Function body_diff_ratio 

pub fn body_diff_ratio(a: &Bytes, b: &Bytes) -> f64

Body content divergence ratio in [0.0, 1.0].

Counts differing byte positions across the overlapping range plus the length difference, normalized by the maximum length. Equal bodies return 0.0; completely disjoint same-length bodies return 1.0; partially overlapping bodies return a fractional ratio. Two empty bodies return 0.0.