This, the Ruby team introduced RBS (.rbs file extension) which allows you add static types but I find it cumbersome to having keep track of two of the same file

This, the Ruby team introduced RBS (.rbs file extension) which allows you add static types but I find it cumbersome to having keep track of two of the same files. If they only allowed static types in the same source code! (I know Sorbet exists, but I haven't really used it yet)