nx_closure_gate.nx

nx_closure_gate.nx -- THE REFEREE FOR LN13b: the non-capturing function literal. WHAT IS ACTUALLY AT RISK HERE, AND WHY THE TEETH ARE SHAPED THIS WAY. Admitting a new construct is easy to observe: the compiler stops refusing it. That is the LEAST interesting thing this gate could measure, because the pre-fix compiler refused the construct outright and any check of compile status would go green the moment the parser stopped erroring -- including on an implementation that lifted the wrong body. The failures worth guarding survive a clean compile: a literal bound to the wrong code address, a parameter read from the wrong frame slot, or a synthesized fall-off-the-end return carrying value id 0, which IS the first parameter. None of those change the compiler's exit status; all of them change what the compiled program COMPUTES. SO THE BEHAVIOUR AXIS IS A RUN, NOT AN ASSERTION ABOUT ASSEMBLY. nx_probe_closure_lift is a self-checking program: it returns 0 only if every arithmetic identity in it held, and a distinct non-zero code otherwise, so a failure names itself. This gate reads that exit code. It does NOT inspect emitted assembly -- an asm-shaped tooth passes on a compiler that emits the right instructions in the wrong order and fails on a compiler that improves its register allocation. AND THE REFUSAL AXIS IS HALF THE RUNG. Rung 1 admits the EMPTY capture set and defers capture to LN13c, so a literal reading a local of the function around it must be refused BY NAME. Without that, the rung would silently compile a name that resolves to nothing, and this parser answers an unresolved name with the CONSTANT ZERO -- a wrong number with no diagnostic. The refusal is therefore not politeness; it is the only honest answer available at this rung, and the tooth asserts the offending NAME appears in the message, not merely that something was refused. THE DISCRIMINATION CONTROL IS LOAD-BEARING. A compiler that refused every func-typed construct would pass the capture tooth perfectly. nx_probe_closure_named uses the PRE-EXISTING bare-name and &name paths through the same func-typed slot; it must still compile and still run to 0. If only that tooth fails, the lift broke a path that shipped long before it. license_tier: ORIGINAL. Forks the compiler under test; writes only under its own /tmp dir. No hw writes (Rule 26).