Worked on the tqec/tqec repository to address a critical consistency issue in the BlockGraph component, focusing on the relabeling of ports within graph structures. Using Python and core software development skills, the developer fixed a bug in the BlockGraph.relabel_cubes method that previously caused incorrect updates to the internal _ports dictionary when port labels changed. This adjustment ensured that mappings from port labels to their corresponding cube objects remained accurate after relabeling, thereby improving the integrity and reliability of graph-based operations. The work reduced downstream errors and regression risks, contributing to a more stable and maintainable codebase for future development.