nx_gramdec_gate.nx

nx_gramdec_gate.nx -- NB10 gate: grammar-constrained decode (nx_gramdec_lib) teeth. T1-T8 = automaton ruler teeth (no model). T9 = LIVE no-op equivalence: on an already-grammatical greedy generation the constrained decode must be BIT-EXACT (prefix) with nsv_generate, zero rejections, accept-stop. T10 = LIVE mask-fires (anti-vacuity + escape): an else-if-baited prompt must (a) make the UNCONSTRAINED model emit `else if` (proves the bait bites -- the vacuity guard), (b) under the mask produce grammar-VALID output with >=1 rejection and NO `else if`. MUTATION PROOF (rung 5): flip GD_NEG_ALLOW_ELSEIF=1 in nx_gramdec_lib.nx, rebuild, run -> T3 accepts the else-if text and T10 sees the escape -> verdict=RED exit 1. Restore -> GREEN. argv: [model.gguf] [probe] (default model /home/elderwesto/nx_stage/nx_15b_model.gguf; "probe" prints raw outputs for tooth calibration instead of judging). license_tier: ORIGINAL No hw writes (Rule 26).