Developed a comprehensive WPF and MVVM Developer Guide for the mamezou-tech-site repository, focusing on onboarding and standardizing desktop application architecture. The guide included practical C# code examples, such as a counter app, and demonstrated integration of dependency injection using Microsoft.Extensions.DependencyInjection. Detailed explanations of LINQ, delayed evaluation, Dispatcher, and nullable types were provided to clarify key C# features and best practices. By centralizing this knowledge in a single resource, the work supported both new and experienced developers in adopting consistent patterns for WPF and MVVM projects, enhancing maintainability and knowledge sharing across the team without addressing bug fixes during the period.