diff --git a/windows/LoginWindow.xaml.cs b/windows/LoginWindow.xaml.cs
new file mode 100644
index 0000000..7d5cb5f
--- /dev/null
+++ b/windows/LoginWindow.xaml.cs
@@ -0,0 +1,53 @@
+using Microsoft.Web.WebView2.Core;
+using System;
+using System.Linq;
+using System.Threading.Tasks;
+using System.Windows;
+
+namespace ClaudeCheckerWindows;
+
+public partial class LoginWindow : Window
+{
+    public LoginWindow()
+    {
+        InitializeComponent();
+        Loaded += async (_, _) => await InitBrowserAsync();
+    }
+
+    private async Task InitBrowserAsync()
+    {
+        var env = await CoreWebView2Environment.CreateAsync(userDataFolder:
+            System.IO.Path.Combine(
+                Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData),
+                "ClaudeChecker", "WebView2"));
+
+        await Browser.EnsureCoreWebView2Async(env);
+        Browser.CoreWebView2.Navigate("https://claude.ai");
+
+        Browser.CoreWebView2.NavigationCompleted += async (_, e) =>
+        {
+            if (!e.IsSuccess) return;
+            var uri = Browser.CoreWebView2.Source;
+            if (uri.Contains("claude.ai") && !uri.Contains("/login"))
+            {
+                // Likely signed in — enable done button
+                var cookies = await Browser.CoreWebView2.CookieManager.GetCookiesAsync("https://claude.ai");
+                var hasSess = cookies.Any(c => c.Name.Contains("session") || c.Name.Contains("sk-"));
+                await Dispatcher.InvokeAsync(() =>
+                {
+                    DoneButton.IsEnabled = hasSess || uri.Contains("/chats") || uri.Contains("/new");
+                    StatusText.Text      = DoneButton.IsEnabled
+                        ? "Signed in! Click Done to continue."
+                        : "Waiting for sign-in…";
+                });
+            }
+        };
+    }
+
+    private async void Done_Click(object sender, RoutedEventArgs e)
+    {
+        var cookies = await Browser.CoreWebView2.CookieManager.GetCookiesAsync("https://claude.ai");
+        UsageViewModel.SaveCookies(cookies);
+        DialogResult = true;
+    }
+}