Function flat_styles_with_finishes 

pub fn flat_styles_with_finishes(
    resolved: &ResolvedPrepass,
    geometry_finishes: &FxHashMap<u32, SpecularMaterial>,
    decoder: &mut EntityDecoder<'_>,
) -> (Vec<u32>, Vec<u8>, Vec<f32>)

flat_styles_rgba8 plus the parallel styleFinishes wire (#5582): two f32 per style id, [metallic, roughness], in the SAME order as ids, f32::NAN for an unauthored field. The id order is decided once, by the rgba8 flatten; the finishes are a per-id lookup over it into geometry_finishes (crate::prepass_styled::resolve_geometry_finishes over the same styled items). A geometry style always wins its id in that flatten, so only geometry-style entries can carry a finish; the indexed-colour, material and element-colour fallbacks are colour-only and get [NAN, NAN].