Now that I've returned to working on the project tonight, I just remembered another failing of our code. (I'm not in any way claiming these are universal problems, just that they are something to be wary of.)

Naming is so incredibly important. The wrong name for a configuration key can have cascading impacts, especially when there is "magic" involved, like stripping out or adding common prefixes to configuration values.

We have a concept called a "domain" which is treated as a magic value everywhere, such as adding a prefix or suffix. But domain isn't well-defined, and in different contexts it is used different ways, and figuring out what the impact is of choosing a domain string is typically a matter of trial and error.