"Environment" is traditionally (in mojito code and docs) as things like "development", "production", "staging", etc. "Runtime" is used to describe the client vs. server. "Affinity" is used to describe which runtime a particular piece of code is intended for.

Unless there's a strongly compelling reason to use _different_ semantics here, it is strongly recommended to stay with the existing semantics. (If we want to change it, we should change it _everywhere_: all code and documentation.) That work (and discussion with the whole mojito team about the value of that work) is beyond the scope of this pull request, so please stick to existing semantics. Consistency aids clarity.