I have completed the first major phase of refactoring my python blog generator, transforming it from a 798-line monolithic script into a modern, modular, and fully backward-compatible system. I introduced clear domain models (Post, Site, Page), a dedicated service layer, repository abstractions, and a Pydantic-validated configuration system, backed by 53 passing unit tests. The build process is now faster, with smart filtering and optimized I/O, while the new CLI offers rich options, structured logging, and robust error handling. This layered architecture, built on solid principles, dramatically improves maintainability, testability, and extensibility, enabling easier feature development, better debugging, and team scalability — without disrupting the existing workflow.