During October 2025, JL0PD enhanced the AvaloniaUI/AvaloniaEdit repository by improving the encapsulation of the TextDocument class. Focusing on C# development and object-oriented programming, JL0PD privatized the internal _undoStack field, reducing the risk of unintended external mutations and supporting safer future refactoring. This adjustment strengthened API boundaries and promoted proper usage patterns, contributing to the long-term maintainability of the codebase. The work demonstrated a thoughtful approach to software design, prioritizing API hygiene and internal state protection. Although the contribution was limited to a single feature, it addressed a core architectural concern and provided clear commit-level documentation for traceability.