python

# Python Coding Guidelines

## Code Style (PEP 8)

- 4 spaces for indentation (never tabs)
- Max line length: 88 chars (Black default) or 79 (strict PEP 8)
- Two blank lines before top-level definitions, one within classes
- Imports: stdlib → third-party → local, alphabetized within groups
- Snake_case for functions/variables, PascalCase for classes, UPPER_CASE for constants

## Before Committing

```bash
# Syntax check (always)
python -m py_compile *.py

# Run tests if present
python -m pytest tests/ -v 2>/dev/null || python -m unittest discover -v 2>/dev/null || echo "No tests found"

# Format check (if available)
ruff check . --fix 2>/dev/null || python -m black --check . 2>/dev/null
```

## Python Version

- **Minimum:** Python 3.10+ (3.9 EOL Oct 2025)
- **Target:** Python 3.11-3.13 for new projects
- Never use Python 2 syntax or patterns
- Use modern features: match statements, walrus operator, type hints

## Dependency Management

Check for uv first, fall back to pip:
```bash
# Prefer uv if available
if command -v uv &>/dev/null; then
    uv pip install <package>
    uv pip compile requirements.in -o requirements.txt
else
    pip install <package>
fi
```

For new projects with uv: `uv init` or `uv venv && source .venv/bin/activate`

## Pythonic Patterns

```python
# ✅ List/dict comprehensions over loops
squares = [x**2 for x in range(10)]
lookup = {item.id: item for item in items}

# ✅ Context managers for resources
with open("file.txt") as f:
    data = f.read()

# ✅ Unpacking
first, *rest = items
a, b = b, a  # swap

# ✅ EAFP over LBYL
try:
    value = d[key]
except KeyError:
    value = default

# ✅ f-strings for formatting
msg = f"Hello {name}, you have {count} items"

# ✅ Type hints
def process(items: list[str]) -> dict[str, int]:
    ...

# ✅ dataclasses/attrs for data containers
from dataclasses import dataclass

@dataclass
class User:
    name: str
    email: str
    active: bool = True

# ✅ pathlib over os.path
from pathlib import Path
config...