Code Simpler - Complexity Reducer Skill

Code Simpler - Complexity Reducer

Simplify overly complex code while preserving correctness.

When to Use

Insight 리포트에서 복잡도 지적이 나왔을 때
중첩이 깊은 코드 (3단계 이상)
함수가 50줄을 초과할 때
불필요한 추상화가 감지될 때
조건문이 과도하게 복잡할 때

Simplification Techniques

1. Early Return (Guard Clause)

// Before: deeply nested
function process(data) {
  if (data) {
    if (data.isValid) {
      if (data.items.length > 0) {
        // actual logic
      }
    }
  }
}

// After: flat
function process(data) {
  if (!data) return;
  if (!data.isValid) return;
  if (data.items.length === 0) return;
  // actual logic
}

2. Extract Method (Long Functions)

Split when a function does more than one thing:

Each function = one responsibility
Name describes WHAT, not HOW
Max 50 lines per function

3. Remove Unnecessary Abstraction

// Before: premature abstraction
class UserValidatorFactory {
  create(type) { return new UserValidator(type); }
}

// After: direct usage (if only one validator exists)
function validateUser(user) { ... }

4. Simplify Conditionals

// Before: complex boolean
if (user.age >= 18 && user.hasLicense && !user.isBanned && user.country === 'KR')

// After: named condition
const canDrive = user.age >= 18 && user.hasLicense && !user.isBanned;
const isKorean = user.country === 'KR';
if (canDrive && isKorean)

5. Replace Loop with Declarative

// Before: imperative
const results = [];
for (const item of items) {
  if (item.active) {
    results.push(item.name);
  }
}

// After: declarative
const results = items.filter(i => i.active).map(i => i.name);

6. Flatten Callback Hell

Replace nested callbacks/promises with async/await or pipeline.

Process

1. Identify complexity (insight report or manual scan)
   ↓
2. Measure: nesting depth, function length, cyclomatic complexity
   ↓
3. Apply simplification technique (one at a time)
   ↓
4. Verify: behavior unchanged, tests still pass
   ↓
5. Repeat until within limits

Complexity Limits

| Metric | Limit | Action | |--------|-------|--------| | Nesting depth | 3 levels | Apply early return | | Function length | 50 lines | Extract method | | Cyclomatic complexity | 10 | Split into smaller functions | | File length | 200 lines | Split into modules | | Parameters | 4 | Use object parameter |

Principles

One change at a time - simplify incrementally
Preserve behavior - never change what the code does
Verify with tests - run tests after each simplification
Don't over-simplify - 3 similar lines > premature abstraction
KISS - the simplest correct solution is the best

Agent Skills: Code Simpler - Complexity Reducer

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