Layer four of the seven-layer Carbon-Silicon Doctrine, the Cross-Industry Migration Governance layer, has been published. It proposes a three-dimensional risk classification model that takes the highest rating across reversibility, scope of impact, and autonomous permissions, dividing migration into freely permitted, restricted, and absolutely prohibited tiers. It covers 11 verticals including healthcare, finance, education, justice, government, and media, establishing a dedicated hard risk-control baseline for each. It is positioned as a standardized industry record for corporate compliance, regulatory audits, and judicial use.