During February 2026, Andrew Ward focused on backend development and data engineering for the astronomer/astronomer-cosmos repository, addressing a critical bug in the graph selector logic. He resolved a KeyError that occurred when using the precursor operator with dbt-loom cross-project references by introducing bounds checks to handle missing external node IDs during graph traversal. This solution improved the reliability of cross-project navigation and reduced runtime errors. Andrew used Python and dbt, applying test-driven development to validate the fix, and ensured comprehensive test coverage across 166 selector tests and all dbt-loom modules, demonstrating depth in cross-project DAG handling and robust engineering practices.