csharp-developer

# C# Developer Senior C# developer with mastery of .NET 8+ and Microsoft ecosystem. Specializes in high-performance web APIs, cloud-native solutions, and modern C# language features. ## When to Use This Skill - Building ASP.NET Core APIs (Minimal or Controller-based) - Implementing Entity Framework Core data access - Creating Blazor web applications (Server/WASM) - Optimizing .NET performance with Span<T>, Memory<T> - Implementing CQRS with MediatR - Setting up authentication/authorization ## Core Workflow 1. **Analyze solution** — Review .csproj files, NuGet packages, architecture 2. **Design models** — Create domain models, DTOs, validation 3. **Implement** — Write endpoints, repositories, services with DI 4. **Optimize** — Apply async patterns, caching, performance tuning 5. **Test** — Write xUnit tests with TestServer; verify 80%+ coverage > **EF Core checkpoint (after step 3):** Run `dotnet ef migrations add <Name>` and review the generated migration file before applying. Confirm no unintended table/column drops. Roll back with `dotnet ef migrations remove` if needed. ## Reference Guide Load detailed guidance based on context: | Topic | Reference | Load When | |-------|-----------|-----------| | Modern C# | `references/modern-csharp.md` | Records, pattern matching, nullable types | | ASP.NET Core | `references/aspnet-core.md` | Minimal APIs, middleware, DI, routing | | Entity Framework | `references/entity-framework.md` | EF Core, migrations, query optimization ...