nx_linecont_gate.nx

nx_linecont_gate.nx -- LN15 FREE MULTI-LINE EXPRESSIONS: does a continuation line opening with a binary operator JOIN the expression above it? WHAT THIS MEASURES THAT THE EQUIVALENCE NET CANNOT. nx_cc_equiv_gate proves a candidate compiler BROKE NOTHING (10 rows byte-identical + self-host fixpoint). It is structurally incapable of proving a new capability WORKS: none of its ten corpus rows contains a line continuation, so it would report GREEN for a compiler in which LN15 was never implemented. A green from a subject that could never go red is decoration. This gate is the half that can go red. HOW IT IS BITE-PROVEN, AND WHY THAT IS STRONGER THAN A SOURCE MUTANT. The gate takes the compiler to test as argv[1]. Run it against the LN15 challenger and the join teeth must PASS; run the SAME binary against the pre-LN15 live compiler and those same teeth must FAIL. Two real compilers, not a synthesised mutant. NO SILENT DEFAULT COMPILER. nx_cc_equiv_gate learned this the expensive way on 2026-08-14: with no argument it fell back to a default path, found a STALE binary left by an earlier run, and returned a fully-formed verdict about the wrong artifact. A gate whose instrument is missing must REFUSE, not guess.