diff --git a/frontend/src/App.tsx b/frontend/src/App.tsx
index 092a4b01..18b0b628 100644
--- a/frontend/src/App.tsx
+++ b/frontend/src/App.tsx
@@ -1714,7 +1714,6 @@ function App() {
       updateChannel,
       updateDownloadProgress,
   } = useAppUpdateManager({
-      isMacRuntime,
       runtimeBuildType,
       t,
   });
diff --git a/frontend/src/hooks/useAppUpdateManager.test.tsx b/frontend/src/hooks/useAppUpdateManager.test.tsx
index 2d9703d8..1e17185c 100644
--- a/frontend/src/hooks/useAppUpdateManager.test.tsx
+++ b/frontend/src/hooks/useAppUpdateManager.test.tsx
@@ -54,10 +54,9 @@ describe('useAppUpdateManager', () => {
     return key;
   };
 
-  const renderHook = (isMacRuntime: boolean) => {
+  const renderHook = () => {
     const Harness = () => {
       hook = useAppUpdateManager({
-        isMacRuntime,
         runtimeBuildType: 'release',
         t,
       });
@@ -113,7 +112,7 @@ describe('useAppUpdateManager', () => {
     backendApp.InstallUpdateAndRestart.mockResolvedValue({ success: true });
     backendApp.OpenDownloadedUpdateDirectory.mockResolvedValue({ success: true });
 
-    renderHook(true);
+    renderHook();
 
     await act(async () => {
       await hook?.checkForUpdates(false);
@@ -146,7 +145,7 @@ describe('useAppUpdateManager', () => {
     });
     backendApp.OpenDownloadedUpdateDirectory.mockResolvedValue({ success: true });
 
-    renderHook(true);
+    renderHook();
 
     await act(async () => {
       await hook?.checkForUpdates(false);
@@ -173,7 +172,7 @@ describe('useAppUpdateManager', () => {
       },
     });
 
-    renderHook(false);
+    renderHook();
 
     await act(async () => {
       await hook?.changeUpdateChannel('dev');
diff --git a/frontend/src/hooks/useAppUpdateManager.ts b/frontend/src/hooks/useAppUpdateManager.ts
index 1c947cba..c09d4bbd 100644
--- a/frontend/src/hooks/useAppUpdateManager.ts
+++ b/frontend/src/hooks/useAppUpdateManager.ts
@@ -40,7 +40,6 @@ type UpdateDownloadResultData = {
 };
 
 type UseAppUpdateManagerOptions = {
-  isMacRuntime: boolean;
   runtimeBuildType: string;
   t: Translator;
 };
@@ -48,6 +47,7 @@ type UseAppUpdateManagerOptions = {
 const createEmptyDownloadProgress = () => ({
   open: false,
   version: '',
+  key: '',
   status: 'idle' as 'idle' | 'start' | 'downloading' | 'done' | 'error',
   percent: 0,
   downloaded: 0,
@@ -64,7 +64,6 @@ const buildUpdateKey = (info: Pick<UpdateInfo, 'channel' | 'latestVersion'> | nu
     : '';
 
 export const useAppUpdateManager = ({
-  isMacRuntime: _isMacRuntime,
   runtimeBuildType,
   t,
 }: UseAppUpdateManagerOptions) => {
@@ -148,7 +147,8 @@ export const useAppUpdateManager = ({
     updateDownloadMetaRef.current = null;
     setUpdateDownloadProgress({
       open: true,
-      version: targetKey,
+      version: info.latestVersion,
+      key: targetKey,
       status: 'start',
       percent: 0,
       downloaded: 0,
@@ -219,7 +219,7 @@ export const useAppUpdateManager = ({
   );
   const isBackgroundProgressForLatestUpdate = Boolean(lastUpdateInfo?.hasUpdate)
     && Boolean(lastUpdateKey)
-    && updateDownloadProgress.version === lastUpdateKey
+    && updateDownloadProgress.key === lastUpdateKey
     && (updateDownloadProgress.status === 'start'
       || updateDownloadProgress.status === 'downloading'
       || updateDownloadProgress.status === 'done'
@@ -292,8 +292,9 @@ export const useAppUpdateManager = ({
           const total = info.assetSize || prev.total || 0;
           return {
             ...prev,
-            open: prev.open && prev.version === infoKey,
-            version: infoKey,
+            open: prev.open && prev.key === infoKey,
+            version: info.latestVersion,
+            key: infoKey,
             status: 'done',
             percent: 100,
             downloaded: total,
@@ -317,7 +318,8 @@ export const useAppUpdateManager = ({
           return {
             ...prev,
             open: false,
-            version: infoKey,
+            version: info.latestVersion,
+            key: infoKey,
             status: 'idle',
             percent: 0,
             downloaded: 0,
@@ -485,6 +487,7 @@ export const useAppUpdateManager = ({
         setUpdateDownloadProgress((prev) => ({
           open: prev.open,
           version: prev.version,
+          key: prev.key,
           status: nextStatus,
           percent,
           downloaded,
diff --git a/internal/app/update_channel_state.go b/internal/app/update_channel_state.go
index d9b88517..de82feaf 100644
--- a/internal/app/update_channel_state.go
+++ b/internal/app/update_channel_state.go
@@ -81,7 +81,18 @@ func (a *App) persistUpdateChannel(channel updateChannel) error {
 	if err != nil {
 		return err
 	}
-	return os.WriteFile(updateChannelMetadataPath(a.configDir), payload, 0o644)
+
+	// 先写临时文件再重命名，避免进程中断留下损坏的 JSON。
+	target := updateChannelMetadataPath(a.configDir)
+	tmp := target + ".tmp"
+	if err := os.WriteFile(tmp, payload, 0o644); err != nil {
+		return err
+	}
+	if err := os.Rename(tmp, target); err != nil {
+		_ = os.Remove(tmp)
+		return err
+	}
+	return nil
 }
 
 func (a *App) currentUpdateChannel() updateChannel {
@@ -115,15 +126,16 @@ func (a *App) SetUpdateChannel(channel string) connection.QueryResult {
 		return connection.QueryResult{Success: false, Message: a.localizedUpdateError(err)}
 	}
 
+	// 检查、持久化与缓存清理必须在同一临界区内完成，
+	// 否则窗口期内启动的下载会把旧通道的安装包写回缓存。
 	a.updateMu.Lock()
+	defer a.updateMu.Unlock()
 	if a.updateState.downloading {
-		a.updateMu.Unlock()
 		return connection.QueryResult{
 			Success: false,
 			Message: a.appText("app.update.backend.message.channel_change_blocked_downloading", nil),
 		}
 	}
-	a.updateMu.Unlock()
 
 	if err := a.persistUpdateChannel(normalized); err != nil {
 		logger.Error(err, "保存更新通道失败")
@@ -133,10 +145,8 @@ func (a *App) SetUpdateChannel(channel string) connection.QueryResult {
 		}
 	}
 
-	a.updateMu.Lock()
 	a.updateState.lastCheck = nil
 	a.updateState.staged = nil
-	a.updateMu.Unlock()
 
 	return connection.QueryResult{
 		Success: true,