David Mudrauskas developed a data engineering feature for the catalyst-cooperative/pudl repository, focusing on transforming EIA-176 energy data into a wide-table format that separates company-specific and aggregate information. Using Python, SQL, and Pandas, he designed new data extraction and transformation modules to support this schema, enabling more efficient querying and comparison across entities. David emphasized data integrity by implementing comprehensive unit tests and modularizing the transformation logic. His work addressed the challenge of aggregating complex energy datasets, resulting in faster, more reliable access to EIA-176 data and laying a foundation for improved data validation and ETL processes within the project.