Hi,

unfortunately, there is not such a model and I am not sure how this could work.

If you customize the code of web part, it is possible that in your custom code you work with code which will be fixed in the the future. We cannot predict the content of your custom code. For example in case you use one of our methods and some new parameter is added by hotfix, we cannot fixed it in your custom code.

Then it is better to have two versions of web parts in which you can compare the code easily. Moreover, the code is not usually changed in the web parts. The API which is used by web parts and full source code is usually changed by hotifx.

Best regards,
Ivana Tomanickova