I have started the process of moving interfaces and base classes out of the bundles. One of the reasons for doing this is to remove dependencies between bundles. All bundles will depend on VespolinaCore so the interfaces are coming from a common source.
Right now, all of the interfaces in the CartBundle have moved to the Vespolina\Entity namespace. ProductInterface and FeatureInterface from the ProductBundle are now coming from the Vespolina\Entity namespace. There will be more breaks coming.
Sorry to those of you who have code that is broken by this, but I believe this will be beneficial in the long run.
Richard