Why: The pinned Backend extension exposes no trusted one-time HITL proof for RDM structure confirmation. Evidence: Fixed RDM/Backend source identities, W3 RED receipt, and Dev READY precheck are cited; no W4b confirmation write was run. Impact: Adds a review-only X3 verifier and RDM atomic-consumption design with permission, recovery, audit and replay checks. Refs: Stage4 design r1 section 5.2; Stage5 W4; TT-D02/D03/T04