CmdPal: Prevent crash on duplicate keybindings; simplify matching (#41714)

## Summary of the Pull Request

Handles duplicate keybindings by using the first occurrence and ignoring
the rest (in `ContextMenuViewModel.Keybindings` and
`IContextMenuContext.Keybindings`).

Replaces LINQ with direct iteration for clarity.

Simplifies `CheckKeybinding` by removing redundant null checks and
clarifying the key-to-binding matching logic, improving both readability
and efficiency.

Add a new method to `KeyChordHelpers.FormatForDebug` that formats
KeyChord as string to help debugging.

Makes `KeyChordHelpers` class a static class.

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## PR Checklist

- [x] Closes: #41712
- [ ] **Communication:** I've discussed this with core contributors
already. If the work hasn't been agreed, this work might be rejected
- [x] **Tests:** all pass
- [x] **Localization:** All end-user-facing strings can be localized
- [x] **Dev docs:** Added/updated
- [x] **New binaries:** Added on the required places
- [ ] [JSON for
signing](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ESRPSigning_core.json)
for new binaries
- [ ] [WXS for
installer](https://github.com/microsoft/PowerToys/blob/main/installer/PowerToysSetup/Product.wxs)
for new binaries and localization folder
- [ ] [YML for CI
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ci/templates/build-powertoys-steps.yml)
for new test projects
- [ ] [YML for signed
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/release.yml)
- [x] **Documentation updated:** If checked, please file a pull request
on [our docs
repo](https://github.com/MicrosoftDocs/windows-uwp/tree/docs/hub/powertoys)
and link it here: #xxx

<!-- Provide a more detailed description of the PR, other things fixed,
or any additional comments/features here -->
## Detailed Description of the Pull Request / Additional comments

<!-- Describe how you validated the behavior. Add automated tests
wherever possible, but list manual validation steps taken as well -->
## Validation Steps Performed

Validated using a custom extension that has a duplicate item in the
context menu.

src/modules/cmdpal/Microsoft.CmdPal.Core.ViewModels/ContextMenuViewModel.cs

@@ -5,6 +5,7 @@
 using System.Collections.ObjectModel;
 using CommunityToolkit.Mvvm.ComponentModel;
 using CommunityToolkit.Mvvm.Messaging;
+using ManagedCommon;
 using Microsoft.CmdPal.Core.ViewModels.Messages;
 using Microsoft.CommandPalette.Extensions;
 using Microsoft.CommandPalette.Extensions.Toolkit;
@@ -117,36 +118,46 @@ public partial class ContextMenuViewModel : ObservableObject,
     /// Generates a mapping of key -> command item for this particular item's
     /// MoreCommands. (This won't include the primary Command, but it will
     /// include the secondary one). This map can be used to quickly check if a
-    /// shortcut key was pressed
+    /// shortcut key was pressed. In case there are duplicate keybindings, the first
+    /// one is used and the rest are ignored.
     /// </summary>
     /// <returns>a dictionary of KeyChord -> Context commands, for all commands
     /// that have a shortcut key set.</returns>
-    public Dictionary<KeyChord, CommandContextItemViewModel> Keybindings()
+    private Dictionary<KeyChord, CommandContextItemViewModel> Keybindings()
     {
-        if (CurrentContextMenu is null)
+        var result = new Dictionary<KeyChord, CommandContextItemViewModel>();
+
+        var menu = CurrentContextMenu;
+        if (menu is null)
         {
-            return [];
+            return result;
         }
 
-        return CurrentContextMenu
-            .OfType<CommandContextItemViewModel>()
-            .Where(c => c.HasRequestedShortcut)
-            .ToDictionary(
-            c => c.RequestedShortcut ?? new KeyChord(0, 0, 0),
-            c => c);
+        foreach (var item in menu)
+        {
+            if (item is CommandContextItemViewModel cmd && cmd.HasRequestedShortcut)
+            {
+                var key = cmd.RequestedShortcut ?? new KeyChord(0, 0, 0);
+                var added = result.TryAdd(key, cmd);
+                if (!added)
+                {
+                    Logger.LogWarning($"Ignoring duplicate keyboard shortcut {KeyChordHelpers.FormatForDebug(key)} on command '{cmd.Title ?? cmd.Name ?? "(unknown)"}'");
+                }
+            }
+        }
+
+        return result;
     }
 
     public ContextKeybindingResult? CheckKeybinding(bool ctrl, bool alt, bool shift, bool win, VirtualKey key)
     {
         var keybindings = Keybindings();
-        if (keybindings is not null)
+
+        // Does the pressed key match any of the keybindings?
+        var pressedKeyChord = KeyChordHelpers.FromModifiers(ctrl, alt, shift, win, key, 0);
+        if (keybindings.TryGetValue(pressedKeyChord, out var item))
         {
-            // Does the pressed key match any of the keybindings?
-            var pressedKeyChord = KeyChordHelpers.FromModifiers(ctrl, alt, shift, win, key, 0);
-            if (keybindings.TryGetValue(pressedKeyChord, out var item))
-            {
-                return InvokeCommand(item);
-            }
+            return InvokeCommand(item);
         }
 
         return null;

src/modules/cmdpal/Microsoft.CmdPal.Core.ViewModels/Messages/UpdateCommandBarMessage.cs

@@ -3,7 +3,9 @@
 // See the LICENSE file in the project root for more information.
 
 using System.ComponentModel;
+using ManagedCommon;
 using Microsoft.CommandPalette.Extensions;
+using Microsoft.CommandPalette.Extensions.Toolkit;
 
 namespace Microsoft.CmdPal.Core.ViewModels.Messages;
 
@@ -32,12 +34,28 @@ public interface IContextMenuContext : INotifyPropertyChanged
     /// that have a shortcut key set.</returns>
     public Dictionary<KeyChord, CommandContextItemViewModel> Keybindings()
     {
-        return MoreCommands
-            .OfType<CommandContextItemViewModel>()
-            .Where(c => c.HasRequestedShortcut)
-            .ToDictionary(
-            c => c.RequestedShortcut ?? new KeyChord(0, 0, 0),
-            c => c);
+        var result = new Dictionary<KeyChord, CommandContextItemViewModel>();
+
+        var menu = MoreCommands;
+        if (menu is null)
+        {
+            return result;
+        }
+
+        foreach (var item in menu)
+        {
+            if (item is CommandContextItemViewModel cmd && cmd.HasRequestedShortcut)
+            {
+                var key = cmd.RequestedShortcut ?? new KeyChord(0, 0, 0);
+                var added = result.TryAdd(key, cmd);
+                if (!added)
+                {
+                    Logger.LogWarning($"Ignoring duplicate keyboard shortcut {KeyChordHelpers.FormatForDebug(key)} on command '{cmd.Title ?? cmd.Name ?? "(unknown)"}'");
+                }
+            }
+        }
+
+        return result;
     }
 }
 

src/modules/cmdpal/ext/SamplePagesExtension/EvilSamplesPage.cs

@@ -219,7 +219,12 @@ public partial class EvilSamplesPage : ListPage
                 }
             ],
         },
-
+        new ListItem(new EvilDuplicateRequestedShortcut())
+        {
+            Title = "Evil keyboard shortcuts",
+            Subtitle = "Two commands with the same shortcut and more...",
+            Icon = new IconInfo("\uE765"),
+        }
     ];
 
     public EvilSamplesPage()
@@ -414,3 +419,42 @@ internal sealed partial class EvilFastUpdatesPage : DynamicListPage
         }
     }
 }
+
+[System.Diagnostics.CodeAnalysis.SuppressMessage("StyleCop.CSharp.MaintainabilityRules", "SA1402:File may only contain a single type", Justification = "Sample code")]
+internal sealed partial class EvilDuplicateRequestedShortcut : ListPage
+{
+    private readonly IListItem[] _items =
+    [
+        new ListItem(new NoOpCommand())
+        {
+            Title = "I'm evil!",
+            Subtitle = "I have multiple commands sharing the same keyboard shortcut",
+            MoreCommands = [
+                new CommandContextItem(new AnonymousCommand(() => new ToastStatusMessage("Me too executed").Show())
+                {
+                    Result = CommandResult.KeepOpen(),
+                })
+                {
+                    Title = "Me too",
+                    RequestedShortcut = KeyChordHelpers.FromModifiers(ctrl: true, vkey: VirtualKey.Number1),
+                },
+                new CommandContextItem(new AnonymousCommand(() => new ToastStatusMessage("Me three executed").Show())
+                {
+                    Result = CommandResult.KeepOpen(),
+                })
+                {
+                    Title = "Me three",
+                    RequestedShortcut = KeyChordHelpers.FromModifiers(ctrl: true, vkey: VirtualKey.Number1),
+                },
+            ],
+        },
+    ];
+
+    public override IListItem[] GetItems() => _items;
+
+    public EvilDuplicateRequestedShortcut()
+    {
+        Icon = new IconInfo(string.Empty);
+        Name = "Open";
+    }
+}

src/modules/cmdpal/extensionsdk/Microsoft.CommandPalette.Extensions.Toolkit/KeyChordHelpers.cs

@@ -6,7 +6,7 @@ using Windows.System;
 
 namespace Microsoft.CommandPalette.Extensions.Toolkit;
 
-public partial class KeyChordHelpers
+public static partial class KeyChordHelpers
 {
     public static KeyChord FromModifiers(
         bool ctrl = false,
@@ -34,4 +34,28 @@ public partial class KeyChordHelpers
     {
         return FromModifiers(ctrl, alt, shift, win, (int)vkey, scanCode);
     }
+
+    public static string FormatForDebug(KeyChord value)
+    {
+        var result = string.Empty;
+
+        if (value.Modifiers.HasFlag(VirtualKeyModifiers.Control))
+        {
+            result += "Ctrl+";
+        }
+
+        if (value.Modifiers.HasFlag(VirtualKeyModifiers.Shift))
+        {
+            result += "Shift+";
+        }
+
+        if (value.Modifiers.HasFlag(VirtualKeyModifiers.Menu))
+        {
+            result += "Alt+";
+        }
+
+        result += (VirtualKey)value.Vkey;
+
+        return result;
+    }
 }