Mark worked on the climatepolicyradar/knowledge-graph repository, focusing on improving the reliability of concept de-indexing and data hygiene. He addressed a bug in the de-indexing logic to ensure models were correctly identified and removed, which reduced the risk of stale concepts persisting in the system. Using Python, he introduced a dedicated Vespa cleanup utility to delete all documents, enhancing test isolation and reliability. Mark also updated the test suite to reflect expected concept counts after partial updates, strengthening validation of the removal workflow. His work demonstrated depth in backend development, data management, and testing, enabling safer and faster model iteration.