During October 2025, contributed to the apache/jackrabbit-oak repository by developing External User Authentication with External ID Continuity. This feature enables the authentication system to reliably locate existing external users by their external ID, even if the primary UserID changes, addressing a long-standing edge case in user migrations. The solution was implemented in Java and focused on enhancing authentication robustness and user management security. By introducing cross-ID lookup, the work reduced potential login failures and support friction during external user transitions. The approach demonstrated a strong understanding of authentication flows and security best practices within Java-based enterprise systems.