Why: The second independent review passed and left three clarifications
for the implementer.
Evidence: Review round 2 PASS at 6db2d614 (fresh session).
Impact: Docs and task card only.
Refs: https://git-home.u1680832.nyat.app:30319/weichen/Agent-System-Dev/pulls/662
Co-authored-by: Cursor <cursoragent@cursor.com>