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 feedback provided to end users, making troubleshooting more actionable and reducing support overhead. Tom’s work involved careful error taxonomy adjustment and user-centric design, ensuring that error messages are both accurate and accessible. The implementation was completed in Java, leveraging backend development and API design skills. The changes were fully traceable through detailed commit messages and pull request linkage, reflecting a thoughtful and maintainable approach to error handling within a large codebase.