2nd/10_Wiki/Topics/Backend/KISS (Keep It Simple, Stupid).md

id, title, category, status, canonical_id, aliases, duplicate_of, source_trust_level, confidence_score, verification_status, tags, raw_sources, last_reinforced, github_commit, tech_stack

id	title	category	status	canonical_id	aliases	duplicate_of	source_trust_level	confidence_score	verification_status	tags	raw_sources	last_reinforced	github_commit	tech_stack
wiki-2026-0508-kiss-keep-it-simple-stupid	KISS (Keep It Simple, Stupid)	10_Wiki/Topics	verified	self	KISS Principle Keep It Simple	none	A	0.95	applied	principle design software-engineering		2026-05-10	pending	language framework any any

KISS (Keep It Simple, Stupid)

매 한 줄

"매 simplest-thing-that-could-possibly-work". 매 1960s Lockheed Skunk Works 의 Kelly Johnson 의 aerospace heuristic → 매 software 매 universal 의 design principle. 매 sibling: YAGNI, Worse-is-Better, Occam's Razor.

매 핵심

매 mechanism

• 매 each abstraction 의 cognitive cost 의 measure.
• 매 minimum-viable design → 매 iterate.
• 매 complexity 매 emergent, never additive cheap.

매 forms

• Code: fewer lines, fewer abstractions, fewer dependencies.
• API: fewer endpoints, fewer params, fewer states.
• System: fewer services, fewer protocols, fewer config knobs.

매 응용

1. Pre-mature abstraction avoidance (Rule of Three).
2. Boring-tech preference (PostgreSQL > custom DB).
3. Monolith-first (Fowler), microservices later if needed.

💻 패턴

KISS 매 too-complex (anti)

// Over-engineered: factory + builder + strategy for "add 2 numbers"
class AdderFactory {
  static create(strategy: AddStrategy): Adder { /* ... */ }
}

KISS 매 right

const add = (a: number, b: number) => a + b;

Service split: simple-first

// Simple: 1 service, postgres
app.post('/order', async (req, res) => {
  const order = await db.orders.create(req.body);
  await sendEmail(order);
  res.json(order);
});

// Only when justified by load/team-size: split into microservices.

Dependency minimalism

# package.json 매 audit — every dep is liability
npm-check --unused
depcheck

Config 매 default-driven

// Bad: 27 required env vars
// Good: smart defaults, override only when needed
const PORT = process.env.PORT ?? 3000;
const DB_URL = process.env.DATABASE_URL ?? 'postgres://localhost/dev';

Naming for clarity

// Bad
function p(d: any[]) { /* ... */ }

// Good
function paginate(items: Item[]): Page<Item> { /* ... */ }

매 결정 기준

상황	Choice
First version	Simplest possible, single file if needed
매 second feature 의 same shape	Still don't abstract
매 third 의 same shape (Rule of Three)	Now abstract

기본값: Inline the code. Abstract only when 매 third 의 same pattern emerges.

🔗 Graph

• 부모: Software-Design-Principles
• 변형: YAGNI
• Adjacent: Premature-Optimization · Rule of Three

🤖 LLM 활용

언제: design review, architecture decision, code review (cut complexity). 언제 X: 매 inherent-complexity domain (compilers, crypto, distributed consensus) 매 simplification 매 wrong-target.

❌ 안티패턴

• Premature abstraction: 1 use 의 abstraction 매 wrong shape.
• Configuration explosion: every-flag-as-knob.
• Microservices day-one: 매 distributed monolith 의 invitation.

🧪 검증 / 중복

• Verified (Kelly Johnson — Lockheed Skunk Works; Rich Hickey — Simple Made Easy talk; Worse-is-Better essay).
• 신뢰도 A.

🕓 Changelog

날짜	변경
2026-05-08	Phase 1
2026-05-10	Manual cleanup — KISS FULL content with anti-patterns