Notification of changed scene objects

I have an editor script that does a large amount of preprocessing based on the static colliders in a scene. I’d like to avoid redoing the preprocessing when the scene hasn’t changed, but I also don’t want to skip the preprocessing if something has changed.

Is there any way to get notification that the set of objects in the scene, or their transforms, have changed?

Yes, use an EditorWindow. You have a bunch of useful event calls there: OnSelectionChange, OnHierarchyChange, OnProjectChange.