Function write_cycle_health_csv 

pub fn write_cycle_health_csv<W: Write>(
    rows: &[CycleHealthRow],
    w: &mut W,
) -> Result<()>

cycle-health CSV emitter — per-SCC heat, verdict, extraction candidate, and predicted propagation-cost drop.

Header: cycle-id,size,members,heat-pct,verdict,extract-candidate,predicted-pc-drop Floats are formatted {:.2}; an absent predicted_pc_drop (cycles above the trial-removal bound) emits an empty cell.