Yes, you are right. For now this is blocked by https://github.com/Dynflow/dynflow/issues/80 for now. We chosen not the best approach how to isolate and represent action phases (see https://github.com/Dynflow/dynflow/issues/80). Each Action has its phases represented as (cached) child classes. It's hard to extend method from a phase since they are being added after method is defined in Action class itself.