surface
Per-terrain-tile composited surface-shape RTT textures, keyed by tile (sector + globe offset), bounded by SURFACE_SHAPE_CACHE_BYTES. Keyed by tile — NOT tile+shapes — so DrawableSurfaceShape reuses a tile's last fully-composited texture while its shapes reassemble (retain-last-good), avoiding both the base-layer flash on pan and the per-frame hash churn that filled the count-bounded texturesCache with 5 MB textures and OOM'd. Releases the GL texture on eviction or in-place replace.