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skills/ln-341-code-quality-checker/references/architecture_violations.md

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+# Architecture Violations Reference
+
+Clean Architecture principles: Separation of concerns, layer independence, dependency inversion.
+
+## Layer Hierarchy
+
+```
+┌─────────────────┐
+│  Controllers    │  (HTTP handlers, routes)
+│    (routes/)    │
+└────────┬────────┘
+         │
+         v
+┌─────────────────┐
+│    Services     │  (Business logic)
+│  (services/)    │
+└────────┬────────┘
+         │
+         v
+┌─────────────────┐
+│  Repositories   │  (Data access)
+│ (repositories/) │
+└─────────────────┘
+```
+
+**Rule:** Only call downward. Controller → Service → Repository.
+
+## Violation Patterns
+
+### 1. Layer Skipping
+
+**Violation:**
+```python
+# controllers/user_controller.py
+from repositories.user_repository import UserRepository  # VIOLATION!
+
+def get_user(user_id):
+    user_repo = UserRepository()  # Skips Service layer
+    return user_repo.get(user_id)
+```
+
+**Fix:**
+```python
+# controllers/user_controller.py
+from services.user_service import UserService
+
+def get_user(user_id):
+    user_service = UserService()
+    return user_service.get_user(user_id)
+
+# services/user_service.py
+from repositories.user_repository import UserRepository
+
+class UserService:
+    def __init__(self):
+        self.user_repo = UserRepository()
+
+    def get_user(self, user_id):
+        return self.user_repo.get(user_id)
+```
+
+**Severity:** HIGH
+
+---
+
+### 2. Circular Dependencies
+
+**Violation:**
+```python
+# module_a.py
+from module_b import function_b
+
+def function_a():
+    return function_b()
+
+# module_b.py
+from module_a import function_a  # CIRCULAR!
+
+def function_b():
+    return function_a()
+```
+
+**Detection:** Build dependency graph, check for cycles
+
+**Fix:** Extract shared code to third module or use dependency injection
+
+**Severity:** HIGH
+
+---
+
+### 3. Business Logic in Wrong Layer
+
+**Violation:**
+```python
+# controllers/user_controller.py
+def create_user(data):
+    # Business logic in controller! VIOLATION!
+    if not data.get('email') or '@' not in data['email']:
+        return {"error": "Invalid email"}
+
+    if len(data.get('password', '')) < 8:
+        return {"error": "Password too short"}
+
+    user = User(**data)
+    db.session.add(user)
+    db.session.commit()
+    return {"success": True}
+```
+
+**Fix:** Move business logic to Service layer
+
+---
+
+## Detection
+
+```python
+def detect_layer_violations(files):
+    violations = []
+
+    for file in files:
+        # Parse imports
+        imports = extract_imports(file)
+
+        # Check layer
+        if 'controllers' in file.path or 'routes' in file.path:
+            # Controller layer
+            for imp in imports:
+                if 'repositories' in imp:
+                    violations.append({
+                        'type': 'Architecture',
+                        'severity': 'HIGH',
+                        'file': file.path,
+                        'description': 'Controller imports Repository (skips Service)',
+                        'suggestion': 'Import from services/ instead'
+                    })
+
+    return violations
+```
+
+---
+
+**Version:** 1.0.0
+**Last Updated:** 2025-11-13