enhance(frontend): タイムライン以外でもスクロール位置の保持を試みるように

packages/frontend/src/components/MkNotifications.vue

@@ -24,8 +24,8 @@ SPDX-License-Identifier: AGPL-3.0-only
 				tag="div"
 			>
 				<template v-for="(notification, i) in notifications" :key="notification.id">
-					<MkNote v-if="['reply', 'quote', 'mention'].includes(notification.type)" :class="$style.item" :note="notification.note" :withHardMute="true"/>
-					<XNotification v-else :class="$style.item" :notification="notification" :withTime="true" :full="true"/>
+					<MkNote v-if="['reply', 'quote', 'mention'].includes(notification.type)" :class="$style.item" :note="notification.note" :withHardMute="true" :data-scroll-anchor="notification.id"/>
+					<XNotification v-else :class="$style.item" :notification="notification" :withTime="true" :full="true" :data-scroll-anchor="notification.id"/>
 				</template>
 			</component>
 		</template>

packages/frontend/src/components/global/PageWithHeader.vue

@@ -20,6 +20,7 @@ import { useTemplateRef } from 'vue';
 import { scrollInContainer } from '@@/js/scroll.js';
 import type { PageHeaderItem } from '@/types/page-header.js';
 import type { Tab } from './MkPageHeader.tabs.vue';
+import { useScrollPositionKeeper } from '@/use/use-scroll-position-keeper.js';
 
 const props = withDefaults(defineProps<{
 	tabs?: Tab[];
@@ -35,6 +36,8 @@ const props = withDefaults(defineProps<{
 const tab = defineModel<string>('tab');
 const rootEl = useTemplateRef('rootEl');
 
+useScrollPositionKeeper(rootEl);
+
 defineExpose({
 	scrollToTop: () => {
 		if (rootEl.value) scrollInContainer(rootEl.value, { top: 0, behavior: 'smooth' });

packages/frontend/src/use/use-scroll-position-keeper.ts

@@ -4,19 +4,22 @@
  */
 
 import { throttle } from 'throttle-debounce';
-import { nextTick, onActivated, onUnmounted, watch } from 'vue';
+import { nextTick, onActivated, onDeactivated, onUnmounted, watch } from 'vue';
 import type { Ref } from 'vue';
 
 // note render skippingがオンだとズレるため、遷移直前にスクロール範囲に表示されているdata-scroll-anchor要素を特定して、復元時に当該要素までスクロールするようにする
 
 export function useScrollPositionKeeper(scrollContainerRef: Ref<HTMLElement | null | undefined>): void {
 	let anchorId: string | null = null;
+	let ready = true;
 
 	watch(scrollContainerRef, (el) => {
 		if (!el) return;
 
 		const onScroll = () => {
 			if (!el) return;
+			if (!ready) return;
+
 			const scrollContainerRect = el.getBoundingClientRect();
 			const viewPosition = scrollContainerRect.height / 2;
 
@@ -41,18 +44,32 @@ export function useScrollPositionKeeper(scrollContainerRef: Ref<HTMLElement | nu
 		immediate: true,
 	});
 
+	const restore = () => {
+		if (!anchorId) return;
+		const scrollContainer = scrollContainerRef.value;
+		if (!scrollContainer) return;
+		const scrollAnchorEl = scrollContainer.querySelector(`[data-scroll-anchor="${anchorId}"]`);
+		if (!scrollAnchorEl) return;
+		scrollAnchorEl.scrollIntoView({
+			behavior: 'instant',
+			block: 'center',
+			inline: 'center',
+		});
+	};
+
+	onDeactivated(() => {
+		ready = false;
+	});
+
 	onActivated(() => {
+		restore();
 		nextTick(() => {
-			if (!anchorId) return;
-			const scrollContainer = scrollContainerRef.value;
-			if (!scrollContainer) return;
-			const scrollAnchorEl = scrollContainer.querySelector(`[data-scroll-anchor="${anchorId}"]`);
-			if (!scrollAnchorEl) return;
-			scrollAnchorEl.scrollIntoView({
-				behavior: 'instant',
-				block: 'center',
-				inline: 'center',
-			});
+			restore();
+			window.setTimeout(() => {
+				restore();
+
+				ready = true;
+			}, 100);
 		});
 	});
 }