lua: Lua 5.0-style arg auto-binding in vararg functions; assert-counter diagnostic +2 tests

plans/lua-on-sx.md

@@ -82,6 +82,7 @@ Each item: implement → tests → tick box → update progress log.
 
 _Newest first. Agent appends on every commit._
 
+- 2026-04-24: lua: scoreboard iteration — Lua 5.0-style `arg` auto-binding inside vararg functions (some PUC-Rio tests still rely on it). `lua-varargs-arg-table` builds `{1=v1, 2=v2, …, n=count}`; transpile adds `arg` binding alongside `__varargs` when `is-vararg`. Diagnosis done with assert-counter instrumentation — literals.lua fails at #4 (long-string NL rule), vararg.lua was at #2 (arg table — FIXED), attrib.lua at #9, locals.lua now past asserts into call-non-fn. 360 tests.
 - 2026-04-24: lua: scoreboard iteration — **`loadstring` scoping**. Temporarily instrumented `lua-assert` with a counter, found `locals.lua` fails at assertion #5: `loadstring('local a = {}')() → assert(type(a) ~= 'table')`. The loadstring'd code's `local a` was leaking to outer scope because `lua-eval-ast` ran at top-level. Fixed by transpiling once and wrapping the AST in `(let () …)` before `eval-expr`.
 - 2026-04-24: lua: scoreboard iteration — **`if`/`else`/`elseif` body scoping** (latent bug). `else local x = 99` was leaking to enclosing scope. Wrap all three branches in `(let () …)` via `lua-tx-if-body`. 358 tests.
 - 2026-04-24: lua: scoreboard iteration — **`do`-block proper scoping**. Was transpiling `do ... end` to a raw `lua-tx` pass-through, so `define`s inside leaked to the enclosing scope (`do local i = 100 end` overwrote outer `i`). Now wraps in `(let () body)` for proper lexical isolation. 355 tests, +2 scoping tests.