code-refactoring-guide

name	code-refactoring-guide
description	Evaluate code quality and suggest refactoring opportunities before committing. Ensure Cooper's codebase stays clean and maintainable.

Code Refactoring Guide

Purpose

Evaluate code quality and suggest refactoring opportunities before committing. Ensure Cooper's codebase stays clean and maintainable.

When to Use

• Before committing code changes (as a final quality check)
• When touching files with known complexity
• During feature implementation that modifies existing code

When NOT to Use

• Emergency hotfixes (refactor separately after)
• Documentation-only changes

Activation Rules

Step 1: Check Quality Metrics

Metric	Target	Action if Exceeded
Function length	< 50 lines	Extract helper functions
File length	< 300 lines	Split into modules
Nesting depth	< 3 levels	Early returns, extract logic
Duplicate code	< 3 occurrences	Extract shared utility

Step 2: Cooper-Specific Checks

• Main process (src/main/): Are IPC handlers focused? One handler per concern?
• Preload (src/preload/): Is the bridge API clean and namespaced?
• Renderer (src/renderer/): Components decomposed? Hooks extracted?
• Types (src/renderer/types/): Interfaces well-defined? No any types?

Step 3: Accept/Reject Refactoring

ACCEPT refactoring if:

• Improves readability without changing behavior
• Reduces duplication
• Makes testing easier
• Stays within the scope of current changes

REJECT refactoring if:

• Touches unrelated code
• High risk of introducing regressions
• Would significantly increase PR size
• Is purely cosmetic (renaming for style preference)

Step 4: Verify After Refactoring

npm run build   # No type errors
npm test        # No regressions

Cooper-Specific Patterns

Extract IPC handler:

// Before: fat handler in main.ts
ipcMain.handle('copilot:send-message', async (_, sessionId, message) => {
  // 50+ lines of logic
});

// After: extracted to module
ipcMain.handle('copilot:send-message', handleSendMessage);

Extract React hook:

// Before: logic in component
const [sessions, setSessions] = useState([]);
useEffect(() => {
  /* fetch logic */
}, []);

// After: custom hook
const { sessions } = useSessions();

Success Criteria

• Quality metrics within targets
• No any types in new code
• Functions focused on single responsibility
• Build and tests pass after refactoring

Related Skills

• review-implementing — For validating refactoring scope
• test-fixing — For fixing tests after refactoring