toAISdkV4Messages()

Converts messages from various input formats to AI SDK V4 UI message format. This function accepts messages in multiple formats (strings, AI SDK V4/V5 messages, Mastra DB messages, etc.) and normalizes them to the AI SDK V4 UIMessage format, which is suitable for use with AI SDK UI components like useChat().

Usage example

app/chat/page.tsx

import { toAISdkV4Messages } from "@mastra/ai-sdk";
import { useChat } from "ai/react"; // AI SDK V4

// Stored messages from your database, memory or API
const storedMessages = [
  { id: "1", role: "user", parts: [{ type: "text", text: "Hello" }] },
  { id: "2", role: "assistant", parts: [{ type: "text", text: "Hi there!" }] }
];

export default function Chat() {
  const { messages } = useChat({
    initialMessages: toAISdkV4Messages(storedMessages)
  });

  return (
    <div>
      {messages.map((message) => (
        <div key={message.id}>
          {message.role}: {message.content}
        </div>
      ))}
    </div>
  );
}

Parameters

messages:

MessageListInput

Messages to convert. Can be a string, array of strings, a single message object, or an array of message objects in any supported format.

Returns

Returns an array of AI SDK V4 UIMessage objects with the following structure:

id:

string

Unique message identifier.

role:

'user' | 'assistant' | 'system'

The role of the message sender.

content:

string

Text content of the message.

parts:

UIMessagePart[]

Array of UI parts including text, tool-invocation, file, reasoning, source, and step markers.

createdAt:

Date

Message creation timestamp.

toolInvocations?:

ToolInvocation[]

Array of tool invocations for assistant messages.

experimental_attachments?:

Attachment[]

File attachments on the message.

metadata?:

Record<string, unknown>

Custom metadata attached to the message.

Examples

Converting simple text messages

import { toAISdkV4Messages } from "@mastra/ai-sdk";

const messages = toAISdkV4Messages(["Hello", "How can I help you today?"]);
// Returns array of UIMessage objects with user role and content string

Loading messages with Mastra client

import { MastraClient } from "@mastra/client-js";
import { toAISdkV4Messages } from "@mastra/ai-sdk";

const client = new MastraClient();

const { messages } = await client.listThreadMessages("thread-id", { agentId: "myAgent" });
const uiMessages = toAISdkV4Messages(messages);