During July 2025, E1223lymm developed foundational domain models for both a Library management system and a Banking system within the next-engineer/next-java-exercise repository. Their work included implementing core Java classes for entities such as Book, Member, Library, Account, and Employee, establishing borrowing, returning, deposit, and withdrawal workflows. By applying object-oriented programming principles and modular project structuring, E1223lymm enabled clear separation of concerns and simplified future feature expansion and testing. The disciplined use of Git for branching and assignment submission further supported maintainability. This initial groundwork provided a robust architectural base for subsequent development, though the scope remained focused and foundational.