nx_sha256_longmsg_gate.nx

nx_sha256_longmsg_gate.nx -- the MISSING KAT row, shipped as a ten-second organ (Doctor+Builder, ENG-BROWSER visit 2026-06-11). WHY: the 2026-06-10 sha256 perf rewrite (HASH-OPT, CAPREG377) was proven byte-identical by a golden diff roll over inputs 0..256 BYTES -- but TLS transcript hashing feeds MULTI-KILOBYTE input through the STREAMING path (init/update/final, arbitrary chunk seams). No gate covered long inputs or streaming==one-shot equivalence. This organ closes that class: K1 abc FIPS 180-2 vector, one-shot K2 two-block-448 FIPS 180-2 vector (56 bytes, crosses one block seam), one-shot K3 million-a FIPS 180-2 LONG vector (1,000,000 bytes), ONE-SHOT K4 million-a-walk same vector via STREAMING updates with a mixed chunk walk (1,63,64,65,255,256,257,1000,4096 cycling -- every buffer-seam residue class) -- streaming must equal the published digest K5 4k-equiv 4096-byte pattern: streaming(100-byte chunks) == one-shot GREEN = the sha256 long/streaming class is exonerated forever (regression-gated); RED = the defect is named mechanically, no human bisect. Durable: SHALONG rows -> knowledge/status/sha256_longmsg.log. Exit 0 iff 5/5. license_tier: ORIGINAL