During November 2024, Hknepshield enhanced the robolectric/robolectric repository by developing a shadow-based SubscriptionManager API to map slot IDs to subscription IDs, focusing on static API support for improved cross-SDK compatibility. Leveraging Java and Android development expertise, Hknepshield implemented static ActiveSubscriptionInfo exposure, enabling reliable static API calls and reducing test flakiness caused by dynamic subscription states. Comprehensive end-to-end unit tests were added for getSubId, getSubscriptionIds, and getSubscriptionId across multiple Android SDK versions. This work strengthened test reliability and developer confidence, providing a robust foundation for subscription-related functionality and ensuring consistent behavior in Robolectric-based testing environments.