assistant-ui

SKILL.md

assistant-ui

Always consult assistant-ui.com/llms.txt for the 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                         │
│   useAui, useAuiState, useAuiEvent │
└─────────────────────────┬───────────────────────────────┘
                          │
┌─────────────────────────▼───────────────────────────────┐
│                    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-stream
Streaming protocol

assistant-cloud
Cloud persistence

Quick Start

import { AssistantRuntimeProvider } from "@assistant-ui/react";
import { Thread } from "@/components/assistant-ui/thread";
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 { useAui, useAuiState } from "@assistant-ui/react";

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

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