diff --git a/src/AcDream.Launcher/MainWindow.axaml b/src/AcDream.Launcher/MainWindow.axaml
index f5029129..44526b0e 100644
--- a/src/AcDream.Launcher/MainWindow.axaml
+++ b/src/AcDream.Launcher/MainWindow.axaml
@@ -350,6 +350,25 @@
               VerticalAlignment="Center">
         <ScrollViewer>
           <StackPanel Spacing="12">
+            <!-- LU4: the completion panel replaces the form outright, so the
+                 user is not left staring at a finished progress bar wondering
+                 whether they are allowed to close the window. -->
+            <StackPanel Spacing="16" IsVisible="{Binding FirstRunWizardShell.IsCompleted}">
+              <TextBlock Text="{Binding FirstRunWizardShell.CompletedTitle}"
+                         FontSize="24"
+                         FontWeight="Bold" />
+              <TextBlock Text="{Binding FirstRunWizardShell.CompletedBody}"
+                         TextWrapping="Wrap" />
+              <Button Content="OK"
+                      Classes="primary"
+                      IsDefault="True"
+                      HorizontalAlignment="Right"
+                      MinWidth="96"
+                      AutomationProperties.Name="Finish first-run setup"
+                      Command="{Binding FirstRunWizardShell.AcknowledgeCompletionCommand}" />
+            </StackPanel>
+
+            <StackPanel Spacing="12" IsVisible="{Binding FirstRunWizardShell.ShowSetupForm}">
             <TextBlock Text="{Binding FirstRunWizardShell.Title}" FontSize="24" FontWeight="Bold" />
             <TextBlock Text="{Binding FirstRunWizardShell.Body}" TextWrapping="Wrap" />
 
@@ -423,6 +442,7 @@
                       AutomationProperties.Name="Build and install client content"
                       Command="{Binding FirstRunWizardShell.StartCommand}" />
             </StackPanel>
+            </StackPanel>
           </StackPanel>
         </ScrollViewer>
       </Border>
diff --git a/src/AcDream.Launcher/ViewModels/FirstRunInstallerViewModel.cs b/src/AcDream.Launcher/ViewModels/FirstRunInstallerViewModel.cs
index 61597ffc..6d4ca733 100644
--- a/src/AcDream.Launcher/ViewModels/FirstRunInstallerViewModel.cs
+++ b/src/AcDream.Launcher/ViewModels/FirstRunInstallerViewModel.cs
@@ -25,6 +25,7 @@ public sealed class FirstRunInstallerViewModel : ObservableObject, IDisposable
     private string? _error;
     private LauncherInstallPhase _phase = LauncherInstallPhase.Idle;
     private double _progressPercent;
+    private bool _isCompleted;
     private bool _isOpen;
     private bool _isRunning;
     private bool _isDatDirectoryValid;
@@ -44,6 +45,9 @@ public sealed class FirstRunInstallerViewModel : ObservableObject, IDisposable
         _canStart = canStart ?? (() => true);
 
         OpenCommand = new RelayCommand(Open, () => !_disposed && _canOpen());
+        AcknowledgeCompletionCommand = new RelayCommand(
+            AcknowledgeCompletion,
+            () => IsCompleted && !IsRunning);
         CloseCommand = new RelayCommand(Close, () => !IsRunning);
         ValidateCommand = new RelayCommand(Validate, () => !IsRunning);
         StartCommand = new AsyncRelayCommand(StartAsync, CanBeginInstall);
@@ -183,6 +187,9 @@ public sealed class FirstRunInstallerViewModel : ObservableObject, IDisposable
 
     public RelayCommand OpenCommand { get; }
 
+    /// <summary>LU4: OK on the "Setup complete" panel.</summary>
+    public RelayCommand AcknowledgeCompletionCommand { get; }
+
     public RelayCommand CloseCommand { get; }
 
     public RelayCommand ValidateCommand { get; }
@@ -200,6 +207,34 @@ public sealed class FirstRunInstallerViewModel : ObservableObject, IDisposable
             : message;
     }
 
+    /// <summary>
+    /// LU4: true once first-run setup has actually succeeded — the pak was
+    /// built, verified, and its record published. The wizard replaces its form
+    /// with a plain "Setup complete" panel whose single OK button returns to
+    /// the launcher, instead of leaving the user looking at a finished
+    /// progress bar wondering whether they may close the window.
+    /// </summary>
+    public bool IsCompleted
+    {
+        get => _isCompleted;
+        private set
+        {
+            if (SetProperty(ref _isCompleted, value))
+            {
+                OnPropertyChanged(nameof(ShowSetupForm));
+                NotifyCommandStates();
+            }
+        }
+    }
+
+    /// <summary>The form and the completion panel are mutually exclusive.</summary>
+    public bool ShowSetupForm => !IsCompleted;
+
+    public string CompletedTitle => "Setup complete";
+
+    public string CompletedBody =>
+        "acdream built and verified your game content. You can play now.";
+
     public void NotifyCommandStates()
     {
         OpenCommand.NotifyCanExecuteChanged();
@@ -207,6 +242,7 @@ public sealed class FirstRunInstallerViewModel : ObservableObject, IDisposable
         ValidateCommand.NotifyCanExecuteChanged();
         StartCommand.NotifyCanExecuteChanged();
         CancelCommand.NotifyCanExecuteChanged();
+        AcknowledgeCompletionCommand.NotifyCanExecuteChanged();
     }
 
     public void Close()
@@ -231,6 +267,15 @@ public sealed class FirstRunInstallerViewModel : ObservableObject, IDisposable
         NotifyCommandStates();
     }
 
+    /// <summary>LU4: OK on the completion panel. Closes the wizard and leaves
+    /// it ready to be reopened as an ordinary form (a user may reinstall
+    /// content later against a different DAT folder).</summary>
+    private void AcknowledgeCompletion()
+    {
+        IsCompleted = false;
+        IsOpen = false;
+    }
+
     private void Open()
     {
         if (string.IsNullOrWhiteSpace(DatDirectory))
@@ -306,6 +351,11 @@ public sealed class FirstRunInstallerViewModel : ObservableObject, IDisposable
             Phase = LauncherInstallPhase.Completed;
             ProgressPercent = 100;
             Status = "Client content installed and verified. Launch is enabled.";
+            // LU4: raised only here, AFTER the record is published, so the
+            // launcher behind the dialog is already in its launch-enabled
+            // state when the user presses OK. The cancelled and failed
+            // branches below deliberately never reach this.
+            IsCompleted = true;
         }
         catch (OperationCanceledException)
         {
diff --git a/tests/AcDream.Launcher.Tests/LauncherWindowViewModelTests.cs b/tests/AcDream.Launcher.Tests/LauncherWindowViewModelTests.cs
index 7bd44358..849e5a7c 100644
--- a/tests/AcDream.Launcher.Tests/LauncherWindowViewModelTests.cs
+++ b/tests/AcDream.Launcher.Tests/LauncherWindowViewModelTests.cs
@@ -442,6 +442,74 @@ public sealed class LauncherWindowViewModelTests
         Assert.True(orchestrator.ClearCalled);
     }
 
+    /// <summary>
+    /// LU4. A successful first-run setup ends with a plain "Setup complete"
+    /// panel and one OK button that returns to the launcher — not a finished
+    /// progress bar the user has to decide what to do with.
+    /// </summary>
+    [Fact]
+    public async Task FirstRunSetupEndsWithACompletionPanelThatOkReturnsFrom()
+    {
+        using var orchestrator = new FakeLauncherOrchestrator
+        {
+            Session = FakeLauncherOrchestrator.CreateSession(
+                LauncherActivityState.Exited,
+                "Exited cleanly."),
+        };
+        var installer = new FakeLauncherInstaller();
+        using var viewModel = CreateInitialized(orchestrator, installer);
+
+        viewModel.FirstRunWizardShell.OpenCommand.Execute(null);
+        Assert.False(viewModel.FirstRunWizardShell.IsCompleted);
+        Assert.True(viewModel.FirstRunWizardShell.ShowSetupForm);
+
+        await viewModel.FirstRunWizardShell.StartCommand.ExecuteAsync();
+
+        Assert.True(viewModel.FirstRunWizardShell.IsCompleted);
+        // The form is gone; the completion panel is what the user sees.
+        Assert.False(viewModel.FirstRunWizardShell.ShowSetupForm);
+        Assert.True(viewModel.FirstRunWizardShell.IsOpen);
+        // The record is already published, so the launcher behind the dialog
+        // is in its launch-enabled state before OK is pressed.
+        Assert.NotNull(orchestrator.InstalledRecord);
+
+        viewModel.FirstRunWizardShell.AcknowledgeCompletionCommand.Execute(null);
+
+        Assert.False(viewModel.FirstRunWizardShell.IsOpen);
+        Assert.False(viewModel.FirstRunWizardShell.IsCompleted);
+        Assert.True(viewModel.FirstRunWizardShell.ShowSetupForm);
+    }
+
+    /// <summary>
+    /// LU4. Cancellation and failure must NOT claim success. They keep their
+    /// existing status/error reporting and leave the form on screen.
+    /// </summary>
+    [Fact]
+    public async Task AFailedFirstRunSetupNeverShowsTheCompletionPanel()
+    {
+        using var orchestrator = new FakeLauncherOrchestrator
+        {
+            Session = FakeLauncherOrchestrator.CreateSession(
+                LauncherActivityState.Exited,
+                "Exited cleanly."),
+        };
+        var installer = new FakeLauncherInstaller
+        {
+            InstallHandler = (_, _, _, _) =>
+                Task.FromException<LauncherInstallResult>(
+                    new LauncherInstallException("The bake tool exited with code 3.")),
+        };
+        using var viewModel = CreateInitialized(orchestrator, installer);
+
+        viewModel.FirstRunWizardShell.OpenCommand.Execute(null);
+        await viewModel.FirstRunWizardShell.StartCommand.ExecuteAsync();
+
+        Assert.False(viewModel.FirstRunWizardShell.IsCompleted);
+        Assert.True(viewModel.FirstRunWizardShell.ShowSetupForm);
+        Assert.True(viewModel.FirstRunWizardShell.HasError);
+        Assert.Null(orchestrator.InstalledRecord);
+    }
+
     /// <summary>
     /// LU1. Ordinary startup trusts a remembered digest so the window is not
     /// held behind a multi-second hash of a ~28 GiB file; "Verify files" is