Constant QSMJL_SMV_DELTA 

pub(crate) const QSMJL_SMV_DELTA: f64 = _; // 0.9999999850988388f64

QSM.jl’s threshold for “the whole ball fits in the mask”: S ∗ mask > 1 − √eps(Float64) (δ in src/bgremove/sharp.jl _sharp!, fde4b92). Shared by SharpVariant::QsmJl and V-SHARP.