AI Sdk UI

AI SDK UI - Frontend React Hooks

Frontend React hooks for AI-powered user interfaces with Vercel AI SDK v5.

Version: AI SDK v5.0.116 (Stable) Framework: React 18+, Next.js 15+ Last Updated: 2025-12-22

Table of Contents

1. Quick Start
2. When to Load References
3. useChat Hook
4. useCompletion Hook
5. useObject Hook
6. Next.js Integration
7. Top UI Errors & Solutions
8. Streaming Best Practices
9. When to Use This Skill
10. Package Versions

Quick Start (5 Minutes)

Installation

bun add ai @ai-sdk/openai  # preferred
# or: bun add ai @ai-sdk/openai

Basic Chat Component (v5)

// app/chat/page.tsx
'use client';
import { useChat } from 'ai/react';
import { useState, FormEvent } from 'react';

export default function Chat() {
  const { messages, sendMessage, isLoading } = useChat({
    api: '/api/chat',
  });
  const [input, setInput] = useState('');

  const handleSubmit = (e: FormEvent) => {
    e.preventDefault();
    sendMessage({ content: input });
    setInput('');
  };

  return (
    <div>
      <div>
        {messages.map(m => (
          <div key={m.id}>
            <strong>{m.role}:</strong> {m.content}
          </div>
        ))}
      </div>
      <form
        <input
          value={input}
          => setInput(e.target.value)}
          placeholder="Type a message..."
          disabled={isLoading}
        />
      </form>
    </div>
  );
}

API Route (Next.js App Router)

// app/api/chat/route.ts
import { streamText } from 'ai';
import { openai } from '@ai-sdk/openai';

export async function POST(req: Request) {
  const { messages } = await req.json();

  const result = streamText({
    model: openai('gpt-4-turbo'),
    messages,
  });

  return result.toDataStreamResponse();
}

Result: A functional chat interface with streaming AI responses in ~10 lines of frontend code.

When to Load References

For detailed implementation guides, API references, and advanced patterns, load the following reference files:

useChat Hook - Complete Reference

Basic Usage (v5 Pattern)

'use client';
import { useChat } from 'ai/react';
import { useState, FormEvent } from 'react';

export default function ChatComponent() {
  const { messages, sendMessage, isLoading, error } = useChat({
    api: '/api/chat',
  });
  const [input, setInput] = useState('');

  const handleSubmit = (e: FormEvent) => {
    e.preventDefault();
    if (!input.trim()) return;

    sendMessage({ content: input });
    setInput('');
  };

  return (
    <div className="flex flex-col h-screen">
      {/* Messages */}
      <div className="flex-1 overflow-y-auto p-4">
        {messages.map(message => (
          <div
            key={message.id}
            className={message.role === 'user' ? 'text-right' : 'text-left'}
          >
            <div className="inline-block p-2 rounded bg-gray-100">
              {message.content}
            </div>
          </div>
        ))}
        {isLoading && <div className="text-gray-500">AI is thinking...</div>}
      </div>

      {/* Input */}
      <form className="p-4 border-t">
        <input
          value={input}
          => setInput(e.target.value)}
          placeholder="Type a message..."
          disabled={isLoading}
          className="w-full p-2 border rounded"
        />
      </form>

      {/* Error */}
      {error && <div className="text-red-500 p-4">{error.message}</div>}
    </div>
  );
}

Full API Reference

const {
  // Messages
  messages,           // Message[] - Chat history
  setMessages,        // (messages: Message[]) => void - Update messages

  // Actions
  sendMessage,        // (message: { content: string }) => void - Send message (v5)
  reload,             // () => void - Reload last response
  stop,               // () => void - Stop current generation

  // State
  isLoading,          // boolean - Is AI responding?
  error,              // Error | undefined - Error if any

  // Data
  data,               // any[] - Custom data from stream
  metadata,           // object - Response metadata
} = useChat({
  // Required
  api: '/api/chat',   // API endpoint

  // Optional
  id: 'chat-1',       // Chat ID for persistence
  initialMessages: [], // Initial messages (controlled mode)

  // Callbacks
  onFinish: (message, options) => {},  // Called when response completes
  onError: (error) => {},              // Called on error

  // Configuration
  headers: {},        // Custom headers
  body: {},           // Additional body data
  credentials: 'same-origin', // Fetch credentials

  // Streaming
  streamProtocol: 'data', // 'data' | 'text' (default: 'data')
});

v4 → v5 Breaking Changes

CRITICAL: useChat no longer manages input state in v5!

v4 (OLD - DON'T USE):

const { messages, input, handleInputChange, handleSubmit, append } = useChat();

<form
  <input value={input} />
</form>

v5 (NEW - CORRECT):

const { messages, sendMessage } = useChat();
const [input, setInput] = useState('');

<form => {
  e.preventDefault();
  sendMessage({ content: input });
  setInput('');
}}>
  <input value={input} => setInput(e.target.value)} />
</form>

Summary of v5 Changes:

1. Input management removed: input, handleInputChange, handleSubmit no longer exist
2. append() → sendMessage(): New method for sending messages
3. onResponse removed: Use onFinish instead
4. initialMessages → controlled mode: Use messages prop for full control
5. maxSteps removed: Handle on server-side only

See references/use-chat-migration.md for complete migration guide.

Advanced Features: useChat supports tool calling (display message.toolInvocations), file attachments (experimental_attachments), and message persistence (localStorage with id + initialMessages). See official docs for implementation examples.

useCompletion & useObject Hooks

useCompletion: For single-prompt completions (not multi-turn chat). Returns { completion, complete, isLoading }. Call complete(prompt) to generate. API route uses streamText().

useObject: Stream structured JSON with live updates using Zod schemas. Returns { object, submit, isLoading } where object is Partial<T> that updates progressively. API route uses streamObject().

See official docs for complete API references and examples.

Next.js Integration

Complete working examples for both App Router and Pages Router with full chat UI components, API routes, and proper streaming setup.

📖 Load references/nextjs-integration.md for complete implementation code including:

• App Router: Full chat page with auto-scroll, loading states, error handling, and API route
• Pages Router: Complete chat implementation with proper streaming setup
• Key Differences: toDataStreamResponse() vs pipeDataStreamToResponse()

Top UI Errors & Solutions

See references/top-ui-errors.md for complete documentation. Quick reference:

1. useChat Failed to Parse Stream

Error: SyntaxError: Unexpected token in JSON at position X

Cause: API route not returning proper stream format.

Solution:

// ✅ CORRECT
return result.toDataStreamResponse();

// ❌ WRONG
return new Response(result.textStream);

2. useChat No Response

Cause: API route not streaming correctly.

Solution:

// App Router - use toDataStreamResponse()
export async function POST(req: Request) {
  const result = streamText({ /* ... */ });
  return result.toDataStreamResponse(); // ✅
}

// Pages Router - use pipeDataStreamToResponse()
export default async function handler(req, res) {
  const result = streamText({ /* ... */ });
  return result.pipeDataStreamToResponse(res); // ✅
}

3. Streaming Not Working When Deployed

Cause: Deployment platform buffering responses.

Solution: Vercel auto-detects streaming. Other platforms may need configuration.

4. Stale Body Values with useChat

Cause: body option captured at first render only.

Solution:

// ❌ WRONG - body captured once
const { userId } = useUser();
const { messages } = useChat({
  body: { userId },  // Stale!
});

// ✅ CORRECT - use controlled mode
const { userId } = useUser();
const { messages, sendMessage } = useChat();

sendMessage({
  content: input,
  data: { userId },  // Fresh on each send
});

5. React Maximum Update Depth

Cause: Infinite loop in useEffect.

Solution:

// ❌ WRONG
useEffect(() => {
  saveMessages(messages);
}, [messages, saveMessages]); // saveMessages triggers re-render!

// ✅ CORRECT
useEffect(() => {
  saveMessages(messages);
}, [messages]); // Only depend on messages

See references/top-ui-errors.md for 7 more common errors.

Streaming Best Practices

Performance

Always use streaming for better UX:

// ✅ GOOD - Streaming (shows tokens as they arrive)
const { messages } = useChat({ api: '/api/chat' });

// ❌ BAD - Non-streaming (user waits for full response)
const response = await fetch('/api/chat', { method: 'POST' });

UX Patterns

Show loading states:

{isLoading && <div>AI is typing...</div>}

Provide stop button:

{isLoading && <button

Auto-scroll to latest message:

useEffect(() => {
  messagesEndRef.current?.scrollIntoView({ behavior: 'smooth' });
}, [messages]);

Disable input while loading:

<input disabled={isLoading} />

See references/streaming-patterns.md for comprehensive best practices.

When to Use This Skill

Use ai-sdk-ui When:

• Building React chat interfaces
• Implementing AI completions in UI
• Streaming AI responses to frontend
• Building Next.js AI applications
• Handling chat message state
• Displaying tool calls in UI
• Managing file attachments with AI
• Migrating from v4 to v5 (UI hooks)
• Encountering useChat/useCompletion errors

Don't Use When:

• Need backend AI functionality → Use ai-sdk-core instead
• Building non-React frontends (Svelte, Vue) → Check official docs
• Need Generative UI / RSC → See https://ai-sdk.dev/docs/ai-sdk-rsc
• Building native apps → Different SDK required

Related Skills:

• ai-sdk-core - Backend text generation, structured output, tools, agents
• Compose both for full-stack AI applications

Package Versions

Required:

{
  "dependencies": {
    "ai": "^5.0.116",
    "@ai-sdk/openai": "^2.0.88",
    "react": "^18.2.0",
    "zod": "^3.23.8",
    "isomorphic-dompurify": "^2.16.0"
  }
}

Next.js:

{
  "dependencies": {
    "next": "^14.0.0",
    "react": "^18.2.0",
    "react-dom": "^18.2.0"
  }
}

Version Notes:

• AI SDK v5.0.116+ (stable)
• React 18+ (React 19 supported)
• Next.js 14+ recommended (13.4+ works)
• Zod 3.23.8+ for schema validation

Links to Official Documentation

Core UI Hooks:

• AI SDK UI Overview: https://ai-sdk.dev/docs/ai-sdk-ui/overview
• useChat: https://ai-sdk.dev/docs/ai-sdk-ui/chatbot
• useCompletion: https://ai-sdk.dev/docs/ai-sdk-ui/completion
• useObject: https://ai-sdk.dev/docs/ai-sdk-ui/object-generation

Advanced Topics (Link Only):

• Generative UI (RSC): https://ai-sdk.dev/docs/ai-sdk-rsc/overview
• Stream Protocols: https://ai-sdk.dev/docs/ai-sdk-ui/stream-protocols
• Message Metadata: https://ai-sdk.dev/docs/ai-sdk-ui/message-metadata

Next.js Integration:

• Next.js App Router: https://ai-sdk.dev/docs/getting-started/nextjs-app-router
• Next.js Pages Router: https://ai-sdk.dev/docs/getting-started/nextjs-pages-router

Migration & Troubleshooting:

• v4→v5 Migration: https://ai-sdk.dev/docs/migration-guides/migration-guide-5-0
• Troubleshooting: https://ai-sdk.dev/docs/troubleshooting
• Common Issues: https://ai-sdk.dev/docs/troubleshooting/common-issues

Vercel Deployment:

• Vercel Functions: https://vercel.com/docs/functions
• Streaming on Vercel: https://vercel.com/docs/functions/streaming

Templates

This skill includes the following templates in templates/:

1. use-chat-basic.tsx - Basic chat with manual input (v5 pattern)
2. use-chat-tools.tsx - Chat with tool calling UI rendering
3. use-chat-attachments.tsx - File attachments support
4. use-completion-basic.tsx - Basic text completion
5. use-object-streaming.tsx - Streaming structured data
6. nextjs-chat-app-router.tsx - Next.js App Router complete example
7. nextjs-chat-pages-router.tsx - Next.js Pages Router complete example
8. nextjs-api-route.ts - API route for both App and Pages Router
9. message-persistence.tsx - Save/load chat history
10. custom-message-renderer.tsx - Custom message components with markdown
11. package.json - Dependencies template

Reference Documents

See references/ for:

• use-chat-migration.md - Complete v4→v5 migration guide
• streaming-patterns.md - UI streaming best practices
• top-ui-errors.md - 12 common UI errors with solutions
• nextjs-integration.md - Next.js setup patterns
• links-to-official-docs.md - Organized links to official docs

Production Tested: WordPress Auditor (https://wordpress-auditor.webfonts.workers.dev) Last Updated: 2025-10-22