PolyfaceMesh / PolygonMesh / SubDMesh fills and 3DFACE quads were
classified as 2D fills and given the draw-order z-bias, so they were
pulled toward the camera and drew over solids. The tessellator emits a
mesh's edges and its fill as separate WireModels (points-only vs
fill-only), so the old `!points.is_empty()` discriminator misrouted the
fill. Classify a fill as a 3D surface by its double-single low residual
(`fill_tris_low`) instead, and drop the draw-order bias from 3DFACE
quads. 2D annotation fills (text greek, MultiLeader / dimension
backgrounds) leave `fill_tris_low` empty and keep ordering by rank.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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