Function gestalt_ratio_capped 

pub fn gestalt_ratio_capped(
    a: &[char],
    b: &[char],
    sam_b: &Sam,
    cap: f64,
) -> f64

Cluster min_sim helper: returns the exact ratio when RO(a,b) <= cap, otherwise a value > cap (it accept-early-exits the instant M exceeds the cap’s bound). Used to find a cluster’s minimum pairwise ratio with cur = cur.min(gestalt_ratio_capped(a, b, sam, cur)): in a dense cluster the dominant high-ratio pairs blow past cur and are pruned after the first block or two, so full M is computed only for the genuinely-low pairs. Bit-identical minimum to the full ratio.