sharpcompress/AGENTS.md

---
description: 'Guidelines for building C# applications'
applyTo: '**/*.cs'
---

# C# Development

## C# Instructions
- Always use the latest version C#, currently C# 13 features.
- Write clear and concise comments for each function.

## General Instructions
- Make only high confidence suggestions when reviewing code changes.
- Write code with good maintainability practices, including comments on why certain design decisions were made.
- Handle edge cases and write clear exception handling.
- For libraries or external dependencies, mention their usage and purpose in comments.

## Naming Conventions

- Follow PascalCase for component names, method names, and public members.
- Use camelCase for private fields and local variables.
- Prefix interface names with "I" (e.g., IUserService).

## Code Formatting

- Use CSharpier for all code formatting to ensure consistent style across the project.
- Install CSharpier globally: `dotnet tool install -g csharpier`
- Format files with: `dotnet csharpier format .`
- **ALWAYS run `dotnet csharpier format .` after making code changes before committing.**
- Configure your IDE to format on save using CSharpier.
- CSharpier configuration can be customized via `.csharpierrc` file in the project root.
- Trust CSharpier's opinionated formatting decisions to maintain consistency.

## Project Setup and Structure

- Guide users through creating a new .NET project with the appropriate templates.
- Explain the purpose of each generated file and folder to build understanding of the project structure.
- Demonstrate how to organize code using feature folders or domain-driven design principles.
- Show proper separation of concerns with models, services, and data access layers.
- Explain the Program.cs and configuration system in ASP.NET Core 9 including environment-specific settings.

## Nullable Reference Types

- Declare variables non-nullable, and check for `null` at entry points.
- Always use `is null` or `is not null` instead of `== null` or `!= null`.
- Trust the C# null annotations and don't add null checks when the type system says a value cannot be null.

## Testing

- Always include test cases for critical paths of the application.
- Guide users through creating unit tests.
- Do not emit "Act", "Arrange" or "Assert" comments.
- Copy existing style in nearby files for test method names and capitalization.
- Explain integration testing approaches for API endpoints.
- Demonstrate how to mock dependencies for effective testing.
- Show how to test authentication and authorization logic.
- Explain test-driven development principles as applied to API development.

## Performance Optimization

- Guide users on implementing caching strategies (in-memory, distributed, response caching).
- Explain asynchronous programming patterns and why they matter for API performance.
- Demonstrate pagination, filtering, and sorting for large data sets.
- Show how to implement compression and other performance optimizations.
- Explain how to measure and benchmark API performance.