Constant CLUSTER_ROWS 

const CLUSTER_ROWS: [(f32, f32, f32); 3];

Where each row of lights sits, nearest first: its depth, the height its lights hover at, and how far each one reaches.

One row per light kind – point, spot, then quad – so every kind’s footprint is a band of its own and a kind written into the wrong cells shows up as a patch in the wrong band rather than as a change of level everywhere.