auto_uv_env shell function

auto_uv_env.sh

command -v uv >/dev/null 2>&1 && {
    auto_uv_env() {
        # Early exit for performance - check if we're in a Python project
        if [[ -f "pyproject.toml" ]]; then
            local py_version=""
            
            # Parse Python version requirement from common pyproject.toml patterns
            # Supports: requires-python = ">=3.11", python_requires = ">=3.11.5", etc.
            if grep -q "requires-python" pyproject.toml; then
                py_version=$(grep "requires-python" pyproject.toml | sed -E 's/.*[">]=?([0-9]+\.[0-9]+(\.[0-9]+)?).*/\1/' | head -1)
            elif grep -q "python_requires" pyproject.toml; then
                py_version=$(grep "python_requires" pyproject.toml | sed -E 's/.*[">]=?([0-9]+\.[0-9]+(\.[0-9]+)?).*/\1/' | head -1)
            fi
            
            # Create virtual environment if it doesn't exist
            if [[ ! -d ".venv" ]]; then
                if [[ -n "$py_version" ]]; then
                    echo "🐍 Setting up Python $py_version environment with UV..."
                    # Install Python version if needed (UV handles this efficiently)
                    uv python install "$py_version" 2>/dev/null || echo "Python $py_version already available"
                    # Create venv with specific Python version
                    uv venv --python "$py_version" || {
                        echo "❌ Failed to create venv with Python $py_version, using default"
                        uv venv
                    }
                else
                    echo "🐍 Creating default Python environment with UV..."
                    uv venv
                fi
                echo "✅ Virtual environment created"
            fi
            
            # Activate venv if exists and we're not already in the correct one
            # Performance: Only activate if path doesn't match current VIRTUAL_ENV
            if [[ -f ".venv/bin/activate" ]] && [[ "$VIRTUAL_ENV" != "$PWD/.venv" ]]; then
                source .venv/bin/activate
                echo "🚀 Activated Python environment ($(python --version 2>/dev/null || echo "unknown"))"
            fi
        elif [[ -n "$VIRTUAL_ENV" ]] && [[ ! -f "pyproject.toml" ]]; then
            # Deactivate when leaving Python projects (smart cleanup)
            deactivate 2>/dev/null
            echo "⬇️  Deactivated Python environment"
        fi
    }
    
    # Register directory change hook for automatic activation
    # This runs auto_uv_env every time you cd into a directory
    autoload -U add-zsh-hook
    add-zsh-hook chpwd auto_uv_env
    
    # Run on shell startup if already in a Python project
    auto_uv_env
}