Feature Request: More UnityEditor Callbacks for prefab instance lifecycle management

I have been scratching my head a few days now trying to come up with a stable way to determine if an object was duplicated by the editor.

It seems the best we have right now is
https://docs.unity3d.com/ScriptReference/GlobalObjectId.html

Which is good enough to uniquely identify an object as long as it doesn't move scenes. That's great except I want to be able to move objects between scenes without my logic breaking.

I am trying to programmatically assign value that I don't want shared when I copy an object in the inspector.
(You guys could also use this kind of logic internally so that duplicating a terrain object doesn't share the terrain data asset, with undesirable results)

Right now it only seems possible to detect object duplication on a per scene basis.

using UnityEditor;

using UnityEngine;

class EditorTrackedObject : MonoBehaviour {



[HideInInspector] public string editorGUID = null;

void Awake () {

if (editorGUID == null) {

//New object

editorGUID = GlobalObjectId.GetGlobalObjectIdSlow (this);

} else if (GlobalObjectId.GetGlobalObjectIdSlow (this) != editorGUID) {

//Object duplicated programmatically or through editor command

//Generate new instance variables that should be unique across duplication

}

}



void ObjectWasMovedBetweenEditorScenes() {

//I need some way for Unity to tell me that this object traveled, that or a truly globally unique ID,

// but I don't think that fits into Unity's current instance serialization scheme.



//NOt a new object, our GUID just changed so update it.

editorGUID = GlobalObjectId.GetGlobalObjectIdSlow (this);

}

}