1# Sections
2 
3This file defines all sections, their ordering, impact levels, and descriptions.
4The section ID (in parentheses) is the filename prefix used to group rules.
5 
6---
7 
8## 1. Architecture (arch)
9 
10**Impact:** CRITICAL
11**Description:** Proper module organization and dependency management are the foundation of maintainable NestJS applications. Circular dependencies and god services are the #1 architecture killer.
12 
13## 2. Dependency Injection (di)
14 
15**Impact:** CRITICAL
16**Description:** NestJS's IoC container is powerful but can be misused. Understanding scopes, injection tokens, and proper patterns is essential for testable code.
17 
18## 3. Error Handling (error)
19 
20**Impact:** HIGH
21**Description:** Consistent error handling improves debugging, user experience, and API reliability. Centralized exception filters ensure uniform error responses.
22 
23## 4. Security (security)
24 
25**Impact:** HIGH
26**Description:** Security vulnerabilities can be catastrophic. Input validation, authentication, authorization, and data protection are non-negotiable.
27 
28## 5. Performance (perf)
29 
30**Impact:** HIGH
31**Description:** Optimizing request handling, caching, and database queries directly impacts application responsiveness and scalability.
32 
33## 6. Testing (test)
34 
35**Impact:** MEDIUM-HIGH
36**Description:** Well-tested applications are more reliable. NestJS testing utilities enable comprehensive unit and e2e coverage.
37 
38## 7. Database & ORM (db)
39 
40**Impact:** MEDIUM-HIGH
41**Description:** Proper database access patterns, transactions, and query optimization are crucial for data-intensive applications.
42 
43## 8. API Design (api)
44 
45**Impact:** MEDIUM
46**Description:** RESTful conventions, versioning, DTOs, and consistent response formats improve API usability and maintainability.
47 
48## 9. Microservices (micro)
49 
50**Impact:** MEDIUM
51**Description:** Building distributed systems requires understanding message patterns, health checks, and inter-service communication.
52 
53## 10. DevOps & Deployment (devops)
54 
55**Impact:** LOW-MEDIUM
56**Description:** Configuration management, structured logging, and graceful shutdown ensure production readiness and zero-downtime deployments.
57