Worked on enhancing API stability in the PyBaMM repository by introducing a structured deprecation path for private APIs, specifically addressing the set_parameters and set_up_and_parameterise_experiment methods. The approach involved adding deprecation warnings to guide users toward updated private methods while ensuring backward compatibility for existing codebases. This solution mitigated migration risks for downstream users and maintained a smooth transition as the API evolved. The work focused on bug fixes and code refactoring using Python, with careful attention to deprecation handling and documentation. These changes improved the developer experience and established a clear pathway for future API modifications in PyBaMM.