Pure-Ruby CLI heuristic checker for rb-string-plus-hot–rb-file-read-hot. rb-hash-merge-in-loop was removed.

Rule	Default	Message
rb-string-plus-hot	off	string `+=` in loop; prefer `<<`
rb-array-plus-rebind	off	Array `+` / concat rebinding in loop; prefer `<<`
rb-puts-hot	off	`puts` / `print` in loop; gate or buffer

Self-dogfood: bash ../scripts/self-lint.sh. Corpus-ready after G3 redesign — see ../docs/corpus.md.

rubyperf-lint