Disk-integrated reflected-light phase curves at 0.55 μm for a TRAPPIST-1b-like configuration using an Apollo regolith analog (sample 10084) from the BUG dataset (M. K. Shepard & P. Helfenstein 2007). The light-blue region shows the uncertainty envelope obtained from single-geometry laboratory conditioning. The green region corresponds to the case where additional grain-scale optical priors constrain ω and b. The red region shows the predictions obtained using the full multiangular BUG dataset. Shaded regions represent the propagated posterior uncertainty in the Hapke parameters (ω, b, B₀, h). The vertical gray band marks the approximate phase-angle range corresponding to secondary-eclipse ingress. Although grain-scale optical constraints partially reduce the uncertainty envelope, substantial uncertainty remains until direct multiangular constraints are introduced.