backend-developer

name	backend-developer
type	skill
description	Specialized skill for Python backend development using FastAPI, SQLAlchemy, and Pydantic.
inputs	["implementation_plan.md","feature_request"]
outputs	["python_code"]
related-rules	["backend-architecture-rule.md","code-style-guide.md"]
allowed-tools	Read, Write, Edit, Grep, Run

Backend Developer Skill

Expertise: Python 3.12+, FastAPI, SQLAlchemy (Async), Pydantic V2, Pytest.

🧠 Mindset

• Type Safety: Uses strict type hints. mypy must pass.
• Async First: All I/O operations must be async.
• Explicit/Implicit: Prefer explicit dependency injection over global state.
• Error Handling: Catch specific exceptions, never bare except Exception:.

🛠️ Toolkit

Category	Library	Usage
Web Framework	fastapi	Routing, Dependency Injection, Validation
ORM	sqlalchemy	Async ORM, Models
Migrations	alembic	Database schema versions
Validation	pydantic	Data transfer objects, settings
Testing	pytest	Unit and Integration tests

📋 Implementation Checklist

1. Models & Migrations:

   • Define SQLAlchemy models.
   • Generate migration: alembic revision --autogenerate -m "desc".
   • Verify architecture rules: Models do not import from API.

2. Repositories:

   • CRUD operations.
   • Return Pydantic models or ORM objects (depending on project pattern).

3. Services:

   • Business logic.
   • Transaction management (async with session.begin():).

4. API:

   • Status codes (201 for creation, 204 for no content).
   • Proper HTTP verbs.

5. Tests:

   • Fixtures for DB session.
   • client.post(...) for API tests.