Function tick_slot_evaluator 

fn tick_slot_evaluator(
    slot: &mut PresetSlot,
    audio: AudioLevels,
    delta_time: f32,
    enable_per_frame: bool,
    display_duration_s: f32,
    track_progress_override: Option<f32>,
)

Advance one slot’s per-frame state: push the shared audio levels + time + frame into its evaluator context, then run its per-frame equations. Called once for current and (during transitions) once for fading_out each frame.

enable_per_frame == false skips the equation eval but still updates the context — keeps time / audio correct in case a downstream path (warp executor, custom waves) reads them.