# @tanstack/ai-react

React hooks for TanStack AI, providing convenient React bindings for the headless client.

## Installation

```bash
npm install @tanstack/ai-react
```

## `useChat(options?)`

Main hook for managing chat state in React with full type safety.

```typescript
import { useChat, fetchServerSentEvents } from "@tanstack/ai-react";
import { 
  clientTools, 
  createChatClientOptions, 
  type InferChatMessages 
} from "@tanstack/ai-client";

function ChatComponent() {
  // Create client tool implementations
  const updateUI = updateUIDef.client((input) => {
    setNotification(input.message);
    return { success: true };
  });

  // Create typed tools array (no 'as const' needed!)
  const tools = clientTools(updateUI);

  const chatOptions = createChatClientOptions({
    connection: fetchServerSentEvents("/api/chat"),
    tools,
  });

  // Fully typed messages!
  type ChatMessages = InferChatMessages<typeof chatOptions>;

  const { messages, sendMessage, isLoading, error, addToolApprovalResponse } =
    useChat(chatOptions);

  return <div>{/* Chat UI with typed messages */}</div>;
}
```

### Options

Extends `ChatClientOptions` from `@tanstack/ai-client`:

- `connection` - Connection adapter (required)
- `tools?` - Array of client tool implementations (with `.client()` method)
- `initialMessages?` - Initial messages array
- `id?` - Unique identifier for this chat instance
- `body?` - Additional body parameters to send
- `onResponse?` - Callback when response is received
- `onChunk?` - Callback when stream chunk is received
- `onFinish?` - Callback when response finishes
- `onError?` - Callback when error occurs
- `streamProcessor?` - Stream processing configuration

**Note:** Client tools are now automatically executed - no `onToolCall` callback needed!

### Returns

```typescript
interface UseChatReturn {
  messages: UIMessage[];
  sendMessage: (content: string) => Promise<void>;
  append: (message: ModelMessage | UIMessage) => Promise<void>;
  addToolResult: (result: {
    toolCallId: string;
    tool: string;
    output: any;
    state?: "output-available" | "output-error";
    errorText?: string;
  }) => Promise<void>;
  addToolApprovalResponse: (response: {
    id: string;
    approved: boolean;
  }) => Promise<void>;
  reload: () => Promise<void>;
  stop: () => void;
  isLoading: boolean;
  error: Error | undefined;
  setMessages: (messages: UIMessage[]) => void;
  clear: () => void;
}
```

## Connection Adapters

Re-exported from `@tanstack/ai-client` for convenience:

```typescript
import {
  fetchServerSentEvents,
  fetchHttpStream,
  stream,
  type ConnectionAdapter,
} from "@tanstack/ai-react";
```

## Example: Basic Chat

```typescript
import { useState } from "react";
import { useChat, fetchServerSentEvents } from "@tanstack/ai-react";

export function Chat() {
  const [input, setInput] = useState("");

  const { messages, sendMessage, isLoading } = useChat({
    connection: fetchServerSentEvents("/api/chat"),
  });

  const handleSubmit = (e: React.FormEvent) => {
    e.preventDefault();
    if (input.trim() && !isLoading) {
      sendMessage(input);
      setInput("");
    }
  };

  return (
    <div>
      <div>
        {messages.map((message) => (
          <div key={message.id}>
            <strong>{message.role}:</strong>
            {message.parts.map((part, idx) => {
              if (part.type === "thinking") {
                return (
                  <div key={idx} className="text-sm text-gray-500 italic">
                    💭 Thinking: {part.content}
                  </div>
                );
              }
              if (part.type === "text") {
                return <span key={idx}>{part.content}</span>;
              }
              return null;
            })}
          </div>
        ))}
      </div>
      <form onSubmit={handleSubmit}>
        <input
          value={input}
          onChange={(e) => setInput(e.target.value)}
          disabled={isLoading}
        />
        <button type="submit" disabled={isLoading}>
          Send
        </button>
      </form>
    </div>
  );
}
```

## Example: Tool Approval

```typescript
import { useChat, fetchServerSentEvents } from "@tanstack/ai-react";

export function ChatWithApproval() {
  const { messages, sendMessage, addToolApprovalResponse } = useChat({
    connection: fetchServerSentEvents("/api/chat"),
  });

  return (
    <div>
      {messages.map((message) =>
        message.parts.map((part) => {
          if (
            part.type === "tool-call" &&
            part.state === "approval-requested" &&
            part.approval
          ) {
            return (
              <div key={part.id}>
                <p>Approve: {part.name}</p>
                <button
                  onClick={() =>
                    addToolApprovalResponse({
                      id: part.approval!.id,
                      approved: true,
                    })
                  }
                >
                  Approve
                </button>
                <button
                  onClick={() =>
                    addToolApprovalResponse({
                      id: part.approval!.id,
                      approved: false,
                    })
                  }
                >
                  Deny
                </button>
              </div>
            );
          }
          return null;
        })
      )}
    </div>
  );
}
```

## Example: Client Tools with Type Safety

```typescript
import { useChat, fetchServerSentEvents } from "@tanstack/ai-react";
import { 
  clientTools, 
  createChatClientOptions, 
  type InferChatMessages 
} from "@tanstack/ai-client";
import { updateUIDef, saveToStorageDef } from "./tool-definitions";
import { useState } from "react";

export function ChatWithClientTools() {
  const [notification, setNotification] = useState(null);

  // Create client implementations
  const updateUI = updateUIDef.client((input) => {
    // ✅ input is fully typed!
    setNotification({ message: input.message, type: input.type });
    return { success: true };
  });

  const saveToStorage = saveToStorageDef.client((input) => {
    localStorage.setItem(input.key, input.value);
    return { saved: true };
  });

  // Create typed tools array (no 'as const' needed!)
  const tools = clientTools(updateUI, saveToStorage);

  const { messages, sendMessage } = useChat({
    connection: fetchServerSentEvents("/api/chat"),
    tools, // ✅ Automatic execution, full type safety
  });

  return (
    <div>
      {messages.map((message) =>
        message.parts.map((part) => {
          if (part.type === "tool-call" && part.name === "updateUI") {
            // ✅ part.input and part.output are fully typed!
            return <div>Tool executed: {part.name}</div>;
          }
        })
      )}
    </div>
  );
}
```

## `createChatClientOptions(options)`

Helper to create typed chat options (re-exported from `@tanstack/ai-client`).

```typescript
import { 
  clientTools, 
  createChatClientOptions, 
  type InferChatMessages 
} from "@tanstack/ai-client";

// Create typed tools array (no 'as const' needed!)
const tools = clientTools(tool1, tool2);

const chatOptions = createChatClientOptions({
  connection: fetchServerSentEvents("/api/chat"),
  tools,
});

type Messages = InferChatMessages<typeof chatOptions>;
```

## Types

Re-exported from `@tanstack/ai-client`:

- `UIMessage<TTools>` - Message type with tool type parameter
- `MessagePart<TTools>` - Message part with tool type parameter
- `TextPart` - Text content part
- `ThinkingPart` - Thinking content part
- `ToolCallPart<TTools>` - Tool call part (discriminated union)
- `ToolResultPart` - Tool result part
- `ChatClientOptions<TTools>` - Chat client options
- `ConnectionAdapter` - Connection adapter interface
- `InferChatMessages<T>` - Extract message type from options

Re-exported from `@tanstack/ai`:

- `toolDefinition()` - Create isomorphic tool definition
- `ToolDefinitionInstance` - Tool definition type
- `ClientTool` - Client tool type
- `ServerTool` - Server tool type

## Next Steps

- [Getting Started](../getting-started/quick-start) - Learn the basics
- [Tools Guide](../tools/tools) - Learn about the isomorphic tool system
- [Client Tools](../tools/client-tools) - Learn about client-side tools