style(backup): fix style

src/renderer/src/pages/settings/DataSettings/S3Settings.tsx

@@ -139,6 +139,37 @@ const S3Settings: FC = () => {
       </SettingTitle>
       <SettingHelpText>{t('settings.data.s3.title.help')}</SettingHelpText>
       <SettingDivider />
+      {/* 覆盖式单文件备份，仅在自动备份开启且保留份数=1时推荐启用 */}
+      <SettingRow>
+        <SettingRowTitle>
+          {t('settings.data.backup.singleFileOverwrite.title') || '覆盖式单文件备份（同名覆盖）'}
+        </SettingRowTitle>
+        <Switch
+          checked={singleFileOverwrite}
+          onChange={onSingleFileOverwriteChange}
+          disabled={!(syncInterval > 0 && maxBackups === 1)}
+        />
+      </SettingRow>
+      <SettingRow>
+        <SettingHelpText>
+          {t('settings.data.backup.singleFileOverwrite.help') ||
+            '当自动备份开启且保留份数为1时，使用固定文件名每次覆盖。S3 会直接覆盖同键对象。'}
+        </SettingHelpText>
+      </SettingRow>
+      <SettingRow>
+        <SettingRowTitle>{t('settings.data.backup.singleFileName.title') || '自定义文件名（可选）'}</SettingRowTitle>
+        <Input
+          placeholder={
+            t('settings.data.backup.singleFileName.placeholder') || '如：cherry-studio.<hostname>.<device>.zip'
+          }
+          value={singleFileName}
+          onChange={(e) => setSingleFileName(e.target.value)}
+          onBlur={onSingleFileNameBlur}
+          style={{ width: 300 }}
+          disabled={!singleFileOverwrite || !(syncInterval > 0 && maxBackups === 1)}
+        />
+      </SettingRow>
+      <SettingDivider />
       <SettingRow>
         <SettingRowTitle>{t('settings.data.s3.endpoint.label')}</SettingRowTitle>
         <Input

src/renderer/src/services/BackupService.ts

@@ -396,7 +396,11 @@ export async function backupToS3({
       showMessage && window.toast.success(i18n.t('message.backup.success'))
 
       // 清理旧备份文件
-      if (s3Config.maxBackups > 0) {
+      // 覆盖式单文件备份启用时（且=1），不进行清理，避免误删历史。后续不会再增长。
+      if (
+        s3Config.maxBackups > 0 &&
+        !(autoBackupProcess && s3Config.maxBackups === 1 && s3Config.singleFileOverwrite)
+      ) {
         try {
           // 获取所有备份文件
           const files = await window.api.backup.listS3Files(s3Config)
@@ -951,7 +955,9 @@ export async function backupToLocal({
   const {
     localBackupDir: localBackupDirSetting,
     localBackupMaxBackups,
-    localBackupSkipBackupFile
+    localBackupSkipBackupFile,
+    localSingleFileOverwrite,
+    localSingleFileName
   } = store.getState().settings
   const localBackupDir = await window.api.resolvePath(localBackupDirSetting)
   let deviceType = 'unknown'
@@ -963,7 +969,11 @@ export async function backupToLocal({
     logger.error('Failed to get device type or hostname:', error as Error)
   }
   const timestamp = dayjs().format('YYYYMMDDHHmmss')
-  const backupFileName = customFileName || `cherry-studio.${timestamp}.${hostname}.${deviceType}.zip`
+  let backupFileName = customFileName || `cherry-studio.${timestamp}.${hostname}.${deviceType}.zip`
+  if (autoBackupProcess && localBackupMaxBackups === 1 && localSingleFileOverwrite) {
+    const base = (localSingleFileName || `cherry-studio.${hostname}.${deviceType}`).trim()
+    backupFileName = base.endsWith('.zip') ? base : `${base}.zip`
+  }
   const finalFileName = backupFileName.endsWith('.zip') ? backupFileName : `${backupFileName}.zip`
   const backupData = await getBackupData()
 
@@ -993,8 +1003,11 @@ export async function backupToLocal({
         })
       }
 
-      // Clean up old backups if maxBackups is set
+      // 覆盖式单文件备份启用时（且=1），不进行清理
-      if (localBackupMaxBackups > 0) {
+      if (
+        localBackupMaxBackups > 0 &&
+        !(autoBackupProcess && localBackupMaxBackups === 1 && localSingleFileOverwrite)
+      ) {
         try {
           // Get all backup files
           const files = await window.api.backup.listLocalBackupFiles(localBackupDir)