I think you're spot-on with moving the focus into the domain. But you definitely need to specify the domain in your Parsley context. Generally; indepenently, of Parsley, domains are likley to be needed by other parts of your application so controlling them by a higher level construct such as an IoC container is mostly the right think to do.
Thanks for the reply.
"But you definitely need to specify the domain in your Parsley context."
Not sure I follow here - probably a question more for the Parsley forum than here, but could you give me a brief example of what you mean? In this instance do you mean somehow register each individual User with the context or maybe a UserProvider?
Yes, you could do that. Check out Parsley's developer manual, chapter 3 and 4.