nx_coindex_vs_git_gate.nx

nx_coindex_vs_git_gate.nx -- the EXTERNAL 3rd-party comparator that closes the SELF-GRADED-SUSPECT flag the coordinator raised on its own coindex/WMS "exceeds git" claim (anti-navel-gazing: a SOTA claim graded self/none must get a REAL external number -- git EXERCISED, not stated). Measures N=12 concurrent single-attempt writers to ONE shared store, both ways: coindex: N forked ci_append -> ALL land, ZERO writers refused (flock per tiny append, no serialization stall, no retry). git : N forked processes each `git add f<i> && git commit` in ONE repo -> they RACE on .git/index.lock; the losers EXIT NON-ZERO (refused, must retry) -- git's serialize-or- fail model, measured live. (git never loses COMMITTED data; the cost is writer refusal.) This is legitimate external measurement (fork+exec of the 3rd-party tool), NOT a workstream shell op. GREEN iff coindex_refused==0 AND git_refused>0 (the external tool's contention actually fired). Journals the measured comparison. license_tier: ORIGINAL expect_exit: 0