nx_js_semantics_gate.nx

nx_js_semantics_gate.nx -- JS semantics pinned during the EarleyBoyer root-cause hunt (2026-07-11), V8-pinned on BOTH tiers. Consolidates the session probes (vardecl/dangling/eq/shape) into one gate: 1. bare `var x;` RE-DECLARATION is a runtime NO-OP (params + prior vars survive; scheme2js re-declares params pervasively -- clobbering them silently corrupted EarleyBoyer's whole computation) 2. \uXXXX string escapes decode ("A"=="A"); UTF-8 byte-length NAMED DIVERGENCE ("ẜ".length==3 here vs V8's 1 UTF-16 unit -- equality/concat/ordering stay self-consistent) 3. dangling-else binds to the INNER if; braced-then + unbraced-else keeps its else 4. string === is CONTENT equality for built (non-literal) strings 5. comma-seq return value + 9-arg closure call from an array slot (scheme2js parse->trees shape) 6. instanceof USER constructor walks a cons chain 7. (n).toString(16) radix + "s".toString() identity 8. property READ on a number primitive -> undefined (not an error); undefined base still errors expect_exit: 0 license_tier: ORIGINAL