Merge branch 'main' into niels9001/deduping-bands

src/modules/cmdpal/Microsoft.CmdPal.UI.ViewModels/CommandProviderWrapper.cs

@@ -499,17 +499,6 @@ public sealed class CommandProviderWrapper : ICommandProviderContext
     public void PinDockBand(string commandId, IServiceProvider serviceProvider, Dock.DockPinSide side = Dock.DockPinSide.Start, bool? showTitles = null, bool? showSubtitles = null)
     {
         var settingsService = serviceProvider.GetRequiredService<ISettingsService>();
-        var settings = settingsService.Settings;
-        var dockSettings = settings.DockSettings;
-
-        // Prevent duplicate pins — check all sections
-        if (dockSettings.StartBands.Any(b => b.CommandId == commandId && b.ProviderId == this.ProviderId) ||
-            dockSettings.CenterBands.Any(b => b.CommandId == commandId && b.ProviderId == this.ProviderId) ||
-            dockSettings.EndBands.Any(b => b.CommandId == commandId && b.ProviderId == this.ProviderId))
-        {
-            Logger.LogDebug($"Dock band '{commandId}' from provider '{this.ProviderId}' is already pinned; skipping.");
-            return;
-        }
 
         var bandSettings = new DockBandSettings
         {
@@ -523,6 +512,18 @@ public sealed class CommandProviderWrapper : ICommandProviderContext
             s =>
             {
                 var dockSettings = s.DockSettings;
+
+                // Prevent duplicate pins — check inside the CAS lambda so
+                // the guard is re-evaluated on every retry against the
+                // latest snapshot.
+                if (dockSettings.StartBands.Any(b => b.CommandId == commandId && b.ProviderId == this.ProviderId) ||
+                    dockSettings.CenterBands.Any(b => b.CommandId == commandId && b.ProviderId == this.ProviderId) ||
+                    dockSettings.EndBands.Any(b => b.CommandId == commandId && b.ProviderId == this.ProviderId))
+                {
+                    Logger.LogDebug($"Dock band '{commandId}' from provider '{this.ProviderId}' is already pinned; skipping.");
+                    return s;
+                }
+
                 return s with
                 {
                     DockSettings = side switch
@@ -583,6 +584,14 @@ public sealed class CommandProviderWrapper : ICommandProviderContext
         Logger.LogDebug($"CommandProviderWrapper.PinDockBand: {ProviderId} - {bandVm.Id}");
 
         var bands = this.DockBandItems.ToList();
+
+        // Prevent duplicate entries in the in-memory band list
+        if (bands.Any(b => b.Id == bandVm.Id))
+        {
+            Logger.LogDebug($"Dock band '{bandVm.Id}' already exists in DockBandItems; skipping.");
+            return;
+        }
+
         bands.Add(bandVm);
         this.DockBandItems = bands.ToArray();
         this.CommandsChanged?.Invoke(this, new ItemsChangedEventArgs());

src/modules/cmdpal/Microsoft.CmdPal.UI.ViewModels/Dock/DockViewModel.cs

@@ -85,9 +85,19 @@ public sealed partial class DockViewModel
         ObservableCollection<DockBandViewModel> target)
     {
         List<DockBandViewModel> newBands = new();
+        HashSet<string> seen = new(StringComparer.Ordinal);
         foreach (var band in bands)
         {
             var commandId = band.CommandId;
+
+            // Skip duplicate entries that share the same provider + command id
+            var key = $"{band.ProviderId}\0{commandId}";
+            if (!seen.Add(key))
+            {
+                Logger.LogWarning($"Skipping duplicate dock band entry {commandId} for provider {band.ProviderId}");
+                continue;
+            }
+
             var topLevelCommand = _topLevelCommandManager.LookupDockBand(commandId);
 
             if (topLevelCommand is null)