nx_gate_bite.nx

nx_gate_bite.nx -- NON-VACUITY BY MUTATION. Answers the one question a green gate cannot answer about itself: CAN THIS GATE EVER FAIL? Closes debt seq1344; the two-operator design closes seq1413. REWRITTEN (rule 3, not patched a fourth time). The first version accumulated four corrections in one session -- an anchor-blind judge, a vacuity overclaim, uncounted invalid mutants, and a single operator. Each was a real defect and the accumulation was the signal to rewrite rather than keep patching. THE METHOD (mutation testing, the 2026 field standard): perturb the SOURCE the gate is supposed to be judging, rebuild, and require the gate to go RED. Killing ONE mutant proves the gate bites; we stop at the first kill because the question is binary, not a score. ★★TWO OPERATORS, ESCALATED -- because ONE OPERATOR CANNOT REACH EVERY ASSERTION SURFACE. phase 1 COMPARISON (`==` -> `!=`): reaches logic. Kills nx_raci_gate, nx_medbill_{nsa,codes,recon,civic}. phase 2 LITERAL (flip a letter inside a copy string): reaches OUTPUT. MEASURED: nx_healthhelp_site_gate asserts on rendered page TEXT (tone phrases, absence of "fight"/"arsenal"), so a comparison flip in a path that does not change emitted copy is a survivor BY CONSTRUCTION -- not a hollow gate. A single-operator harness makes every text-asserting gate permanently unprovable and would slander all of them. The operator must be chosen by what the gate ASSERTS ON, so we try both before concluding. ★A MUTANT THAT DOES NOT COMPILE IS NOT A KILL. nx_sov_build_run RUNS the gate as its final step, so a non-zero build exit means EITHER the gate went RED (real kill) OR the source failed to compile (proves only that I broke the code). Counting the second as the first would let this organ certify non-vacuity it never observed -- the `green>=1` overclaim rebuilt inside the tool built to catch it. ★NO KILL IS NOT PROOF OF VACUITY. Killing one mutant proves a gate CAN fail; failing to kill N proves only that those N perturbations did not reach its assertions. INCONCLUSIVE is the honest word. ★THE JUDGE IS DIALECT-TOLERANT. Gates do not all speak one form: nx_medbill_nsa_gate ends `ADV3 ...: GREEN` with NO `verdict=` anchor. Reading "anchor absent" as "not green" made an earlier build of this organ report a 21/21 gate as broken -- an instrument reporting its own blindness as the subject's defect. Prefer the verdict line; fall back to the exit code; always print which judge decided. FAIL-SAFE BY CONSTRUCTION (rule 26 spirit): pristine bytes held before the first mutation, the mutation window is the narrowest possible (mutate -> build -> RESTORE -> only then judge), the restore is byte-verified, and the organ REFUSES to exit 0 if it cannot prove the restore. usage: nx_gate_bite <gate_target> <source.nx> [max_sites] [aim <func> <skip> | aimlist <func>] (CWD = nxc2 root) AIMED MODE (2026-08-03, debt 1785779063): mutation testing has THREE axes -- assertion strength, fixture coverage, and SITE REACHABILITY. Position-picked sites in a large shared subject land in guards, early helpers and sibling codecs the gate never executes, and A TOOTH CANNOT KILL A MUTANT THAT NEVER EXECUTES.