My biggest concern of the application has been solved to my satisfaction; I won't go into any more detail on my code spike because I'll reuse some of this code later once it's been tidied up.

I moved on to working out the role of controllers in this application. What user-initiated events will we need to handle?

Initial sketches for controllers; there are several things here that didn't make it into the final version

The user can perform two main actions: completing the questionnaire itself and navigating between pages. It's the navigation that the controller will concern itself with.

At this point, I felt fairly confident that I'd fleshed out most of the tricky parts of the application. In the role of an architect, each of the diagrams and interactions that I sketched need to be turned into formal documentation in order to provide a point of reference for developers. Here's what I came up with for the UI:

There's no point in duplicating the work I've already shown you, so I...