Release and proof boundary

and proof boundary{ Constructed: the companion support statement, an explicit off-causal-plateau diagnostic, the shell rewriting of the Einstein row, and cancellation on the named local configuration subclass.

Proved obstructed: unqualified invariance of ${{\Phi }^{(2)}}_{\mathrm{D}}$ on the complete gauge-fixed free shell. A compact plateau witness satisfies the copied causal plateau condition and has a strictly nonzero auxiliary pairing.

Unresolved as a separate future problem: an additional co-transformation or observable completion cancelling that pairing. Its absence is not promoted to a general no-go theorem.

No quantum retarded product, interacting differential, state, loop, antibracket, sharp limit, or coupled-jet repair is claimed. The inherited inverse coefficient and insertion sign are unchanged.}