Causal and normalization audit

The retarded comparison uses the free quantum product, not classical multiplication without a specialization proof. Its reality proof explicitly uses order-reversing free involution and anti-time ordering.

The condition with $J^{+}$ includes null relations in the excluded future. It does not prescribe boundary values when supports meet that future. Diagonal contacts and noncoincident lightlike singularities remain distinct.

The formal quotient by $\hslash$ is unique only at one lower available order. No normalized order-three result is inferred from an order-three numerator.