Code Smell
Find structural problems before they calcify into permanent pain.
Quick Start
/code-smell — full codebase smell analysis
/code-smell --file src/user.ts — analyze single file
/code-smell --category god-class — hunt specific smell type
/code-smell --fix — apply safe refactors (extract method, rename)
/code-smell --rank — sort files by smell density
Smell Catalog
Bloaters (things that grew too big)
| Smell |
Signal |
Fix |
| Long Method |
>20 lines, multiple levels of abstraction |
Extract Method |
| Large Class |
>300 lines, too many responsibilities |
Extract Class / SRP |
| Long Parameter List |
>4 params |
Introduce Parameter Object |
| Data Clumps |
Same 3+ vars always appear together |
Extract Class |
| Primitive Obsession |
string for email/money/status |
Value Object |
OO Abusers
| Smell |
Signal |
Fix |
| Switch Statements |
Switch/if-chain on type |
Polymorphism |
| Temporary Field |
Field only set in one method |
Extract Class |
| Refused Bequest |
Child ignores most of parent |
Replace Inheritance with Delegation |
| Alternative Classes |
Two classes do the same thing |
Merge |
Change Preventers
| Smell |
Signal |
Fix |
| Divergent Change |
Changing feature X always touches Class Y |
Split class |
| Shotgun Surgery |
One change → 8 files |
Move Method / Inline Class |
| Parallel Inheritance |
Adding subclass A requires subclass B |
Merge hierarchies |
Dispensables (things to delete)
| Smell |
Signal |
Fix |
| Dead Code |
Unreachable / never called |
Delete |
| Speculative Generality |
AbstractFactory for one use case |
Simplify |
| Lazy Class |
Class does almost nothing |
Inline Class |
| Duplicate Code |
Copy-paste across files |
Extract + reuse |
Couplers
| Smell |
Signal |
Fix |
| Feature Envy |
Method uses other class's data more than own |
Move Method |
| Inappropriate Intimacy |
Two classes read each other's privates |
Move / Extract |
| Message Chains |
a.b().c().d().e() |
Introduce delegate method |
| Middle Man |
Class delegates everything to another |
Inline Class |
Output Format
CODE SMELL ANALYSIS — 2026-06-14
===================================
Files analyzed: 147 | Smell density: 2.3 smells/100 lines (HIGH)
CRITICAL
[C1] src/services/UserService.ts — GOD CLASS (847 lines, 23 methods)
Handles: auth, profile, billing, notifications, admin, analytics
→ Extract: AuthService, BillingService, NotificationService
Estimated effort: 2 days | Risk: HIGH (many callers)
[C2] src/api/checkout.ts:145 — LONG METHOD (94 lines, 7 abstraction levels)
→ Extract: validateCart(), applyDiscounts(), chargePayment(), sendConfirmation()
HIGH
[H1] src/models/Product.ts:12 — PRIMITIVE OBSESSION
price: number (no currency, no precision)
→ type Money = { amount: number; currency: Currency }
[H2] src/components/AdminPanel.tsx — FEATURE ENVY
References user.subscription.plan.features 14 times
→ Move canAccessFeature(featureId) to User or Subscription model
MEDIUM
[M1] src/utils/helpers.ts — DEAD CODE (3 exported functions, 0 callers)
formatLegacyDate(), parseOldSKU(), migrateV1User()
→ Safe to delete (confirmed by grep + git log)
[M2] src/api/ — DUPLICATE CODE
validateEmail() defined in auth.ts, users.ts, and checkout.ts
→ Extract to src/utils/validation.ts
LOW
[L1] 12 occurrences of magic numbers (HTTP status codes, timeout values)
→ Extract to src/constants/http.ts and src/config/timeouts.ts
Safe Refactor Patterns
Extract Method
// ❌ 60-line method
async processOrder(cart: Cart, user: User) {
// validate cart
if (!cart.items.length) throw new Error('Empty cart')
const inventory = await this.checkInventory(cart.items)
// ... 50 more lines
}
// ✅ decomposed
async processOrder(cart: Cart, user: User) {
await this.validateCart(cart)
const payment = await this.chargePayment(cart, user)
await this.fulfillOrder(cart, payment)
await this.sendConfirmation(user, payment)
}
Introduce Value Object
// ❌ primitive obsession
function charge(amount: number, currency: string) { ... }
// ✅ value object
class Money {
constructor(readonly amount: number, readonly currency: 'USD' | 'BRL' | 'EUR') {}
plus(other: Money): Money {
if (this.currency !== other.currency) throw new Error('Currency mismatch')
return new Money(this.amount + other.amount, this.currency)
}
}
Replace Switch with Map
// ❌ switch smells
function getDiscount(tier: string): number {
switch (tier) {
case 'bronze': return 0.05
case 'silver': return 0.10
case 'gold': return 0.20
default: return 0
}
}
// ✅ data-driven
const DISCOUNTS: Record<string, number> = { bronze: 0.05, silver: 0.10, gold: 0.20 }
const getDiscount = (tier: string) => DISCOUNTS[tier] ?? 0
Andersonlimahw