FAILOPEN REGRESSION V3 — Codex V2 attack replayed against the V3 gates [PASS] M1 mutation applied to copy (sys.exit(4) -> sys.exit(0) in 3 SUT files) [PASS] M2 mutated SUT is genuinely fail-open: missing-doc CLI OBSERVED exit == 0 — observed_exit=0 [PASS] M3 laundering blocked: manifest_tool --emit on fail-open SUT OBSERVED exit != 0 — observed_exit=1 [PASS] M4 verification blocked: manifest_tool --verify on fail-open SUT OBSERVED exit != 0 — observed_exit=1 [PASS] M5 black-box suite catches it: blackbox_negative_suite on fail-open SUT OBSERVED exit != 0 — observed_exit=1 [PASS] M6 canonical packet unchanged (tree hash identical before/after) — 4a26d7301b839f63... FAILOPEN_REGRESSION: PASS (6/6 — a fail-open CLI mutation must be caught by emit, verify, and the black-box suite before any PASS)