diff --git a/Shared/KBSkinManager.m b/Shared/KBSkinManager.m
index 545ea06..6f2040f 100644
--- a/Shared/KBSkinManager.m
+++ b/Shared/KBSkinManager.m
@@ -60,6 +60,20 @@ static NSString * const kKBSkinAccount = @"current";              // Keychain ac
 
 @implementation KBSkinManager
 
+/// 判断指定 skinId 在 App Group 中是否存在资源目录（Skins/<skinId>/...）。
+/// 默认皮肤（nil / @"default"）始终视为存在。
++ (BOOL)kb_hasAssetsForSkinId:(NSString *)skinId {
+    if (skinId.length == 0 || [skinId isEqualToString:@"default"]) {
+        return YES;
+    }
+    NSURL *containerURL = [[NSFileManager defaultManager] containerURLForSecurityApplicationGroupIdentifier:AppGroup];
+    if (!containerURL) return NO;
+    NSString *skinsRoot = [containerURL.path stringByAppendingPathComponent:@"Skins"];
+    NSString *skinRoot  = [skinsRoot stringByAppendingPathComponent:skinId];
+    BOOL isDir = NO;
+    return [[NSFileManager defaultManager] fileExistsAtPath:skinRoot isDirectory:&isDir] && isDir;
+}
+
 + (instancetype)shared {
     static KBSkinManager *m; static dispatch_once_t onceToken; dispatch_once(&onceToken, ^{ m = [KBSkinManager new]; });
     return m;
@@ -67,7 +81,12 @@ static NSString * const kKBSkinAccount = @"current";              // Keychain ac
 
 - (instancetype)init {
     if (self = [super init]) {
-        _current = [self p_loadFromKeychain] ?: [self.class defaultTheme];
+        KBSkinTheme *t = [self p_loadFromKeychain];
+        // 若 Keychain 中的皮肤在 App Group 中找不到对应资源目录（如首次安装 / 已被清理），则回退到默认皮肤。
+        if (!t || ![self.class kb_hasAssetsForSkinId:t.skinId]) {
+            t = [self.class defaultTheme];
+        }
+        _current = t;
         // Observe Darwin notification for cross-process updates
         CFNotificationCenterAddObserver(CFNotificationCenterGetDarwinNotifyCenter(),
                                         (__bridge const void *)(self),
@@ -347,7 +366,10 @@ static void KBSkinDarwinCallback(CFNotificationCenterRef center, void *observer,
 }
 
 - (void)p_reloadFromKeychainAndBroadcast:(BOOL)broadcast {
-    KBSkinTheme *t = [self p_loadFromKeychain] ?: [self.class defaultTheme];
+    KBSkinTheme *t = [self p_loadFromKeychain];
+    if (!t || ![self.class kb_hasAssetsForSkinId:t.skinId]) {
+        t = [self.class defaultTheme];
+    }
     self.current = t;
     if (broadcast) {
         [[NSNotificationCenter defaultCenter] postNotificationName:KBSkinDidChangeNotification object:nil];