diff --git a/.github/workflows/lint.yml b/.github/workflows/lint.yml
index 7fe94eefa5..63ae5c7397 100644
--- a/.github/workflows/lint.yml
+++ b/.github/workflows/lint.yml
@@ -17,7 +17,9 @@ on:
       - packages/misskey-bubble-game/**
       - packages/misskey-reversi/**
       - packages/shared/eslint.config.js
+      - scripts/check-dts*.mjs
       - .github/workflows/lint.yml
+      - package.json
   pull_request:
     paths:
       - packages/backend/**
@@ -31,7 +33,9 @@ on:
       - packages/misskey-bubble-game/**
       - packages/misskey-reversi/**
       - packages/shared/eslint.config.js
+      - scripts/check-dts*.mjs
       - .github/workflows/lint.yml
+      - package.json
 jobs:
   pnpm_install:
     runs-on: ubuntu-latest
@@ -113,3 +117,22 @@ jobs:
     - run: pnpm i --frozen-lockfile
     - run: pnpm --filter "${{ matrix.workspace }}^..." run build
     - run: pnpm --filter ${{ matrix.workspace }} run typecheck
+
+  check-dts:
+    needs: [pnpm_install]
+    runs-on: ubuntu-latest
+    continue-on-error: true
+    steps:
+    - uses: actions/checkout@v6.0.2
+      with:
+        fetch-depth: 0
+        submodules: true
+    - name: Setup pnpm
+      uses: pnpm/action-setup@v6.0.3
+    - uses: actions/setup-node@v6.4.0
+      with:
+        node-version-file: '.node-version'
+        cache: 'pnpm'
+    - run: pnpm i --frozen-lockfile
+    - run: node --test scripts/check-dts.test.mjs
+    - run: pnpm check-dts
diff --git a/package.json b/package.json
index 33925d773a..5dcc85c172 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
 	"name": "misskey",
-	"version": "2026.6.1-alpha.1",
+	"version": "2026.7.0-alpha.0",
 	"codename": "nasubi",
 	"repository": {
 		"type": "git",
@@ -39,7 +39,8 @@
 		"migrateandstart": "pnpm migrate && pnpm start",
 		"watch": "pnpm dev",
 		"dev": "node scripts/dev.mjs",
-		"lint": "pnpm --no-bail -r lint",
+		"check-dts": "node scripts/check-dts.mjs",
+		"lint": "pnpm --no-bail -r lint && pnpm check-dts",
 		"cy:open": "pnpm cypress open --config-file=cypress.config.ts",
 		"cy:run": "pnpm cypress run",
 		"e2e": "pnpm start-server-and-test start:test http://localhost:61812 cy:run",
diff --git a/packages/backend/src/@types/probe-image-size.d.ts b/packages/backend/src/@types/probe-image-size.d.ts
index 538836475c..f2efbc082d 100644
--- a/packages/backend/src/@types/probe-image-size.d.ts
+++ b/packages/backend/src/@types/probe-image-size.d.ts
@@ -26,7 +26,6 @@ declare module 'probe-image-size' {
 	function probeImageSize(src: string | ReadStream, callback: (err: Error | null, result?: ProbeResult) => void): void;
 	function probeImageSize(src: string | ReadStream, options: ProbeOptions, callback: (err: Error | null, result?: ProbeResult) => void): void;
 
-	namespace probeImageSize {} // Hack
-
-	export = probeImageSize;
+	// eslint-disable-next-line import/no-default-export
+	export { probeImageSize as default };
 }
diff --git a/packages/backend/test/setup.e2e.ts b/packages/backend/test/setup.e2e.ts
index 3141dc15ad..59bc6fcc62 100644
--- a/packages/backend/test/setup.e2e.ts
+++ b/packages/backend/test/setup.e2e.ts
@@ -7,6 +7,9 @@ import { beforeAll } from 'vitest';
 import { initTestDb, sendEnvResetRequest } from './utils.js';
 
 beforeAll(async () => {
-	await initTestDb(false);
+	// 前ファイルのNestJSアプリをdispose(env-reset)した後にスキーマをdrop & 再作成する。
+	// 逆順だと、前ファイルの最後のテストが投げっぱなしにした非同期処理(cacheServiceのrefresh等)が
+	// dispose前のdrop中に発火し、Unhandled Rejection (relation does not exist) でクラッシュしうる。
 	await sendEnvResetRequest();
+	await initTestDb(false);
 });
diff --git a/packages/frontend-builder/tsconfig.json b/packages/frontend-builder/tsconfig.json
index ab943fded4..e2d1f7ada0 100644
--- a/packages/frontend-builder/tsconfig.json
+++ b/packages/frontend-builder/tsconfig.json
@@ -9,6 +9,7 @@
 		"sourceMap": false,
 		"noEmit": true,
 		"removeComments": true,
+		"skipLibCheck": true,
 		"resolveJsonModule": true,
 		"strict": true,
 		"strictFunctionTypes": true,
diff --git a/packages/frontend-embed/@types/theme.d.ts b/packages/frontend-embed/@types/theme.d.ts
index 6ac1037493..6a010889d6 100644
--- a/packages/frontend-embed/@types/theme.d.ts
+++ b/packages/frontend-embed/@types/theme.d.ts
@@ -4,7 +4,7 @@
  */
 
 declare module '@@/themes/*.json5' {
-	import { Theme } from '@/theme.js';
+	import { Theme } from '@@/js/theme.js';
 
 	const theme: Theme;
 
diff --git a/packages/frontend-embed/tsconfig.json b/packages/frontend-embed/tsconfig.json
index 24fa71de19..d0d7591f23 100644
--- a/packages/frontend-embed/tsconfig.json
+++ b/packages/frontend-embed/tsconfig.json
@@ -13,6 +13,7 @@
 		"module": "ES2022",
 		"moduleResolution": "Bundler",
 		"removeComments": false,
+		"skipLibCheck": true,
 		"noLib": false,
 		"strict": true,
 		"strictNullChecks": true,
diff --git a/packages/frontend-shared/tsconfig.json b/packages/frontend-shared/tsconfig.json
index c2600dc45e..e038b9ca23 100644
--- a/packages/frontend-shared/tsconfig.json
+++ b/packages/frontend-shared/tsconfig.json
@@ -9,6 +9,7 @@
 		"sourceMap": false,
 		"outDir": "./js-built",
 		"removeComments": true,
+		"skipLibCheck": true,
 		"resolveJsonModule": true,
 		"strict": true,
 		"strictFunctionTypes": true,
diff --git a/packages/frontend/@types/theme.d.ts b/packages/frontend/@types/theme.d.ts
index 6ac1037493..6a010889d6 100644
--- a/packages/frontend/@types/theme.d.ts
+++ b/packages/frontend/@types/theme.d.ts
@@ -4,7 +4,7 @@
  */
 
 declare module '@@/themes/*.json5' {
-	import { Theme } from '@/theme.js';
+	import { Theme } from '@@/js/theme.js';
 
 	const theme: Theme;
 
diff --git a/packages/frontend/src/components/MkNote.vue b/packages/frontend/src/components/MkNote.vue
index 1cb562fb62..e55a496bfe 100644
--- a/packages/frontend/src/components/MkNote.vue
+++ b/packages/frontend/src/components/MkNote.vue
@@ -144,7 +144,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 				<button v-else :class="$style.footerButton" class="_button" disabled>
 					<i class="ti ti-ban"></i>
 				</button>
-				<button ref="reactButton" :class="$style.footerButton" class="_button" @click="toggleReact()">
+				<button ref="reactButton" :class="$style.footerButton" class="_button" @click="handleToggleReact()">
 					<i v-if="appearNote.reactionAcceptance === 'likeOnly' && $appearNote.myReaction != null" class="ti ti-heart-filled" style="color: var(--MI_THEME-love);"></i>
 					<i v-else-if="$appearNote.myReaction != null" class="ti ti-minus" style="color: var(--MI_THEME-accent);"></i>
 					<i v-else-if="appearNote.reactionAcceptance === 'likeOnly'" class="ti ti-heart"></i>
@@ -192,58 +192,38 @@ SPDX-License-Identifier: AGPL-3.0-only
 		MkDateSeparatedList uses TransitionGroup which requires single element in the child elements
 		so MkNote create empty div instead of no elements
 	-->
-</div>
+	</div>
 </template>
 
 <script lang="ts" setup>
-import { computed, inject, onMounted, ref, useTemplateRef, provide } from 'vue';
-import * as mfm from 'mfm-js';
-import * as Misskey from 'misskey-js';
-import { isLink } from '@@/js/is-link.js';
-import { shouldCollapsed } from '@@/js/collapsed.js';
-import { host } from '@@/js/config.js';
+import { inject, ref, useTemplateRef, provide, computed } from 'vue';
 import type { Ref } from 'vue';
-import type { MenuItem } from '@/types/menu.js';
-import type { OpenOnRemoteOptions } from '@/utility/please-login.js';
+import * as Misskey from 'misskey-js';
+import { $i } from '@/i.js';
+import { useNote } from '@/composables/use-note.js';
+import { prefer } from '@/preferences.js';
+import { i18n } from '@/i18n.js';
+import { userPage } from '@/filters/user.js';
+import { noteEvents } from '@/composables/use-note-capture.js';
+import { getNoteSummary } from '@/utility/get-note-summary.js';
+import { isEnabledUrlPreview } from '@/utility/url-preview.js';
+import { focusPrev, focusNext } from '@/utility/focus.js';
+import { misskeyApi } from '@/utility/misskey-api.js';
+import number from '@/filters/number.js';
+import * as sound from '@/utility/sound.js';
+import { DI } from '@/di.js';
 import type { Keymap } from '@/utility/hotkey.js';
+
+// コンポーネント外部の依存関係
 import MkNoteSub from '@/components/MkNoteSub.vue';
 import MkNoteHeader from '@/components/MkNoteHeader.vue';
 import MkNoteSimple from '@/components/MkNoteSimple.vue';
 import MkReactionsViewer from '@/components/MkReactionsViewer.vue';
-import MkReactionsViewerDetails from '@/components/MkReactionsViewer.details.vue';
 import MkMediaList from '@/components/MkMediaList.vue';
 import MkCwButton from '@/components/MkCwButton.vue';
 import MkPoll from '@/components/MkPoll.vue';
-import MkUsersTooltip from '@/components/MkUsersTooltip.vue';
 import MkUrlPreview from '@/components/MkUrlPreview.vue';
 import MkInstanceTicker from '@/components/MkInstanceTicker.vue';
-import { pleaseLogin } from '@/utility/please-login.js';
-import { checkWordMute } from '@/utility/check-word-mute.js';
-import { notePage } from '@/filters/note.js';
-import { userPage } from '@/filters/user.js';
-import number from '@/filters/number.js';
-import * as os from '@/os.js';
-import * as sound from '@/utility/sound.js';
-import { misskeyApi, misskeyApiGet } from '@/utility/misskey-api.js';
-import { reactionPicker } from '@/utility/reaction-picker.js';
-import { extractUrlFromMfm } from '@/utility/extract-url-from-mfm.js';
-import { $i } from '@/i.js';
-import { i18n } from '@/i18n.js';
-import { getAbuseNoteMenu, getCopyNoteLinkMenu, getNoteClipMenu, getNoteMenu, getRenoteMenu } from '@/utility/get-note-menu.js';
-import { noteEvents, useNoteCapture } from '@/composables/use-note-capture.js';
-import { deepClone } from '@/utility/clone.js';
-import { useTooltip } from '@/composables/use-tooltip.js';
-import { claimAchievement } from '@/utility/achievements.js';
-import { getNoteSummary } from '@/utility/get-note-summary.js';
-import MkRippleEffect from '@/components/MkRippleEffect.vue';
-import { showMovedDialog } from '@/utility/show-moved-dialog.js';
-import { isEnabledUrlPreview } from '@/utility/url-preview.js';
-import { focusPrev, focusNext } from '@/utility/focus.js';
-import { getAppearNote } from '@/utility/get-appear-note.js';
-import { prefer } from '@/preferences.js';
-import { getPluginHandlers } from '@/plugin.js';
-import { DI } from '@/di.js';
-import { globalEvents } from '@/events.js';
 
 const props = withDefaults(defineProps<{
 	note: Misskey.entities.Note;
@@ -254,48 +234,21 @@ const props = withDefaults(defineProps<{
 	mock: false,
 });
 
-provide(DI.mock, props.mock);
-
 const emit = defineEmits<{
 	(ev: 'reaction', emoji: string): void;
 	(ev: 'removeReaction', emoji: string): void;
 }>();
 
+provide(DI.mock, props.mock);
+
+// 周辺コンテキストのインジェクト
 const inTimeline = inject<boolean>('inTimeline', false);
 const tl_withSensitive = inject<Ref<boolean>>('tl_withSensitive', ref(true));
 const inChannel = inject(DI.inChannel, null);
 const currentClip = inject<Ref<Misskey.entities.Clip> | null>('currentClip', null);
 const currentAntenna = inject<Ref<Misskey.entities.Antenna | null> | null>('currentAntenna', null);
 
-let note = deepClone(props.note);
-
-// plugin
-const noteViewInterruptors = getPluginHandlers('note_view_interruptor');
-const hideByPlugin = ref(false);
-if (noteViewInterruptors.length > 0) {
-	let result: Misskey.entities.Note | null = deepClone(note);
-	for (const interruptor of noteViewInterruptors) {
-		try {
-			result = interruptor.handler(result!) as Misskey.entities.Note | null;
-		} catch (err) {
-			console.error(err);
-		}
-	}
-	if (result == null) {
-		hideByPlugin.value = true;
-	} else {
-		note = result as Misskey.entities.Note;
-	}
-}
-
-const isRenote = Misskey.note.isPureRenote(note);
-const appearNote = getAppearNote(note) ?? note;
-const { $note: $appearNote, subscribe: subscribeManuallyToNoteCapture } = useNoteCapture({
-	note: appearNote,
-	parentNote: note,
-	mock: props.mock,
-});
-
+// Template Refsの定義
 const rootEl = useTemplateRef('rootEl');
 const menuButton = useTemplateRef('menuButton');
 const renoteButton = useTemplateRef('renoteButton');
@@ -303,64 +256,80 @@ const renoteTime = useTemplateRef('renoteTime');
 const reactButton = useTemplateRef('reactButton');
 const clipButton = useTemplateRef('clipButton');
 const galleryEl = useTemplateRef('galleryEl');
-const isMyRenote = $i && ($i.id === note.userId);
-const showContent = ref(false);
-const parsed = computed(() => appearNote.text ? mfm.parse(appearNote.text) : null);
-const urls = computed(() => parsed.value ? extractUrlFromMfm(parsed.value).filter((url) => appearNote.renote?.url !== url && appearNote.renote?.uri !== url) : null);
-const isLong = shouldCollapsed(appearNote, urls.value ?? []);
-const collapsed = ref(appearNote.cw == null && isLong);
-const muted = ref(checkMute(appearNote, $i?.mutedWords));
-const hardMuted = ref(props.withHardMute && checkMute(appearNote, $i?.hardMutedWords, true));
+
+// コンポーサブルの呼び出し
+const {
+	note,
+	appearNote,
+	$appearNote,
+	hideByPlugin,
+	isRenote,
+	showContent,
+	translating,
+	translation,
+	muted,
+	hardMuted,
+	collapsed,
+	renoteCollapsed,
+	parsed,
+	urls,
+	isLong,
+	showTicker,
+	canRenote,
+
+	renote,
+	reply,
+	react,
+	reactViaMfmEmoji,
+	toggleReact,
+	onContextmenu,
+	showMenu,
+	clip,
+	showRenoteMenu,
+	blur,
+} = useNote(props, {
+	rootEl,
+	menuButton,
+	renoteButton,
+	renoteTime,
+	reactButton,
+	clipButton,
+}, {
+	inTimeline,
+	tl_withSensitive,
+	inChannel,
+	currentClip,
+	currentAntenna,
+});
+
+// provide
+provide(DI.mfmEmojiReactCallback, reactViaMfmEmoji);
+
+// MkNote固有
 const showSoftWordMutedWord = computed(() => prefer.s.showSoftWordMutedWord);
-const translation = ref<Misskey.entities.NotesTranslateResponse | null>(null);
-const translating = ref(false);
-const showTicker = (prefer.s.instanceTicker === 'always') || (prefer.s.instanceTicker === 'remote' && appearNote.user.instance);
-const canRenote = computed(() => ['public', 'home'].includes(appearNote.visibility) || (appearNote.visibility === 'followers' && appearNote.userId === $i?.id));
-const renoteCollapsed = ref(
-	prefer.s.collapseRenotes && isRenote && (
-		($i && ($i.id === note.userId || $i.id === appearNote.userId)) || // `||` must be `||`! See https://github.com/misskey-dev/misskey/issues/13131
-		($appearNote.myReaction != null)
-	),
-);
 
-const pleaseLoginContext = computed<OpenOnRemoteOptions>(() => ({
-	type: 'lookup',
-	url: `https://${host}/notes/${appearNote.id}`,
-}));
-
-/* eslint-disable no-redeclare */
-/** checkOnlyでは純粋なワードミュート結果をbooleanで返却する */
-function checkMute(noteToCheck: Misskey.entities.Note, mutedWords: Array<string | string[]> | undefined | null, checkOnly: true): boolean;
-function checkMute(noteToCheck: Misskey.entities.Note, mutedWords: Array<string | string[]> | undefined | null, checkOnly?: false): Array<string | string[]> | false | 'sensitiveMute';
-
-function checkMute(noteToCheck: Misskey.entities.Note, mutedWords: Array<string | string[]> | undefined | null, checkOnly = false): Array<string | string[]> | boolean | 'sensitiveMute' {
-	if (mutedWords != null) {
-		const result = checkWordMute(noteToCheck, $i, mutedWords);
-		if (Array.isArray(result)) {
-			return checkOnly ? (result.length > 0) : result;
+function handleToggleReact() {
+	toggleReact((reaction) => {
+		if ($appearNote.myReaction === reaction) {
+			emit('removeReaction', reaction);
+		} else {
+			emit('reaction', reaction);
+			$appearNote.reactions[reaction] = 1;
+			$appearNote.reactionCount++;
+			$appearNote.myReaction = reaction;
 		}
-
-		const replyResult = noteToCheck.reply && checkWordMute(noteToCheck.reply, $i, mutedWords);
-		if (Array.isArray(replyResult)) {
-			return checkOnly ? (replyResult.length > 0) : replyResult;
-		}
-
-		const renoteResult = noteToCheck.renote && checkWordMute(noteToCheck.renote, $i, mutedWords);
-		if (Array.isArray(renoteResult)) {
-			return checkOnly ? (renoteResult.length > 0) : renoteResult;
-		}
-	}
-
-	if (checkOnly) return false;
-
-	if (inTimeline && tl_withSensitive.value === false && noteToCheck.files?.some((v) => v.isSensitive)) {
-		return 'sensitiveMute';
-	}
-
-	return false;
+	});
 }
-/* eslint-enable no-redeclare */
 
+function emitUpdReaction(emoji: string, delta: number) {
+	if (delta < 0) {
+		emit('removeReaction', emoji);
+	} else if (delta > 0) {
+		emit('reaction', emoji);
+	}
+}
+
+// キーボードショートカットマップ
 const keymap = {
 	'r': () => {
 		if (renoteCollapsed.value) return;
@@ -392,7 +361,7 @@ const keymap = {
 			renoteCollapsed.value = false;
 		} else if (appearNote.cw != null) {
 			showContent.value = !showContent.value;
-		} else if (isLong) {
+		} else if (isLong.value) {
 			collapsed.value = !collapsed.value;
 		}
 	},
@@ -402,321 +371,13 @@ const keymap = {
 	},
 	'up|k|shift+tab': {
 		allowRepeat: true,
-		callback: () => focusBefore(),
+		callback: () => focusPrev(rootEl.value),
 	},
 	'down|j|tab': {
 		allowRepeat: true,
-		callback: () => focusAfter(),
+		callback: () => focusNext(rootEl.value),
 	},
 } as const satisfies Keymap;
-
-provide(DI.mfmEmojiReactCallback, (reaction) => {
-	sound.playMisskeySfx('reaction');
-	misskeyApi('notes/reactions/create', {
-		noteId: appearNote.id,
-		reaction: reaction,
-	}).then(() => {
-		noteEvents.emit(`reacted:${appearNote.id}`, {
-			userId: $i!.id,
-			reaction: reaction,
-		});
-	});
-});
-
-if (!props.mock) {
-	useTooltip(renoteButton, async (showing) => {
-		const renotes = await misskeyApi('notes/renotes', {
-			noteId: appearNote.id,
-			limit: 11,
-		});
-
-		const users = renotes.map(x => x.user);
-
-		if (users.length < 1 || renoteButton.value == null) return;
-
-		const { dispose } = os.popup(MkUsersTooltip, {
-			showing,
-			users,
-			count: appearNote.renoteCount,
-			anchorElement: renoteButton.value,
-		}, {
-			closed: () => dispose(),
-		});
-	});
-
-	if (appearNote.reactionAcceptance === 'likeOnly') {
-		useTooltip(reactButton, async (showing) => {
-			const reactions = await misskeyApiGet('notes/reactions', {
-				noteId: appearNote.id,
-				limit: 10,
-				_cacheKey_: $appearNote.reactionCount,
-			});
-
-			const users = reactions.map(x => x.user);
-
-			if (users.length < 1) return;
-
-			const { dispose } = os.popup(MkReactionsViewerDetails, {
-				showing,
-				reaction: '❤️',
-				users,
-				count: $appearNote.reactionCount,
-				anchorElement: reactButton.value!,
-			}, {
-				closed: () => dispose(),
-			});
-		});
-	}
-}
-
-async function renote() {
-	if (props.mock) return;
-
-	const isLoggedIn = await pleaseLogin({ openOnRemote: pleaseLoginContext.value });
-	if (!isLoggedIn) return;
-
-	showMovedDialog();
-
-	const { menu } = getRenoteMenu({ note: note, renoteButton, mock: props.mock });
-	os.popupMenu(menu, renoteButton.value);
-
-	subscribeManuallyToNoteCapture();
-}
-
-async function reply() {
-	if (props.mock) return;
-
-	const isLoggedIn = await pleaseLogin({ openOnRemote: pleaseLoginContext.value });
-	if (!isLoggedIn) return;
-
-	os.post({
-		reply: appearNote,
-		channel: appearNote.channel,
-	}).then(() => {
-		focus();
-	});
-}
-
-async function react() {
-	const isLoggedIn = await pleaseLogin({ openOnRemote: pleaseLoginContext.value });
-	if (!isLoggedIn) return;
-
-	showMovedDialog();
-	if (appearNote.reactionAcceptance === 'likeOnly') {
-		sound.playMisskeySfx('reaction');
-
-		if (props.mock) {
-			return;
-		}
-
-		misskeyApi('notes/reactions/create', {
-			noteId: appearNote.id,
-			reaction: '❤️',
-		}).then(() => {
-			noteEvents.emit(`reacted:${appearNote.id}`, {
-				userId: $i!.id,
-				reaction: '❤️',
-			});
-		});
-		const el = reactButton.value;
-		if (el && prefer.s.animation) {
-			const rect = el.getBoundingClientRect();
-			const x = rect.left + (el.offsetWidth / 2);
-			const y = rect.top + (el.offsetHeight / 2);
-			const { dispose } = os.popup(MkRippleEffect, { x, y }, {
-				end: () => dispose(),
-			});
-		}
-	} else {
-		blur();
-		reactionPicker.show(reactButton.value ?? null, note, async (reaction) => {
-			if (prefer.s.confirmOnReact) {
-				const confirm = await os.confirm({
-					type: 'question',
-					text: i18n.tsx.reactAreYouSure({ emoji: reaction.replace('@.', '') }),
-				});
-
-				if (confirm.canceled) return;
-			}
-
-			sound.playMisskeySfx('reaction');
-
-			if (props.mock) {
-				emit('reaction', reaction);
-				$appearNote.reactions[reaction] = 1;
-				$appearNote.reactionCount++;
-				$appearNote.myReaction = reaction;
-				return;
-			}
-
-			misskeyApi('notes/reactions/create', {
-				noteId: appearNote.id,
-				reaction: reaction,
-			}).then(() => {
-				noteEvents.emit(`reacted:${appearNote.id}`, {
-					userId: $i!.id,
-					reaction: reaction,
-				});
-			});
-
-			if (appearNote.text && appearNote.text.length > 100 && (Date.now() - new Date(appearNote.createdAt).getTime() < 1000 * 3)) {
-				claimAchievement('reactWithoutRead');
-			}
-		}, () => {
-			focus();
-		});
-	}
-}
-
-function undoReact(): void {
-	const oldReaction = $appearNote.myReaction;
-	if (!oldReaction) return;
-
-	if (props.mock) {
-		emit('removeReaction', oldReaction);
-		return;
-	}
-
-	misskeyApi('notes/reactions/delete', {
-		noteId: appearNote.id,
-	}).then(() => {
-		noteEvents.emit(`unreacted:${appearNote.id}`, {
-			userId: $i!.id,
-			reaction: oldReaction,
-		});
-	});
-}
-
-function toggleReact() {
-	if ($appearNote.myReaction == null) {
-		react();
-	} else {
-		undoReact();
-	}
-}
-
-function onContextmenu(ev: PointerEvent): void {
-	if (props.mock) {
-		return;
-	}
-
-	if (ev.target && isLink(ev.target as HTMLElement)) return;
-	if (window.getSelection()?.toString() !== '') return;
-
-	if (prefer.s.useReactionPickerForContextMenu) {
-		ev.preventDefault();
-		react();
-	} else {
-		const { menu, cleanup } = getNoteMenu({ note: note, translating, translation, currentClip: currentClip?.value, currentAntenna: currentAntenna?.value ?? undefined });
-		os.contextMenu(menu, ev).then(focus).finally(cleanup);
-	}
-}
-
-function showMenu(): void {
-	if (props.mock) {
-		return;
-	}
-
-	const { menu, cleanup } = getNoteMenu({ note: note, translating, translation, currentClip: currentClip?.value, currentAntenna: currentAntenna?.value ?? undefined });
-	os.popupMenu(menu, menuButton.value).then(focus).finally(cleanup);
-}
-
-async function clip(): Promise<void> {
-	if (props.mock) {
-		return;
-	}
-
-	os.popupMenu(await getNoteClipMenu({ note: note, currentClip: currentClip?.value }), clipButton.value).then(focus);
-}
-
-async function showRenoteMenu() {
-	if (props.mock) {
-		return;
-	}
-	const isLoggedIn = await pleaseLogin({ openOnRemote: pleaseLoginContext.value });
-	if (!isLoggedIn) return;
-
-	function getUnrenote(): MenuItem {
-		return {
-			text: i18n.ts.unrenote,
-			icon: 'ti ti-trash',
-			danger: true,
-			action: () => {
-				misskeyApi('notes/delete', {
-					noteId: note.id,
-				}).then(() => {
-					globalEvents.emit('noteDeleted', note.id);
-				});
-			},
-		};
-	}
-
-	const renoteDetailsMenu: MenuItem[] = [{
-		type: 'link',
-		text: i18n.ts.renoteDetails,
-		icon: 'ti ti-info-circle',
-		to: notePage(note),
-	}];
-
-	if (
-		props.note.channelId != null &&
-		(inChannel == null || props.note.channelId !== inChannel.value)
-	) {
-		renoteDetailsMenu.push({
-			type: 'link',
-			text: i18n.ts.viewRenotedChannel,
-			icon: 'ti ti-device-tv',
-			to: `/channels/${props.note.channelId}`,
-		});
-	}
-
-	if (isMyRenote) {
-		os.popupMenu([
-			...renoteDetailsMenu,
-			getCopyNoteLinkMenu(note, i18n.ts.copyLinkRenote),
-			{ type: 'divider' },
-			getUnrenote(),
-		], renoteTime.value);
-	} else {
-		os.popupMenu([
-			...renoteDetailsMenu,
-			getCopyNoteLinkMenu(note, i18n.ts.copyLinkRenote),
-			{ type: 'divider' },
-			getAbuseNoteMenu(note, i18n.ts.reportAbuseRenote),
-			...(($i?.isModerator || $i?.isAdmin) ? [getUnrenote()] : []),
-		], renoteTime.value);
-	}
-}
-
-function focus() {
-	rootEl.value?.focus();
-}
-
-function blur() {
-	rootEl.value?.blur();
-}
-
-function focusBefore() {
-	focusPrev(rootEl.value);
-}
-
-function focusAfter() {
-	focusNext(rootEl.value);
-}
-
-function readPromo() {
-	misskeyApi('promo/read', {
-		noteId: appearNote.id,
-	});
-}
-
-function emitUpdReaction(emoji: string, delta: number) {
-	if (delta < 0) {
-		emit('removeReaction', emoji);
-	} else if (delta > 0) {
-		emit('reaction', emoji);
-	}
-}
 </script>
 
 <style lang="scss" module>
diff --git a/packages/frontend/src/components/MkNoteDetailed.vue b/packages/frontend/src/components/MkNoteDetailed.vue
index 6bd47ebae4..b6e53adcaf 100644
--- a/packages/frontend/src/components/MkNoteDetailed.vue
+++ b/packages/frontend/src/components/MkNoteDetailed.vue
@@ -239,92 +239,45 @@ SPDX-License-Identifier: AGPL-3.0-only
 </template>
 
 <script lang="ts" setup>
-import { computed, inject, markRaw, provide, ref, useTemplateRef } from 'vue';
-import * as mfm from 'mfm-js';
+import { inject, provide, ref, useTemplateRef, markRaw, computed } from 'vue';
 import * as Misskey from 'misskey-js';
-import { isLink } from '@@/js/is-link.js';
-import { host } from '@@/js/config.js';
-import type { OpenOnRemoteOptions } from '@/utility/please-login.js';
+import { useNote } from '@/composables/use-note.js';
+import { prefer } from '@/preferences.js';
+import { i18n } from '@/i18n.js';
+import { userPage } from '@/filters/user.js';
+import { notePage } from '@/filters/note.js';
+import { isEnabledUrlPreview } from '@/utility/url-preview.js';
+import { Paginator } from '@/utility/paginator.js';
+import { misskeyApi } from '@/utility/misskey-api.js';
+import number from '@/filters/number.js';
+import { DI } from '@/di.js';
 import type { Keymap } from '@/utility/hotkey.js';
-import type { MenuItem } from '@/types/menu.js';
+
+// コンポーネント外部の依存関係
 import MkNoteSub from '@/components/MkNoteSub.vue';
 import MkNoteSimple from '@/components/MkNoteSimple.vue';
 import MkReactionsViewer from '@/components/MkReactionsViewer.vue';
-import MkReactionsViewerDetails from '@/components/MkReactionsViewer.details.vue';
 import MkMediaList from '@/components/MkMediaList.vue';
 import MkCwButton from '@/components/MkCwButton.vue';
 import MkPoll from '@/components/MkPoll.vue';
-import MkUsersTooltip from '@/components/MkUsersTooltip.vue';
 import MkUrlPreview from '@/components/MkUrlPreview.vue';
 import MkInstanceTicker from '@/components/MkInstanceTicker.vue';
-import { pleaseLogin } from '@/utility/please-login.js';
-import { checkWordMute } from '@/utility/check-word-mute.js';
-import { userPage } from '@/filters/user.js';
-import { notePage } from '@/filters/note.js';
-import number from '@/filters/number.js';
-import * as os from '@/os.js';
-import { misskeyApi, misskeyApiGet } from '@/utility/misskey-api.js';
-import * as sound from '@/utility/sound.js';
-import { reactionPicker } from '@/utility/reaction-picker.js';
-import { extractUrlFromMfm } from '@/utility/extract-url-from-mfm.js';
-import { $i } from '@/i.js';
-import { i18n } from '@/i18n.js';
-import { getNoteClipMenu, getNoteMenu, getRenoteMenu } from '@/utility/get-note-menu.js';
-import { noteEvents, useNoteCapture } from '@/composables/use-note-capture.js';
-import { deepClone } from '@/utility/clone.js';
-import { useTooltip } from '@/composables/use-tooltip.js';
-import { claimAchievement } from '@/utility/achievements.js';
-import MkRippleEffect from '@/components/MkRippleEffect.vue';
-import { showMovedDialog } from '@/utility/show-moved-dialog.js';
 import MkUserCardMini from '@/components/MkUserCardMini.vue';
 import MkPagination from '@/components/MkPagination.vue';
 import MkReactionIcon from '@/components/MkReactionIcon.vue';
 import MkButton from '@/components/MkButton.vue';
-import { isEnabledUrlPreview } from '@/utility/url-preview.js';
-import { getAppearNote } from '@/utility/get-appear-note.js';
-import { prefer } from '@/preferences.js';
-import { getPluginHandlers } from '@/plugin.js';
-import { DI } from '@/di.js';
-import { globalEvents, useGlobalEvent } from '@/events.js';
-import { Paginator } from '@/utility/paginator.js';
 
 const props = withDefaults(defineProps<{
 	note: Misskey.entities.Note;
-	initialTab?: string;
+	initialTab?: 'replies' | 'renotes' | 'reactions';
 }>(), {
 	initialTab: 'replies',
 });
 
+// 周辺コンテキストのインジェクト
 const inChannel = inject(DI.inChannel, null);
 
-let note = deepClone(props.note);
-
-// plugin
-const noteViewInterruptors = getPluginHandlers('note_view_interruptor');
-const hideByPlugin = ref(false);
-if (noteViewInterruptors.length > 0) {
-	let result: Misskey.entities.Note | null = deepClone(note);
-	for (const interruptor of noteViewInterruptors) {
-		try {
-			result = interruptor.handler(result!) as Misskey.entities.Note | null;
-		} catch (err) {
-			console.error(err);
-		}
-	}
-	if (result == null) {
-		hideByPlugin.value = true;
-	} else {
-		note = result as Misskey.entities.Note;
-	}
-}
-
-const isRenote = Misskey.note.isPureRenote(note);
-const appearNote = getAppearNote(note) ?? note;
-const { $note: $appearNote, subscribe: subscribeManuallyToNoteCapture } = useNoteCapture({
-	note: appearNote,
-	parentNote: note,
-});
-
+// Template Refsの定義
 const rootEl = useTemplateRef('rootEl');
 const menuButton = useTemplateRef('menuButton');
 const renoteButton = useTemplateRef('renoteButton');
@@ -332,30 +285,96 @@ const renoteTime = useTemplateRef('renoteTime');
 const reactButton = useTemplateRef('reactButton');
 const clipButton = useTemplateRef('clipButton');
 const galleryEl = useTemplateRef('galleryEl');
-const isMyRenote = $i && ($i.id === note.userId);
-const showContent = ref(false);
-const isDeleted = ref(false);
-const muted = ref($i ? checkWordMute(appearNote, $i, $i.mutedWords) : false);
-const translation = ref<Misskey.entities.NotesTranslateResponse | null>(null);
-const translating = ref(false);
-const parsed = appearNote.text ? mfm.parse(appearNote.text) : null;
-const urls = parsed ? extractUrlFromMfm(parsed).filter((url) => appearNote.renote?.url !== url && appearNote.renote?.uri !== url) : null;
-const showTicker = (prefer.s.instanceTicker === 'always') || (prefer.s.instanceTicker === 'remote' && appearNote.user.instance);
-const conversation = ref<Misskey.entities.Note[]>([]);
-const replies = ref<Misskey.entities.Note[]>([]);
-const canRenote = computed(() => ['public', 'home'].includes(appearNote.visibility) || appearNote.userId === $i?.id);
 
-useGlobalEvent('noteDeleted', (noteId) => {
-	if (noteId === note.id || noteId === appearNote.id) {
-		isDeleted.value = true;
-	}
+// コンポーサブルの呼び出し
+const {
+	note,
+	appearNote,
+	$appearNote,
+	hideByPlugin,
+	isRenote,
+	showContent,
+	isDeleted,
+	translating,
+	translation,
+	muted,
+	canRenote,
+	isMyRenote,
+	parsed,
+	urls,
+	showTicker,
+
+	// 関数群
+	renote,
+	reply,
+	react,
+	reactViaMfmEmoji,
+	toggleReact,
+	onContextmenu,
+	showMenu,
+	clip,
+	showRenoteMenu,
+	blur,
+} = useNote(props, {
+	rootEl,
+	menuButton,
+	renoteButton,
+	renoteTime,
+	reactButton,
+	clipButton,
+}, {
+	inChannel,
 });
 
-const pleaseLoginContext = computed<OpenOnRemoteOptions>(() => ({
-	type: 'lookup',
-	url: `https://${host}/notes/${appearNote.id}`,
+// provide
+provide(DI.mfmEmojiReactCallback, reactViaMfmEmoji);
+
+// MkNoteDetailed固有
+const tab = ref(props.initialTab);
+const reactionTabType = ref<string | null>(null);
+
+const renotesPaginator = markRaw(new Paginator('notes/renotes', {
+	limit: 10,
+	params: {
+		noteId: appearNote.id,
+	},
 }));
 
+const reactionsPaginator = markRaw(new Paginator('notes/reactions', {
+	limit: 10,
+	computedParams: computed(() => ({
+		noteId: appearNote.id,
+		type: reactionTabType.value,
+	})),
+}));
+
+const replies = ref<Misskey.entities.Note[]>([]);
+const repliesLoaded = ref(false);
+
+function loadReplies() {
+	repliesLoaded.value = true;
+	misskeyApi('notes/children', {
+		noteId: appearNote.id,
+		limit: 30,
+	}).then(res => {
+		replies.value = res;
+	});
+}
+
+const conversation = ref<Misskey.entities.Note[]>([]);
+const conversationLoaded = ref(false);
+
+function loadConversation() {
+	conversationLoaded.value = true;
+	if (appearNote.replyId == null) return;
+	misskeyApi('notes/conversation', {
+		noteId: appearNote.replyId,
+	}).then(res => {
+		conversation.value = res.reverse();
+	});
+}
+
+// キーボードショートカットマップ
 const keymap = {
 	'r': () => reply(),
 	'e|a|plus': () => react(),
@@ -378,281 +397,6 @@ const keymap = {
 		callback: () => blur(),
 	},
 } as const satisfies Keymap;
-
-provide(DI.mfmEmojiReactCallback, (reaction) => {
-	sound.playMisskeySfx('reaction');
-	misskeyApi('notes/reactions/create', {
-		noteId: appearNote.id,
-		reaction: reaction,
-	}).then(() => {
-		noteEvents.emit(`reacted:${appearNote.id}`, {
-			userId: $i!.id,
-			reaction: reaction,
-		});
-	});
-});
-
-const tab = ref(props.initialTab);
-const reactionTabType = ref<string | null>(null);
-
-const renotesPaginator = markRaw(new Paginator('notes/renotes', {
-	limit: 10,
-	params: {
-		noteId: appearNote.id,
-	},
-}));
-
-const reactionsPaginator = markRaw(new Paginator('notes/reactions', {
-	limit: 10,
-	computedParams: computed(() => ({
-		noteId: appearNote.id,
-		type: reactionTabType.value,
-	})),
-}));
-
-useTooltip(renoteButton, async (showing) => {
-	const anchorElement = renoteButton.value;
-	if (anchorElement == null) return;
-
-	const renotes = await misskeyApi('notes/renotes', {
-		noteId: appearNote.id,
-		limit: 11,
-	});
-
-	const users = renotes.map(x => x.user);
-
-	if (users.length < 1) return;
-
-	const { dispose } = os.popup(MkUsersTooltip, {
-		showing,
-		users,
-		count: appearNote.renoteCount,
-		anchorElement: anchorElement,
-	}, {
-		closed: () => dispose(),
-	});
-});
-
-if (appearNote.reactionAcceptance === 'likeOnly') {
-	useTooltip(reactButton, async (showing) => {
-		const reactions = await misskeyApiGet('notes/reactions', {
-			noteId: appearNote.id,
-			limit: 10,
-			_cacheKey_: $appearNote.reactionCount,
-		});
-
-		const users = reactions.map(x => x.user);
-
-		if (users.length < 1) return;
-
-		const { dispose } = os.popup(MkReactionsViewerDetails, {
-			showing,
-			reaction: '❤️',
-			users,
-			count: $appearNote.reactionCount,
-			anchorElement: reactButton.value!,
-		}, {
-			closed: () => dispose(),
-		});
-	});
-}
-
-async function renote() {
-	const isLoggedIn = await pleaseLogin({ openOnRemote: pleaseLoginContext.value });
-	if (!isLoggedIn) return;
-
-	showMovedDialog();
-
-	const { menu } = getRenoteMenu({ note: note, renoteButton });
-	os.popupMenu(menu, renoteButton.value);
-
-	// リノート後は反応が来る可能性があるので手動で購読する
-	subscribeManuallyToNoteCapture();
-}
-
-async function reply() {
-	const isLoggedIn = await pleaseLogin({ openOnRemote: pleaseLoginContext.value });
-	if (!isLoggedIn) return;
-
-	showMovedDialog();
-	os.post({
-		reply: appearNote,
-		channel: appearNote.channel,
-	}).then(() => {
-		focus();
-	});
-}
-
-async function react() {
-	const isLoggedIn = await pleaseLogin({ openOnRemote: pleaseLoginContext.value });
-	if (!isLoggedIn) return;
-
-	showMovedDialog();
-	if (appearNote.reactionAcceptance === 'likeOnly') {
-		sound.playMisskeySfx('reaction');
-
-		misskeyApi('notes/reactions/create', {
-			noteId: appearNote.id,
-			reaction: '❤️',
-		}).then(() => {
-			noteEvents.emit(`reacted:${appearNote.id}`, {
-				userId: $i!.id,
-				reaction: '❤️',
-			});
-		});
-		const el = reactButton.value;
-		if (el && prefer.s.animation) {
-			const rect = el.getBoundingClientRect();
-			const x = rect.left + (el.offsetWidth / 2);
-			const y = rect.top + (el.offsetHeight / 2);
-			const { dispose } = os.popup(MkRippleEffect, { x, y }, {
-				end: () => dispose(),
-			});
-		}
-	} else {
-		blur();
-		reactionPicker.show(reactButton.value ?? null, note, async (reaction) => {
-			if (prefer.s.confirmOnReact) {
-				const confirm = await os.confirm({
-					type: 'question',
-					text: i18n.tsx.reactAreYouSure({ emoji: reaction.replace('@.', '') }),
-				});
-
-				if (confirm.canceled) return;
-			}
-
-			sound.playMisskeySfx('reaction');
-
-			misskeyApi('notes/reactions/create', {
-				noteId: appearNote.id,
-				reaction: reaction,
-			}).then(() => {
-				noteEvents.emit(`reacted:${appearNote.id}`, {
-					userId: $i!.id,
-					reaction: reaction,
-				});
-			});
-			if (appearNote.text && appearNote.text.length > 100 && (Date.now() - new Date(appearNote.createdAt).getTime() < 1000 * 3)) {
-				claimAchievement('reactWithoutRead');
-			}
-		}, () => {
-			focus();
-		});
-	}
-}
-
-function undoReact(targetNote: Misskey.entities.Note): void {
-	const oldReaction = targetNote.myReaction;
-	if (!oldReaction) return;
-	misskeyApi('notes/reactions/delete', {
-		noteId: targetNote.id,
-	}).then(() => {
-		noteEvents.emit(`unreacted:${appearNote.id}`, {
-			userId: $i!.id,
-			reaction: oldReaction,
-		});
-	});
-}
-
-function toggleReact() {
-	if (appearNote.myReaction == null) {
-		react();
-	} else {
-		undoReact(appearNote);
-	}
-}
-
-function onContextmenu(ev: PointerEvent): void {
-	if (ev.target && isLink(ev.target as HTMLElement)) return;
-	if (window.getSelection()?.toString() !== '') return;
-
-	if (prefer.s.useReactionPickerForContextMenu) {
-		ev.preventDefault();
-		react();
-	} else {
-		const { menu, cleanup } = getNoteMenu({ note: note, translating, translation });
-		os.contextMenu(menu, ev).then(focus).finally(cleanup);
-	}
-}
-
-function showMenu(): void {
-	const { menu, cleanup } = getNoteMenu({ note: note, translating, translation });
-	os.popupMenu(menu, menuButton.value).then(focus).finally(cleanup);
-}
-
-async function clip(): Promise<void> {
-	os.popupMenu(await getNoteClipMenu({ note: note }), clipButton.value).then(focus);
-}
-
-async function showRenoteMenu() {
-	if (!isMyRenote) return;
-
-	const isLoggedIn = await pleaseLogin({ openOnRemote: pleaseLoginContext.value });
-	if (!isLoggedIn) return;
-
-	const menu: MenuItem[] = [];
-
-	if (isMyRenote) {
-		menu.push({
-			text: i18n.ts.unrenote,
-			icon: 'ti ti-trash',
-			danger: true,
-			action: () => {
-				misskeyApi('notes/delete', {
-					noteId: note.id,
-				}).then(() => {
-					globalEvents.emit('noteDeleted', note.id);
-				});
-			},
-		});
-	}
-
-	if (
-		props.note.channelId != null &&
-		(inChannel == null || props.note.channelId !== inChannel.value)
-	) {
-		menu.push({
-			type: 'link',
-			text: i18n.ts.viewRenotedChannel,
-			icon: 'ti ti-device-tv',
-			to: `/channels/${props.note.channelId}`,
-		});
-	}
-
-	os.popupMenu(menu, renoteTime.value);
-}
-
-function focus() {
-	rootEl.value?.focus();
-}
-
-function blur() {
-	rootEl.value?.blur();
-}
-
-const repliesLoaded = ref(false);
-
-function loadReplies() {
-	repliesLoaded.value = true;
-	misskeyApi('notes/children', {
-		noteId: appearNote.id,
-		limit: 30,
-	}).then(res => {
-		replies.value = res;
-	});
-}
-
-const conversationLoaded = ref(false);
-
-function loadConversation() {
-	conversationLoaded.value = true;
-	if (appearNote.replyId == null) return;
-	misskeyApi('notes/conversation', {
-		noteId: appearNote.replyId,
-	}).then(res => {
-		conversation.value = res.reverse();
-	});
-}
 </script>
 
 <style lang="scss" module>
diff --git a/packages/frontend/src/composables/use-note.ts b/packages/frontend/src/composables/use-note.ts
new file mode 100644
index 0000000000..0d526bbe55
--- /dev/null
+++ b/packages/frontend/src/composables/use-note.ts
@@ -0,0 +1,473 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { ref, computed } from 'vue';
+import type { Ref } from 'vue';
+import * as mfm from 'mfm-js';
+import * as Misskey from 'misskey-js';
+import { isLink } from '@@/js/is-link.js';
+import { shouldCollapsed } from '@@/js/collapsed.js';
+import { host } from '@@/js/config.js';
+import { pleaseLogin } from '@/utility/please-login.js';
+import type { OpenOnRemoteOptions } from '@/utility/please-login.js';
+import { checkWordMute } from '@/utility/check-word-mute.js';
+import { misskeyApi, misskeyApiGet } from '@/utility/misskey-api.js';
+import * as sound from '@/utility/sound.js';
+import * as os from '@/os.js';
+import { reactionPicker } from '@/utility/reaction-picker.js';
+import { extractUrlFromMfm } from '@/utility/extract-url-from-mfm.js';
+import { getNoteClipMenu, getNoteMenu, getRenoteMenu, getAbuseNoteMenu, getCopyNoteLinkMenu } from '@/utility/get-note-menu.js';
+import { noteEvents, useNoteCapture } from '@/composables/use-note-capture.js';
+import { deepClone } from '@/utility/clone.js';
+import { useTooltip } from '@/composables/use-tooltip.js';
+import { claimAchievement } from '@/utility/achievements.js';
+import { showMovedDialog } from '@/utility/show-moved-dialog.js';
+import { getAppearNote } from '@/utility/get-appear-note.js';
+import { prefer } from '@/preferences.js';
+import { getPluginHandlers } from '@/plugin.js';
+import { $i } from '@/i.js';
+import { i18n } from '@/i18n.js';
+import { globalEvents, useGlobalEvent } from '@/events.js';
+import MkUsersTooltip from '@/components/MkUsersTooltip.vue';
+import MkReactionsViewerDetails from '@/components/MkReactionsViewer.details.vue';
+import MkRippleEffect from '@/components/MkRippleEffect.vue';
+import { notePage } from '@/filters/note.js';
+import type { DI as DIType } from '@/di.js';
+import type { ExtractInjectedType } from '@/types/misc.js';
+import type { MenuItem } from '@/types/menu.js';
+
+export interface UseNoteProps {
+	note: Misskey.entities.Note;
+	pinned?: boolean;
+	mock?: boolean;
+	withHardMute?: boolean;
+}
+
+export interface UseNoteElements {
+	rootEl?: Ref<HTMLElement | null>;
+	menuButton?: Ref<HTMLElement | null>;
+	renoteButton?: Ref<HTMLElement | null>;
+	renoteTime?: Ref<HTMLElement | null>;
+	reactButton?: Ref<HTMLElement | null>;
+	clipButton?: Ref<HTMLElement | null>;
+}
+
+export interface UseNoteOptions {
+	inTimeline?: boolean;
+	tl_withSensitive?: Ref<boolean>;
+	inChannel?: ExtractInjectedType<typeof DIType['inChannel']>;
+	currentClip?: Ref<Misskey.entities.Clip | null> | null;
+	currentAntenna?: Ref<Misskey.entities.Antenna | null> | null;
+}
+
+/* eslint-disable no-redeclare */
+export function calculateMuteStatus(
+	noteToCheck: Misskey.entities.Note,
+	user: typeof $i,
+	inTimeline: boolean,
+	tl_withSensitive: boolean,
+	checkOnly: true,
+): boolean;
+export function calculateMuteStatus(
+	noteToCheck: Misskey.entities.Note,
+	user: typeof $i,
+	inTimeline: boolean,
+	tl_withSensitive: boolean,
+	checkOnly?: false,
+): Array<string | string[]> | false | 'sensitiveMute';
+
+export function calculateMuteStatus(
+	noteToCheck: Misskey.entities.Note,
+	user: typeof $i,
+	inTimeline: boolean,
+	tl_withSensitive: boolean,
+	checkOnly = false
+): Array<string | string[]> | boolean | 'sensitiveMute' {
+	if (user?.mutedWords != null) {
+		const result = checkWordMute(noteToCheck, user, user.mutedWords);
+		if (Array.isArray(result)) return checkOnly ? (result.length > 0) : result;
+
+		const replyResult = noteToCheck.reply && checkWordMute(noteToCheck.reply, user, user.mutedWords);
+		if (Array.isArray(replyResult)) return checkOnly ? (replyResult.length > 0) : replyResult;
+
+		const renoteResult = noteToCheck.renote && checkWordMute(noteToCheck.renote, user, user.mutedWords);
+		if (Array.isArray(renoteResult)) return checkOnly ? (renoteResult.length > 0) : renoteResult;
+	}
+
+	if (checkOnly) return false;
+
+	if (inTimeline && tl_withSensitive === false && noteToCheck.files?.some((v) => v.isSensitive)) {
+		return 'sensitiveMute';
+	}
+
+	return false;
+}
+/* eslint-enable no-redeclare */
+
+/** MkNote, MkNoteDetailedの共通ロジック */
+export function useNote(
+	props: UseNoteProps,
+	els: UseNoteElements = {},
+	options: UseNoteOptions = {},
+) {
+	const inTimeline = options.inTimeline ?? false;
+	const tl_withSensitive = options.tl_withSensitive ?? ref(true);
+	const inChannel = options.inChannel ?? null;
+	const currentClip = options.currentClip ?? null;
+	const currentAntenna = options.currentAntenna ?? null;
+
+	// プラグインの割り込み処理
+	let rawNote = deepClone(props.note);
+	const hideByPlugin = ref(false);
+	const noteViewInterruptors = getPluginHandlers('note_view_interruptor');
+
+	if (noteViewInterruptors.length > 0) {
+		let result: Misskey.entities.Note | null = deepClone(rawNote);
+		for (const interruptor of noteViewInterruptors) {
+			try {
+				result = interruptor.handler(result!) as Misskey.entities.Note | null;
+			} catch (err) {
+				console.error(err);
+			}
+		}
+		if (result == null) {
+			hideByPlugin.value = true;
+		} else {
+			rawNote = result as Misskey.entities.Note;
+		}
+	}
+
+	// 基本状態
+	const isRenote = Misskey.note.isPureRenote(rawNote);
+	const appearNote = getAppearNote(rawNote) ?? rawNote;
+
+	// キャプチャ（ストリーム購読）
+	const { $note: $appearNote, subscribe: subscribeManuallyToNoteCapture } = useNoteCapture({
+		note: appearNote,
+		parentNote: rawNote,
+		mock: props.mock,
+	});
+
+	// 各種フラグ状態
+	const showContent = ref(false);
+	const isDeleted = ref(false);
+	const translating = ref(false);
+	const translation = ref<Misskey.entities.NotesTranslateResponse | null>(null);
+
+	// ミュート判定
+	const muted = ref($i ? (options.inTimeline ? calculateMuteStatus(appearNote, $i, inTimeline, tl_withSensitive.value) : checkWordMute(appearNote, $i, $i.mutedWords)) : false);
+	const hardMuted = ref(props.withHardMute && $i && calculateMuteStatus(appearNote, $i, inTimeline, tl_withSensitive.value, true));
+
+	// 計算プロパティ (Computed)
+	const isMyRenote = computed(() => $i && ($i.id === rawNote.userId));
+	const parsed = computed(() => appearNote.text ? mfm.parse(appearNote.text) : null);
+	const urls = computed(() => parsed.value ? extractUrlFromMfm(parsed.value).filter((url) => appearNote.renote?.url !== url && appearNote.renote?.uri !== url) : null);
+	const isLong = computed(() => shouldCollapsed(appearNote, urls.value ?? []));
+	const collapsed = ref(appearNote.cw == null && isLong.value);
+	const showTicker = computed(() => (prefer.s.instanceTicker === 'always') || (prefer.s.instanceTicker === 'remote' && appearNote.user.instance));
+	const canRenote = computed(() => ['public', 'home'].includes(appearNote.visibility) || (appearNote.visibility === 'followers' && appearNote.userId === $i?.id));
+	const renoteCollapsed = ref(prefer.s.collapseRenotes && isRenote && (($i && ($i.id === rawNote.userId || $i.id === appearNote.userId)) || ($appearNote.myReaction != null)));
+
+	const pleaseLoginContext = computed<OpenOnRemoteOptions>(() => ({
+		type: 'lookup',
+		url: `https://${host}/notes/${appearNote.id}`,
+	}));
+
+	// グローバルイベントの監視
+	useGlobalEvent('noteDeleted', (noteId) => {
+		if (noteId === rawNote.id || noteId === appearNote.id) {
+			isDeleted.value = true;
+		}
+	});
+
+	// ツールチップのセットアップ (Mockでない場合のみ)
+	if (!props.mock) {
+		if (els.renoteButton != null) {
+			useTooltip(els.renoteButton, async (showing) => {
+				const renotes = await misskeyApi('notes/renotes', {
+					noteId: appearNote.id,
+					limit: 11,
+				});
+				const users = renotes.map(x => x.user);
+				if (users.length < 1 || els.renoteButton!.value == null) return;
+				const { dispose } = os.popup(MkUsersTooltip, {
+					showing,
+					users,
+					count: appearNote.renoteCount,
+					anchorElement: els.renoteButton!.value,
+				}, {
+					closed: () => dispose(),
+				});
+			});
+		}
+
+		if (appearNote.reactionAcceptance === 'likeOnly' && els.reactButton != null) {
+			useTooltip(els.reactButton, async (showing) => {
+				const reactions = await misskeyApiGet('notes/reactions', {
+					noteId: appearNote.id,
+					limit: 10,
+					_cacheKey_: $appearNote.reactionCount,
+				});
+				const users = reactions.map(x => x.user);
+				if (users.length < 1 || els.reactButton!.value == null) return;
+				const { dispose } = os.popup(MkReactionsViewerDetails, {
+					showing,
+					reaction: '❤️',
+					users,
+					count: $appearNote.reactionCount,
+					anchorElement: els.reactButton!.value,
+				}, {
+					closed: () => dispose(),
+				});
+			});
+		}
+	}
+
+	// 共通アクション関数群
+	async function renote() {
+		if (props.mock) return;
+		const isLoggedIn = await pleaseLogin({ openOnRemote: pleaseLoginContext.value });
+		if (!isLoggedIn) return;
+		showMovedDialog();
+		if (els.renoteButton == null) return;
+		const { menu } = getRenoteMenu({
+			note: rawNote,
+			renoteButton: els.renoteButton,
+			mock: props.mock,
+		});
+		os.popupMenu(menu, els.renoteButton.value);
+		subscribeManuallyToNoteCapture();
+	}
+
+	async function reply() {
+		if (props.mock) return;
+		const isLoggedIn = await pleaseLogin({ openOnRemote: pleaseLoginContext.value });
+		if (!isLoggedIn) return;
+		os.post({
+			reply: appearNote,
+			channel: appearNote.channel,
+		}).then(() => {
+			focus();
+		});
+	}
+
+	async function react(customCallback?: (reaction: string) => void) {
+		const isLoggedIn = await pleaseLogin({ openOnRemote: pleaseLoginContext.value });
+		if (!isLoggedIn) return;
+		showMovedDialog();
+
+		if (appearNote.reactionAcceptance === 'likeOnly') {
+			sound.playMisskeySfx('reaction');
+			if (props.mock) return;
+			misskeyApi('notes/reactions/create', {
+				noteId: appearNote.id,
+				reaction: '❤️',
+			}).then(() => {
+				noteEvents.emit(`reacted:${appearNote.id}`, { userId: $i!.id, reaction: '❤️' });
+			});
+			if (els.reactButton != null && els.reactButton.value != null && prefer.s.animation) {
+				const rect = els.reactButton.value.getBoundingClientRect();
+				const { dispose } = os.popup(MkRippleEffect, {
+					x: rect.left + (els.reactButton.value.offsetWidth / 2),
+					y: rect.top + (els.reactButton.value.offsetHeight / 2),
+				}, {
+					end: () => dispose(),
+				});
+			}
+		} else {
+			blur();
+			reactionPicker.show(els.reactButton?.value ?? null, rawNote, async (reaction) => {
+				if (prefer.s.confirmOnReact) {
+					const confirm = await os.confirm({
+						type: 'question',
+						text: i18n.tsx.reactAreYouSure({ emoji: reaction.replace('@.', '') }),
+					});
+					if (confirm.canceled) return;
+				}
+				sound.playMisskeySfx('reaction');
+				if (props.mock) {
+					if (customCallback) customCallback(reaction);
+					return;
+				}
+				misskeyApi('notes/reactions/create', {
+					noteId: appearNote.id,
+					reaction: reaction,
+				}).then(() => {
+					noteEvents.emit(`reacted:${appearNote.id}`, { userId: $i!.id, reaction: reaction });
+				});
+				if (appearNote.text && appearNote.text.length > 100 && (Date.now() - new Date(appearNote.createdAt).getTime() < 1000 * 3)) {
+					claimAchievement('reactWithoutRead');
+				}
+			}, () => { focus(); });
+		}
+	}
+
+	async function reactViaMfmEmoji(reaction: string) {
+		if (props.mock) return;
+		const isLoggedIn = await pleaseLogin({ openOnRemote: pleaseLoginContext.value });
+		if (!isLoggedIn) return;
+		showMovedDialog();
+		sound.playMisskeySfx('reaction');
+		misskeyApi('notes/reactions/create', {
+			noteId: appearNote.id,
+			reaction: reaction,
+		}).then(() => {
+			noteEvents.emit(`reacted:${appearNote.id}`, {
+				userId: $i!.id,
+				reaction: reaction,
+			});
+		});
+	}
+
+	function undoReact(): void {
+		const oldReaction = $appearNote.myReaction;
+		if (!oldReaction) return;
+		if (props.mock) return;
+		misskeyApi('notes/reactions/delete', { noteId: appearNote.id }).then(() => {
+			noteEvents.emit(`unreacted:${appearNote.id}`, { userId: $i!.id, reaction: oldReaction });
+		});
+	}
+
+	function toggleReact(customMockCallback?: (reaction: string) => void) {
+		if ($appearNote.myReaction == null) {
+			react(customMockCallback);
+		} else {
+			if (props.mock && customMockCallback) {
+				customMockCallback($appearNote.myReaction);
+			} else {
+				undoReact();
+			}
+		}
+	}
+
+	function onContextmenu(ev: PointerEvent): void {
+		if (props.mock) return;
+		if (ev.target && isLink(ev.target as HTMLElement)) return;
+		if (window.getSelection()?.toString() !== '') return;
+
+		if (prefer.s.useReactionPickerForContextMenu) {
+			ev.preventDefault();
+			react();
+		} else {
+			const { menu, cleanup } = getNoteMenu({
+				note: rawNote,
+				translating,
+				translation,
+				currentClip: currentClip?.value,
+				currentAntenna: currentAntenna?.value ?? undefined,
+			});
+			os.contextMenu(menu, ev).then(focus).finally(cleanup);
+		}
+	}
+
+	function showMenu(): void {
+		if (props.mock || els.menuButton == null) return;
+		const { menu, cleanup } = getNoteMenu({
+			note: rawNote,
+			translating,
+			translation,
+			currentClip: currentClip?.value,
+			currentAntenna: currentAntenna?.value ?? undefined,
+		});
+		os.popupMenu(menu, els.menuButton.value).then(focus).finally(cleanup);
+	}
+
+	async function clip(): Promise<void> {
+		if (props.mock) return;
+		os.popupMenu(await getNoteClipMenu({
+			note: rawNote,
+			currentClip: currentClip?.value,
+		}), els.clipButton?.value).then(focus);
+	}
+
+	async function showRenoteMenu() {
+		if (props.mock) return;
+		const isLoggedIn = await pleaseLogin({ openOnRemote: pleaseLoginContext.value });
+		if (!isLoggedIn) return;
+
+		const getUnrenote = () => ({
+			text: i18n.ts.unrenote,
+			icon: 'ti ti-trash',
+			danger: true,
+			action: () => {
+				misskeyApi('notes/delete', { noteId: rawNote.id }).then(() => { globalEvents.emit('noteDeleted', rawNote.id); });
+			},
+		});
+
+		const menuItems: MenuItem[] = [{
+			type: 'link',
+			text: i18n.ts.renoteDetails,
+			icon: 'ti ti-info-circle',
+			to: notePage(rawNote),
+		}];
+
+		if (props.note.channelId != null && (inChannel == null || props.note.channelId !== inChannel.value)) {
+			menuItems.push({
+				type: 'link',
+				text: i18n.ts.viewRenotedChannel,
+				icon: 'ti ti-device-tv',
+				to: `/channels/${props.note.channelId}`,
+			});
+		}
+
+		menuItems.push(getCopyNoteLinkMenu(rawNote, i18n.ts.copyLinkRenote));
+		menuItems.push({ type: 'divider' });
+
+		if (isMyRenote.value) {
+			menuItems.push(getUnrenote());
+			os.popupMenu(menuItems, els.renoteTime?.value);
+		} else {
+			menuItems.push(getAbuseNoteMenu(rawNote, i18n.ts.reportAbuseRenote));
+			if ($i?.isModerator || $i?.isAdmin) {
+				menuItems.push(getUnrenote());
+			}
+
+			os.popupMenu(menuItems, els.renoteTime?.value);
+		}
+	}
+
+	// フォーカス制御
+	function focus() { els.rootEl?.value?.focus(); }
+
+	function blur() { els.rootEl?.value?.blur(); }
+
+	return {
+		// 状態・データ
+		note: rawNote,
+		appearNote,
+		$appearNote,
+		hideByPlugin,
+		isRenote,
+		showContent,
+		isDeleted,
+		translating,
+		translation,
+		muted,
+		hardMuted,
+		collapsed,
+		renoteCollapsed,
+
+		// 計算プロパティ
+		isMyRenote,
+		parsed,
+		urls,
+		isLong,
+		showTicker,
+		canRenote,
+
+		// アクション関数
+		renote,
+		reply,
+		react,
+		reactViaMfmEmoji,
+		toggleReact,
+		onContextmenu,
+		showMenu,
+		clip,
+		showRenoteMenu,
+		focus,
+		blur,
+	};
+}
diff --git a/packages/frontend/src/pages/admin/email-settings.vue b/packages/frontend/src/pages/admin/email-settings.vue
index 340391a12f..6cc667fdce 100644
--- a/packages/frontend/src/pages/admin/email-settings.vue
+++ b/packages/frontend/src/pages/admin/email-settings.vue
@@ -47,7 +47,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 										</MkInput>
 									</SearchMarker>
 									<SearchMarker>
-										<MkInput v-model="smtpPass" type="password">
+										<MkInput v-model="smtpPass" type="password" autocomplete="new-password">
 											<template #label><SearchLabel>{{ i18n.ts.smtpPass }}</SearchLabel></template>
 										</MkInput>
 									</SearchMarker>
diff --git a/packages/frontend/src/pages/admin/object-storage.vue b/packages/frontend/src/pages/admin/object-storage.vue
index d6ac72571e..f1b62825ed 100644
--- a/packages/frontend/src/pages/admin/object-storage.vue
+++ b/packages/frontend/src/pages/admin/object-storage.vue
@@ -58,7 +58,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 						</SearchMarker>
 
 						<SearchMarker>
-							<MkInput v-model="objectStorageSecretKey" type="password">
+							<MkInput v-model="objectStorageSecretKey" type="password" autocomplete="new-password">
 								<template #prefix><i class="ti ti-key"></i></template>
 								<template #label><SearchLabel>Secret key</SearchLabel></template>
 							</MkInput>
diff --git a/packages/frontend/src/pages/admin/security.vue b/packages/frontend/src/pages/admin/security.vue
index 517549122e..91a8eb6dfc 100644
--- a/packages/frontend/src/pages/admin/security.vue
+++ b/packages/frontend/src/pages/admin/security.vue
@@ -46,7 +46,8 @@ SPDX-License-Identifier: AGPL-3.0-only
 							</SearchMarker>
 
 							<SearchMarker :keywords="['api', 'key', 'token', 'sensitive']">
-								<MkInput v-model="sensitiveMediaDetectionForm.state.sensitiveMediaDetectionApiKey" type="password">
+								<MkInput v-model="sensitiveMediaDetectionForm.state.sensitiveMediaDetectionApiKey" type="password" autocomplete="new-password">
+									<template #prefix><i class="ti ti-key"></i></template>
 									<template #label><SearchLabel>{{ i18n.ts._sensitiveMediaDetection.apiKey }}</SearchLabel></template>
 									<template #caption><SearchText>{{ i18n.ts._sensitiveMediaDetection.apiKeyDescription }}</SearchText></template>
 								</MkInput>
diff --git a/packages/frontend/src/pages/note.vue b/packages/frontend/src/pages/note.vue
index 2bbd7b2511..1698eca891 100644
--- a/packages/frontend/src/pages/note.vue
+++ b/packages/frontend/src/pages/note.vue
@@ -76,6 +76,12 @@ const note = ref<null | Misskey.entities.Note>(CTX_NOTE);
 const clips = ref<Misskey.entities.Clip[]>();
 const showPrev = ref<'user' | 'channel' | false>(false);
 const showNext = ref<'user' | 'channel' | false>(false);
+const initialTab = computed<'reactions' | 'replies' | 'renotes' | undefined>(() => {
+	if (['reactions', 'replies', 'renotes'].includes(props.initialTab ?? '')) {
+		return props.initialTab as 'reactions' | 'replies' | 'renotes';
+	}
+	return undefined;
+});
 const error = ref();
 
 const prevUserPaginator = markRaw(new Paginator('users/notes', {
diff --git a/packages/frontend/src/types/misc.ts b/packages/frontend/src/types/misc.ts
index 3ddd732531..bdd1b1dcf0 100644
--- a/packages/frontend/src/types/misc.ts
+++ b/packages/frontend/src/types/misc.ts
@@ -2,5 +2,8 @@
  * SPDX-FileCopyrightText: syuilo and misskey-project
  * SPDX-License-Identifier: AGPL-3.0-only
  */
+import type { InjectionKey } from 'vue';
 
-export type Awaitable <T> = T | Promise<T>;
+export type Awaitable<T> = T | Promise<T>;
+
+export type ExtractInjectedType<T extends InjectionKey<any>> = T extends InjectionKey<infer U> ? U : never;
diff --git a/packages/frontend/src/utility/get-note-menu.ts b/packages/frontend/src/utility/get-note-menu.ts
index a6168d0550..1a7da6f77f 100644
--- a/packages/frontend/src/utility/get-note-menu.ts
+++ b/packages/frontend/src/utility/get-note-menu.ts
@@ -33,7 +33,7 @@ const isInBrowserTranslationAvailable = (
 
 export async function getNoteClipMenu(props: {
 	note: Misskey.entities.Note;
-	currentClip?: Misskey.entities.Clip;
+	currentClip?: Misskey.entities.Clip | null;
 }) {
 	function getClipName(clip: Misskey.entities.Clip) {
 		if ($i && clip.userId === $i.id && clip.notesCount != null) {
@@ -181,8 +181,8 @@ export function getNoteMenu(props: {
 	note: Misskey.entities.Note;
 	translation: Ref<Misskey.entities.NotesTranslateResponse | null>;
 	translating: Ref<boolean>;
-	currentClip?: Misskey.entities.Clip;
-	currentAntenna?: Misskey.entities.Antenna;
+	currentClip?: Misskey.entities.Clip | null;
+	currentAntenna?: Misskey.entities.Antenna | null;
 }) {
 	const appearNote = getAppearNote(props.note) ?? props.note;
 	const link = appearNote.url ?? appearNote.uri;
diff --git a/packages/icons-subsetter/tsconfig.json b/packages/icons-subsetter/tsconfig.json
index 08315a91cf..7bf3fd3cbf 100644
--- a/packages/icons-subsetter/tsconfig.json
+++ b/packages/icons-subsetter/tsconfig.json
@@ -8,6 +8,7 @@
 		"strictFunctionTypes": true,
 		"strictNullChecks": true,
 		"esModuleInterop": true,
+		"skipLibCheck": true,
 		"lib": [
 			"esnext",
 			"dom"
diff --git a/packages/misskey-bubble-game/tsconfig.json b/packages/misskey-bubble-game/tsconfig.json
index 0bb0c13c3a..e7d8e810c2 100644
--- a/packages/misskey-bubble-game/tsconfig.json
+++ b/packages/misskey-bubble-game/tsconfig.json
@@ -9,6 +9,7 @@
 		"sourceMap": false,
 		"outDir": "./built",
 		"removeComments": true,
+		"skipLibCheck": true,
 		"strict": true,
 		"strictFunctionTypes": true,
 		"strictNullChecks": true,
diff --git a/packages/misskey-js/package.json b/packages/misskey-js/package.json
index 813e45b50b..9461b55c07 100644
--- a/packages/misskey-js/package.json
+++ b/packages/misskey-js/package.json
@@ -1,7 +1,7 @@
 {
 	"type": "module",
 	"name": "misskey-js",
-	"version": "2026.6.1-alpha.1",
+	"version": "2026.7.0-alpha.0",
 	"description": "Misskey SDK for JavaScript",
 	"license": "MIT",
 	"main": "./built/index.js",
diff --git a/packages/misskey-js/tsconfig.json b/packages/misskey-js/tsconfig.json
index e1197570fd..ef92336356 100644
--- a/packages/misskey-js/tsconfig.json
+++ b/packages/misskey-js/tsconfig.json
@@ -9,6 +9,7 @@
 		"sourceMap": false,
 		"outDir": "./built",
 		"removeComments": true,
+		"skipLibCheck": true,
 		"strict": true,
 		"strictFunctionTypes": true,
 		"strictNullChecks": true,
diff --git a/packages/misskey-reversi/tsconfig.json b/packages/misskey-reversi/tsconfig.json
index 0bb0c13c3a..e7d8e810c2 100644
--- a/packages/misskey-reversi/tsconfig.json
+++ b/packages/misskey-reversi/tsconfig.json
@@ -9,6 +9,7 @@
 		"sourceMap": false,
 		"outDir": "./built",
 		"removeComments": true,
+		"skipLibCheck": true,
 		"strict": true,
 		"strictFunctionTypes": true,
 		"strictNullChecks": true,
diff --git a/packages/sw/tsconfig.json b/packages/sw/tsconfig.json
index 9732a438ce..2669ac5277 100644
--- a/packages/sw/tsconfig.json
+++ b/packages/sw/tsconfig.json
@@ -13,6 +13,7 @@
 		"module": "nodenext",
 		"moduleResolution": "nodenext",
 		"removeComments": false,
+		"skipLibCheck": true,
 		"noLib": false,
 		"strict": true,
 		"strictNullChecks": true,
diff --git a/scripts/check-dts.mjs b/scripts/check-dts.mjs
new file mode 100644
index 0000000000..e6eba67966
--- /dev/null
+++ b/scripts/check-dts.mjs
@@ -0,0 +1,198 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import fs from 'node:fs';
+import path from 'node:path';
+import process from 'node:process';
+import { fileURLToPath } from 'node:url';
+import ts from 'typescript';
+
+const scriptDir = path.dirname(fileURLToPath(import.meta.url));
+const defaultRootDir = path.resolve(scriptDir, '..');
+
+// パス判定は OS 差分を避けるため、必要なところだけ POSIX 形式へ寄せる。
+function toPosixPath(filePath) {
+	return filePath.split(path.sep).join('/');
+}
+
+function isInside(parentDir, filePath) {
+	const relative = path.relative(parentDir, filePath);
+	return relative !== '' && !relative.startsWith('..') && !path.isAbsolute(relative);
+}
+
+// skipLibCheck で隠したくない、リポジトリ管理下の手書き .d.ts だけを検査する。
+export function isCheckableDeclarationFile(filePath, rootDir = defaultRootDir) {
+	const absoluteRootDir = path.resolve(rootDir);
+	const absoluteFilePath = path.resolve(filePath);
+	if (!isInside(absoluteRootDir, absoluteFilePath)) return false;
+	if (!absoluteFilePath.endsWith('.d.ts')) return false;
+
+	const relativePath = toPosixPath(path.relative(absoluteRootDir, absoluteFilePath));
+	const segments = relativePath.split('/');
+	if (segments.includes('node_modules') || segments.includes('.pnpm')) return false;
+	if (segments.includes('built') || segments.includes('js-built')) return false;
+
+	return true;
+}
+
+// root package.json の workspaces を信頼して、検査対象 package を列挙する。
+function readJson(filePath) {
+	return JSON.parse(fs.readFileSync(filePath, 'utf8'));
+}
+
+function getWorkspacePackageDirs(rootDir) {
+	const rootPackageJson = readJson(path.join(rootDir, 'package.json'));
+	return rootPackageJson.workspaces
+		.filter((workspace) => !workspace.includes('*'))
+		.map((workspace) => path.resolve(rootDir, workspace))
+		.filter((workspaceDir) => fs.existsSync(path.join(workspaceDir, 'package.json')));
+}
+
+function getTsconfigPaths(packageDir) {
+	return ts.sys.readDirectory(
+		packageDir,
+		['.json'],
+		['node_modules'],
+		['**/tsconfig.json'],
+		undefined,
+	);
+}
+
+// tsconfig の include から漏れる package 直下の shim も拾えるよう、補助的に探索する。
+function discoverDeclarationFiles(packageDir, rootDir) {
+	return ts.sys.readDirectory(
+		packageDir,
+		['.d.ts'],
+		undefined,
+		['**/*.d.ts'],
+		undefined,
+	).filter((filePath) => isCheckableDeclarationFile(filePath, rootDir));
+}
+
+// 各 package の設定をそのまま使い、検査時だけ skipLibCheck を後で上書きする。
+function readTsconfig(tsconfigPath) {
+	if (!fs.existsSync(tsconfigPath)) return undefined;
+
+	const config = ts.readConfigFile(tsconfigPath, ts.sys.readFile);
+	if (config.error != null) {
+		throw new Error(ts.flattenDiagnosticMessageText(config.error.messageText, '\n'));
+	}
+
+	return ts.parseJsonConfigFileContent(config.config, ts.sys, path.dirname(tsconfigPath));
+}
+
+function createFormatHost(rootDir) {
+	return {
+		getCanonicalFileName: (fileName) => fileName,
+		getCurrentDirectory: () => rootDir,
+		getNewLine: () => ts.sys.newLine,
+	};
+}
+
+// 通常の tsconfig は include 対象を使い、root tsconfig だけ package 直下の shim を足す。
+function isRootTsconfig(packageDir, tsconfigPath) {
+	return path.resolve(packageDir, 'tsconfig.json') === path.resolve(tsconfigPath);
+}
+
+function getDeclarationFilesForTsconfig(packageDir, tsconfigPath, parsedConfig, rootDir) {
+	const declarationFiles = parsedConfig.fileNames
+		.filter((filePath) => isCheckableDeclarationFile(filePath, rootDir));
+
+	if (!isRootTsconfig(packageDir, tsconfigPath)) {
+		return declarationFiles;
+	}
+
+	const extraRootConfigDeclarationFiles = discoverDeclarationFiles(packageDir, rootDir)
+		.filter((filePath) => {
+			return path.dirname(filePath) === packageDir;
+		});
+
+	return [...new Set([...declarationFiles, ...extraRootConfigDeclarationFiles])];
+}
+
+// node_modules 側の診断は出さず、対象 .d.ts 自身に出た診断だけを失敗扱いにする。
+function checkTsconfigDeclarations(packageDir, tsconfigPath, rootDir) {
+	const parsedConfig = readTsconfig(tsconfigPath);
+	if (parsedConfig == null) {
+		return { declarationFiles: [], diagnostics: [] };
+	}
+
+	const declarationFiles = getDeclarationFilesForTsconfig(packageDir, tsconfigPath, parsedConfig, rootDir);
+	if (declarationFiles.length === 0) {
+		return { declarationFiles, diagnostics: [] };
+	}
+
+	const program = ts.createProgram({
+		rootNames: declarationFiles,
+		options: {
+			...parsedConfig.options,
+			noEmit: true,
+			skipLibCheck: false,
+		},
+	});
+
+	const diagnostics = ts.getPreEmitDiagnostics(program)
+		.filter((diagnostic) => diagnostic.file != null && isCheckableDeclarationFile(diagnostic.file.fileName, rootDir));
+
+	return { declarationFiles, diagnostics };
+}
+
+// 複数 tsconfig で同じ宣言を読むことがあるため、同一診断をまとめる。
+function deduplicateDiagnostics(diagnostics) {
+	const seen = new Set();
+	return diagnostics.filter((diagnostic) => {
+		const key = [
+			diagnostic.file?.fileName ?? '',
+			diagnostic.start ?? '',
+			diagnostic.code,
+			ts.flattenDiagnosticMessageText(diagnostic.messageText, '\n'),
+		].join('\0');
+		if (seen.has(key)) return false;
+		seen.add(key);
+		return true;
+	});
+}
+
+function checkPackageDeclarations(packageDir, rootDir) {
+	const results = getTsconfigPaths(packageDir)
+		.map((tsconfigPath) => checkTsconfigDeclarations(packageDir, tsconfigPath, rootDir));
+
+	return {
+		declarationFiles: [...new Set(results.flatMap((result) => result.declarationFiles))],
+		diagnostics: deduplicateDiagnostics(results.flatMap((result) => result.diagnostics)),
+	};
+}
+
+// workspace 全体を走査し、CI が扱いやすい件数と診断リストに集約する。
+export function checkDeclarations(rootDir = defaultRootDir) {
+	const workspacePackageDirs = getWorkspacePackageDirs(rootDir);
+	const results = workspacePackageDirs.map((packageDir) => ({
+		packageDir,
+		...checkPackageDeclarations(packageDir, rootDir),
+	}));
+
+	return {
+		results,
+		declarationFileCount: results.reduce((count, result) => count + result.declarationFiles.length, 0),
+		diagnostics: results.flatMap((result) => result.diagnostics),
+	};
+}
+
+// CLI 実行時は TypeScript 標準の formatter で、通常の tsc に近い形で表示する。
+function main() {
+	const { declarationFileCount, diagnostics } = checkDeclarations(defaultRootDir);
+
+	if (diagnostics.length === 0) {
+		console.log(`Checked ${declarationFileCount} repository declaration files.`);
+		return;
+	}
+
+	console.error(ts.formatDiagnosticsWithColorAndContext(diagnostics, createFormatHost(defaultRootDir)));
+	process.exitCode = 1;
+}
+
+if (process.argv[1] === fileURLToPath(import.meta.url)) {
+	main();
+}
diff --git a/scripts/check-dts.test.mjs b/scripts/check-dts.test.mjs
new file mode 100644
index 0000000000..0b9cb14dbf
--- /dev/null
+++ b/scripts/check-dts.test.mjs
@@ -0,0 +1,25 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import assert from 'node:assert/strict';
+import test from 'node:test';
+import { isCheckableDeclarationFile } from './check-dts.mjs';
+
+const rootDir = '/repo';
+
+test('detects repository-owned declaration files that should be checked', () => {
+	assert.equal(isCheckableDeclarationFile(`${rootDir}/packages/frontend/@types/theme.d.ts`, rootDir), true);
+	assert.equal(isCheckableDeclarationFile(`${rootDir}/packages/frontend/src/utility/virtual.d.ts`, rootDir), true);
+	assert.equal(isCheckableDeclarationFile(`${rootDir}/packages/backend/test/global.d.ts`, rootDir), true);
+});
+
+test('ignores declarations outside the repository-owned surface', () => {
+	assert.equal(isCheckableDeclarationFile(`${rootDir}/node_modules/@types/node/index.d.ts`, rootDir), false);
+	assert.equal(isCheckableDeclarationFile(`${rootDir}/packages/frontend/node_modules/@types/foo/index.d.ts`, rootDir), false);
+	assert.equal(isCheckableDeclarationFile(`${rootDir}/node_modules/.pnpm/typescript/lib/lib.dom.d.ts`, rootDir), false);
+	assert.equal(isCheckableDeclarationFile(`${rootDir}/packages/misskey-js/built/index.d.ts`, rootDir), false);
+	assert.equal(isCheckableDeclarationFile(`${rootDir}/packages/frontend-shared/js-built/i18n.d.ts`, rootDir), false);
+	assert.equal(isCheckableDeclarationFile(`${rootDir}/packages/frontend/src/theme.ts`, rootDir), false);
+});