Worked on the SciCompMod/memilio repository to enhance the stability and correctness of age-structured SEIR ODE modeling in C++. Focused on resolving a critical indexing error in the model’s handling of susceptible compartments across multiple age groups, which previously led to inaccurate scenario analyses. Addressed this by updating model.h and introducing a targeted regression test, get_flows_two_agegroups, in test_odeseir.cpp to ensure correct flow calculations and prevent future regressions. Emphasized software testing and maintainable code, with all changes isolated to avoid performance regressions. The work improved model reliability and accuracy without introducing new user-facing features during the development period.