Juan Villegas focused on enhancing data integrity in the qibocal repository by addressing a complex issue with JSON deserialization for dictionary keys. He corrected the serialization logic to convert nested lists within keys to tuples, resolving unhashable key errors that previously caused runtime exceptions during data loading. This fix stabilized data storage and retrieval in the pipeline, ensuring reliable experiment analytics. Juan applied his expertise in Python, data handling, and JSON parsing to document the solution clearly, improving maintainability and future edge-case support. His work demonstrated a deep understanding of serialization challenges and contributed to robust, traceable code quality.