Flag count is fixed by duration: none for quarter/half/whole, one for eighth, two for sixteenth, three for thirty-second

Flag count is a direct function of duration relative to the quarter note: quarter and longer get no flag (unbeamed), eighth gets one, sixteenth gets two, thirty-second gets three.

A rendered note whose flag glyph count doesn't match its authored duration — most likely a font/glyph-table regression, since flag selection is automatic.

SMuFL glyph naming (`flag8thUp`/`flag8thDown`, `flag16thUp`/`flag16thDown`, `flag32ndUp`/`flag32ndDown`); Gould, Behind Bars, flags section; Read, Music Notation.

This rule is about where marks land on the page, so it can only be judged after engraving. Collision and spacing faults live here.