Worked on stabilizing the startup validation process for the Orange-OpenSource/waltid-identity repository, focusing on backend reliability and onboarding flow integrity. Addressed a critical bug by aligning certificate validity checks in the OpenAPI example, specifically resolving discrepancies between IACA.notBefore and DS.notBefore dates to ensure DocumentSignerOnboardingRequest validation after January 2026. Utilized Kotlin and API development skills to implement a targeted fix that reduces startup risk and minimizes potential onboarding failures. Updated documentation and onboarding notes to reflect these changes, contributing to smoother deployment and fewer support incidents. The work demonstrated careful attention to backend validation and cross-certificate consistency.