Return a snapshot from GetCommandsToUndo instead of a live query [patch]

UndoRedo.Test/UndoRedoStackTests.cs

@@ -882,6 +882,46 @@ public async Task UndoToSaveBoundary_BoundaryRemovedByBranching_ReturnsFalse()
 		Assert.IsEmpty(stack.GetCommandsToUndo(removedBoundary));
 	}
 
+	[TestMethod]
+	public void GetCommandsToUndo_EnumeratedAfterBranching_ReflectsStateAtCall()
+	{
+		// Arrange
+		UndoRedoService stack = CreateService();
+		stack.MarkAsSaved();
+		stack.Execute(new DelegateCommand("A", () => { }, () => { }));
+		stack.Execute(new DelegateCommand("B", () => { }, () => { }));
+		SaveBoundary boundary = stack.SaveBoundaries[0];
+
+		// Act
+		IEnumerable<ICommand> commandsToUndo = stack.GetCommandsToUndo(boundary);
+		stack.Undo();
+		stack.Execute(new DelegateCommand("C", () => { }, () => { })); // Replaces B in the live stack
+
+		// Assert
+		string descriptions = string.Join(",", commandsToUndo.Select(c => c.Description));
+		Assert.AreEqual("A,B", descriptions, "The result should be a snapshot of the stack when it was requested");
+	}
+
+	[TestMethod]
+	public void GetChangeVisualizations_EnumeratedAfterExecute_ReflectsStateAtCall()
+	{
+		// Arrange
+		UndoRedoService stack = CreateService();
+		stack.Execute(new DelegateCommand("A", () => { }, () => { }));
+
+		// Act
+		IEnumerable<ChangeVisualization> visualizations = stack.GetChangeVisualizations();
+		stack.MarkAsSaved();
+		stack.Execute(new DelegateCommand("C", () => { }, () => { }));
+
+		// Assert
+		List<ChangeVisualization> snapshot = [.. visualizations];
+		Assert.HasCount(1, snapshot, "Commands executed after the call should not appear");
+		Assert.AreEqual("A", snapshot[0].Command.Description);
+		Assert.IsTrue(snapshot[0].IsExecuted);
+		Assert.IsFalse(snapshot[0].HasSaveBoundary, "A save boundary created after the call should not appear");
+	}
+
 	[TestMethod]
 	public async Task UndoToSaveBoundary_WhenAlreadyAtPosition_ReturnsFalse()
 	{

UndoRedo/Services/SaveBoundaryManager.cs

@@ -97,9 +97,10 @@ public IEnumerable<ICommand> GetCommandsToUndo(SaveBoundary saveBoundary, int cu
 		Ensure.NotNull(saveBoundary);
 		Ensure.NotNull(commands);
 
+		// Materialize so the result is a snapshot, not a view that changes with the live stack
 		return currentPosition <= saveBoundary.Position
 			? []
-			: commands.Skip(saveBoundary.Position + 1).Take(currentPosition - saveBoundary.Position);
+			: [.. commands.Skip(saveBoundary.Position + 1).Take(currentPosition - saveBoundary.Position)];
 	}
 
 	/// <inheritdoc />