Enforce and apply modern, aesthetic C# architecture principles across .NET codebases. Provides opinionated guidance for Vertical Slice Architecture, CQRS, Minimal APIs, C# 12-14 language features, and clean code practices. Includes a 100+ item review checklist, anti-pattern detection with fixes, EF Core query patterns, and cross-cutting concern pipelines. The skill validates target framework prerequisites before suggesting newer C# syntax and covers naming conventions, premature optimization, composition over inheritance, functional patterns, and exception handling best practices.