Why: Preserve the owner’s Stage 5 decision and implementation method on the reviewed plan object.
Evidence: Owner approved plan 28c4ceb in the task conversation; git diff --check and relative links passed (SELF).
Impact: Documentation status only; Dev implementation remains subject to Stage 6 and 7 review.
Refs: Agent-System-Documents #105; Agent-System-Dev #518
Why: The approved Stage 4 design needs a reviewable Stage 5 implementation and test sequence.
Evidence: git diff --check, relative-link validation, M2-1 through M2-6 coverage, and placeholder scan passed (SELF).
Impact: Documentation only; no Dev queue activation or task takeover.
Refs: Agent-System-Documents #104; Agent-System-Dev #518