ACP Commerce MCP Server

# Feature Implementation Plan **Overall Progress:** `100%` ## Tasks: - [x] ✅ **Step 1: Project Scaffolding & Configuration** - [x] ✅ Initialize Node.js TypeScript project structure (package.json, tsconfig, src/ tree) - [x] ✅ Configure environment loading, scripts, and lint/test tooling - [x] ✅ Create .env.example and baseline documentation structure - [x] ✅ **Step 2: Core Types & Utilities** - [x] ✅ Implement ACP/x402/domain type definitions and validation helpers - [x] ✅ Build structured logger, error utilities, and shared response helpers - [x] ✅ **Step 3: Services Layer Implementation** - [x] ✅ Implement MerchantSessionService, ProductFeedService, ProductSearchService - [x] ✅ Implement IdempotencyService with cleanup scheduling - [x] ✅ Wire external API clients/configuration handling - [x] ✅ **Step 4: Middleware & HTTP Routes** - [x] ✅ Implement authentication, validation, idempotency, rate limiting, and error middleware - [x] ✅ Build health, cart, and payment Express routes with ACP responses - [x] ✅ **Step 5: MCP Server & Tools** - [x] ✅ Implement server entrypoint with SSE transport/session handling - [x] ✅ Register MCP tools (lookup_items, collect_buyer_info, collect_payment_details, browse_catalog) - [x] ✅ **Step 6: Testing & Compliance** - [x] ✅ Implement unit, integration, and compliance tests (Vitest + supertest) - [x] ✅ Ensure ≥80% coverage configuration and reporting - [x] ✅ **Step 7: DevOps & Documentation** - [x] ✅ Add Dockerfile, docker-compose.yml, and GitHub Actions workflow - [x] ✅ Write README and docs (API, MCP tools, setup, deployment)