Optionalsheen_color?: stringOptionalattenuation_color?: stringOptionalalpha_cutoff?: numberOptionalrefract_data?: booleanThe LIVE refract_data switch (spec §3.4 Phase 3): the glass draws after, and
refracts, the emissive data. Always present on a physical layer (absent authored
attr = false) so the toggle always has a state to show.
The AUTHORED physical knobs of a mesh layer, as the panel lists them read-only.
Only knobs actually present are returned — an absent knob renders as three's default, and the panel says so rather than printing a number the author never wrote. Read off the node, else off its first mesh descendant, for the same kind=partition reason as
deriveMeshAttrFromDescendants.