Grace notes always render stem-up in Gradus, regardless of pitch or clef — a confirmed, previously-unflagged bug distinct from the main-note pivot bug

A grace note's stem follows the same pitch-vs-middle-line rule as any other note (Gould/Read state no exception for grace notes' stem direction, only for their proportionally smaller size and shorter stem length).

Gould, Behind Bars, grace notes section (grace notes follow ordinary stem-direction rules, scaled down); GraceNote extends StaveNote in VexFlow with no override of stem-direction defaulting logic (verified: gracenote.ts declares no constructor override of the stem-assignment block inherited from `StaveNote`).

This rule can be decided from pitches, durations and voices — no layout required. A validator can check it before anything is drawn.