nx_srcfresh_gate.nx

nx_srcfresh_gate.nx -- TEETH FOR THE EXTRACTED FRESHNESS PREDICATE (nx_srcfresh.nx). T1-T5 are DELIBERATELY THE SAME FIVE CASES _freshness_gate.nx already locks against the original oi_src_stale, re-asserted against the extracted copy. An extraction that is not re-asserted is a claim of equivalence, not a proof of it -- and the copies already in this tree are exactly what happens when the claim is trusted (several read only tv_sec and disagree with the predicate the gate proved). T6/T7 ARE THE LOAD-BEARING PAIR AND ARE NEW. They set two files to the SAME SECOND and different NANOSECONDS. Every second-granularity implementation of this predicate answers 0 (fresh) for T6, because the two mtimes compare EQUAL -- so T6 is the tooth that fails for the copies and passes only for a real nanosecond comparison. T7 drives the same fixture the other way so the pair discriminates in BOTH directions and cannot be satisfied by a function that simply always returns 1. LAW: A TOOTH THAT ONLY THE CORRECT IMPLEMENTATION PASSES IS THE ONLY KIND WORTH ADDING TO A COPY. T8-T10 lock the MAGNITUDE, including the absent-artifact case returning -1 rather than 0: "no measurable lag" and "no lag" are different facts, and folding them is the defect class this session kept finding. DETERMINISTIC: mtimes are set explicitly via sys_utimensat -- no sleeps, no filesystem-resolution races. Fixtures live in /tmp and are unlinked at the end. Inherits nx_gate_verdict (D001). license_tier: ORIGINAL No hw writes (Rule 26). expect_exit: 0