Synthetic recovery test for the power-law limb-darkening coefficient as a function of input angular diameter. The left panel shows the recovered H- and K-band coefficients for independent and joint H + K fits, with 1σ uncertainties; points at θ < 1.5 mas are deemphasized because the recovery is unstable. The right panel shows the corresponding coefficient uncertainties, with σ_α = 0.02 marked for reference. Vertical lines at θ = 1.8 and 2.3 mas indicate the approximate transition to robust H-band and independent K-band recovery, respectively.