# chatRoute()

Creates a chat route handler for streaming agent conversations using the AI SDK format. This function registers an HTTP `POST` endpoint that accepts messages, executes an agent, and streams the response back to the client in AI SDK-compatible format. You have to use it inside a [custom API route](https://mastra.ai/docs/server/custom-api-routes).

Use [`handleChatStream()`](https://mastra.ai/reference/ai-sdk/handle-chat-stream) if you need a framework-agnostic handler.

`chatRoute()` keeps the existing AI SDK v5/default behavior. If your app is typed against AI SDK v6, pass `version: 'v6'`.

> **Disconnect behavior:** `chatRoute()` forwards the incoming request's `AbortSignal` to `agent.stream()`. If the client disconnects, Mastra aborts the in-flight generation.
>
> If you want the server to continue generation and persist the final response after disconnect, build a [custom API route](https://mastra.ai/docs/server/custom-api-routes) around `agent.stream()` and call `consumeStream()` on the returned `MastraModelOutput`.

## Usage example

This example shows how to set up a chat route at the `/chat` endpoint that uses an agent with the ID `weatherAgent`.

```typescript
import { Mastra } from '@mastra/core'
import { chatRoute } from '@mastra/ai-sdk'

export const mastra = new Mastra({
  server: {
    apiRoutes: [
      chatRoute({
        path: '/chat',
        agent: 'weatherAgent',
      }),
    ],
  },
})
```

You can also use dynamic agent routing based on an `agentId`. The URL `/chat/weatherAgent` will resolve to the agent with the ID `weatherAgent`.

```typescript
import { Mastra } from '@mastra/core'
import { chatRoute } from '@mastra/ai-sdk'

export const mastra = new Mastra({
  server: {
    apiRoutes: [
      chatRoute({
        path: '/chat/:agentId',
      }),
    ],
  },
})
```

## Parameters

**version** (`'v5' | 'v6'`): Selects the AI SDK stream contract to emit. Omit it or pass \`'v5'\` for the existing default behavior. Pass \`'v6'\` when your app is typed against AI SDK v6 response helpers. (Default: `'v5'`)

**path** (`string`): The route path (e.g., \`/chat\` or \`/chat/:agentId\`). Include \`:agentId\` for dynamic agent routing. (Default: `'/chat/:agentId'`)

**agent** (`string`): The ID of the agent to use for this chat route. Required if the path doesn't include \`:agentId\`.

**defaultOptions** (`AgentExecutionOptions`): Default options passed to agent execution. These can include instructions, memory configuration, maxSteps, and other execution settings.

**sendStart** (`boolean`): Whether to send start events in the stream. (Default: `true`)

**sendFinish** (`boolean`): Whether to send finish events in the stream. (Default: `true`)

**sendReasoning** (`boolean`): Whether to include reasoning steps in the stream. (Default: `false`)

**sendSources** (`boolean`): Whether to include source citations in the stream. (Default: `false`)

## Additional configuration

You can use [`prepareSendMessagesRequest`](https://ai-sdk.dev/docs/reference/ai-sdk-ui/use-chat#transport.default-chat-transport.prepare-send-messages-request) to customize the request sent to the chat route, for example to pass additional configuration to the agent:

```typescript
const { error, status, sendMessage, messages, regenerate, stop } = useChat({
  transport: new DefaultChatTransport({
    api: 'http://localhost:4111/chat',
    prepareSendMessagesRequest({ messages }) {
      return {
        body: {
          messages,
          // Pass memory config
          memory: {
            thread: 'user-1',
            resource: 'user-1',
          },
        },
      }
    },
  }),
})
```