Worked on the openrewrite/rewrite repository to enhance the reliability of character encoding detection in Java input/output streams. Addressed a bug where CJK content could be misidentified as Windows-1252, leading to UnmappableCharacterExceptions during write-back. Introduced a canEncode verification step to ensure the detected charset can re-encode the content, and implemented a safe fallback to UTF-8 when misdetections occur. Optimized performance by adding a lightweight U+FFFD-based pre-scan to avoid unnecessary heavy encoding checks. Collaborated with other contributors to ensure robust review and knowledge sharing, focusing on character encoding, input/output handling, and Java for multilingual repository support.