1. What was the most important improvement made to our sample service?
This is subjective, and as such, there is no right answer. For me, it's either the decoupling or the removal of the globals. When the code becomes decoupled, it becomes easier for me test and each piece becomes a bite-sized chunk, which means it's easy to work on. Basically, I don't have to think too hard or remember too much context.
As to the globals, I've been bitten by this in the past, particularly the data races that happen during testing. I can't stand it when my tests are not reliable.
2. In our dependency graph, why isn't the data package under main?
We could refactor to make it this way, but at the moment we are using JIT injection between the model and data layers. This means the UX of the code is improved, but the dependency...