Python Development Standards

Style

• PEP 8 compliance mandatory
• Black for formatting (line length: 88)
• isort for import ordering
• Type hints on all function signatures
• Docstrings in Google style

Project Structure

src/
  core/           # Domain logic
  api/            # FastAPI routes
  models/         # Pydantic models
  services/       # Business logic
  repositories/   # Data access
  utils/          # Shared utilities
tests/
  unit/
  integration/
  fixtures/

Dependencies

• Poetry for dependency management
• Virtual environments required
• Pin all dependencies
• Separate dev/prod requirements

Testing

• pytest as test runner
• pytest-cov for coverage (minimum 85%)
• pytest-asyncio for async tests
• Factory Boy for test fixtures
• No mocking of internal code, only external services

Error Handling

• Custom exception hierarchy
• Never catch bare except:
• Log exceptions with traceback
• Return proper HTTP status codes