I didn't mean to suggest the constants module was a separate, reusable module, but a component of the same piece of software. By "module" here I meant "director

I didn't mean to suggest the constants module was a separate, reusable module, but a component of the same piece of software. By "module" here I meant "directory which can contain multiple importable files," so you could namespace your constants (constants/rfc_abcd.xyz, constants/customer_limits.xyz, etc). I'd rather copy-paste any reused constants to different projects to avoid coupling, unless there was some kind of compelling domain/project specific reason.