A native chat app built with assistant-ui and Expo. It runs on iOS, Android, and the web from a single codebase, and is styled to match the assistant-ui web kit: a clean, neutral, ChatGPT-grade look with subtle hairline borders.

The chat is powered by @assistant-ui/react-native with the AI SDK runtime (@assistant-ui/react-ai-sdk). The example leans on native Expo APIs throughout:

SF Symbols (expo-symbols) for native iconography on iOS, with a Material Icons fallback on Android and the web.
Haptics (expo-haptics) for tactile feedback on send, stop, and selection.
Image picker (expo-image-picker) and expo-image for attachments.
Clipboard (expo-clipboard) so the copy action works natively.
A native drawer (@react-navigation/drawer) for the thread list, with a swipe gesture to switch conversations.

It follows the assistant-ui component conventions: MessagePrimitive.Parts for message rendering, AuiIf for declarative state-driven UI, the ThreadList / ThreadListItem primitives for the drawer, and a "use generative" toolkit (components/assistant-ui/tools.tsx) that renders weather cards inline.

Get started

Install dependencies from the repository root:
```
pnpm install
```
Configure the chat backend. Copy .env.example to .env and set your key:
```
cp .env.example .env
```
The bundled API route (app/api/chat+api.ts) needs OPENAI_API_KEY. To point the app at a separately hosted backend instead, set EXPO_PUBLIC_CHAT_ENDPOINT_URL.
Start the app:
```
pnpm --filter with-expo start
```
From there you can open it in the iOS simulator, an Android emulator, or the browser.

Project structure

app/_layout.tsx wires the runtime, the toolkit, and the drawer navigation.
app/index.tsx renders the Thread.
components/assistant-ui/ holds the composer, message, action bar, branch picker, and tool UIs.
components/thread-list/ holds the drawer thread list.
constants/theme.ts and hooks/use-theme.ts define the shared design tokens.
components/ui/icon.tsx is the cross-platform icon (SF Symbols on iOS, Material Icons elsewhere).

README.md

assistant-ui + Expo

Get started

Project structure

Learn more