Looking for best-practice suggestions on this, with a goal of simplicity:

My image (specifically, the class schema in my monticello) evolves. I have 
multiple repositories with snapshots of object graphs persisted, each from 
some version of the image. At any time I want to be working with the latest 
version of the image, across all snapshots.

What kind of version-related information should I save with (a) the image 
(b) the persisted snapshots? What policy to use to keep these in sync? Would 
some Squeak equivalent of Rails/migrations be relevant, and what might it 
look like?

Thanks!

Sophie