refactor

What I do

• Safely refactor code without changing behavior
• Extract methods, classes, and interfaces
• Apply DDD patterns and clean code principles
• Preserve existing tests and functionality

When to use me

Use this when you need to:

• Refactor legacy code
• Extract duplicated logic
• Apply design patterns
• Improve code organization

MCP-First Workflow

Always use MCP servers in this order:

1. codebase - Search for refactoring patterns

   search_codebase("refactoring patterns Python DDD clean code", top_k=10)
   

2. filesystem - view_file the code to refactor

   read_file("src/module.py")
   

3. git - Check usages and history

   git_diff("HEAD~10..HEAD", path="src/")
   

4. exa - Research best practices

   web_search("Python refactoring patterns 2025", num_results=5)
   

Safe Refactoring Principles

Extract Method

# BEFORE
def process_order(order):
    # 50 lines of code
    return order

# AFTER
def process_order(order):
    self._validate(order)
    self._calculate(order)
    return order

Replace Conditional with Polymorphism

# BEFORE
def calculate_shipping(weight, type):
    if type == "standard":
        return weight * 0.5
    elif type == "express":
        return weight * 1.5

# AFTER
class ShippingStrategy:
    def calculate(self, weight): ...

class StandardShipping(ShippingStrategy):
    def calculate(self, weight):
        return weight * 0.5

Pre-Refactoring Checklist

• Tests exist and pass
• All usages identified
• Breaking changes evaluated
• Rollback plan ready

Post-Refactoring Checklist

• All tests pass
• Type hints intact
• Docstrings updated
• No new lint errors