Worked on Guardsquare/proguard-core to deliver a targeted reliability improvement in the code injection subsystem, specifically addressing the handling of primitive array types. Refactored the CodeInjector component using Java and Kotlin to update internal type representations and ensure primitive arrays are correctly managed and pushed during injection. Enhanced the robustness of the codebase by adding focused unit tests for methods with primitive array arguments, thereby increasing regression coverage and correctness for these scenarios. The work demonstrated a methodical approach to bug fixing and test-driven development, emphasizing code quality and maintainability through careful refactoring and comprehensive validation of edge cases.