This repository is a comprehensive WPF UI library (WPF-UI) that implements Microsoft's Fluent Design System for Windows Presentation Foundation. It provides over 70 custom controls (NavigationView, ContentDialog, Snackbar, TitleBar, NumberBox, ToggleSwitch, etc.), a full theme management system with dynamic light/dark/high-contrast switching, Win32 interop for modern window chrome and taskbar integration, and a navigation framework with DI support. The library is distributed via NuGet and includes Visual Studio project templates. The codebase is well-structured with a folder-per-control pattern, partial classes for separation of concerns, and extensive use of dependency properties, routed events, and attached behaviors. The core library targets .NET 10/9/8 and .NET Framework 4.6.2–4.8.1, with abstractions targeting .NET Standard 2.0/2.1 for maximum compatibility. The repository also contains a comprehensive demo application (Wpf.Ui.Gallery) that showcases all controls with MVVM (CommunityToolkit.Mvvm), localization, and an embedded Monaco Editor for live code samples. Integration tests using FlaUI and unit tests for animations and symbol extensions are present. The architecture is documented with C4 diagrams and ADRs. The library is actively maintained with frequent commits, CI/CD via GitHub Actions, and responsive issue triage. While the codebase is generally high-quality, there are some work-in-progress controls (TreeGrid), deprecated APIs in ContentDialog, and vendored third-party assets (Monaco Editor) that introduce minor maintenance risks. Overall, this is a strong, production-ready UI library with clean abstractions and several reusable patterns.