Issue 1585: mesh-sdk and mesh-delivery are both over 500 unit tests; ADR 0578's tests replace, never add. Claude-Session: https://claude.ai/code/session_01NcbgfJ9Gum47zkFKWRaovL
Issue 1585, S1: catalogue.Decode sets an unknown field aside and names it (SetAside); only a manifest not read past the field is still left out. Claude-Session: https://claude.ai/code/session_01NcbgfJ9Gum47zkFKWRaovL