A domain built so span integration holds by construction: sums of
nonnegative compact ellipsoid kernels in a mass-conserving multiplicative
cascade, per-kernel affine warp, all nonlinearity moved into placement.
Measured on Yggdrasil against the shipped void and wells, with a physical
reference (Beer-Lambert, single scattering with HG).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
