refactor: move vm hooks into view model folder (#31832)

packages/shared-components/src/viewmodel/useViewModel.ts

@@ -0,0 +1,21 @@
+/*
+Copyright 2025 New Vector Ltd.
+
+SPDX-License-Identifier: AGPL-3.0-only OR GPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE files in the repository root for full details.
+*/
+
+import { useSyncExternalStore } from "react";
+
+import { type ViewModel } from "./ViewModel";
+
+/**
+ * A small wrapper around useSyncExternalStore to use a view model in a shared component view
+ * @param vm The view model to use
+ * @returns The current snapshot
+ */
+export function useViewModel<T>(vm: ViewModel<T>): T {
+    // We need to pass the same getSnapshot function as getServerSnapshot as this
+    // is used when making the HTML chat export.
+    return useSyncExternalStore(vm.subscribe, vm.getSnapshot, vm.getSnapshot);
+}