Initial commit

skills/codebase-patterns.md

@@ -0,0 +1,160 @@
+---
+name: codebase-patterns
+description: Common codebase patterns, anti-patterns, and architectural conventions. Auto-loaded when analyzing code structure or discussing architecture.
+---
+
+# Common Codebase Patterns
+
+## Architecture Patterns
+
+### MVC (Model-View-Controller)
+- **Models**: Data and business logic
+- **Views**: UI/presentation layer
+- **Controllers**: Handle requests, coordinate models/views
+- Common in: Rails, Django, Laravel, ASP.NET MVC
+
+### Layered Architecture
+- **Presentation**: UI components
+- **Business Logic**: Core application logic
+- **Data Access**: Database interactions
+- **Common separation**: `/controllers`, `/services`, `/repositories`
+
+### Microservices
+- Independent services with own databases
+- Communication via REST/gRPC/message queues
+- Look for: Docker, Kubernetes configs, service directories
+
+### Repository Pattern
+```
+/repositories
+  - UserRepository.ts
+  - ProductRepository.ts
+```
+Abstracts data access logic
+
+### Service Layer Pattern
+```
+/services
+  - AuthService.ts
+  - PaymentService.ts
+```
+Business logic separation from controllers
+
+## Common Anti-Patterns
+
+### God Class/Object
+- Class with too many responsibilities
+- **Signs**: 500+ lines, handles everything
+- **Fix**: Split into smaller, focused classes
+
+### Spaghetti Code
+- Complex, tangled dependencies
+- **Signs**: Hard to follow flow, circular dependencies
+- **Fix**: Refactor to clear dependencies
+
+### Magic Numbers/Strings
+```javascript
+// Bad
+if (status === 1) { }
+
+// Good
+const STATUS_ACTIVE = 1;
+if (status === STATUS_ACTIVE) { }
+```
+
+### N+1 Query Problem
+```python
+# Bad - N+1 queries
+for user in users:
+    user.posts  # Separate query for each user
+
+# Good - Single query
+users = User.objects.prefetch_related('posts')
+```
+
+## File Organization Patterns
+
+### Feature-based
+```
+/features
+  /auth
+    - login.ts
+    - signup.ts
+  /dashboard
+    - dashboard.ts
+```
+
+### Layer-based
+```
+/controllers
+/models
+/views
+/services
+```
+
+### Domain-driven Design
+```
+/domain
+  /user
+  /order
+  /payment
+```
+
+## Naming Conventions
+
+### Functions
+- **JavaScript/TypeScript**: `camelCase` - `getUserById()`
+- **Python**: `snake_case` - `get_user_by_id()`
+- **Go**: `PascalCase` for exported - `GetUserByID()`
+
+### Classes
+- **All languages**: `PascalCase` - `UserController`, `PaymentService`
+
+### Constants
+- **All languages**: `SCREAMING_SNAKE_CASE` - `MAX_RETRIES`, `API_URL`
+
+### Files
+- **React**: `PascalCase.tsx` - `UserProfile.tsx`
+- **Others**: `kebab-case` or `snake_case` - `user-service.ts`
+
+## Common Directory Structures
+
+### React/Next.js
+```
+/app or /pages
+/components
+/lib or /utils
+/hooks
+/styles
+/public
+```
+
+### Express/Node
+```
+/routes
+/controllers
+/models
+/middleware
+/services
+/config
+```
+
+### Django
+```
+/app_name
+  /models
+  /views
+  /templates
+  /migrations
+```
+
+### Go
+```
+/cmd
+/internal
+/pkg
+/api
+/configs
+```
+
+Use these patterns to quickly understand and navigate unfamiliar codebases.