One of the things I really like about ENVY (as found in VA Smalltalk) is that packages are formally modelled and are distinct from method categories. (Another is that a method can have multiple categories.) And by formally modelling packages, one can easily include proper dependency relationships and more easily detect references to behaviours outside a packages prerequisites chain.
I realize that is a huge departure from current Squeak and Pharo practice. But, I hope it's one that will get consideration. (Given all the other first class modelling you've been adding to Pharo, I think this would be consistent with the current philosophy!)
+1 Multiple categories for methods and proper modelling of Packages seems like a very strong feature to have. Multiple tags per class is also a big plus.