I recently worked on a payment integration which was effectively the entitlement layer as well, and I knew it was bad design at the time but hadn’t worked out a solution. It was a situation where we needed to move quickly and if it mattered later we could totally overhaul all of it, but it really rubbed me the wrong way knowing that it definitely wasn’t a good solution.

This covers everything I was unsure about, plus a lot I hadn’t considered. Thanks very much – this will save a lot of pain the next time I work on something similar.