Worked on the marimo-team/marimo repository to address a data classification issue in backend systems. Focused on refining the Data Primitive Classification logic, the developer fixed a bug where class-like objects implementing an __array__ method were incorrectly identified as data primitives. The solution involved strengthening type-checking mechanisms and introducing regression tests to ensure correct behavior and prevent future misclassifications. All changes were covered by unit tests and integrated into the continuous integration pipeline, supporting ongoing stability. The work relied on Python and emphasized robust data handling practices, contributing to improved reliability and maintainability across the marimo codebase during the development period.