{# check cell — tri-valence geometric mark (check / dash / cross), SEMANTIC
   hue (genome-invariant) + shape dual-coding so it survives forced-colors. #}
  <path d="{{ cell.mark_d }}" fill="none" stroke="{{ cell.tone }}" stroke-width="{{ cell.stroke_width }}" stroke-linecap="round" stroke-linejoin="round" data-hw-cell="check-{{ cell.mark_state }}"/>
