enhance(frontend): チャット画面で確実に最下部へスクロール追従するように

packages/frontend/src/use/use-mutation-observer.ts

@@ -0,0 +1,21 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { onUnmounted, watch } from 'vue';
+import type { Ref, ShallowRef } from 'vue';
+
+export function useMutationObserver(targetNodeRef: Ref<HTMLElement | undefined>, options: MutationObserverInit, callback: MutationCallback): void {
+	const observer = new MutationObserver(callback);
+
+	watch(targetNodeRef, (targetNode) => {
+		if (targetNode) {
+			observer.observe(targetNode, options);
+		}
+	}, { immediate: true });
+
+	onUnmounted(() => {
+		observer.disconnect();
+	});
+}