diff --git a/userfront/lib/core/services/auth_token_store_web.dart b/userfront/lib/core/services/auth_token_store_web.dart
index 8fb4f26b..9e076351 100644
--- a/userfront/lib/core/services/auth_token_store_web.dart
+++ b/userfront/lib/core/services/auth_token_store_web.dart
@@ -1,6 +1,16 @@
-// ignore_for_file: avoid_web_libraries_in_flutter, deprecated_member_use
+// ignore_for_file: avoid_web_libraries_in_flutter
 
-import 'dart:html' as html;
+import 'dart:js_interop';
+
+@JS('window.localStorage')
+external _JSStorage get _localStorage;
+
+@JS()
+extension type _JSStorage(JSObject _) implements JSObject {
+  external String? getItem(String key);
+  external void setItem(String key, String value);
+  external void removeItem(String key);
+}
 
 class AuthTokenStore {
   static const _tokenKey = 'baron_auth_token';
@@ -8,43 +18,77 @@ class AuthTokenStore {
   static const _cookieModeKey = 'baron_auth_cookie_mode';
   static const _pendingProviderKey = 'baron_auth_pending_provider';
 
-  String? getToken() => html.window.localStorage[_tokenKey];
+  String? getToken() {
+    try {
+      return _localStorage.getItem(_tokenKey);
+    } catch (_) {
+      return null;
+    }
+  }
 
-  String? getProvider() => html.window.localStorage[_providerKey];
+  String? getProvider() {
+    try {
+      return _localStorage.getItem(_providerKey);
+    } catch (_) {
+      return null;
+    }
+  }
 
-  bool usesCookie() => html.window.localStorage[_cookieModeKey] == '1';
+  bool usesCookie() {
+    try {
+      return _localStorage.getItem(_cookieModeKey) == '1';
+    } catch (_) {
+      return false;
+    }
+  }
 
   void setToken(String token, {String? provider}) {
-    html.window.localStorage[_tokenKey] = token;
-    html.window.localStorage.remove(_cookieModeKey);
-    if (provider != null) {
-      html.window.localStorage[_providerKey] = provider;
+    try {
+      _localStorage.setItem(_tokenKey, token);
+      _localStorage.removeItem(_cookieModeKey);
+      if (provider != null) {
+        _localStorage.setItem(_providerKey, provider);
+      }
+    } catch (e) {
+      print("[AuthTokenStore] CRITICAL - Failed to set token: $e");
     }
   }
 
   void setCookieMode({String? provider}) {
-    html.window.localStorage[_cookieModeKey] = '1';
-    html.window.localStorage.remove(_tokenKey);
-    if (provider != null) {
-      html.window.localStorage[_providerKey] = provider;
+    try {
+      _localStorage.setItem(_cookieModeKey, '1');
+      _localStorage.removeItem(_tokenKey);
+      if (provider != null) {
+        _localStorage.setItem(_providerKey, provider);
+      }
+    } catch (_) {}
+  }
+
+  String? getPendingProvider() {
+    try {
+      return _localStorage.getItem(_pendingProviderKey);
+    } catch (_) {
+      return null;
     }
   }
 
-  String? getPendingProvider() => html.window.localStorage[_pendingProviderKey];
-
   void setPendingProvider(String? provider) {
-    if (provider == null || provider.isEmpty) {
-      html.window.localStorage.remove(_pendingProviderKey);
-      return;
-    }
-    html.window.localStorage[_pendingProviderKey] = provider;
+    try {
+      if (provider == null || provider.isEmpty) {
+        _localStorage.removeItem(_pendingProviderKey);
+        return;
+      }
+      _localStorage.setItem(_pendingProviderKey, provider);
+    } catch (_) {}
   }
 
   void clear() {
-    html.window.localStorage.remove(_tokenKey);
-    html.window.localStorage.remove(_providerKey);
-    html.window.localStorage.remove(_cookieModeKey);
-    html.window.localStorage.remove(_pendingProviderKey);
+    try {
+      _localStorage.removeItem(_tokenKey);
+      _localStorage.removeItem(_providerKey);
+      _localStorage.removeItem(_cookieModeKey);
+      _localStorage.removeItem(_pendingProviderKey);
+    } catch (_) {}
   }
 }
 
diff --git a/userfront/lib/core/services/web_window.dart b/userfront/lib/core/services/web_window.dart
index 1fe2792d..1283b271 100644
--- a/userfront/lib/core/services/web_window.dart
+++ b/userfront/lib/core/services/web_window.dart
@@ -1 +1 @@
-export 'web_window_stub.dart' if (dart.library.html) 'web_window_web.dart';
+export 'web_window_web.dart';
diff --git a/userfront/lib/core/services/web_window_web.dart b/userfront/lib/core/services/web_window_web.dart
index fc1659be..dbd56548 100644
--- a/userfront/lib/core/services/web_window_web.dart
+++ b/userfront/lib/core/services/web_window_web.dart
@@ -1,11 +1,45 @@
 // ignore_for_file: avoid_web_libraries_in_flutter, deprecated_member_use
-
 import 'dart:html' as html;
 import 'package:flutter/foundation.dart';
 
+// ignore_for_file: avoid_web_libraries_in_flutter
+import 'dart:async';
+import 'dart:js_interop';
+
+@JS('window')
+external _JSWindow get _window;
+
+@JS('document')
+external _JSDocument get _document;
+
+@JS()
+extension type _JSWindow(JSObject _) implements JSObject {
+  external void alert(JSString message);
+  external void close();
+  external JSObject? get opener;
+  external _JSLocation get location;
+}
+
+@JS()
+extension type _JSDocument(JSObject _) implements JSObject {
+  external set title(JSString value);
+}
+
+@JS()
+extension type _JSOpener(JSObject _) implements JSObject {
+  external _JSLocation get location;
+}
+
+@JS()
+extension type _JSLocation(JSObject _) implements JSObject {
+  external set href(JSString value);
+}
+
 class WebWindow {
   void setTitle(String title) {
-    html.document.title = title;
+    try {
+      _document.title = title.toJS;
+    } catch (_) {}
   }
 
   void redirectTo(String url) {
@@ -28,7 +62,17 @@ class WebWindow {
       "[WebWindow] redirectTo start: current=$currentHref, target=$url, target_host=${targetUri?.host ?? ''}, target_path=${targetUri?.path ?? ''}, same_origin=$sameOrigin",
     );
 
-    html.window.location.href = url;
+    print("[WebWindow] FINAL REDIRECT ATTEMPT. URL: $url");
+    // Explicitly use the href setter on the window.location object.
+    // This is the most standard-compliant way for JS Interop in WASM.
+    Future.delayed(Duration.zero, () {
+      try {
+        print("[WebWindow] Executing JS href assignment for: $url");
+        _window.location.href = url.toJS;
+      } catch (e) {
+        print("[WebWindow] CRITICAL JS ERROR: $e");
+      }
+    });
 
     // 이동이 차단되거나 즉시 원위치되는 경우를 추적하기 위한 후속 로그입니다.
     Future<void>.delayed(const Duration(milliseconds: 800), () {
@@ -54,24 +98,30 @@ class WebWindow {
   }
 
   void alert(String message) {
-    html.window.alert(message);
+    try {
+      _window.alert(message.toJS);
+    } catch (_) {}
   }
 
   void close() {
-    html.window.close();
+    try {
+      _window.close();
+    } catch (_) {}
   }
 
   bool hasOpener() {
-    return html.window.opener != null;
+    try {
+      return _window.opener != null;
+    } catch (_) {
+      return false;
+    }
   }
 
   bool redirectOpenerTo(String url) {
-    final opener = html.window.opener;
-    if (opener == null) {
-      return false;
-    }
     try {
-      opener.location.href = url;
+      final opener = _window.opener;
+      if (opener == null) return false;
+      (_JSOpener(opener)).location.href = url.toJS;
       return true;
     } catch (_) {
       return false;