lua: strip (else (raise e)) from loop-guard (SX guard re-raise hangs)

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 — stripped `(else (raise e))` from `lua-tx-loop-guard`. SX `guard` with `(else (raise e))` hangs in a loop (re-enters the same guard). Since unmatched sentinels fall through to the enclosing guard naturally, the else is unnecessary. Diagnosed `calls.lua` undefined-`fat`: `function fat(x)` defined at Lua top-level is scoped inside the SX top-level guard's scope; loadstring-captured closures don't see it via lexical env. Fix would require either dropping the top-level guard (breaking top-level `return`) or dynamic env access — deferred.
 - 2026-04-24: lua: scoreboard iteration — **method-call double-evaluation bug**. `lua-tx-method-call` emitted `(lua-call (lua-get OBJ name) OBJ args…)` which evaluated OBJ TWICE, so `a:add(10):add(20):add(30).x` computed `110` instead of `60` (side effects applied twice). Fixed by `(let ((__obj OBJ)) (lua-call (lua-get __obj name) __obj args…))`. 373/373 green (+1 chaining test).
 - 2026-04-24: lua: **🎉 FIRST PASSING PUC-Rio TEST — 1/16 runnable (6.2%)**. `verybig.lua` now passes: needed `io.output`/`io.input`/`io.stdout`/`io.stderr` stubs, made `os.remove` return `true` (test asserts on it), and added `dofile`/`loadfile` stubs. All cumulative fixes (returns/break/scoping/escapes/precedence/vararg/tonumber-trim) combined make this test's full happy path work end-to-end. 372 unit tests. Failure mix: 10× assertion / 4× timeout / 1× call-non-fn.
 - 2026-04-24: lua: scoreboard iteration — **proper `break` via guard+raise sentinel** (`lua-brk`) + auto-first multi-values in arith/concat. Loop break dispatch was previously a no-op (emitted bare `'lua-break-marker` symbol that nothing caught); converted to raise+catch pattern, wrapping the OUTER invocation of `_while_loop`/`_for_loop`/`_repeat_loop`/`__for_loop` in a break-guard (wrapping body doesn't work — break would just be caught and loop keeps recursing). Also `lua-arith`/`lua-concat`/`lua-concat-coerce` now `lua-first` their operands so multi-returns auto-truncate at scalar boundaries. 372/372 green (+4 break tests). Scoreboard: 10×assert / 4×timeout / 2×call-non-fn (no more undef-symbol or compare-incompat).