[rustyzig]

> - Why Redis over in-memory cache? - Why GraphQL for this one service but REST everywhere else? - Why that strange exception in the auth flow for enterprise users?

These are all implementation details that shouldn't actually matter. What does matter is that the properties of your system are accounted for and validated. That goes in your test suite, or type system if your language has a sufficiently advanced type system.

If replacing Redis with an in-memory cache is a problem technically, your tests/compiler should prevent you from switching to an in-memory cache. If you don't have that, that is where you need to start. Once you have those tests/types, many of the questions will also get answered. It won't necessarily answer why Redis over Valkey, but it will demonstrate with clear intent why not an in-memory cache.