Chat History for LangGraph Cloud

Overview

With the help of assistant-cloud, you can add thread management and thread history capabilities to assistant-ui.
This guide will walk you through the process of integrating assistant-cloud with LangGraph Cloud.

Prerequisites

You need an assistant-cloud account to follow this guide.
You can sign up here: https://cloud.assistant-ui.com/

Setting up an assistant-cloud project

To get started, follow the steps below:

Create a new project on the assistant-cloud dashboard.
Navigate to the "Settings" tab and copy the Frontend API URL.
Add this URL to your .env file

NEXT_PUBLIC_ASSISTANT_BASE_URL=https://<your-frontend-api-url>

Connecting the runtime provider

Now that we have everything set up, let's write the code for the runtime provider.

The code below is a simple LangGraph runtime provider that uses the assistant-cloud API to create and manage threads.

const useMyLangGraphRuntime = () => {
  const threadListItemRuntime = useThreadListItemRuntime();
  const runtime = useLangGraphRuntime({
    stream: async function* (messages) {
      const { externalId } = await threadListItemRuntime.initialize();
      if (!externalId) throw new Error("Thread not found");

      return sendMessage({ threadId: externalId, messages });
    },
    onSwitchToThread: async (externalId) => {
      const state = await getThreadState(externalId);
      return {
        messages:
          (state.values as { messages?: LangChainMessage[] }).messages ?? [],
      };
    },
  });

  return runtime;
};

export function MyRuntimeProvider({
  children,
}: Readonly<{
  children: React.ReactNode;
}>) {
  const { getToken } = useAuth();

  const cloud = useMemo(
    () =>
      new AssistantCloud({
        baseUrl: process.env["NEXT_PUBLIC_ASSISTANT_BASE_URL"]!,
        authToken: async () => getToken({ template: "assistant-ui" }),
      }),
    [getToken],
  );

  const runtime = useCloudThreadListRuntime({
    cloud,
    runtimeHook: useMyLangGraphRuntime,
    create: async () => {
      const { thread_id } = await createThread();
      return { externalId: thread_id };
    },
  });

  return (
    <AssistantRuntimeProvider runtime={runtime}>
      {children}
    </AssistantRuntimeProvider>
  );
}

Observe that the useMyLangGraphRuntime hook is extracted into a separate function. This hook will be mounted multiple times, once per active thread.

Displaying a ThreadList component

Now, you can add a ThreadList component to your application. This component will display a list of threads and allow users to switch between them.

npx shadcn@latest add "https://r.assistant-ui.com/thread-list"

<div className="grid grid-cols-[250px_1fr]">
  <ThreadList />
  <Thread />
</div>