nx_nif_lib.nx

nx_nif_lib.nx -- NETIMMERSE/GAMEBRYO NIF STRUCTURAL FACTS CORE (the Bethesda mesh container; /compare/koikatsu KK12 contract, legs 1+2 2026-08-30). SCHEMA GROUND TRUTH is the mirrored niftools nif.xml (GPL-3.0, read as an ORACLE) plus REAL fixtures from the nifly test corpus, hex-measured the same day: magic line then u32 version 0x14020007, u8 endian, u32 user version, u32 num blocks, BSStreamHeader, u16 num block types, SizedString type table, u16 type index per block, u32 size per block, string table, groups. BSStreamHeader export-string rule, VERCONDS FROM nif.xml AND CONFIRMED ON REAL BYTES (SE bsver 100 and FO76 bsver 155): Author always; one u32 when BS > 130; Process Script when BS < 131; Export Script always; Max Filepath when BS >= 103. THREE-STATE HONESTY: is_nif = 0 not a NIF; 1 parsed (modern layout); 2 RECOGNIZED-UNSUPPORTED -- the magic line is real but the version or a bound refuses, so every count ABSTAINS at -1 rather than misparse into confident garbage. A bounds failure is a named abstention, never a guess. MEASURED COVERAGE: Skyrim SE (100), Skyrim LE (83) and FO76 (155) headers all parse. GEOMETRY LEG (nif_geom): per-TriShape vertex/triangle counts extracted at the SSE BSTriShape tuple (desc u64, tri u16, vert u16, datasize u32 behind the 100+4*extra NiAVObject prefix) and VERIFIED BY THE SCHEMA'S OWN ARITHMETIC -- nif.xml declares DataSize = (desc AND 0xF) * verts * 4 + tris * 6, so a tuple that satisfies it is self-proven and one that does not is counted UNVERIFIED by name (LE NiTriShape and FO76 layouts land there deliberately). Full vertex DATA extraction to .nxmesh remains the contract's declared final half. SCOPE DECLARED: the census counts blocks whose TYPE NAME contains TriShape; NiTriStrips is not counted -- stated imprecision, widen deliberately. Slots: [0] is_nif [1] version [2] bs_version [3] num_blocks [4] num_block_types [5] trishape_blocks [6] total_block_bytes [7] num_strings [8] header_bytes [9] endian license_tier: ORIGINAL No hw writes (Rule 26).