MDriven PreDelete + auto cascade deletes, what is rolled back if deletion is canceled?

Using MDriven Framework, we want to use PreDelete to clean up some linked objects that can't be handled automatically due to interdependencies (they need to be deleted in a particular order).

The class in question also has some M-M links with link objects (that should be auto deleted by the framework) and some composite links (that should result in linked objects to be auto deleted by the framework).

I assume that those auto deletions happen after return from PreDelete.

What happens if some of these auto deletions fail? (E.g. if some cascade PreDelete returns with canDelete == false.)

Is the entire delete operation rolled back, including the operations performed by the original/main object's PreDelete?

I would assume that the entire delete operation is wrapped by a transaction (IUndoService.StartTransaction). Is this true? Otherwise, how is it done and what happens if the delete is canceled or throws?

Yes - everything is wrapped in a transaction and on fail to perform the whole everything is rolledback. Below is a snap of the code to get an idea of the flow: