fix: remove dead localStorage writes and hardcoded key

- Remove unused `dns_settings_enabled` localStorage writes in
  setting-clash.tsx — state is sourced from verge config, these
  writes were never read anywhere.
- Replace hardcoded `'last_check_update'` localStorage read in
  system-info-card.tsx with exported `readLastCheckTime()` from
  the useUpdate hook, keeping the key in a single source of truth.

src/components/home/system-info-card.tsx

@@ -7,13 +7,17 @@ import {
 } from '@mui/icons-material'
 import { Typography, Stack, Divider, Chip, IconButton } from '@mui/material'
 import { useLockFn } from 'ahooks'
-import { useCallback, useEffect, useMemo, useReducer } from 'react'
+import { useCallback, useEffect, useMemo, useState } from 'react'
 import { useTranslation } from 'react-i18next'
 import { useNavigate } from 'react-router'
 
 import { useServiceInstaller } from '@/hooks/use-service-installer'
 import { useSystemState } from '@/hooks/use-system-state'
-import { useUpdate } from '@/hooks/use-update'
+import {
+  useUpdate,
+  updateLastCheckTime,
+  readLastCheckTime,
+} from '@/hooks/use-update'
 import { useVerge } from '@/hooks/use-verge'
 import { getSystemInfo } from '@/services/cmds'
 import { showNotice } from '@/services/notice-service'
@@ -21,29 +25,6 @@ import { version as appVersion } from '@root/package.json'
 
 import { EnhancedCard } from './enhanced-card'
 
-interface SystemState {
-  osInfo: string
-  lastCheckUpdate: string
-}
-
-type SystemStateAction =
-  | { type: 'set-os-info'; payload: string }
-  | { type: 'set-last-check-update'; payload: string }
-
-const systemStateReducer = (
-  state: SystemState,
-  action: SystemStateAction,
-): SystemState => {
-  switch (action.type) {
-    case 'set-os-info':
-      return { ...state, osInfo: action.payload }
-    case 'set-last-check-update':
-      return { ...state, lastCheckUpdate: action.payload }
-    default:
-      return state
-  }
-}
-
 export const SystemInfoCard = () => {
   const { t } = useTranslation()
   const { verge, patchVerge } = useVerge()
@@ -51,28 +32,18 @@ export const SystemInfoCard = () => {
   const { isAdminMode, isSidecarMode } = useSystemState()
   const { installServiceAndRestartCore } = useServiceInstaller()
 
-  // 自动检查更新逻辑
-  const { checkUpdate: triggerCheckUpdate } = useUpdate(true, {
-    onSuccess: () => {
-      const now = Date.now()
-      localStorage.setItem('last_check_update', now.toString())
-      dispatchSystemState({
-        type: 'set-last-check-update',
-        payload: new Date(now).toLocaleString(),
-      })
-    },
-  })
+  // 自动检查更新逻辑（lastCheckUpdate 由 useUpdate 统一管理）
+  const { checkUpdate: triggerCheckUpdate, lastCheckUpdate } = useUpdate(true)
 
-  // 系统信息状态
-  const [systemState, dispatchSystemState] = useReducer(systemStateReducer, {
-    osInfo: '',
-    lastCheckUpdate: '-',
-  })
+  const [osInfo, setOsInfo] = useState('')
+
+  const lastCheckUpdateText = useMemo(
+    () => (lastCheckUpdate ? new Date(lastCheckUpdate).toLocaleString() : '-'),
+    [lastCheckUpdate],
+  )
 
   // 初始化系统信息
   useEffect(() => {
-    let timeoutId: number | undefined
-
     getSystemInfo()
       .then((info) => {
         const lines = info.split('\n')
@@ -87,49 +58,23 @@ export const SystemInfoCard = () => {
             sysVersion = sysVersion.substring(sysName.length).trim()
           }
 
-          dispatchSystemState({
-            type: 'set-os-info',
-            payload: `${sysName} ${sysVersion}`,
-          })
+          setOsInfo(`${sysName} ${sysVersion}`)
         }
       })
       .catch(console.error)
+  }, [])
 
-    // 获取最后检查更新时间
-    const lastCheck = localStorage.getItem('last_check_update')
-    if (lastCheck) {
-      try {
-        const timestamp = parseInt(lastCheck, 10)
-        if (!isNaN(timestamp)) {
-          dispatchSystemState({
-            type: 'set-last-check-update',
-            payload: new Date(timestamp).toLocaleString(),
-          })
-        }
-      } catch (e) {
-        console.error('Error parsing last check update time', e)
-      }
-    } else if (verge?.auto_check_update) {
-      // 如果启用了自动检查更新但没有记录，设置当前时间并延迟检查
-      const now = Date.now()
-      localStorage.setItem('last_check_update', now.toString())
-      dispatchSystemState({
-        type: 'set-last-check-update',
-        payload: new Date(now).toLocaleString(),
-      })
+  // 如果启用了自动检查更新但没有记录，设置当前时间并延迟检查
+  useEffect(() => {
+    if (!verge?.auto_check_update) return
+    if (readLastCheckTime() !== null) return
 
-      timeoutId = window.setTimeout(() => {
-        if (verge?.auto_check_update) {
-          triggerCheckUpdate().catch(console.error)
-        }
-      }, 5000)
-    }
-    return () => {
-      if (timeoutId !== undefined) {
-        window.clearTimeout(timeoutId)
-      }
-    }
-  }, [verge?.auto_check_update, dispatchSystemState, triggerCheckUpdate])
+    updateLastCheckTime()
+    const timeoutId = window.setTimeout(() => {
+      triggerCheckUpdate().catch(console.error)
+    }, 5000)
+    return () => window.clearTimeout(timeoutId)
+  }, [verge?.auto_check_update, triggerCheckUpdate])
 
   // 导航到设置页面
   const goToSettings = useCallback(() => {
@@ -157,12 +102,6 @@ export const SystemInfoCard = () => {
   const onCheckUpdate = useLockFn(async () => {
     try {
       const info = await triggerCheckUpdate()
-      const now = Date.now()
-      localStorage.setItem('last_check_update', now.toString())
-      dispatchSystemState({
-        type: 'set-last-check-update',
-        payload: new Date(now).toLocaleString(),
-      })
       if (!info?.available) {
         showNotice.success(
           'settings.components.verge.advanced.notifications.latestVersion',
@@ -280,7 +219,7 @@ export const SystemInfoCard = () => {
             {t('home.components.systemInfo.fields.osInfo')}
           </Typography>
           <Typography variant="body2" fontWeight="medium">
-            {systemState.osInfo}
+            {osInfo}
           </Typography>
         </Stack>
         <Divider />
@@ -341,7 +280,7 @@ export const SystemInfoCard = () => {
               '&:hover': { opacity: 0.7 },
             }}
           >
-            {systemState.lastCheckUpdate}
+            {lastCheckUpdateText}
           </Typography>
         </Stack>
         <Divider />

src/components/setting/setting-clash.tsx

@@ -78,7 +78,6 @@ const SettingClash = ({ onError }: Props) => {
   const handleDnsToggle = useLockFn(async (enable: boolean) => {
     try {
       setDnsSettingsEnabled(enable)
-      localStorage.setItem('dns_settings_enabled', String(enable))
       await patchVerge({ enable_dns_settings: enable })
       await invoke('apply_dns_config', { apply: enable })
       setTimeout(() => {
@@ -86,7 +85,6 @@ const SettingClash = ({ onError }: Props) => {
       }, 500)
     } catch (err: any) {
       setDnsSettingsEnabled(!enable)
-      localStorage.setItem('dns_settings_enabled', String(!enable))
       showNotice.error(err)
       await patchVerge({ enable_dns_settings: !enable }).catch(() => {})
       throw err

src/components/setting/setting-verge-advanced.tsx

@@ -4,6 +4,7 @@ import { useCallback, useRef } from 'react'
 import { useTranslation } from 'react-i18next'
 
 import { DialogRef, TooltipIcon } from '@/components/base'
+import { updateLastCheckTime } from '@/hooks/use-update'
 import {
   exitApp,
   exportDiagnosticInfo,
@@ -45,6 +46,7 @@ const SettingVergeAdvanced = ({ onError: _ }: Props) => {
   const onCheckUpdate = async () => {
     try {
       const info = await checkUpdate()
+      updateLastCheckTime()
       if (!info?.available) {
         showNotice.success(
           'settings.components.verge.advanced.notifications.latestVersion',

src/hooks/use-update.ts

@@ -1,4 +1,4 @@
-import useSWR, { SWRConfiguration } from 'swr'
+import useSWR, { mutate as globalMutate, SWRConfiguration } from 'swr'
 
 import { checkUpdateSafe } from '@/services/update'
 
@@ -12,6 +12,26 @@ export interface UpdateInfo {
   downloadAndInstall: (onEvent?: any) => Promise<void>
 }
 
+// --- Last check timestamp (shared via SWR + localStorage) ---
+
+const LAST_CHECK_KEY = 'last_check_update'
+
+export const readLastCheckTime = (): number | null => {
+  const stored = localStorage.getItem(LAST_CHECK_KEY)
+  if (!stored) return null
+  const ts = parseInt(stored, 10)
+  return isNaN(ts) ? null : ts
+}
+
+export const updateLastCheckTime = (timestamp?: number): number => {
+  const now = timestamp ?? Date.now()
+  localStorage.setItem(LAST_CHECK_KEY, now.toString())
+  globalMutate(LAST_CHECK_KEY, now, false)
+  return now
+}
+
+// --- useUpdate hook ---
+
 export const useUpdate = (
   enabled: boolean = true,
   options?: SWRConfiguration,
@@ -36,11 +56,22 @@ export const useUpdate = (
     refreshInterval: 24 * 60 * 60 * 1000, // 24 hours
     dedupingInterval: 60 * 60 * 1000, // 1 hour
     ...options,
+    onSuccess: (...args) => {
+      updateLastCheckTime()
+      options?.onSuccess?.(...args)
+    },
+  })
+
+  // Shared last check timestamp
+  const { data: lastCheckUpdate } = useSWR(LAST_CHECK_KEY, readLastCheckTime, {
+    revalidateOnFocus: false,
+    revalidateOnReconnect: false,
   })
 
   return {
     updateInfo,
     checkUpdate,
     loading: isValidating,
+    lastCheckUpdate: lastCheckUpdate ?? null,
   }
 }