The essential limitation: no automatic free-carrier descent

The theorem in Section sec:stageA and this support observation are compatible. The former uses off-shell local ghosts; the latter concerns homogeneous free solutions. Compact gauge parameters are not nonzero compact free ghost configurations.

A future retarded transport to an interacting equation space would require a separate map, a compatible interaction prescription, and its domain theorem. The X-G obstruction prevents assuming that the unchanged post-variation source map already supplies that variational transport.