading or outdated information in this skill, report it so Expo can improve:
npx --yes submit-expo-feedback@latest --category skills --subject "expo-ui" "<actionable feedback>"
Only submit when you have something specific and actionable to report. Include as much relevant context as possible. If an AI agent repeatedly failed or the user had to take over an Expo task, load the expo-skill-feedback skill and follow its eval-candidate flow instead of reusing the command above.
expo brownfield
Framework (OSS). Navigation and routing for Expo Router. Covers file-based routes, groups and dynamic routes, folder organization, Link with previews and context menus, native Stack, page titles, modals and form sheets, NativeTabs, headers and toolbars, and header search bars.
Safely upgrade Expo SDK versions with migration guidance and breaking change resolution.
Framework (OSS). Use when implementing or debugging ANY network request, API call, or data fetching. Covers fetch API, React Query, SWR, error handling, caching, offline support, and Expo Router data loaders (`useLoaderData`).
Framework (OSS). Expo's official example projects - the expo/examples repo of ~70 `with-*` integrations (Stripe, Clerk, Supabase, OpenAI, maps, Reanimated, SQLite, Skia, NativeWind, and more). Use when integrating a third-party library or service into an existing Expo app and you want the canonical, version-matched pattern to adapt, or when scaffolding a new project from one with `npx create-expo --example`.
Deploy Expo apps to production with EAS Build and app store submission workflows.
Evaluate Expo skills in this repo end-to-end - trigger accuracy, generated code quality, and runtime screenshots on iOS simulator and Android emulator via Expo Go (web optional). Use when the user wants to eval an Expo skill, test that a skill produces working code, benchmark a skill with device screenshots, or verify a skill's output renders correctly.
EAS service (paid). Helps understand and write EAS workflow YAML files for Expo projects. Use this skill when the user asks about CI/CD or workflows in an Expo or EAS context, mentions .eas/workflows/, or wants help with EAS build pipelines or deployment automation.
Framework (OSS). Use Expo DOM components to run web code in a webview on native and as-is on web. Migrate web code to native incrementally. For the end-to-end migration of a whole web app, use the expo-web-to-native skill.
EAS service (paid). Run and control a user's app on a remote iOS/Android simulator hosted on EAS cloud. Read before running any `eas simulator:*` commands - it has the current syntax for this experimental API. Use whenever the user needs a simulator they can't run locally - 'run my app on a cloud simulator', 'use eas simulator to run/install/screenshot my app', 'I'm on Linux/Cursor and need an iOS device', 'no sim on this box / headless CI', 'let an agent click through my app and screenshot it', 'test my dev build on a remote sim with live reload', 'stream a sim to my browser' - even when they don't say 'EAS Simulator' or 'cloud'. On a host WITHOUT a local simulator (Linux, CI, cloud sandbox) it's the default; on macOS, do NOT auto-trigger for a plain 'run on the simulator' - use it only for a cloud/remote/shareable sim, an iOS version they lack, or an agent-driven session. NOT for local sims (expo run:ios, Xcode, Android Studio), EAS Build/Update, web preview, or physical devices.
Framework (OSS). Add an iOS App Clip target to an Expo app. Use when the user mentions App Clip, AASA, apple-app-site-association, appclips, smart app banner, or wants to ship a lightweight iOS Clip invoked from a URL alongside their parent app.
Framework (OSS). Migrate an existing web React app to a native iOS/Android app with Expo. Use when the user wants to turn a website into a mobile app, port a Next.js/Vite/CRA React codebase to React Native, reuse web code on native incrementally, or asks how web idioms (the DOM, CSS, React Router, localStorage, window) map to native. This is the end-to-end migration guide; use the `expo-dom` skill for the DOM-component mechanism itself.
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