Got adding working again

Toolkit.Foundation/Aggerate.cs

@@ -1,10 +0,0 @@
-namespace Toolkit.Foundation;
-
-public record Aggerate<TValue, TOptions>(TOptions? Options = null) : 
-    IAggerate
-    where TOptions : class
-{
-    public object? Key { get; init; }
-
-    public AggerateMode Mode { get; init; }
-}

Toolkit.Foundation/AggerateAttribute.cs

@@ -0,0 +1,7 @@
+namespace Toolkit.Foundation;
+
+public class AggerateAttribute(object key,
+    AggerateMode mode = AggerateMode.Reset) : NotificationAttribute(key)
+{
+    public AggerateMode Mode => mode;
+}

Toolkit.Foundation/AggerateEventArgs.cs

@@ -1,12 +1,31 @@
 namespace Toolkit.Foundation;
 
-public record AggerateEventArgs<TValue> : 
+public record Aggerate
+{
+    public static AggerateEventArgs<TValue, TOptions> With<TValue, TOptions>(TOptions options) where TOptions : class
+    {
+        return new AggerateEventArgs<TValue, TOptions>(options);
+    }
+
+    public static AggerateEventArgs<TValue> With<TValue>()
+    {
+        return new AggerateEventArgs<TValue>();
+    }
+}
+
+public record AggerateEventArgs<TValue, TOptions>(TOptions? Options = null) :
+    IAggerate
+    where TOptions : class
+{
+    public object? Key { get; init; }
+
+    public AggerateMode Mode { get; init; }
+}
+
+public record AggerateEventArgs<TValue> :
     IAggerate
 {
     public object? Key { get; init; }
 
-    public static Aggerate<TValue, TOptions> With<TOptions>(TOptions options) where TOptions : class
-    {
-        return new Aggerate<TValue, TOptions>(options);
-    }
+    public AggerateMode Mode { get; init; }
 }

Toolkit.Foundation/NotificationAttribute.cs

@@ -5,9 +5,3 @@ public class NotificationAttribute(object key) : Attribute
 {
     public object Key => key;
 }
-
-public class EnumerateAttribute(object key,
-    AggerateMode mode = AggerateMode.Reset) : NotificationAttribute(key)
-{
-    public AggerateMode Mode => mode;
-}

Toolkit.Foundation/ObservableCollection.cs

@@ -250,9 +250,9 @@ public partial class ObservableCollection<TItem> :
         Disposer.Dispose(this);
     }
 
-    public void Aggerate()
+    public void BeginAggregation()
     {
-        if (this.GetAttribute<EnumerateAttribute>() is EnumerateAttribute attribute)
+        if (this.GetAttribute<AggerateAttribute>() is AggerateAttribute attribute)
         {
             if (attribute.Mode == AggerateMode.Reset)
             {
@@ -260,7 +260,7 @@ public partial class ObservableCollection<TItem> :
             }
 
             object? key = this.GetPropertyValue(() => attribute.Key) is { } value ? value : attribute.Key;
-            Publisher.PublishUI(OnAggerate(key));
+            Publisher.PublishUI(OnPrepareAggregation(key));
         }
     }
 
@@ -338,7 +338,7 @@ public partial class ObservableCollection<TItem> :
         }
 
         Initialized = true;
-        Aggerate();
+        BeginAggregation();
 
         return Task.CompletedTask;
     }
@@ -442,7 +442,7 @@ public partial class ObservableCollection<TItem> :
         collection.Insert(index, item);
     }
 
-    protected virtual IAggerate OnAggerate(object? key) =>
+    protected virtual IAggerate OnPrepareAggregation(object? key) =>
         new AggerateEventArgs<TItem>() with { Key = key };
 
     protected virtual void RemoveItem(int index) =>