Developed a configurable Diagnostic Session Management feature for the esrlabs/openbsw repository, focusing on automotive software requirements using C++ and system design principles. The work introduced a structured approach to managing diagnostic session types and transitions, enabling flexible configuration between default, extended, and programming sessions. By refactoring the core session handling logic, the implementation improved both configurability and maintainability, simplifying future adaptations for customer-specific diagnostic workflows. This foundation reduces maintenance overhead and streamlines onboarding for new session types. The contribution did not involve bug fixes but demonstrated depth in C++ development and automotive system architecture within a focused, one-month development period.