nx_gltf2mesh_units_gate.nx

nx_gltf2mesh_units_gate.nx -- THE GATE FOR UNIT DETERMINATION IN THE glTF INGEST. WHAT IT GUARDS. nx_gltf2mesh used to carry a hardcoded 500-2500mm window and refuse anything outside it. That window was ANTHROPOMETRY -- "the subject is a HUMAN between 0.5 and 2.5 metres" -- welded into a FORMAT CONVERTER. Measured 2026-08-22 over the full 18-file GLB population (corpus_complete=1) it refused 2 of 18 assets, both a legitimate 2.615 m character, for being 115 mm too tall. glTF 2.0 fixes the unit of length as the METRE, so a conformant donor needs no guessing at all; the sniffing exists only for donors authored in another power of 1000. THE SUBJECT IS FORKED FOR REAL. The organ's contract is its EXIT CODE (0 convert, 8 refuse-units, 2 usage) and /api/gate_run derives verdicts from exit codes, so every tooth here asserts an exit code. Output markers are checked only where the exit code alone cannot distinguish two states. THE NEGATIVE CONTROL IS LOAD-BEARING AND IT IS T4. A guard that ACCEPTS EVERYTHING passes every accept-test, so proving "the 2.615 m human now converts" is only half a proof. T4 forces the refusal branch by pointing the organ at a /tmp conf whose floor no scale can clear, and gv_bite judges T1 and T4 together: it must fire on the bad input AND stay silent on the good one. FIXTURES ARE /tmp ONLY. The organ's units_conf= override exists precisely so this gate never edits the production conf -- a gate that shares a fixture with a production beat reports on the fixture rather than on the code, which is how a RED can track scratch state instead of a defect. license_tier: ORIGINAL No hw writes (Rule 26). expect_exit: 0