Service: one-click Update-service-to-this-version (no uninstall/reinstall)

Because the service now runs from its own admin-only copy, getting a new build into it
meant uninstall+reinstall (two UAC prompts). Add a DoUpdate path + Service-menu item
that does it in one: stop -> overwrite the ProgramData bin copy from the running app ->
start. Wired as the --update-service verb (elevated), recognised by the service-verb
gate. Enabled only when the service is installed; falls back to a plain install if not.

Note: the service bin folder stays admin-only writable on purpose (a user-writable
SYSTEM binary would be a privilege-escalation hole), so the copy is done elevated via
the one UAC prompt rather than in-process.

Gate: 40/40.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/RemSound.App/MainForm.cs

@@ -2228,6 +2228,8 @@ public sealed class MainForm : Form
         install.Click += (_, _) => ServiceAction(ServiceControl.InstallVerb, "install", confirm: true);
         var uninstall = new ToolStripMenuItem("&Uninstall service") { AccessibleName = "Uninstall service" };
         uninstall.Click += (_, _) => ServiceAction(ServiceControl.UninstallVerb, "uninstall", confirm: true);
+        var update = new ToolStripMenuItem("Up&date service to this version") { AccessibleName = "Update service to this version — copies the currently-running RemSound build into the service" };
+        update.Click += (_, _) => ServiceAction(ServiceControl.UpdateVerb, "update", confirm: false);
         var start = new ToolStripMenuItem("S&tart service") { AccessibleName = "Start service" };
         start.Click += (_, _) => ServiceAction(ServiceControl.StartVerb, "start", confirm: false);
         var stop = new ToolStripMenuItem("Sto&p service") { AccessibleName = "Stop service" };
@@ -2241,7 +2243,7 @@ public sealed class MainForm : Form
         {
             status, new ToolStripSeparator(),
             configure, new ToolStripSeparator(),
-            install, uninstall, start, stop, new ToolStripSeparator(),
+            install, uninstall, update, start, stop, new ToolStripSeparator(),
             activityLog, updateLog,
         });
         serviceMenu.DropDownOpening += (_, _) =>
@@ -2261,6 +2263,7 @@ public sealed class MainForm : Form
                 var installed = state != ServiceState.NotInstalled;
                 install.Enabled = !installed;
                 uninstall.Enabled = installed;
+                update.Enabled = installed; // refresh the service's copy with the running build (stop→copy→start)
                 start.Enabled = installed && state is ServiceState.Stopped;
                 stop.Enabled = installed && state is ServiceState.Running;
             }

src/RemSound.App/Program.cs

@@ -22,8 +22,8 @@ internal static class Program
     /// never reached.</summary>
     internal static bool IsServiceInvocation(string[] args) =>
         HasArg(args, ServiceControl.RunVerb) || HasArg(args, ServiceControl.InstallVerb)
-        || HasArg(args, ServiceControl.UninstallVerb) || HasArg(args, ServiceControl.StartVerb)
-        || HasArg(args, ServiceControl.StopVerb);
+        || HasArg(args, ServiceControl.UninstallVerb) || HasArg(args, ServiceControl.UpdateVerb)
+        || HasArg(args, ServiceControl.StartVerb) || HasArg(args, ServiceControl.StopVerb);
 
     // Writes an otherwise-fatal exception to a timestamped crash file in the logs folder, so a
     // "RemSound just disappeared, no dialog" report (#16) leaves a stack behind to diagnose instead

src/RemSound.App/SelfTest.cs

@@ -1399,7 +1399,7 @@ internal static class SelfTest
         foreach (var verb in new[]
                  {
                      ServiceControl.RunVerb, ServiceControl.InstallVerb, ServiceControl.UninstallVerb,
-                     ServiceControl.StartVerb, ServiceControl.StopVerb,
+                     ServiceControl.UpdateVerb, ServiceControl.StartVerb, ServiceControl.StopVerb,
                  })
         {
             Check(Program.IsServiceInvocation(new[] { verb }), $"'{verb}' must be recognised as a service invocation");
@@ -1417,7 +1417,7 @@ internal static class SelfTest
         if (!loadedBefore)
             Check(!IsAssemblyLoaded(svcAsm), "deciding a normal launch must not load the Windows-service assembly");
 
-        return "normal launches stay load-safe; all five service verbs recognised (case-insensitive)";
+        return "normal launches stay load-safe; all six service verbs recognised (case-insensitive)";
     }
 
     /// <summary>The Service menu's "View service log" opens the newest diagnostic log — the log that says

src/RemSound.App/ServiceControl.cs

@@ -33,6 +33,7 @@ public static class ServiceControl
     /// the Program.cs dispatcher agree.</summary>
     public const string InstallVerb = "--install-service";
     public const string UninstallVerb = "--uninstall-service";
+    public const string UpdateVerb = "--update-service";
     public const string StartVerb = "--start-service";
     public const string StopVerb = "--stop-service";
     public const string RunVerb = "--run-service";
@@ -201,6 +202,29 @@ public static class ServiceControl
         return rc;
     }
 
+    /// <summary>Refreshes the service's OWN copy of the program with the CURRENTLY-running build, without
+    /// an uninstall/reinstall: stop → overwrite the binaries in <see cref="ServiceStore.BinDirectory"/>
+    /// from this exe's folder → start. Must be run elevated (writing into the admin-only service bin
+    /// folder, and stop/start). Returns 0 on success. Used by the Service menu's "Update service" so a new
+    /// build reaches the service in one UAC prompt.</summary>
+    public static int DoUpdate()
+    {
+        if (!IsInstalled()) return DoInstall(); // not installed yet — a plain install does the copy too
+        var exe = Environment.ProcessPath;
+        var sourceDir = string.IsNullOrEmpty(exe) ? null : Path.GetDirectoryName(exe);
+        if (string.IsNullOrEmpty(sourceDir)) return 2;
+
+        try { DoStop(); } catch { /* best-effort — copy may still fail if files stay locked, handled below */ }
+        try { CopyProgramTo(sourceDir, ServiceStore.BinDirectory); }
+        catch (Exception ex)
+        {
+            ServiceStore.AppendServiceEvent($"update: copy program failed: {ex.GetType().Name}: {ex.Message}");
+            try { DoStart(); } catch { /* leave it stopped rather than half-updated */ }
+            return 5;
+        }
+        return DoStart();
+    }
+
     /// <summary>Starts the service. Must be run elevated. Returns 0 on success.</summary>
     public static int DoStart()
     {

src/RemSound.App/ServiceEntry.cs

@@ -36,6 +36,7 @@ internal static class ServiceEntry
 
         var verb = Has(args, ServiceControl.InstallVerb) ? "install"
             : Has(args, ServiceControl.UninstallVerb) ? "uninstall"
+            : Has(args, ServiceControl.UpdateVerb) ? "update"
             : Has(args, ServiceControl.StartVerb) ? "start"
             : Has(args, ServiceControl.StopVerb) ? "stop"
             : null;
@@ -52,6 +53,7 @@ internal static class ServiceEntry
             {
                 "install" => ServiceControl.DoInstall(),
                 "uninstall" => ServiceControl.DoUninstall(),
+                "update" => ServiceControl.DoUpdate(),
                 "start" => ServiceControl.DoStart(),
                 "stop" => ServiceControl.DoStop(),
                 _ => 0,