nx_voxchunk.nx

nx_voxchunk.nx -- the SOVEREIGN CHUNKED VOXEL WORLD PART. nx_gamebench gap-queue rank 1 (voxel-world-chunked, PARTIAL): the craft organ's world is a FIXED 64x32x64 volume -- honest evidence for rendering and editing, but NOT for the Minecraft-class bar the capability names: an unbounded world streamed through a BOUNDED resident set of chunks. This part is that bar, built on the certified parts (persistence = nx_gamesave, so a dirty chunk survives eviction with atomicity/corruption-refusal/additive-only inherited, not re-derived). THE INVARIANTS THIS PART EXISTS TO HOLD (each a gate tooth in nx_voxchunk_gate): 1. DETERMINISTIC GENERATION. A virgin chunk is a pure function of (world_seed, cx, cz): load -> evict -> reload is bit-identical. No stored world is needed for unvisited land. 2. BOUNDED RESIDENCY BY CONSTRUCTION. At most `cap` chunks are ever resident; walking 10,000 chunks costs the same memory as walking 10. The eviction is the design, not an afterthought. 3. EDITS SURVIVE EVICTION. A modified (dirty) chunk is flushed through gs_save before its slot is reused, and reload prefers the saved file over regeneration -- the Minecraft law: virgin land from the seed, touched land from disk. Losing edits on eviction is the classic chunk-corruption bug class; here it is structurally impossible while the flush path holds. 4. SEAM-CONSISTENT WORLD ACCESS. Callers address blocks in WORLD coordinates; chunk math is internal. A query at a chunk border resolves identically whether the neighbour is resident, evicted, or never visited. 5. WHOLE-SESSION DURABILITY. The session arena is flat i64 words -> gs_save; dirty state is flushed first, so a saved world reopens exactly where it left off. Chunk geometry: 16 x 32 x 16 blocks (8192 bytes), packed 8 blocks/word in the arena tail. license_tier: ORIGINAL expect_exit: 0