Exercise markdown diff, mail export/share, drive latest/depth, whiteboard,
and diff-engine edges via TestCrossPlatformCoverage*; add small injectable
seams only where defensive branches are otherwise unreachable.
Co-authored-by: Cursor <cursoragent@cursor.com>
Port calendar event instances, markdown diff, drive list --latest,
mail calendar/calendar-event/shared-with-me/export/share-to-chat, and
doc whiteboard insert so open edition matches documented Wukong test
command surfaces.
Co-authored-by: Cursor <cursoragent@cursor.com>
