During their work on the PrairieLearn/PrairieLearn repository, Alex Tong focused on enhancing the reliability of notebook autograding by addressing a key issue in traceback handling for Jupyter notebook executions. They implemented a targeted patch in Python to improve line caching for ipynb files, ensuring that error tracebacks accurately point to the correct source within notebooks. This backend development effort involved adding comprehensive tests around notebook execution to prevent future regressions. By refining the autograder’s traceback generation, Alex improved the debugging experience for students and reduced support overhead, demonstrating depth in Python, autograding systems, and backend engineering within educational technology.