The S1 review round ordered cell-shell batches by source surface index in
ObjectMeshManager.UploadGfxObjMeshData but left the index segments handed
to the arena in TextureBatches dictionary order. FirstIndex is positional
over the segments, so every cell shell's batch pointed at another batch's
index range: magenta placeholder walls, stretched textures, and missing
faces in every dungeon and house (G1 FAIL 2026-09-02). One upload order is
now computed once and used by the count, fill, and batch loops alike.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
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