Labels, background_color and preset ids go through the choke point (S13); ambiguous preset names fail with their ids (S13a); fullwidth + rows is an error. Carry-ins: control characters stripped before the marker check (S32), kind override may only tighten, reference alt texts dropped, color check via VariableRef::typeOf (S33). Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01At3V6SjwbMe6eMzVGW3Hs7