docs: add npm/CI badges + Cost & Performance section, run tests in CI

.github/workflows/ci.yml

@@ -27,3 +27,6 @@ jobs:
 
       - name: Build
         run: npm run build
+
+      - name: Test
+        run: npm test

README.ko.md

@@ -1,5 +1,11 @@
 # DUUL
 
+[![npm version](https://img.shields.io/npm/v/@planningo/duul.svg)](https://www.npmjs.com/package/@planningo/duul)
+[![npm downloads](https://img.shields.io/npm/dm/@planningo/duul.svg)](https://www.npmjs.com/package/@planningo/duul)
+[![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://opensource.org/licenses/MIT)
+[![CI](https://github.com/Planningo/duul/actions/workflows/ci.yml/badge.svg)](https://github.com/Planningo/duul/actions/workflows/ci.yml)
+[![Node](https://img.shields.io/node/v/@planningo/duul.svg)](https://nodejs.org)
+
 **D**ual-phase **U**pfront-plan & **U**nit-verify **L**oop — LLM을 개발 계획 및 코드의 리뷰어로 활용하는 MCP 서버. OpenAI, Anthropic, Google, OpenRouter 및 OpenAI 호환 프로바이더를 지원합니다.
 
 > [English README](./README.md)
@@ -227,6 +233,31 @@ npm run build
 
 ---
 
+## 비용 & 성능
+
+이 레포에서 실제 DUUL을 돌리며 측정한 수치 (리뷰어 호출 42회, gpt-5.4, prompt caching 활성). 프로젝트 크기·리뷰 복잡도에 따라 달라지므로 대략적인 예산 가이드로 활용하세요.
+
+| 툴 | 호출당 평균 토큰 | 호출당 평균 비용 | 캐시 hit rate |
+|----|-----------------:|----------------:|--------------:|
+| `plan_review` | 100,966 | **$0.065** | 79% |
+| `code_review` | 179,837 | **$0.122** | 79% |
+| **전체 평균** | 132,890 | **$0.088** | 79% |
+
+일반적인 작업 (plan 1~3라운드 + code 1~2라운드)은 보통 **$0.30~$0.50** 정도의 리뷰어 비용이 듭니다.
+
+**비용 절감 요인:**
+- Anthropic / OpenAI prompt caching (반복 세션에서 약 30% 절감, cache read는 input의 0.1× 가격)
+- 도구별 모델 오버라이드 (`reviewer_config.model = { code: "claude-opus-4" }`로 code만 강화)
+- 옵션: 파일 읽기 예산 (`DUUL_MAX_REVIEWER_BYTES`)으로 비용 상한 강제
+
+**직접 측정하기:**
+```bash
+node scripts/token-report.mjs --plan max20 --all-time
+```
+`~/.duul/usage.jsonl`(MCP env에 `DUUL_DEBUG_TOKEN=1` 설정 시 로깅 활성)과 `~/.claude/projects/<encoded-cwd>/*.jsonl`을 합쳐서 Claude Code + 리뷰어 통합 breakdown을 보여줍니다.
+
+---
+
 ## 작동 방식
 
 ### 전체 리뷰 루프

README.md

@@ -1,5 +1,11 @@
 # DUUL
 
+[![npm version](https://img.shields.io/npm/v/@planningo/duul.svg)](https://www.npmjs.com/package/@planningo/duul)
+[![npm downloads](https://img.shields.io/npm/dm/@planningo/duul.svg)](https://www.npmjs.com/package/@planningo/duul)
+[![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://opensource.org/licenses/MIT)
+[![CI](https://github.com/Planningo/duul/actions/workflows/ci.yml/badge.svg)](https://github.com/Planningo/duul/actions/workflows/ci.yml)
+[![Node](https://img.shields.io/node/v/@planningo/duul.svg)](https://nodejs.org)
+
 **D**ual-phase **U**pfront-plan & **U**nit-verify **L**oop — an MCP server that uses LLMs as peer reviewers for development plans and code. Supports OpenAI, Anthropic, Google, OpenRouter, and any OpenAI-compatible provider.
 
 > [한국어 README](./README.ko.md)
@@ -227,6 +233,31 @@ Each review request can include a `reviewer_config` object to override provider
 
 ---
 
+## Cost & Performance
+
+Empirical numbers from real DUUL usage in this repo (42 reviewer calls, gpt-5.4, prompt caching enabled). Treat as a rough budgeting guide — your numbers will vary with project size and review complexity.
+
+| Tool | Avg tokens/call | Avg cost/call | Cache hit rate |
+|------|----------------:|--------------:|---------------:|
+| `plan_review` | 100,966 | **$0.065** | 79% |
+| `code_review` | 179,837 | **$0.122** | 79% |
+| **Combined avg** | 132,890 | **$0.088** | 79% |
+
+A typical task (1–3 plan rounds + 1–2 code rounds) usually lands around **$0.30–$0.50** in reviewer cost.
+
+**What drives cost down:**
+- Anthropic / OpenAI prompt caching (~30% reduction on iterating sessions; cache reads billed at 0.1× input rate)
+- Per-tool model override (`reviewer_config.model = { code: "claude-opus-4" }` to escalate code-only)
+- Optional file-read budget (`DUUL_MAX_REVIEWER_BYTES`) for hard cost ceilings
+
+**Measure your own usage:**
+```bash
+node scripts/token-report.mjs --plan max20 --all-time
+```
+Reads `~/.duul/usage.jsonl` (set `DUUL_DEBUG_TOKEN=1` in your MCP env to enable logging) and `~/.claude/projects/<encoded-cwd>/*.jsonl` for combined Claude Code + reviewer breakdown.
+
+---
+
 ## How It Works
 
 ### Full Review Loop