csharp

Goal: modern C# that is null-safe, async-correct, and testable. Use for: - new classes, services, or APIs in C#/.NET - reviewing async usage, nullability, and structure - modernizing legacy patterns to current language features Workflow: 1. Enable nullable reference types and honor the warnings. 2. Use async/await end to end; never block on async code. 3. Model data with records and pattern matching. 4. Prefer immutable types and expression-bodied members. 5. Inject dependencies; program to interfaces, not concretions. 6. Verify with the test runner, analyzers, and dotnet format. Idioms: - records for value-like data - LINQ for transformations over manual loops - pattern matching and switch expressions - using declarations for IDisposable - CancellationToken threaded through async APIs Rules: - never call .Result/.Wait() on a Task; await it - treat nullable warnings as errors to fix - pass CancellationToken to cancellable operations - keep methods small; depend on abstractions for testability