AI SDK v5 (legacy)

Reference for projects still on AI SDK v5. New projects should use v6.

AI SDK v5 is a legacy version. New projects should use AI SDK v6. v5 users stay on @assistant-ui/[email protected]; the latest line targets v6+.

Why legacy

AI SDK v6 introduced major API changes: async convertToModelMessages, a new tool schema, and toUIMessageStreamResponse(). v5 still works but no longer receives new features in @assistant-ui/react-ai-sdk. Pinning to @0.x keeps you on the v5-compatible surface.

This page is reference for existing v5 projects. Plan to migrate to v6 when feasible.

Setup

Install v5-compatible versions

npm install @assistant-ui/react @assistant-ui/[email protected] ai@^5 @ai-sdk/openai@^1 zod

Backend route

@/app/api/chat/route.ts

import { openai } from "@ai-sdk/openai";
import { streamText, tool } from "ai";
import type { Message } from "ai";
import { z } from "zod";

export const maxDuration = 30;

export async function POST(req: Request) {
  const { messages }: { messages: Message[] } = await req.json();
  const result = streamText({
    model: openai("gpt-4o"),
    messages,
    tools: {
      get_current_weather: tool({
        description: "Get the current weather",
        parameters: z.object({ city: z.string() }),
        execute: async ({ city }) => `The weather in ${city} is sunny`,
      }),
    },
  });
  return result.toDataStreamResponse();
}

Frontend

@/app/page.tsx

"use client";

import { Thread } from "@/components/assistant-ui/thread";
import { AssistantRuntimeProvider } from "@assistant-ui/react";
import { useChatRuntime } from "@assistant-ui/react-ai-sdk";

export default function Home() {
  const runtime = useChatRuntime();
  return (
    <AssistantRuntimeProvider runtime={runtime}>
      <div className="h-full">
        <Thread />
      </div>
    </AssistantRuntimeProvider>
  );
}

On @assistant-ui/react-ai-sdk versions older than 0.11.3, use useVercelUseChatRuntime with useChat from ai/react instead:

import { useChat } from "ai/react";
import { useVercelUseChatRuntime } from "@assistant-ui/react-ai-sdk";

const chat = useChat({ api: "/api/chat" });
const runtime = useVercelUseChatRuntime(chat);

Differences from v6

Feature	v5	v6
`ai` package	`ai@^5`	`ai@^6`
`@assistant-ui/react-ai-sdk`	`@0.x`	`@latest`
`@ai-sdk/openai`	`^1`	`^3`
Message type	`Message`	`UIMessage`
`convertToModelMessages`	Sync	Async (`await`)
Tool schema	`parameters: z.object({...})`	`inputSchema: zodSchema(z.object({...}))`
Response	`toDataStreamResponse()`	`toUIMessageStreamResponse()`

Migration to v6

When you are ready to upgrade:

Update ai from @^5 to @^6, and @assistant-ui/react-ai-sdk to the latest line.
Add await to convertToModelMessages(...) calls.
Convert tool schemas: parameters: z.object({...}) → inputSchema: zodSchema(z.object({...})).
Replace toDataStreamResponse() with toUIMessageStreamResponse().
Switch the Message type to UIMessage.

AI SDK provides codemods at ai-sdk.dev/docs/migration-guides/migration-guide-6-0 that handle most of the package-side rewrites.

AI SDK v6Current integration; what new projects should target.AI SDK v4 (legacy)The earlier legacy version using react-data-stream.