Mastra•5d ago

How to migrate off of `format:'aisdk'` with custom Next route?

We have a next.js app with an embedded mastra instance.

We have a custom

/api/chat

/api/chat

/api/chat

/api/chat that performs a bunch of business logic before streaming the response.

// /api/chat
export async function POST(req: Request) {
  // lots of business logic...

  const stream = await myAgent.stream(messages, {
    format: "aisdk", // Enable AI SDK v5 compatibility

// /api/chat
export async function POST(req: Request) {
  // lots of business logic...

  const stream = await myAgent.stream(messages, {
    format: "aisdk", // Enable AI SDK v5 compatibility

// /api/chat
export async function POST(req: Request) {
  // lots of business logic...

  const stream = await myAgent.stream(messages, {
    format: "aisdk", // Enable AI SDK v5 compatibility

// /api/chat
export async function POST(req: Request) {
  // lots of business logic...

  const stream = await myAgent.stream(messages, {
    format: "aisdk", // Enable AI SDK v5 compatibility

I'm following the upgrade guide here

it says:

The format: "aisdk" option in stream()/generate() methods is deprecated. Use the @mastra/ai-sdk package instead. Learn more in the Using Vercel AI SDK documentation.

When I follow that link it says to use

chatRoute()

chatRoute()

chatRoute()

chatRoute() which "automatically formats the agent stream into an AI SDK-compatible format".

example given:

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

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

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

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

This looks like nice DX if you're deploying a standalone mastra server, but does this even work if I'm embedding mastra into my next app?

Is there an equivalent way (as before) that I can use aisdk in my own api route?

_roamin_•12/11/25, 11:37 PM

Hey @ldp ! In your case you can use our stream transformer directly, like this example:

import { toAISdkStream } from "@mastra/ai-sdk";
import { createUIMessageStreamResponse } from "ai";

const weatherAgent = mastra.getAgent("weatherAgent");

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

  const stream = await weatherAgent.stream(messages, {
    memory: {
      thread: "example-user-id",
      resource: "weather-chat",
    },
  });

  return createUIMessageStreamResponse({
    stream: toAISdkStream(stream, { from: "agent" }),
  })
}

import { toAISdkStream } from "@mastra/ai-sdk";
import { createUIMessageStreamResponse } from "ai";

const weatherAgent = mastra.getAgent("weatherAgent");

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

  const stream = await weatherAgent.stream(messages, {
    memory: {
      thread: "example-user-id",
      resource: "weather-chat",
    },
  });

  return createUIMessageStreamResponse({
    stream: toAISdkStream(stream, { from: "agent" }),
  })
}

ldpOP•12/12/25, 3:30 AM

this looks perfect, will try this out tomorrow, thank you!

LekoArts•12/12/25, 8:46 AM

Once you upgrade to the v1 beta, it'll become even easier

https://mastra.ai/guides/v1/build-your-ui/ai-sdk-ui#framework-agnostic

Using AI SDK UI | Frameworks | Mastra Docs v1 Beta

Mastra v1 Beta: Learn how Mastra leverages the AI SDK UI library and how you can leverage it further with Mastra