Worked on the pybamm-team/PyBaMM repository to enhance the reliability and security of continuous integration workflows. Focused on improving CI/CD processes by pinning GitHub Actions to specific release hashes using YAML, this approach ensured that builds remained reproducible and protected against unintended updates from upstream changes. By explicitly referencing release hashes, the work strengthened the auditability and governance of the CI pipeline, reducing operational risk and supporting more stable release cycles. The contribution addressed a key aspect of CI workflow management, leveraging expertise in GitHub Actions and YAML to deliver a targeted feature that improved both security and maintainability.