Function fit_route 

pub fn fit_route(
    registry: &dyn ParamRegistry,
    field: &str,
    (source, dest): (&str, &str),
    depth: Semitones,
    polarity: Option<PolarityText>,
    reason: &str,
    confidence: Level,
) -> Mapped

A route of a depth in semitones into a destination stored in semitones, such as an envelope into oscillator pitch.

A depth beyond the destination’s stored span lands on the span and the rest is listed. A route amount is an interim law until the calibration set measures it, so the edit is always uncalibrated. A destination outside the registry, a legacy one or one not stored in semitones gives no edit and a not_in_synth entry; a zero depth gives nothing.