Authored is the default: ornaments and arpeggiation remain notation
semantics on one event. Measured single-note tremolos are an exception: their written
strokes determine repeated attacks in every profile. Other ornament realization remains opt-in.
Deterministic chromatic ornament attacks and chord arpeggiation for preview providers.
Trills and shakes alternate the written pitch with one chromatic semitone above; mordents
and turns use a fixed four-attack figure. Chord tones marked arpeggiate are staggered
low-to-high (or high-to-low) by at most 0.18 beats. This is a reproducible preview policy,
not a claim about historical performance practice.