Tom Fenwick enhanced user-facing error messaging in the apache/druid repository by reclassifying query planning errors from an administrative to a user context. This adjustment improved the clarity and relevance of error feedback, enabling end users to troubleshoot issues more effectively and reducing unnecessary support cycles. Tom’s work involved careful error taxonomy adjustment and user-centric design, ensuring that actionable information reached the appropriate audience. The implementation was carried out in Java, demonstrating skills in backend development, API design, and robust error handling. All changes were traceable through detailed commit messages and pull request linkage, supporting future code reviews and auditability.