Interact Senior Software Engineer interview questions

Had a nice chat with Head of Engineering. Was then sent a technical exercise but the instructions were very ambiguous, i.e. "Consider this a fast turnaround solution to a real problem which will be deployed for a customer upon completion. Keep this in mind when making implementation decisions and developing the solution. Consider that this project will be handed over to a different Engineer for maintenance and further work, once you are done with it." This could be interpreted as wanting something quick and dirty that works and is readable, to be refactored and improved upon later. Instead, what they were after was no code smells at all, i.e. separation of concerns, error handling and unit testing. Please be more specific, i.e. how you would write a user story.