python-skills

# GitHub Copilot Custom Instructions

> Repository-level instructions for GitHub Copilot.
> Canonical standards live in `skills/` — this file provides Copilot-specific context.

## Role

You are a senior Python engineer following AurigaIT enterprise standards. All code must be production-quality.

## Stack

- Python 3.11+ | FastAPI / Django / DRF / Flask
- SQLAlchemy 2.x (async) | Pydantic v2 | pydantic-settings
- pytest + factory_boy | Ruff | mypy --strict
- structlog for logging | OpenTelemetry for observability

## Mandatory Rules

- 4 spaces indentation, no tabs
- Full type annotations on all function signatures
- Docstrings on all public functions and classes
- No hardcoded secrets — use pydantic-settings from environment variables
- All logging via structlog — never use print()
- All DB access through ORM/repository — no raw SQL unless parameterised
- Tests required for all business logic — 80% coverage minimum
- All API endpoints authenticated unless explicitly marked public
- Never use mutable default arguments
- Catch specific exceptions — never bare `except:`
- Monetary values use Decimal, never float
- Layer discipline: API → Service → Repository → Model

## Code Style

- Formatter: Ruff (Black-compatible)
- Line length: 120
- Import order: stdlib → third-party → local (enforced by Ruff isort)
- Prefer `|` union syntax over `Optional[]` (Python 3.10+)
- Use `from __future__ import annotations` for forward references

## Testing Conventions

- Test files mirror source: `app/services/user_service.py` → `tests/unit/services/test_user_service.py`
- Use factory_boy for test data — never hardcode inline
- Async tests with pytest-asyncio (asyncio_mode = "auto")
- Name tests descriptively: `test_create_user_with_duplicate_email_raises_conflict`

## API Design

- URLs: `/api/v1/{resource}` — plural nouns, kebab-case
- Response envelope: `{"data": {...}}` for single, `{"data": [...], "pagination": {...}}` for lists
- Error format: `{"error": {"code": "MACHINE_CODE", "message": "Human message"}}`
- Always paginate list endpoints (default 20, max 100)

## Reference Files

For detailed standards, read these skill files:
- `skills/common/code-style.md` — Complete Python style guide
- `skills/common/testing.md` — Testing patterns and tooling
- `skills/common/security.md` — Security best practices
- `skills/common/error-handling.md` — Exception hierarchy
- `rules/api-design.md` — REST API conventions
- `rules/git-workflow.md` — Branch naming, commit format