fix(ui): prevent race conditions during backend switch

- Add mutation key to useUpdateBackend for tracking
- Detect backend switching with useIsMutating in ProxyStatusWidget
- Disable install/controls during backend switch (prevents wrong-backend install)
- Reduce useCliproxyVersions staleTime from 1h to 5min for faster refresh
- Enable refetchOnWindowFocus for versions query

ui/src/components/monitoring/proxy-status-widget.tsx

@@ -46,7 +46,7 @@ import {
   AlertDialogTitle,
 } from '@/components/ui/alert-dialog';
 import { Tooltip, TooltipContent, TooltipProvider, TooltipTrigger } from '@/components/ui/tooltip';
-import { useQuery } from '@tanstack/react-query';
+import { useQuery, useIsMutating } from '@tanstack/react-query';
 import { api, type CliproxyServerConfig } from '@/lib/api-client';
 import {
   useProxyStatus,
@@ -167,6 +167,9 @@ export function ProxyStatusWidget() {
     staleTime: 30000, // 30 seconds
   });
 
+  // Detect if backend switch is in progress (prevents race condition)
+  const isBackendSwitching = useIsMutating({ mutationKey: ['update-backend'] }) > 0;
+
   // Determine if remote mode is enabled
   const remoteConfig = cliproxyConfig?.remote;
   const isRemoteMode = remoteConfig?.enabled && remoteConfig?.host;
@@ -176,7 +179,8 @@ export function ProxyStatusWidget() {
     startProxy.isPending ||
     stopProxy.isPending ||
     restartProxy.isPending ||
-    installVersion.isPending;
+    installVersion.isPending ||
+    isBackendSwitching;
   const hasUpdate = updateCheck?.hasUpdate ?? false;
   const isUnstable = updateCheck?.isStable === false;
   const currentVersion = updateCheck?.currentVersion;

ui/src/hooks/use-cliproxy.ts

@@ -349,6 +349,7 @@ export function useUpdateBackend() {
   const queryClient = useQueryClient();
 
   return useMutation({
+    mutationKey: ['update-backend'], // Used by ProxyStatusWidget to detect backend switching
     mutationFn: ({ backend, force = false }: { backend: 'original' | 'plus'; force?: boolean }) =>
       api.cliproxyServer.updateBackend(backend, force),
     onSuccess: () => {
@@ -378,8 +379,8 @@ export function useCliproxyVersions() {
   return useQuery({
     queryKey: ['cliproxy-versions'],
     queryFn: () => api.cliproxy.versions(),
-    staleTime: 60 * 60 * 1000, // 1 hour (matches backend cache)
+    staleTime: 5 * 60 * 1000, // 5 minutes (reduced for faster backend switch response)
-    refetchOnWindowFocus: false,
+    refetchOnWindowFocus: true, // Refetch on focus to catch backend changes
   });
 }