Function spurious_bias_floor 

pub fn spurious_bias_floor(register_len: usize, samples: usize) -> f64

The spurious-bias floor: the expected maximum |agreement − ½| when the best of 2^register_len uncorrelated states is chosen on n samples — ≈ √(L·ln2 / 2n), from the tail of the maximum of 2^L centered binomials. A recovered CorrelationAttack::bias well above this floor is a genuine correlation (a certified combiner leak); at or below it, the register does not measurably leak.