Function halftime_click_track 

pub fn halftime_click_track(
    bpm: f32,
    secs: f32,
    weak: f32,
    format: AudioFormat,
) -> Vec<f32>

A sparse half-time feel at bpm: full clicks on beats 1 and 3, weak times that on beats 2 and 4 — the half-time trap (Plan 0095 Phase 1).

The beat grid is still fully populated, so the notated tempo is bpm; what changes is that the accent pattern repeats every two beats, so the envelope’s strongest periodicity is at twice the beat period. At weak = 1 this is click_track; at weak = 0 it stops being half-time material and simply becomes a click train at bpm / 2, which is why the probe sweeps the middle rather than the ends.