During January 2026, Jae Kim focused on backend reliability improvements across the spring-security and spring-ai repositories. He addressed a potential NullPointerException in AuthoritiesAuthorizationManager by implementing null-safe handling for GrantedAuthority values, ensuring the authorization flow remains robust even when authority strings are missing. This fix, written in Java, was reinforced with a dedicated regression test to validate null-authority scenarios. In the spring-ai repository, Jae resolved issues with Elasticsearch query generation by correcting IN and NIN value quoting and grouping, which improved search accuracy. His work demonstrated careful attention to error prevention, code maintainability, and the nuances of backend development.