view_tiers compares the kept assignment revision whose catalog carries the source revision with the one kept before it, through the seat mesh-wants' verbs revision and difference (view/difference.go, tiers.go Tiers), and reads the tiers and each module's after (module and edge kind) from the answer; the view orders nothing. The manifest invokes the two verbs. Builds: design 47 G §512, §186, A-242