Re-query menu commands via a shared CommandManager

Avalonia has no global ICommand re-query signal like WPF's CommandManager.RequerySuggested, so state-dependent main-menu commands were frozen at their startup CanExecute: a NativeMenuItem only re-reads CanExecute when the command raises CanExecuteChanged, and nothing did. The assembly list is empty when the menu is built, so Clear assembly list was disabled forever; Save and Remove-assemblies-with-load-errors had the same latent bug. Add a weak global CommandManager (held weakly so menu/toolbar items aren't pinned) that SimpleCommand routes CanExecuteChanged through -- exactly as WPF's SimpleCommand routed it -- and invalidate it at the central state-change points: tree selection, the active assembly list, and background-load-sweep completion (so load errors surface). One signal, every platform: NativeMenuItem maps CanExecute onto IsEnabled, which the macOS Cocoa, Linux DBus, and in-window menu exporters all track.

Assisted-by: Claude:claude-opus-4-8:Claude Code

ILSpy.Tests/Commands/ClearAssemblyListCommandTests.cs

@@ -0,0 +1,66 @@
+// Copyright (c) 2026 AlphaSierraPapa for the SharpDevelop Team
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy of this
+// software and associated documentation files (the "Software"), to deal in the Software
+// without restriction, including without limitation the rights to use, copy, modify, merge,
+// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
+// to whom the Software is furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all copies or
+// substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
+// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+using System;
+using System.Threading.Tasks;
+
+using Avalonia.Headless.NUnit;
+using Avalonia.Threading;
+
+using AwesomeAssertions;
+
+using ICSharpCode.ILSpy.Properties;
+
+using ILSpy.AppEnv;
+using ILSpy.Commands;
+
+using NUnit.Framework;
+
+namespace ICSharpCode.ILSpy.Tests;
+
+[TestFixture]
+public class ClearAssemblyListCommandTests
+{
+	[AvaloniaTest]
+	public async Task Clear_Assembly_List_Re_Raises_CanExecute_When_The_List_Changes()
+	{
+		// The native menu only re-reads CanExecute when CanExecuteChanged fires. The command used to
+		// never raise it, so it stayed at its startup value -- the list was empty then, leaving the
+		// menu item disabled forever. Now CanExecuteChanged is routed through the shared CommandManager,
+		// which the assembly-list change invalidates -- so the item re-queries whenever the list changes.
+		var (_, vm) = await TestHarness.BootAsync(1);
+		var command = AppComposition.Current.GetExport<MainMenuCommandRegistry>()
+			.GetCommand(nameof(Resources.ClearAssemblyList));
+
+		command.CanExecute(null).Should().BeTrue("with assemblies loaded the command is enabled");
+
+		bool raised = false;
+		// Keep the handler rooted: CommandManager holds subscribers weakly, so an inline lambda with
+		// no other reference could be collected before the raise.
+		EventHandler handler = (_, _) => raised = true;
+		command.CanExecuteChanged += handler;
+
+		vm.AssemblyTreeModel.AssemblyList!.Clear();
+		Dispatcher.UIThread.RunJobs();
+
+		raised.Should().BeTrue(
+			"clearing the list must re-raise CanExecuteChanged so the menu re-queries the command's enablement");
+		command.CanExecute(null).Should().BeFalse("an empty list disables the command");
+		GC.KeepAlive(handler);
+	}
+}

ILSpy.Tests/Commands/SaveCommandEnablementTests.cs

@@ -0,0 +1,65 @@
+// Copyright (c) 2026 AlphaSierraPapa for the SharpDevelop Team
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy of this
+// software and associated documentation files (the "Software"), to deal in the Software
+// without restriction, including without limitation the rights to use, copy, modify, merge,
+// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
+// to whom the Software is furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all copies or
+// substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
+// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+using System;
+using System.Threading.Tasks;
+
+using Avalonia.Headless.NUnit;
+using Avalonia.Threading;
+
+using AwesomeAssertions;
+
+using ICSharpCode.ILSpy.Properties;
+
+using ILSpy.AppEnv;
+using ILSpy.Commands;
+
+using NUnit.Framework;
+
+namespace ICSharpCode.ILSpy.Tests;
+
+/// <summary>
+/// The general fix (routing SimpleCommand.CanExecuteChanged through the shared CommandManager,
+/// invalidated on selection changes) must apply to every selection-dependent menu command, not just
+/// the one originally reported. Save Code is the canonical case.
+/// </summary>
+[TestFixture]
+public class SaveCommandEnablementTests
+{
+	[AvaloniaTest]
+	public async Task Save_Command_Enables_When_A_Tree_Node_Is_Selected()
+	{
+		var (_, vm) = await TestHarness.BootAsync(1);
+		var command = AppComposition.Current.GetExport<MainMenuCommandRegistry>()
+			.GetCommand(nameof(Resources._SaveCode));
+
+		command.CanExecute(null).Should().BeFalse("with nothing selected at startup, Save is disabled");
+
+		bool raised = false;
+		EventHandler handler = (_, _) => raised = true; // rooted; CommandManager holds handlers weakly
+		command.CanExecuteChanged += handler;
+
+		vm.AssemblyTreeModel.SelectNode(vm.AssemblyTreeModel.Root!.Children[0]);
+		Dispatcher.UIThread.RunJobs();
+
+		raised.Should().BeTrue(
+			"selecting a node must re-raise CanExecuteChanged so the menu re-queries the command's enablement");
+		command.CanExecute(null).Should().BeTrue("a selected tree node enables Save");
+		GC.KeepAlive(handler);
+	}
+}

ILSpy/AssemblyTree/AssemblyTreeModel.cs

@@ -228,6 +228,9 @@ namespace ILSpy.AssemblyTree
 			// Pub-sub fan-out: panes (e.g. Debug Steps) that need to invalidate their state
 			// when the selection moves listen on this message.
 			Util.MessageBus.Send(this, new Util.AssemblyTreeSelectionChangedEventArgs());
+
+			// Selection-dependent menu commands (Save, Analyze-via-menu, ...) re-evaluate CanExecute.
+			Commands.CommandManager.InvalidateRequerySuggested();
 		}
 
 		// Walks already-materialized children and re-raises Text PropertyChanged so the cell
@@ -528,6 +531,9 @@ namespace ILSpy.AssemblyTree
 					}
 					await Task.WhenAll(loadTasks).ConfigureAwait(false);
 					AppEnv.AppLog.Mark("Background-load sweep dispatched");
+					// Load errors only surface once a load completes (no list change fires for them),
+					// so re-evaluate now -- this is what enables "Remove assemblies with load errors".
+					Commands.CommandManager.InvalidateRequerySuggested();
 				}
 				catch (Exception ex)
 				{
@@ -982,6 +988,10 @@ namespace ILSpy.AssemblyTree
 				}
 			}
 			Util.MessageBus.Send(this, new Util.CurrentAssemblyListChangedEventArgs(e));
+
+			// List-dependent menu commands (Clear assembly list, Remove assemblies with load errors)
+			// re-evaluate CanExecute now that the list gained or lost entries.
+			Commands.CommandManager.InvalidateRequerySuggested();
 		}
 
 		// Coalesces burst F5 / programmatic Refresh() calls into a single async pipeline.

ILSpy/Commands/CommandManager.cs

@@ -0,0 +1,140 @@
+// Copyright (c) 2026 AlphaSierraPapa for the SharpDevelop Team
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy of this
+// software and associated documentation files (the "Software"), to deal in the Software
+// without restriction, including without limitation the rights to use, copy, modify, merge,
+// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
+// to whom the Software is furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all copies or
+// substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
+// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+using System;
+using System.Collections.Generic;
+using System.Reflection;
+
+namespace ILSpy.Commands
+{
+	/// <summary>
+	/// A poor-man's equivalent of WPF's <c>CommandManager.RequerySuggested</c>. Avalonia has no
+	/// global "re-query your CanExecute" signal, so <see cref="SimpleCommand"/> routes its
+	/// <c>CanExecuteChanged</c> through this one (exactly as WPF's SimpleCommand routed it through
+	/// <c>CommandManager.RequerySuggested</c>). Call <see cref="InvalidateRequerySuggested"/> whenever
+	/// application state that a command's <c>CanExecute</c> reads might have changed (tree selection,
+	/// the assembly list, a background load finishing); every bound command then re-evaluates.
+	///
+	/// This works on every platform: a bound <c>NativeMenuItem</c> subscribes to the command's
+	/// CanExecuteChanged and, when it fires, sets <c>IsEnabled = CanExecute()</c>; the macOS Cocoa,
+	/// Linux DBus, and in-window menu exporters all track that <c>IsEnabled</c> property.
+	///
+	/// Subscribers are held WEAKLY (by target + method, like <see cref="Util.WeakEventSource{T}"/>),
+	/// so a rebuilt menu or toolbar -- whose items subscribe via the routed CanExecuteChanged -- is
+	/// not pinned for the lifetime of this static type. NOTE: a handler with no other strong reference
+	/// (e.g. an inline lambda) may be collected before the next raise; callers that need it to survive
+	/// must keep it rooted, just as with WPF's weak RequerySuggested.
+	/// </summary>
+	public static class CommandManager
+	{
+		static readonly object gate = new();
+		static readonly List<WeakHandler> handlers = new();
+
+		/// <summary>Subscribes <paramref name="handler"/> (weakly) to the global re-query signal.</summary>
+		public static void AddRequerySuggested(EventHandler handler)
+		{
+			ArgumentNullException.ThrowIfNull(handler);
+			lock (gate)
+				handlers.Add(new WeakHandler(handler));
+		}
+
+		/// <summary>Removes a previously added handler.</summary>
+		public static void RemoveRequerySuggested(EventHandler handler)
+		{
+			ArgumentNullException.ThrowIfNull(handler);
+			lock (gate)
+			{
+				for (int i = handlers.Count - 1; i >= 0; i--)
+				{
+					if (handlers[i].Matches(handler))
+					{
+						handlers.RemoveAt(i);
+						break;
+					}
+				}
+			}
+		}
+
+		/// <summary>
+		/// Asks every bound command to re-evaluate its <c>CanExecute</c>. Marshalled to the UI thread
+		/// (handlers touch UI state such as <c>NativeMenuItem.IsEnabled</c>), so it is safe to call from
+		/// a background thread (e.g. a load sweep finishing off the thread pool).
+		/// </summary>
+		public static void InvalidateRequerySuggested()
+		{
+			var dispatcher = global::Avalonia.Threading.Dispatcher.UIThread;
+			if (dispatcher.CheckAccess())
+				Raise();
+			else
+				dispatcher.Post(Raise);
+		}
+
+		static void Raise()
+		{
+			// Snapshot under lock so add/remove during dispatch doesn't perturb this raise.
+			WeakHandler[] snapshot;
+			lock (gate)
+				snapshot = handlers.ToArray();
+			List<WeakHandler>? dead = null;
+			foreach (var h in snapshot)
+			{
+				if (!h.TryInvoke())
+					(dead ??= new()).Add(h);
+			}
+			if (dead != null)
+			{
+				lock (gate)
+					foreach (var h in dead)
+						handlers.Remove(h);
+			}
+		}
+
+		sealed class WeakHandler
+		{
+			readonly WeakReference<object>? targetRef;
+			readonly MethodInfo method;
+
+			public WeakHandler(EventHandler handler)
+			{
+				method = handler.Method;
+				// Static handlers (null Target) are kept until Remove drops them explicitly.
+				targetRef = handler.Target is null ? null : new WeakReference<object>(handler.Target);
+			}
+
+			public bool Matches(EventHandler handler)
+			{
+				if (method != handler.Method)
+					return false;
+				if (targetRef == null)
+					return handler.Target == null;
+				return targetRef.TryGetTarget(out var t) && ReferenceEquals(t, handler.Target);
+			}
+
+			public bool TryInvoke()
+			{
+				object? target;
+				if (targetRef == null)
+					target = null;
+				else if (!targetRef.TryGetTarget(out target!))
+					return false; // collected -> caller prunes
+				method.Invoke(target, new object?[] { null, EventArgs.Empty });
+				return true;
+			}
+		}
+	}
+}

ILSpy/Commands/SimpleCommand.cs

@@ -24,22 +24,26 @@ using global::Avalonia.Data;
 namespace ILSpy.Commands
 {
 	/// <summary>
-	/// Minimal ICommand base. Avalonia has no global RequerySuggested signal like WPF's
-	/// CommandManager, so derived commands fire CanExecuteChanged themselves when they care.
-	/// MenuItems also re-query CanExecute when the parent menu opens, which covers most cases.
+	/// Minimal ICommand base. Avalonia has no global RequerySuggested signal like WPF's CommandManager,
+	/// so CanExecuteChanged is routed through our own <see cref="CommandManager"/> (mirroring how WPF's
+	/// SimpleCommand routed it through CommandManager.RequerySuggested). State-change sites call
+	/// <see cref="CommandManager.InvalidateRequerySuggested"/> and every bound command re-evaluates --
+	/// no per-command wiring, and the menu/toolbar item updates its enabled state on every platform.
 	/// </summary>
 	public abstract class SimpleCommand : ICommand
 	{
-		public event EventHandler? CanExecuteChanged;
+		public event EventHandler? CanExecuteChanged {
+			add { if (value is not null) CommandManager.AddRequerySuggested(value); }
+			remove { if (value is not null) CommandManager.RemoveRequerySuggested(value); }
+		}
 
 		public abstract void Execute(object? parameter);
 
 		public virtual bool CanExecute(object? parameter) => true;
 
-		protected void RaiseCanExecuteChanged()
-		{
-			CanExecuteChanged?.Invoke(this, EventArgs.Empty);
-		}
+		/// <summary>Asks all bound commands to re-evaluate CanExecute (a global invalidate -- the
+		/// re-query is shared, so this is not scoped to this single command).</summary>
+		protected static void RaiseCanExecuteChanged() => CommandManager.InvalidateRequerySuggested();
 	}
 
 	/// <summary>