Review round 1 (Codex gpt-5.6-terra) found: a case-only edit could
suppress the duplicate-name warning even when a DIFFERENT child
already carried the normalised name, because the edit path compared
only against the child's own old name. The scan now always runs on
the resulting state and excludes only the child being edited
(exclude_child_id), so case-only edits and stay-duplicated renames
warn like any other collision; renaming to your own name stays
warning-free when no other child holds the name. Tests: new
case-only-collision test, stay-duplicated rename assertion, and a
split self-rename test; suite at 848 passed.
Joshua King
712527d5ba