Worked on the starsimhub/starsim repository to address a critical bug in the Timeline component, focusing on the correct handling of vectorized year data for batched multi-year simulations. Applied Python and software development skills to refactor the Timeline class, replacing the use of a scalar year variable with a vectorized yearvec approach. This targeted fix improved the reliability and data integrity of core timeline computations, reducing the risk of user-facing errors. The solution involved careful debugging and updating of conditional logic to ensure accurate processing of simulation data, resulting in more stable and maintainable code for complex simulation workflows.