nx_four_pillars.nx

nx_four_pillars.nx -- the ENGINEER's FOUR-PILLAR GUARD: the intelligent, additive guard that makes a defect class un-recurring (operator: "the guard you describe if intelligent and additive is the four pillars work i wanted the engineer to address as its responsibility"). This is the team's established pattern (G1 regalloc guard, nx-int alias guard) formalized + made the Engineer's owned responsibility. The four pillars (ALL required -- a partial guard is not a guard): 1. GATE -- a regression gate that FAILS LOUD if the class recurs (CI smoke). 2. PROBE -- a minimal repro that isolates the root cause (proves we understand it). 3. KAT -- a known-answer test locking the correct behavior forever. 4. PREVENTION -- the structural fix that makes the bad input IMPOSSIBLE (loud-fail / pinned / data-driven). INTELLIGENT = the class is LEARNED from a real captured diagnostic (data-driven, like the Doctor learning the offending keyword), not a hardcoded match. ADDITIVE = adds new artifacts, never clobbers protected source. Owned by the ENGINEER (RACI). license_tier: ORIGINAL Formalizes the poka-yoke in nx_pipeline_metrics.