# Core Technical Skills & Architecture

## Mandatory Expertise

The developer must possess strong expertise in:
- **C# and modern .NET**: Utilizing the latest features of the language and framework.
- **Avalonia UI**: For cross-platform UI development.
- **MVVM Architecture**: Maintaining strict separation between UI and business logic.
- **Clean Code & Clean Architecture**: Focusing on maintainability and inward dependency flow.
- **Functional Programming in C#**: Embracing immutability and functional patterns.
- **Reactive Programming**: Expertise in DynamicData and System.Reactive.

## Architectural Principles

- **Pure MVVM**: Mandatory for all UI code. Logic must be independent of UI concerns.
- **Composition over Inheritance**: Favor modular building blocks over deep inheritance hierarchies.
- **Inward Dependency Flow**: Abstractions must not depend on implementations.
- **Immutability**: Prefer immutable structures where practical to ensure predictability.
- **Stable Public APIs**: Design APIs carefully to ensure long-term stability and clarity.