In this talk, I discuss a novel procedure for analyzing the lattice-QCD spectrum via the finite-volume formalism to obtain constraints on
multi-hadron scattering amplitudes at both real and complex energies. This approach combines a Bayesian reconstruction of the
scattering amplitude on the real axis with numerical analytic continuation to complex-valued energies using Nevanlinna-Pick
interpolation. The method is non-parametric, inherently accounting for parametrization dependence within the uncertainty. We
demonstrate the applicability of this approach using real lattice-QCD data on two-nucleon scattering and the sigma resonance.