diff --git a/windows/PopupWindow.xaml b/windows/PopupWindow.xaml
new file mode 100644
index 0000000..e585d7a
--- /dev/null
+++ b/windows/PopupWindow.xaml
@@ -0,0 +1,251 @@
+<Window x:Class="ClaudeCheckerWindows.PopupWindow"
+        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        xmlns:ctrl="clr-namespace:ClaudeCheckerWindows.Controls"
+        Title="ClaudeChecker"
+        Width="480"
+        SizeToContent="Height"
+        WindowStyle="None"
+        AllowsTransparency="True"
+        Background="Transparent"
+        ShowInTaskbar="False"
+        Topmost="True"
+        ResizeMode="NoResize">
+
+    <Border Background="{StaticResource BackgroundBrush}"
+            CornerRadius="12"
+            BorderBrush="{StaticResource BorderBrush}"
+            BorderThickness="0.5">
+        <Border.Effect>
+            <DropShadowEffect BlurRadius="24" ShadowDepth="4" Opacity="0.5" Color="Black"/>
+        </Border.Effect>
+
+        <Grid>
+            <!-- Main panel -->
+            <StackPanel x:Name="MainPanel">
+
+                <!-- Header -->
+                <Grid Margin="16,11">
+                    <Grid.ColumnDefinitions>
+                        <ColumnDefinition Width="Auto"/>
+                        <ColumnDefinition Width="*"/>
+                        <ColumnDefinition Width="Auto"/>
+                        <ColumnDefinition Width="6"/>
+                        <ColumnDefinition Width="Auto"/>
+                    </Grid.ColumnDefinitions>
+
+                    <Image Grid.Column="0" Width="24" Height="24"
+                           Source="Assets/icon.png" RenderOptions.BitmapScalingMode="HighQuality"/>
+
+                    <TextBlock Grid.Column="1" Text="ClaudeChecker"
+                               FontSize="14" FontWeight="SemiBold" Foreground="White"
+                               VerticalAlignment="Center" Margin="10,0,0,0"/>
+
+                    <Button Grid.Column="2" Style="{StaticResource IconButton}"
+                            Click="Settings_Click" x:Name="SettingsButton">
+                        <TextBlock Text="⚙" FontSize="11" Foreground="{StaticResource SecondaryBrush}"/>
+                    </Button>
+                    <Button Grid.Column="4" Style="{StaticResource IconButton}"
+                            Click="Close_Click">
+                        <TextBlock Text="✕" FontSize="11" Foreground="{StaticResource SecondaryBrush}"/>
+                    </Button>
+                </Grid>
+
+                <Rectangle Height="0.5" Fill="{StaticResource BorderBrush}" Opacity="0.4"/>
+
+                <!-- Update banner -->
+                <Border x:Name="UpdateBanner" Visibility="Collapsed"
+                        Background="#0A3B82F6" Cursor="Hand" MouseLeftButtonUp="UpdateBanner_Click">
+                    <Grid Margin="16,10">
+                        <Grid.ColumnDefinitions>
+                            <ColumnDefinition Width="Auto"/>
+                            <ColumnDefinition Width="*"/>
+                            <ColumnDefinition Width="Auto"/>
+                        </Grid.ColumnDefinitions>
+                        <TextBlock Grid.Column="0" Text="⬇" FontSize="14"
+                                   Foreground="{StaticResource BlueBrush}" VerticalAlignment="Center"/>
+                        <StackPanel Grid.Column="1" Margin="10,0">
+                            <TextBlock x:Name="UpdateBannerTitle" FontSize="12" FontWeight="SemiBold" Foreground="White"/>
+                            <TextBlock Text="Tap to view what's new &amp; install."
+                                       FontSize="11" Foreground="{StaticResource SecondaryBrush}"/>
+                        </StackPanel>
+                        <Button Grid.Column="2" Content="Update"
+                                Style="{StaticResource SmallButton}"
+                                Background="{StaticResource BlueBrush}"
+                                Foreground="White" Click="UpdateBanner_Click"/>
+                    </Grid>
+                    <Border.Effect>
+                        <DropShadowEffect ShadowDepth="0" BlurRadius="0" Opacity="0"/>
+                    </Border.Effect>
+                </Border>
+                <Rectangle x:Name="UpdateBannerDiv" Height="0.5" Fill="{StaticResource BorderBrush}"
+                           Opacity="0.3" Visibility="Collapsed"/>
+
+                <!-- Limit cards -->
+                <ScrollViewer VerticalScrollBarVisibility="Hidden" MaxHeight="600">
+                    <StackPanel x:Name="CardsPanel" Margin="0,0,0,4"/>
+                </ScrollViewer>
+
+                <Rectangle Height="0.5" Fill="{StaticResource BorderBrush}" Opacity="0.3"/>
+
+                <!-- Footer -->
+                <Grid Margin="16,9">
+                    <Grid.ColumnDefinitions>
+                        <ColumnDefinition Width="*"/>
+                        <ColumnDefinition Width="Auto"/>
+                        <ColumnDefinition Width="8"/>
+                        <ColumnDefinition Width="Auto"/>
+                    </Grid.ColumnDefinitions>
+                    <TextBlock x:Name="LastUpdatedText" Grid.Column="0"
+                               FontSize="10" Foreground="#60888888" VerticalAlignment="Center"/>
+                    <ProgressBar x:Name="LoadingBar" Grid.Column="1"
+                                 IsIndeterminate="True" Width="14" Height="14"
+                                 Visibility="Collapsed" Style="{x:Null}"/>
+                    <Button Grid.Column="3" Content="↻  Refresh"
+                            Style="{StaticResource SmallButton}" Click="Refresh_Click"/>
+                </Grid>
+            </StackPanel>
+
+            <!-- Settings panel -->
+            <Border x:Name="SettingsPanel" Visibility="Collapsed"
+                    Background="{StaticResource BackgroundBrush}" CornerRadius="12">
+                <ScrollViewer VerticalScrollBarVisibility="Auto" MaxHeight="700">
+                    <StackPanel Margin="16">
+
+                        <Button Content="← Back" HorizontalAlignment="Left"
+                                Style="{StaticResource SmallButton}"
+                                BorderThickness="0" Foreground="{StaticResource BlueBrush}"
+                                Click="BackFromSettings_Click" Margin="0,0,0,12"/>
+
+                        <TextBlock Text="Settings" FontSize="16" FontWeight="SemiBold"
+                                   Foreground="White" Margin="0,0,0,16"/>
+
+                        <!-- Auth -->
+                        <TextBlock Text="🔐  Authentication" Style="{StaticResource HeaderText}" Margin="0,0,0,8"/>
+                        <StackPanel x:Name="AuthPanel" Margin="0,0,0,8"/>
+                        <TextBlock Text="Your session is stored locally and persists across restarts."
+                                   FontSize="11" Foreground="{StaticResource SecondaryBrush}"
+                                   TextWrapping="Wrap" Margin="0,0,0,8"/>
+                        <StackPanel Orientation="Horizontal" Margin="0,0,0,16">
+                            <Button x:Name="SignInButton" Content="Sign In"
+                                    Style="{StaticResource SmallButton}" Click="SignIn_Click" Margin="0,0,8,0"/>
+                            <Button x:Name="SignOutButton" Content="Sign Out"
+                                    Style="{StaticResource SmallButton}" Click="SignOut_Click"
+                                    Foreground="#EF4444" Visibility="Collapsed"/>
+                        </StackPanel>
+
+                        <Rectangle Height="0.5" Fill="{StaticResource BorderBrush}" Margin="0,0,0,16"/>
+
+                        <!-- Beta channel -->
+                        <TextBlock Text="📡  Update channel" Style="{StaticResource HeaderText}" Margin="0,0,0,8"/>
+                        <Grid Margin="0,0,0,16">
+                            <Grid.ColumnDefinitions>
+                                <ColumnDefinition Width="*"/>
+                                <ColumnDefinition Width="Auto"/>
+                            </Grid.ColumnDefinitions>
+                            <StackPanel>
+                                <TextBlock Text="Beta updates" FontSize="12" Foreground="White"/>
+                                <TextBlock Text="Receive early access builds — may be less stable"
+                                           FontSize="11" Foreground="{StaticResource SecondaryBrush}"/>
+                            </StackPanel>
+                            <CheckBox Grid.Column="1" x:Name="BetaToggle" VerticalAlignment="Center"
+                                      Checked="BetaToggle_Changed" Unchecked="BetaToggle_Changed"/>
+                        </Grid>
+
+                        <Rectangle Height="0.5" Fill="{StaticResource BorderBrush}" Margin="0,0,0,16"/>
+
+                        <!-- Refresh interval -->
+                        <TextBlock Text="⏱  Auto-refresh interval" Style="{StaticResource HeaderText}" Margin="0,0,0,8"/>
+                        <ComboBox x:Name="RefreshPicker" SelectionChanged="RefreshPicker_Changed"
+                                  Margin="0,0,0,16" FontSize="12"/>
+
+                        <Rectangle Height="0.5" Fill="{StaticResource BorderBrush}" Margin="0,0,0,16"/>
+
+                        <!-- About -->
+                        <Grid>
+                            <Grid.ColumnDefinitions>
+                                <ColumnDefinition Width="Auto"/>
+                                <ColumnDefinition Width="*"/>
+                                <ColumnDefinition Width="Auto"/>
+                            </Grid.ColumnDefinitions>
+                            <Image Width="36" Height="36" Source="Assets/icon.png"
+                                   RenderOptions.BitmapScalingMode="HighQuality" Margin="0,0,12,0"/>
+                            <StackPanel Grid.Column="1" VerticalAlignment="Center">
+                                <StackPanel Orientation="Horizontal">
+                                    <TextBlock Text="ClaudeChecker" FontSize="12" FontWeight="SemiBold" Foreground="White"/>
+                                    <Border Background="#0FFFFFFF" CornerRadius="4" Margin="6,0,0,0" Padding="5,1">
+                                        <TextBlock x:Name="VersionLabel" FontSize="11"
+                                                   Foreground="{StaticResource SecondaryBrush}"
+                                                   FontFamily="Consolas"/>
+                                    </Border>
+                                </StackPanel>
+                                <TextBlock Text="Built by superdooper86 &amp; claude"
+                                           FontSize="11" Foreground="{StaticResource SecondaryBrush}"/>
+                            </StackPanel>
+                            <Button Grid.Column="2" x:Name="CheckUpdateButton"
+                                    Style="{StaticResource SmallButton}" Click="CheckUpdate_Click"
+                                    VerticalAlignment="Center"/>
+                        </Grid>
+
+                    </StackPanel>
+                </ScrollViewer>
+            </Border>
+
+            <!-- Update sheet -->
+            <Border x:Name="UpdatePanel" Visibility="Collapsed"
+                    Background="{StaticResource BackgroundBrush}" CornerRadius="12">
+                <StackPanel>
+                    <Grid Margin="16,12">
+                        <Grid.ColumnDefinitions>
+                            <ColumnDefinition Width="*"/>
+                            <ColumnDefinition Width="Auto"/>
+                        </Grid.ColumnDefinitions>
+                        <TextBlock Text="Update ClaudeChecker" FontSize="14" FontWeight="SemiBold"
+                                   Foreground="White" VerticalAlignment="Center"/>
+                        <Button Grid.Column="1" Content="Not Now" Style="{StaticResource SmallButton}"
+                                Click="CloseUpdate_Click" x:Name="NotNowButton"/>
+                    </Grid>
+                    <Rectangle Height="0.5" Fill="{StaticResource BorderBrush}"/>
+                    <StackPanel Margin="20">
+                        <Grid Margin="0,0,0,16">
+                            <Grid.ColumnDefinitions>
+                                <ColumnDefinition Width="Auto"/>
+                                <ColumnDefinition Width="*"/>
+                            </Grid.ColumnDefinitions>
+                            <Image Width="48" Height="48" Source="Assets/icon.png"
+                                   RenderOptions.BitmapScalingMode="HighQuality" Margin="0,0,14,0"/>
+                            <StackPanel Grid.Column="1" VerticalAlignment="Center">
+                                <StackPanel Orientation="Horizontal">
+                                    <TextBlock x:Name="CurrentVerLabel" FontSize="12" FontFamily="Consolas"
+                                               Foreground="{StaticResource SecondaryBrush}"/>
+                                    <TextBlock Text=" → " FontSize="10"
+                                               Foreground="{StaticResource SecondaryBrush}" VerticalAlignment="Center"/>
+                                    <TextBlock x:Name="NewVerLabel" FontSize="13" FontWeight="SemiBold"
+                                               FontFamily="Consolas" Foreground="{StaticResource BlueBrush}"/>
+                                </StackPanel>
+                                <TextBlock x:Name="ReleaseNotesText" FontSize="11" TextWrapping="Wrap"
+                                           Foreground="{StaticResource SecondaryBrush}" Margin="0,4,0,0"
+                                           MaxHeight="180"/>
+                            </StackPanel>
+                        </Grid>
+
+                        <TextBlock x:Name="UpdateStatusText" Foreground="{StaticResource SecondaryBrush}"
+                                   FontSize="11" TextWrapping="Wrap" TextAlignment="Center"
+                                   Visibility="Collapsed" Margin="0,0,0,10"/>
+
+                        <ProgressBar x:Name="UpdateProgress" Visibility="Collapsed"
+                                     Height="4" Margin="0,0,0,12" Foreground="{StaticResource BlueBrush}"/>
+
+                        <TextBlock Text="ClaudeChecker will download the update, replace itself, and relaunch automatically."
+                                   FontSize="11" Foreground="{StaticResource SecondaryBrush}"
+                                   TextWrapping="Wrap" TextAlignment="Center" Margin="0,0,0,12"/>
+
+                        <Button x:Name="InstallButton" Content="⬇  Install Update"
+                                Style="{StaticResource PrimaryButton}" HorizontalAlignment="Stretch"
+                                Click="Install_Click"/>
+                    </StackPanel>
+                </StackPanel>
+            </Border>
+        </Grid>
+    </Border>
+</Window>