Worked on the python/mypy repository to address a memory leak in the mypyc backend, focusing on native attribute setters for refcounted unboxed types. Applied expertise in C and memory management to correct reference ownership, ensuring that unboxed operations borrow rather than duplicate references, which previously led to unbounded memory growth in long-running Python applications. Developed and integrated a regression test suite to validate the fix across dataclass fields and tuple-typed attributes, supporting test-driven development practices. This work improved the reliability and performance of mypyc-compiled code paths, particularly in object-heavy workloads that manipulate unboxed primitives and tuple fields.