Worked on the anthropics/beam repository to deliver a deterministic serialization improvement for type hints in Python. Addressed nondeterministic behavior in pickling and testing by switching UnionConstraint storage from a set to a list and implementing type sorting, ensuring stable and reproducible type-hint representations across environments. Updated equality and hashing logic to support the new list-based storage while maintaining set-like semantics in comparisons. Focused on serialization, type hinting, and unit testing to enhance reliability and simplify debugging. This targeted feature improved build consistency and test reliability, reflecting a thoughtful approach to cross-environment determinism in Python codebases.