Hanna Tuerk contributed to the metatensor/metatensor repository by improving the accuracy of the C API documentation, specifically addressing the semantics of the mts_labels_union function. She identified and corrected a documentation error, clarifying that the function computes the intersection rather than the union of two label sets. This update, implemented in C++ and Rust, ensures that the documentation now accurately reflects the function’s behavior, reducing the risk of developer confusion and misuse. Hanna’s work focused on aligning technical documentation with actual code, enhancing API maintainability and supporting clearer onboarding for future contributors. The contribution addressed one bug and no new features.