nx_str_gate.nx

nx_str_gate.nx -- the gate for the string vocabulary 109 modules import. WHY: nx_gensota's gen-3 worklist ranked it #3 by importers with no gate sibling. It DOES carry a self-test -- inside its own main() -- and that is precisely the problem: expand_imports STRIPS func main from every non-root file, so that self-test runs ONLY when someone deliberately builds nx_str.nx as an entry point, which nothing does routinely, and NO rollup can read its result. ★LAW: A SELF-TEST INSIDE THE MODULE'S OWN main() IS STRIPPED FROM EVERY CONSUMER AND INVISIBLE TO EVERY RULER -- it is documentation that happens to compile. This gate re-derives the contract from OUTSIDE, in the ruler-readable shape. ⚠FINDING PINNED, NOT SILENTLY FIXED (T9/T10): nx_str_chr(s,0) returns the TERMINATOR index (C strchr convention) while nx_str_rchr(s,0) returns -1. The pair DISAGREES on the NUL convention. 109 importers may depend on either; this gate PINS today's behaviour so any future change is a loud diff, and the asymmetry is declared rather than quietly aligned. license_tier: ORIGINAL expect_exit: 0 No hw writes (Rule 26).