C# Refactoring Skill

Systematically refactors C# code to improve maintainability, readability, and adherence to best practices.

Arguments

•$ARGUMENTS[0]: Target file path (optional, will scan for .cs files if not provided)
•$ARGUMENTS[1]: Refactor type (optional): solid, pattern, modern, extract, all

Execution Steps

Step 1: Identify Target

If no file specified ($ARGUMENTS[0] is empty):

•Scan for recently modified .cs files
•Ask user to select target file(s)

Step 2: Analyze Code

Read and analyze the target code for refactoring opportunities.

Step 3: Apply Refactoring

Based on $ARGUMENTS[1] or analyze all categories:

Refactoring Categories

SOLID Refactoring (`solid`)

Violation	Refactoring
SRP	Extract class, Split responsibilities
OCP	Introduce Strategy/Template Method pattern
LSP	Fix inheritance hierarchy, Use composition
ISP	Split interface into smaller ones
DIP	Extract interface, Inject dependencies

Pattern Introduction (`pattern`)

Code Smell	Suggested Pattern
Complex object creation	Builder, Factory Method
Multiple conditionals on type	Strategy, State
Global state access	Singleton (cautiously), DI
Complex subsystem	Facade
Tree/composite structures	Composite
Adding features dynamically	Decorator
Request handling chain	Chain of Responsibility

Modern C# Syntax (`modern`)

Old Syntax	Modern Alternative
Constructor + field assignment	Primary constructor
`new List<T> { ... }`	Collection expressions `[...]`
Multiple null checks	Pattern matching, `?.`, `??`
Verbose switch statements	Switch expressions
Manual INPC implementation	`[ObservableProperty]` (CommunityToolkit.Mvvm)
Mutable properties (non-MVVM)	`required`, `init` for immutability
Class for simple data	Record types
Traditional foreach	LINQ where appropriate

Extract Refactoring (`extract`)

•Extract Method: Long methods → smaller, focused methods
•Extract Class: Large class → multiple cohesive classes
•Extract Interface: Concrete dependencies → interface abstraction
•Extract Base Class: Duplicate code → shared base
•Extract Parameter Object: Many parameters → single object

Output Format

markdown

# Refactoring Results

## Target
- File: {file_path}
- Refactor Type: {type}

## Changes Applied

### {Refactoring Name}
- Location: `file.cs:line`
- Before:
```csharp
// old code

•After:

csharp

// refactored code

•Benefit: {explanation}

Summary

•Total refactorings: {N}
•Lines changed: {N}
•New files created: {list if any}

Recommendations

•Further improvements that could be made
•Related patterns to consider

code


## Guidelines

- Preserve existing functionality (no behavior changes)
- Make incremental changes, not massive rewrites
- Prioritize readability over cleverness
- Consider team familiarity with patterns
- Add comments only where logic is non-obvious
- Run tests after each refactoring if available