A bit more fuel for the bikesheding aspect of this:

Subtree borrowing.

(Single ownership stemming from main is a tree of owners; each path specifies some subtree)

(Btw. I enjoyed reading it)

FWIW `foo in bar` implies iteration to me, not a path. In the .NET world, for example, `bar` would be a collection that we’re iterating through, assigning each element to `foo` in turn.

Assuming “groups” are mainly about grouped invalidation, I agree, Path Borrowing is the better name, since it describes the core idea rather than the implementation mechanism.

Love both.