Interesting

1. Search state emphasis is on undoing, not fyi this is what you have done

2. wording “narrow” and “expand”

3. note the repetition of “narrow by” and “show all” – I didn’t read them but I wonder if over time they offer good cues to users?

4. redundant functionality – category breadcrumb across top as well as category navigator in left (though this is equivalent to undo all)