Per-chord-tone partial ties are not representable in either authoring surface

Real engraving frequently ties only some notes of a chord while others re-attack (e.g. soprano sustains, alto/tenor restrike) — a legitimate and common voice-leading device, especially in chorale writing.

Any chorale or SATB lesson that needs 'soprano ties over the barline, alto restrikes' cannot express it: `tie: true` in JSX applies to the WHOLE note object (all chord tones at once), and `tiedToNext` in the public API is likewise one flag per whole `NoteObject`.

Gould shows partial-chord ties explicitly; Stone's 20th-century notation survey documents them as standard in keyboard and choral engraving. Read likewise treats each chord member's tie independently.

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