Review finding, measured: the leading-trivia prefix regex
(`^\s*(?:comment|comment|\s+)*export …`) partitions a whitespace run
ambiguously between its outer `\s*` and the starred `\s+` alternative,
so a script that ultimately FAILS the match backtracks exponentially —
~19 ms at 35 leading whitespace characters, ~174 ms at 38, ×2.2 per
character; a realistic near-miss (a comment header, blank indented
lines, then `const meta` missing its `export`) did not finish in 10
seconds. The regex ran on the HOST stack inside the synchronous
`start()`, where no vm timeout applies and no abort can interleave — a
benign one-token typo, exactly what SCRIPT_PARSE exists to bounce back
to the model, hung the whole process instead of reaching that designed
recovery.
Replaced with a hand-rolled linear trivia scan (whitespace + `//` and
`/* */` comments — the module already scans characters for the literal)
followed by an anchored `^export\s+const\s+meta\s*=\s*` on the
remainder, whose quantifiers cannot backtrack ambiguously. An
unterminated block comment before the statement now gets its own
SCRIPT_PARSE message. Regressions: the near-miss shape must reject in
under a second (the old regex would trip the suite timeout), plus the
unterminated-leading-comment and comment-to-EOF edges.
Tianyi Cui
ed3972a9c6