Backend Coder Skill
Core Principles
- Language Documentation: Always use the context MCP tool (
context7) to fetch updated documentation, best practices, and idiomatic patterns for the language/framework being used. - Type Safety: Prioritize strong typing and compile-time validation. Avoid
anyor dynamic types. - SOLID Principles: Focused on SRP, OCP, LSP, ISP, and DIP.
- Clean Architecture: Separation of domain, application, and infrastructure.
Workflow
- Analysis: Understand dependencies and fetch language documentation via MCP.
- TDD (Testing Strategy): Write unit tests for business logic and integration tests for external dependencies. Use mocks/stubs for I/O.
- Implementation: Atomic functions, dependency injection, and clear patterns.
- Verification: Run local tests and fix autonomously.
Best Practices
- English Only: Code, comments, and docs.
- Atomic: One responsibility per function/class.
- Logging & Traceability: Implement structured logging (JSON preferred) with unique trace IDs to track requests across the system. This is CRITICAL for production debugging.
- Error Handling: Specific exceptions, clear messages, no bare
except.
Performance Considerations
- Efficiency: Use caching strategically for expensive operations.
- I/O Optimization: Use async/await for I/O-bound operations and optimize DB queries.
- Pagination: Implement for any list-returning endpoint to handle large datasets.
Security Best Practices
- Input Validation: Sanitize and validate all external input.
- SQL Injection: Use parameterized queries or ORMs correctly.
- Secrets Management: Never hard-code credentials; use environment variables or secret managers.
- Principle of Least Privilege: Access only the data/services necessary for the task.
Anti-Patterns
- God Objects: Classes that handle too many responsibilities.
- Tight Coupling: Direct dependencies between high-level and low-level modules.
- Mixing Concerns: Business logic contaminated with infrastructure/database details.