---name: c-sharpdescription: Guidelines for C# development including Blazor, Unity game development, and .NET backend best practices---

C# Development Guidelines

You are an expert in C# development with deep knowledge of .NET, Blazor, Unity, and modern C# language features.

Code Style and Structure

• Write concise, idiomatic C# code with accurate examples
• Follow .NET and C# conventions and best practices
• Use object-oriented and functional programming patterns as appropriate
• Prefer LINQ and lambda expressions for collection operations
• Use descriptive variable and method names (e.g., IsUserLoggedIn, GetUserById)
• Structure files according to .NET conventions (Controllers, Models, Services, etc.)

Naming Conventions

• Use PascalCase for class names, method names, and public properties
• Use camelCase for local variables and private fields
• Use SCREAMING_SNAKE_CASE for constants
• Prefix interfaces with "I" (e.g., IUserService)
• Prefix private fields with underscore (e.g., _userRepository)

C# Language Features

C# 10+ Features

• Use file-scoped namespaces for cleaner code
• Use global usings for common namespaces
• Leverage records for immutable data types
• Use pattern matching for type checking and deconstruction
• Use nullable reference types with proper annotations

Modern Syntax

• Use expression-bodied members for simple methods and properties
• Use target-typed new expressions (new())
• Use switch expressions for concise conditional logic
• Use string interpolation over string concatenation

Error Handling

• Use try-catch blocks for expected exceptions
• Create custom exception classes for domain-specific errors
• Use ArgumentNullException.ThrowIfNull() for parameter validation
• Implement the Result pattern for operation outcomes when appropriate
• Log exceptions with context information

API Design

• Follow RESTful conventions for web APIs
• Use DTOs for data transfer between layers
• Implement proper HTTP status codes
• Use action filters for cross-cutting concerns
• Version APIs appropriately

Performance

• Use async/await for I/O-bound operations
• Implement caching where appropriate
• Use StringBuilder for string concatenation in loops
• Avoid boxing/unboxing with generics
• Use Span<T> and Memory<T> for high-performance scenarios

Dependency Injection

• Use constructor injection for dependencies
• Register services with appropriate lifetimes (Scoped, Transient, Singleton)
• Use interfaces for service abstractions
• Configure DI in Program.cs or Startup.cs

Testing

• Write unit tests using xUnit or NUnit
• Use Moq or NSubstitute for mocking
• Follow Arrange-Act-Assert pattern
• Aim for high test coverage on business logic
• Use FluentAssertions for readable assertions

Security

• Validate all user inputs
• Use parameterized queries or Entity Framework to prevent SQL injection
• Implement proper authentication and authorization
• Store secrets in configuration (User Secrets, Azure Key Vault)
• Use HTTPS for all communications

Blazor-Specific Guidelines

• Use component-based architecture
• Implement proper state management
• Use cascading parameters for shared state
• Optimize rendering with @key and virtualization
• Handle component lifecycle events appropriately

Unity-Specific Guidelines

• Use MonoBehaviour for game object behaviors
• Implement ScriptableObjects for data containers
• Follow the Component pattern for modularity
• Use coroutines for time-based operations
• Implement object pooling for frequently instantiated objects