assistant-ui

Always consult assistant-ui.com/llms.txt for latest API.

React library for building AI chat interfaces with composable primitives.

References

• ./references/architecture.md -- Core architecture and layered system
• ./references/packages.md -- Package overview and selection guide

When to Use

Use Case	Best For
Chat UI from scratch	Full control over UX
Existing AI backend	Connects to any streaming backend
Custom message types	Tools, images, files, custom parts
Multi-thread apps	Built-in thread list management
Production apps	Cloud persistence, auth, analytics

Architecture

┌─────────────────────────────────────────────────────────┐
│                  UI Components (Primitives)             │
│    ThreadPrimitive, MessagePrimitive, ComposerPrimitive │
└─────────────────────────┬───────────────────────────────┘
                          │
┌─────────────────────────▼───────────────────────────────┐
│                   Context Hooks                         │
│   useAssistantApi, useAssistantState, useAssistantEvent │
└─────────────────────────┬───────────────────────────────┘
                          │
┌─────────────────────────▼───────────────────────────────┐
│                    Runtime Layer                        │
│  AssistantRuntime → ThreadRuntime → MessageRuntime      │
└─────────────────────────┬───────────────────────────────┘
                          │
┌─────────────────────────▼───────────────────────────────┐
│                   Adapters/Backend                      │
│   AI SDK · LangGraph · Custom · Cloud Persistence       │
└─────────────────────────────────────────────────────────┘

Pick a Runtime

Using AI SDK?
├─ Yes → useChatRuntime (recommended)
└─ No
   ├─ External state (Redux/Zustand)? → useExternalStoreRuntime
   ├─ LangGraph agent? → useLangGraphRuntime
   ├─ AG-UI protocol? → useAgUiRuntime
   ├─ A2A protocol? → useA2ARuntime
   └─ Custom API → useLocalRuntime

Core Packages

Package	Purpose
@assistant-ui/react	UI primitives & hooks
@assistant-ui/react-ai-sdk	Vercel AI SDK v6 adapter
@assistant-ui/react-langgraph	LangGraph adapter
@assistant-ui/react-markdown	Markdown rendering
@assistant-ui/styles	Pre-built CSS
assistant-stream	Streaming protocol
assistant-cloud	Cloud persistence

Quick Start

import { AssistantRuntimeProvider, Thread } from "@assistant-ui/react";
import { useChatRuntime, AssistantChatTransport } from "@assistant-ui/react-ai-sdk";

function App() {
  const runtime = useChatRuntime({
    transport: new AssistantChatTransport({ api: "/api/chat" }),
  });
  return (
    <AssistantRuntimeProvider runtime={runtime}>
      <Thread />
    </AssistantRuntimeProvider>
  );
}

State Access

import { useAssistantApi, useAssistantState } from "@assistant-ui/react";

const api = useAssistantApi();
api.thread().append({ role: "user", content: [{ type: "text", text: "Hi" }] });
api.thread().cancelRun();

const messages = useAssistantState(s => s.thread.messages);
const isRunning = useAssistantState(s => s.thread.isRunning);

Related Skills

• /setup - Installation and configuration
• /primitives - UI component customization
• /runtime - State management deep dive
• /tools - Tool registration and UI
• /streaming - Streaming protocols
• /cloud - Persistence and auth
• /thread-list - Multi-thread management
• /update - Version updates and migrations