Python Venv

Python Environment Management Skill

Core Principles

1. Reuse Existing Environments - Don't recreate, reuse existing virtual environments
2. Use Project-Type Decision - Auto-select based on lock files
3. Recommend by Popularity - uv > pip > conda > venv
4. Minimize Interruption - Only ask when necessary

Tool Popularity Ranking

Decision Flow

┌─────────────────────────────────────┐
│  Detect project dependency files     │
└─────────────────────────────────────┘
              ↓
    ┌─────────┴─────────┐
    ↓                   ↓
  Clear decision       Unclear
    ↓                   ↓
  Use directly     Detect existing env
                        ↓
                  ┌─────┴─────┐
                  ↓           ↓
              Has env        No env
                  ↓           ↓
              Reuse      Assess complexity
                            ↓
                  ┌─────────┴─────────┐
                  ↓                   ↓
              Simple task       Needs deps
                  ↓                   ↓
            System Python      Recommend uv/conda

1. Clear Decisions (Execute Directly, No Ask)

When these files are detected, use the corresponding tool directly:

2. Detect Existing Environments (Reuse First)

# Priority: uv venv > conda > venv

# 2.1 Detect uv virtual environment
ls -la .venv/ 2>/dev/null && uv pip list 2>/dev/null | head -3

# 2.2 Detect conda environment
conda info --envs 2>/dev/null | grep "*" || echo $CONDA_PREFIX

# 2.3 Detect standard venv
ls -la venv/ .venv/ env/ 2>/dev/null

# 2.4 If exists → Reuse (activate and run commands)

Reuse Example:

Detected existing .venv/ directory
→ Activate: source .venv/bin/activate
→ Run: uv pip install <package>

3. When Unclear (Assess Complexity)

4. When to Ask User (Only These Cases)

✅ Ask:

1. Empty project + first dependency install → Ask which tool
2. Both requirements.txt + pyproject.toml → Ask which to use
3. User explicitly wants different tool → e.g., "I want conda"

❌ Don't Ask:

• Has uv.lock but user didn't specify
• Has .venv/ directory
• Regular pip install task

5. Recommended Tool (No Clear Directive)

First: uv
  ├── uv venv (create)
  ├── uv pip install (install)
  └── uv sync (sync)

Backup: pip
  ├── python3 -m venv .venv
  └── pip install

Special: conda
  ├── conda create -n envname python=x.x
  └── conda env create

Detection Commands

# Check available tools
which uv
which conda
which pip
which python3

# Check project files
ls -la *.lock pyproject.toml requirements.txt environment.yml Pipfile 2>/dev/null

# Check existing environments
ls -la .venv/ venv/ env/ 2>/dev/null
conda info --envs 2>/dev/null

# Check current environment
echo $VIRTUAL_ENV
echo $CONDA_PREFIX

Interaction Examples (Only When Needed)

🔍 Detection result:
- Project file: pyproject.toml
- Existing env: None
- Recommended: uv (fastest)

Running: uv pip install <package>

🔍 Detection result:
- Project file: requirements.txt
- Existing env: None
- Recommended: uv

Available options:
1) uv (recommended) - faster
2) pip - better compatibility
3) venv - uses stdlib
4) conda - if specific version needed

Enter option or press Enter to use recommended:

Quick Command Reference

Core Principle

"Do more, ask less" - Execute directly when you can determine, only ask when truly unclear.