Build a mobile agent app

The Agent SDK mobile app is a complete Expo and React Native client for persistent Letta agents. It can connect to Letta Cloud or directly to a Letta App Server running on your own computer.

Use this demo when you want to study a mobile interface with conversation history, streaming, tools, approvals, interruption, queued messages, image attachments, and reconnect handling already wired to the portable Agent SDK.

Run the app

Clone the repository and start the iOS or Android build:

git clone https://github.com/letta-ai/agent-sdk-mobile-app.git
cd agent-sdk-mobile-app
bun install
bun run ios
# or: bun run android

You can also use npm install and the equivalent npm scripts.

The first screen offers two connection choices:

• Letta Cloud opens the browser for OAuth or accepts a Letta API key. The app stores credentials in the device keychain with expo-secure-store.
• Your own server connects to a Letta App Server over WebSocket. Start one on the computer where you want the agent to run tools:

npm install -g @letta-ai/letta-code
openssl rand -hex 24 > /tmp/ws-token
letta server --listen ws://0.0.0.0:4610 \
  --ws-auth capability-token \
  --ws-token-file /tmp/ws-token

Enter ws://<your-machine>:4610 and the generated token in the app. Use TLS or a private network when the server is available beyond your local network. An agent connected to this server can read files and run commands on that computer.

What it demonstrates

• Browsing and managing agents and conversations through the portable client
• Streaming assistant text, reasoning, tool calls, and tool results
• Reducing live events and saved history with createTranscriptAccumulator()
• Showing tool approval requests and changing permission modes
• Interrupting a turn and queuing follow-up messages
• Sending screenshots and photos as image input
• Reconnecting after the app moves between foreground and background
• Keeping Cloud credentials in the device keychain

Follow the SDK integration

The main SDK path is intentionally small:

File	What it shows
src/lib/letta/ChatSession.ts	Resume a session, consume stream(), resolve approvals, interrupt, and queue messages
src/lib/letta/transcriptProjection.ts	Project SDK transcript rows into mobile render state
src/lib/letta/api.ts	Manage agents, conversations, models, and message history through the portable client
src/lib/letta/model.ts	Define the state shared by the real and mock transports
src/lib/letta/mockSession.ts	Render every UI state without credentials or a running server

The app imports @letta-ai/letta-agent-sdk/client, so its UI code works in React Native without Node.js runtime dependencies. Run the /gallery route to inspect all component states against the mock transport.

For the full screen map and connection lifecycle, read the repository’s docs/design-doc.md and docs/architecture.md.