> My theory now is that whichever ActiveRecord model is closest to the UI will grow huge as it comes to incorporate a comprehensive catalog of user interactions

> My theory now is that whichever ActiveRecord model is closest to the UI will grow huge as it comes to incorporate a comprehensive catalog of user interactions. It's an interesting question, but it's also a topic for another time. User preferences, settings, interaction history, whatever can be stored in different models. The User model can be slim.