diff --git a/program/MainWindow.cs b/program/MainWindow.cs
index 2f91720..83c5453 100644
--- a/program/MainWindow.cs
+++ b/program/MainWindow.cs
@@ -5,6 +5,7 @@
 using Gtk;
 using UI = Gtk.Builder.ObjectAttribute;
 using System.Runtime.InteropServices;
+using System.Diagnostics;
 
 public class MainWindow : Window
 {
@@ -556,16 +557,46 @@
 
     private void OnCloseClicked(object sender, EventArgs e)
     {
+        if (KioskMode && !ConfirmPowerOff()) return;
         Shutdown();
     }
 
     private void Shutdown()
     {
+        // _arduino.Disconnect();
+        // _arduino.Dispose();
+        // // _settingsWindow?.Destroy();
+        // Application.Quit();
+         // Release hardware before the OS starts killing things.
+        if (_mapWindow != null) _mapWindow.StopSession();
+        WavePlayer.Stop();
+        StopAutoRetry();
+        if (_batteryTimerId != 0) { GLib.Source.Remove(_batteryTimerId); _batteryTimerId = 0; }
         _arduino.Disconnect();
         _arduino.Dispose();
-        // _settingsWindow?.Destroy();
+
+        if (!KioskMode) { Application.Quit(); return; }
+
+        // CloseButton is the only label MainWindow itself owns on the splash page.
+        CloseButton.Label       = _Language["Close.ShuttingDown"];
+        CloseButton.Sensitive   = false;
+        Option1Button.Sensitive = false;
+        Option2Button.Sensitive = false;
+        Option3Button.Sensitive = false;
+        SettingButton.Sensitive = false;
+
+        // Return to the main loop so that repaint actually happens, then fire.
+        GLib.Timeout.Add(200, new GLib.TimeoutHandler(OnPowerOffTick));
+    }
+    private bool OnPowerOffTick()
+{
+    if (!RequestPowerOff())
+    {
+        Console.WriteLine("poweroff refused - quitting instead");
         Application.Quit();
     }
+    return false;                      // one shot
+}
 
     private void OnNormalSessionClicked(object sender, EventArgs e)
     {
@@ -613,4 +644,58 @@
     {
         RootNoteBook.CurrentPage = PageSound;   // back to disease list
     }
+
+    // ---------- power ----------
+
+    // Same master switch the boot scripts read. On a dev box the flag is absent,
+    // so Close just exits the app instead of killing your machine.
+    private static bool KioskMode
+    {
+        get
+        {
+            string home = System.Environment.GetEnvironmentVariable("HOME");
+            if (string.IsNullOrEmpty(home)) return false;
+            return System.IO.File.Exists(
+                System.IO.Path.Combine(home, "kiosk/enabled"));
+        }
+    }
+
+    private bool ConfirmPowerOff()
+    {
+        var dlg = new MessageDialog(this,
+            DialogFlags.Modal | DialogFlags.DestroyWithParent,
+            MessageType.Question, ButtonsType.None,
+            "{0}", _Language["Close.ConfirmPowerOff"]);
+
+        dlg.AddButton(_Language["Common.Cancel"],   (int)ResponseType.Cancel);
+        dlg.AddButton(_Language["Common.PowerOff"], (int)ResponseType.Ok);
+        dlg.DefaultResponse = ResponseType.Cancel;
+
+        var r = (ResponseType)dlg.Run();
+        dlg.Destroy();
+        return r == ResponseType.Ok;
+    }
+
+
+    private static bool RequestPowerOff()
+    {
+         if (Spawn("systemctl", "poweroff")) return true;       // logind + polkit
+        if (Spawn("sudo", "-n /sbin/poweroff")) return true;   // sudoers fallback
+        return false;
+    }
+    private static bool Spawn(string exe, string args)
+    {
+        try
+        {
+            var psi = new System.Diagnostics.ProcessStartInfo(exe, args);
+            psi.UseShellExecute = false;
+            var proc = System.Diagnostics.Process.Start(psi);
+            if (proc == null) return false;
+            if (!proc.WaitForExit(5000)) return true;   // still running = request accepted
+            return proc.ExitCode == 0;
+        }
+        catch { return false; }
+    }
+
+
 }
\ No newline at end of file