What's a good name for a façade class?

I know this seems trite, but... have you considered using "ModelFacade" as the class name for the facade class? I think with documentation that indicates that the interface was already named Model, it seems relatively straightforward, and makes it very clear which design pattern you're using.

How about *Provider and *Consumer? I think you said it yourself in your question. Perhaps *Producer and *Consumer is a better match?

In discussions within our team, another option has been proposed: we can rename the existing Model interface to something else, and just call the new façade Model. In fact, they can both be called Model right now, because they will live in separate packages. (Although I'm not a fan of identically-named classes in different namespaces.)