diff --git a/.github/workflows/lint.yml b/.github/workflows/lint.yml
index ef42291d17..73fbe1537c 100644
--- a/.github/workflows/lint.yml
+++ b/.github/workflows/lint.yml
@@ -78,6 +78,7 @@ jobs:
       matrix:
         workspace:
         - backend
+        - sw
         - cherrypick-js
     steps:
     - uses: actions/checkout@v4.1.1
@@ -92,7 +93,7 @@ jobs:
     - run: corepack enable
     - run: pnpm i --frozen-lockfile
     - run: pnpm --filter cherrypick-js run build
-      if: ${{ matrix.workspace == 'backend' }}
+      if: ${{ matrix.workspace == 'backend' || matrix.workspace == 'sw' }}
     - run: pnpm --filter misskey-reversi run build
       if: ${{ matrix.workspace == 'backend' }}
     - run: pnpm --filter ${{ matrix.workspace }} run typecheck
diff --git a/packages/sw/src/scripts/create-notification.ts b/packages/sw/src/scripts/create-notification.ts
index 6eb3d2e519..3e6fb1b604 100644
--- a/packages/sw/src/scripts/create-notification.ts
+++ b/packages/sw/src/scripts/create-notification.ts
@@ -59,7 +59,7 @@ async function composeNotification(data: PushNotificationDataMap[keyof PushNotif
 					const userDetail = await cli.request('users/show', { userId: data.body.userId }, account.token);
 					return [i18n.ts._notification.youWereFollowed, {
 						body: `${getUserName(data.body.user)} (@${data.body.user.username}${data.body.user.host != null ? '@' + data.body.user.host : ''})`,
-						icon: data.body.user.avatarUrl,
+						icon: data.body.user.avatarUrl ?? undefined,
 						badge: iconUrl('user-plus'),
 						data,
 						actions: userDetail.isFollowing ? [] : [
@@ -74,7 +74,7 @@ async function composeNotification(data: PushNotificationDataMap[keyof PushNotif
 				case 'mention':
 					return [i18n.tsx._notification.youGotMention({ name: getUserName(data.body.user) }), {
 						body: data.body.note.text ?? '',
-						icon: data.body.user.avatarUrl,
+						icon: data.body.user.avatarUrl ?? undefined,
 						badge: iconUrl('at'),
 						data,
 						actions: [
@@ -88,7 +88,7 @@ async function composeNotification(data: PushNotificationDataMap[keyof PushNotif
 				case 'reply':
 					return [i18n.tsx._notification.youGotReply({ name: getUserName(data.body.user) }), {
 						body: data.body.note.text ?? '',
-						icon: data.body.user.avatarUrl,
+						icon: data.body.user.avatarUrl ?? undefined,
 						badge: iconUrl('arrow-back-up'),
 						data,
 						actions: [
@@ -102,7 +102,7 @@ async function composeNotification(data: PushNotificationDataMap[keyof PushNotif
 				case 'renote':
 					return [i18n.tsx._notification.youRenoted({ name: getUserName(data.body.user) }), {
 						body: data.body.note.text ?? '',
-						icon: data.body.user.avatarUrl,
+						icon: data.body.user.avatarUrl ?? undefined,
 						badge: iconUrl('repeat'),
 						data,
 						actions: [
@@ -116,7 +116,7 @@ async function composeNotification(data: PushNotificationDataMap[keyof PushNotif
 				case 'quote':
 					return [i18n.tsx._notification.youGotQuote({ name: getUserName(data.body.user) }), {
 						body: data.body.note.text ?? '',
-						icon: data.body.user.avatarUrl,
+						icon: data.body.user.avatarUrl ?? undefined,
 						badge: iconUrl('quote'),
 						data,
 						actions: [
@@ -136,7 +136,7 @@ async function composeNotification(data: PushNotificationDataMap[keyof PushNotif
 				case 'note':
 					return [i18n.ts._notification.newNote + ': ' + getUserName(data.body.user), {
 						body: data.body.note.text ?? '',
-						icon: data.body.user.avatarUrl,
+						icon: data.body.user.avatarUrl ?? undefined,
 						data,
 					}];
 
@@ -163,9 +163,9 @@ async function composeNotification(data: PushNotificationDataMap[keyof PushNotif
 
 					const tag = `reaction:${data.body.note.id}`;
 					return [i18n.tsx._notification.youGotReact({ name: getUserName(data.body.user) }), {
-						// eslint-disable-next-line @typescript-eslint/no-unnecessary-condition,no-constant-binary-expression
-						body: (reaction1.startsWith(':') ? `:${ reaction }:` : `${ reaction }`) + '\n' + data.body.note.text ?? '',
-						icon: data.body.user.avatarUrl,
+						// eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
+						body: (reaction1.startsWith(':') ? `:${ reaction }:` : `${ reaction }` + '\n' + data.body.note.text) ?? '',
+						icon: data.body.user.avatarUrl ?? undefined,
 						tag,
 						badge,
 						data,
@@ -181,7 +181,7 @@ async function composeNotification(data: PushNotificationDataMap[keyof PushNotif
 				case 'receiveFollowRequest':
 					return [i18n.ts._notification.youReceivedFollowRequest, {
 						body: getUserName(data.body.user),
-						icon: data.body.user.avatarUrl,
+						icon: data.body.user.avatarUrl ?? undefined,
 						badge: iconUrl('user-plus'),
 						data,
 						actions: [
@@ -199,7 +199,7 @@ async function composeNotification(data: PushNotificationDataMap[keyof PushNotif
 				case 'followRequestAccepted':
 					return [i18n.ts._notification.yourFollowRequestAccepted, {
 						body: getUserName(data.body.user),
-						icon: data.body.user.avatarUrl,
+						icon: data.body.user.avatarUrl ?? undefined,
 						badge: iconUrl('circle-check'),
 						data,
 					}];
@@ -255,9 +255,9 @@ async function composeNotification(data: PushNotificationDataMap[keyof PushNotif
 			}
 		case 'unreadMessagingMessage':
 			if (data.body.groupId === null) {
-				return [getUserName(data.body.user), {
+				return [getUserName(data.body.user ?? { name: null, username: '' }), {
 					body: data.body.text ?? '',
-					icon: data.body.user.avatarUrl,
+					icon: data.body.user?.avatarUrl ?? undefined,
 					badge: iconUrl('messages'),
 					tag: `messaging:user:${data.body.userId}`,
 					data,
@@ -265,8 +265,8 @@ async function composeNotification(data: PushNotificationDataMap[keyof PushNotif
 				}];
 			}
 			return [data.body.group?.name ?? '', {
-				body: `${getUserName(data.body.user)}: ${data.body.text ?? ''}`,
-				icon: data.body.user.avatarUrl,
+				body: `${getUserName(data.body.user ?? { name: null, username: '' })}: ${data.body.text ?? ''}`,
+				icon: data.body.user?.avatarUrl ?? undefined,
 				badge: iconUrl('messages'),
 				tag: `messaging:group:${data.body.groupId}`,
 				data,
@@ -275,7 +275,7 @@ async function composeNotification(data: PushNotificationDataMap[keyof PushNotif
 		case 'unreadAntennaNote':
 			return [i18n.tsx._notification.unreadAntennaNote({ name: data.body.antenna.name }), {
 				body: `${getUserName(data.body.note.user)}: ${data.body.note.text ?? ''}`,
-				icon: data.body.note.user.avatarUrl,
+				icon: data.body.note.user.avatarUrl ?? undefined,
 				badge: iconUrl('antenna'),
 				tag: `antenna:${data.body.antenna.id}`,
 				data,
diff --git a/packages/sw/src/scripts/get-account-from-id.ts b/packages/sw/src/scripts/get-account-from-id.ts
index 19bfe052ee..2fa132138a 100644
--- a/packages/sw/src/scripts/get-account-from-id.ts
+++ b/packages/sw/src/scripts/get-account-from-id.ts
@@ -4,9 +4,10 @@
  */
 
 import { get } from 'idb-keyval';
+import * as Misskey from 'cherrypick-js';
 
-export async function getAccountFromId(id: string): Promise<{ token: string; id: string } | void> {
-	const accounts = await get<{ token: string; id: string }[]>('accounts');
+export async function getAccountFromId(id: string): Promise<Pick<Misskey.entities.SignupResponse, 'id' | 'token'> | undefined> {
+	const accounts = await get<Pick<Misskey.entities.SignupResponse, 'id' | 'token'>[]>('accounts');
 	if (!accounts) {
 		console.log('Accounts are not recorded');
 		return;
diff --git a/packages/sw/src/scripts/operations.ts b/packages/sw/src/scripts/operations.ts
index 22135105b6..231583fa5f 100644
--- a/packages/sw/src/scripts/operations.ts
+++ b/packages/sw/src/scripts/operations.ts
@@ -14,15 +14,22 @@ import { getUrlWithLoginId } from '@/scripts/login-id.js';
 
 export const cli = new Misskey.api.APIClient({ origin, fetch: (...args): Promise<Response> => fetch(...args) });
 
-export async function api<E extends keyof Misskey.Endpoints, O extends Misskey.Endpoints[E]['req']>(endpoint: E, userId?: string, options?: O): Promise<void | ReturnType<typeof cli.request<E, O>>> {
-	let account: { token: string; id: string } | void = undefined;
+export async function api<
+	E extends keyof Misskey.Endpoints,
+	P extends Misskey.Endpoints[E]['req']
+>(endpoint: E, userId?: string, params?: P): Promise<Misskey.api.SwitchCaseResponseType<E, P> | undefined> {
+	let account: Pick<Misskey.entities.SignupResponse, 'id' | 'token'> | undefined;
 
 	if (userId) {
 		account = await getAccountFromId(userId);
 		if (!account) return;
 	}
 
-	return cli.request(endpoint, options, account?.token);
+	return (cli.request as <E extends keyof Misskey.Endpoints, P extends Misskey.Endpoints[E]['req']>(
+		endpoint: E,
+		params: P,
+		credential?: string | null,
+	) => Promise<Misskey.api.SwitchCaseResponseType<E, P>>)(endpoint, params, account?.token);
 }
 
 // mark-all-as-read送出を1秒間隔に制限する
@@ -33,7 +40,7 @@ export function sendMarkAllAsRead(userId: string): Promise<null | undefined | vo
 	return new Promise(resolve => {
 		setTimeout(() => {
 			readBlockingStatus.set(userId, false);
-			api('notifications/mark-all-as-read', userId).then(resolve, resolve);
+			(api('notifications/mark-all-as-read', userId) as Promise<void>).then(resolve, resolve);
 		}, 1000);
 	});
 }
diff --git a/packages/sw/src/sw.ts b/packages/sw/src/sw.ts
index 41f7b3e4fd..8a7b147e43 100644
--- a/packages/sw/src/sw.ts
+++ b/packages/sw/src/sw.ts
@@ -189,8 +189,8 @@ globalThis.addEventListener('notificationclick', (ev: ServiceWorkerGlobalScopeEv
 					case 'markAllAsRead':
 						await globalThis.registration.getNotifications()
 							.then(notifications => notifications.forEach(n => n.tag !== 'read_notification' && n.close()));
-						await get('accounts').then(accounts => {
-							return Promise.all(accounts.map(async account => {
+						await get<Pick<Misskey.entities.SignupResponse, 'id' | 'token'>[]>('accounts').then(accounts => {
+							return Promise.all((accounts ?? []).map(async account => {
 								await swos.sendMarkAllAsRead(account.id);
 							}));
 						});
diff --git a/packages/sw/tsconfig.json b/packages/sw/tsconfig.json
index 50d4aae19d..f3f3543013 100644
--- a/packages/sw/tsconfig.json
+++ b/packages/sw/tsconfig.json
@@ -2,6 +2,7 @@
 	"compilerOptions": {
 		"allowJs": true,
 		"noEmitOnError": false,
+		"noImplicitAny": false,
 		"noImplicitReturns": true,
 		"noUnusedParameters": false,
 		"noUnusedLocals": true,