Threads

Single-thread, cloud, and custom-database thread management.

Every assistant-ui runtime starts with a single in-memory thread. Multi-thread support is added through one of three mechanisms depending on which runtime you are using and where you want threads to live.

Single thread (default)

With no thread configuration, the runtime renders one thread that resets when the page reloads. Fine for prototypes, demos, and stateless interactions.

If you only want session persistence (single thread, durable across reloads), provide a history adapter instead of going to multi-thread.

Multi-thread paths

Three options. Choose based on what you want to own.

Path	Runtime	Who owns thread metadata	Best for
AssistantCloud	LocalRuntime and adapters built on it	assistant-cloud	You want it managed; auth, sync, persistence handled
RemoteThreadListRuntime	LocalRuntime and adapters built on it	Your database	You have your own backend and want full control
ExternalStoreThreadListAdapter	ExternalStoreRuntime only	Your store	You keep state in redux, zustand, etc.

AssistantCloud

AssistantCloud is the managed multi-thread service. Pass an instance to useLocalRuntime (or any adapter built on it) and threads, persistence, sync, and titles are handled for you.

import { useLocalRuntime } from "@assistant-ui/react";
import { AssistantCloud } from "assistant-cloud";

const cloud = new AssistantCloud({
  baseUrl: process.env.NEXT_PUBLIC_ASSISTANT_BASE_URL,
  anonymous: true,
});

const runtime = useLocalRuntime(modelAdapter, { cloud });

Framework adapters take cloud directly:

const runtime = useChatRuntime({ cloud });
const runtime = useLangGraphRuntime({ cloud /* stream, load, ... */ });
const runtime = useAdkRuntime({ cloud, stream });

See the cloud documentation for setup, auth, and self-host options.

RemoteThreadListRuntime (custom database)

useRemoteThreadListRuntime lets you back the thread list with any database while keeping the per-thread runtime simple. You provide a RemoteThreadListAdapter describing how to list, create, rename, archive, and delete threads.

Works with any LocalRuntime-based runtime, including framework adapters that build on it (react-ai-sdk, react-google-adk, react-a2a, useDataStreamRuntime).

app/MyProvider.tsx

"use client";

import {
  AssistantRuntimeProvider,
  useLocalRuntime,
  useRemoteThreadListRuntime,
  type RemoteThreadListAdapter,
} from "@assistant-ui/react";
import { createAssistantStream } from "assistant-stream";
import { modelAdapter } from "./model-adapter";

const adapter: RemoteThreadListAdapter = {
  async list() {
    const threads = await fetch("/api/threads").then((r) => r.json());
    return {
      threads: threads.map((t: any) => ({
        status: t.archived ? "archived" : "regular",
        remoteId: t.id,
        title: t.title,
      })),
    };
  },
  async initialize(localId) {
    const t = await fetch("/api/threads", {
      method: "POST",
      body: JSON.stringify({ localId }),
    }).then((r) => r.json());
    return { remoteId: t.id };
  },
  async rename(remoteId, title) {
    await fetch(`/api/threads/${remoteId}`, {
      method: "PATCH",
      body: JSON.stringify({ title }),
    });
  },
  async archive(remoteId) {
    await fetch(`/api/threads/${remoteId}/archive`, { method: "POST" });
  },
  async unarchive(remoteId) {
    await fetch(`/api/threads/${remoteId}/unarchive`, { method: "POST" });
  },
  async delete(remoteId) {
    await fetch(`/api/threads/${remoteId}`, { method: "DELETE" });
  },
  async fetch(remoteId) {
    const t = await fetch(`/api/threads/${remoteId}`).then((r) => r.json());
    return {
      status: t.archived ? "archived" : "regular",
      remoteId: t.id,
      title: t.title,
    };
  },
  async generateTitle(remoteId, messages) {
    return createAssistantStream(async (controller) => {
      const { title } = await fetch(`/api/threads/${remoteId}/title`, {
        method: "POST",
        body: JSON.stringify({ messages }),
      }).then((r) => r.json());
      controller.appendText(title);
    });
  },
};

export function MyProvider({ children }: { children: React.ReactNode }) {
  const runtime = useRemoteThreadListRuntime({
    runtimeHook: () => useLocalRuntime(modelAdapter),
    adapter,
  });
  return (
    <AssistantRuntimeProvider runtime={runtime}>
      {children}
    </AssistantRuntimeProvider>
  );
}

Persisting messages with `unstable_Provider`

RemoteThreadListAdapter only manages thread metadata. To persist messages within each thread, expose a thread-scoped history adapter via the optional unstable_Provider:

import {
  RuntimeAdapterProvider,
  useAui,
  type ThreadHistoryAdapter,
} from "@assistant-ui/react";
import { useMemo } from "react";

const adapterWithHistory: RemoteThreadListAdapter = {
  // ...metadata methods above...
  unstable_Provider({ children }) {
    const aui = useAui();
    const history = useMemo<ThreadHistoryAdapter>(
      () => ({
        async load() {
          const { remoteId } = aui.threadListItem().getState();
          if (!remoteId) return { messages: [] };
          const rows = await fetch(
            `/api/threads/${remoteId}/messages`,
          ).then((r) => r.json());
          return { messages: rows.map(toThreadMessage) };
        },
        async append({ message, parentId }) {
          const { remoteId } = await aui.threadListItem().initialize();
          await fetch(`/api/threads/${remoteId}/messages`, {
            method: "POST",
            body: JSON.stringify({ message, parentId }),
          });
        },
      }),
      [aui],
    );
    return (
      <RuntimeAdapterProvider adapters={{ history }}>
        {children}
      </RuntimeAdapterProvider>
    );
  },
};

unstable_Provider must render children synchronously on first commit. Do not gate children behind a loading state, suspense, or useEffect. If you need to load data before the thread is usable, do it inside an always-rendered child (for example via the history adapter), not by withholding children.

Avoiding the first-message race

append may be called before the thread record exists in your backend. Always await aui.threadListItem().initialize() before writing:

async append({ message, parentId }) {
  const { remoteId } = await aui.threadListItem().initialize();
  await saveMessage(remoteId, parentId, message);
}

initialize() is safe to call multiple times. It always resolves to the same remoteId for the active thread.

Reloading after async authentication

If your adapter depends on a user that resolves asynchronously (oidc, next-auth, better-auth), the initial list() may run before the user is available. Call aui.threads().reload() after auth completes:

function ReloadOnAuth() {
  const aui = useAui();
  const { isLoading, user } = useAuth();
  useEffect(() => {
    if (!isLoading && user) aui.threads().reload();
  }, [isLoading, user?.id]);
  return null;
}

reload() discards in-flight responses from superseded calls, so it is safe to invoke on every auth transition.

Adapter contract

RemoteThreadListAdapter

list: () => Promise<{ threads: RemoteThreadMetadata[] }>

Hydrate threads on mount. Each thread must include status and remoteId; title, externalId, and custom are optional.

initialize: (localId: string) => Promise<{ remoteId: string; externalId?: string }>

Create a new remote record when the user starts a conversation. Return the canonical ids.

rename: (remoteId: string, title: string) => Promise<void>

Persist title changes from the UI.

archive: (remoteId: string) => Promise<void>

Mark thread archived.

unarchive: (remoteId: string) => Promise<void>

Restore an archived thread.

delete: (remoteId: string) => Promise<void>

Permanently remove the thread.

fetch: (threadId: string) => Promise<RemoteThreadMetadata>

Fetch metadata for a single thread when switching.

generateTitle: (remoteId: string, messages: readonly ThreadMessage[]) => Promise<AssistantStream>

Stream a title back. Use createAssistantStream and controller.appendText.

unstable_Providerunstable?: ComponentType<PropsWithChildren>

Optional wrapper rendered around each active thread. Inject thread-scoped adapters (history, attachments) here.

Custom metadata

RemoteThreadMetadata includes an optional custom?: Record<string, unknown> slot for backend-specific fields (timestamps, owner ids, workspace ids, tags, model name). Whatever you return from list() and fetch() flows through to the thread list item state and is reachable from any UI primitive via useAuiState.

type MyThreadMetadata = RemoteThreadMetadata & {
  readonly custom: {
    readonly createdAt: string;
    readonly ownerId: string;
  };
};

import { useAuiState } from "@assistant-ui/react";

function ThreadListItemMeta() {
  const custom = useAuiState(
    (s) => s.threadListItem.custom as MyThreadMetadata["custom"] | undefined,
  );
  return (
    <span>
      {custom?.ownerId} · {custom?.createdAt}
    </span>
  );
}

custom is preserved across rename, archive, unarchive, and generateTitle. To mutate it, return updated values from a subsequent fetch() or call runtime.threads.reload().

ExternalStoreThreadListAdapter

For ExternalStoreRuntime users only. Wires multi-thread support into an external state store.

const threadListAdapter: ExternalStoreThreadListAdapter = {
  threadId: currentThreadId,
  threads: threadList.filter((t) => t.status === "regular"),
  archivedThreads: threadList.filter((t) => t.status === "archived"),
  onSwitchToNewThread: () => {
    /* create + switch */
  },
  onSwitchToThread: (id) => setCurrentThreadId(id),
  onRename: (id, title) => {
    /* update */
  },
  onArchive: (id) => {
    /* archive */
  },
  onUnarchive: (id) => {
    /* unarchive */
  },
  onDelete: (id) => {
    /* delete */
  },
};

const runtime = useExternalStoreRuntime({
  messages: threads.get(currentThreadId) ?? [],
  setMessages: (messages) =>
    setThreads((m) => new Map(m).set(currentThreadId, messages)),
  onNew,
  adapters: { threadList: threadListAdapter },
});

Unlike RemoteThreadListAdapter, this adapter is synchronous and inline. You keep thread metadata and messages in your own store; the runtime just renders what you provide.

The runtime's currentThreadId and your store's selected thread must stay in sync. Mismatched thread ids cause messages to appear in the wrong thread or vanish entirely. Centralize thread id state in a context, never in component-local state.

Choosing

Ask three questions in order:

Do you want it managed? Use AssistantCloud. You do not write database code.
Do you have your own backend? Use RemoteThreadListRuntime if you are on LocalRuntime (or any adapter built on it). You implement the adapter, you own the data.
Are you on ExternalStoreRuntime? Use ExternalStoreThreadListAdapter. Threads live in your store next to messages.

AdaptersThe shared adapter contracts (attachments, history, speech, feedback).ArchitectureThe three-layer runtime model and how threads flow through it.AssistantCloudThe managed multi-thread service.