UV Quickstart Guide for Coding Agents

This guide outlines the standard operating procedures for managing Python projects, scripts, and dependencies using uv.

🚨 CRITICAL RULE: Never use the bare python command. Barely ever should you run python file.py or python -c. Always use uv run to ensure you are executing within the correct, managed environment. If you are stuck or forget a command's syntax, always use uv --help or uv <command> --help.

1. Project Management (Permanent)

When managing a standard Python project, prefer uv's built-in project management over traditional pip workflows.

• Create a new project: uv init
• Add a dependency: uv add <package>
• Remove a dependency: uv remove <package>
• Resync dependencies: uv sync (Use this to clean up the environment or after manually modifying pyproject.toml).

2. Temporary Scripts & Debugging

Do not pollute the global environment or the permanent project files with temporary debugging dependencies.

• Run a script with temporary dependencies: uv run --with pack1,pack2 file.py
• Run a quick Python command: uv run python -c "print('hello')"
• Run a quick Python command with a temporary dependency: uv run --with requests python -c "import requests; print(requests.get('https://example.com').status_code)"

3. Standalone Scripts (Permanent for User)

When creating a single-file script for the user that needs to reliably run on its own across different machines, embed the dependency metadata directly into the script.

• Add inline dependencies to a script: uv add --script myscript.py pack1,pack2 (This modifies the script file to include standard inline metadata).
• Execute the script: Once dependencies are added, simply run uv run myscript.py. uv will automatically read the file, create an isolated environment, and include those dependencies on the fly.

4. Python Execution & Version Control

• Specify a Python version: Pass the --python flag to uv run. uv run --python 3.14 file.py
• Run binaries installed in the project: Use uv run to execute tools installed within the project's environment. uv run uvicorn main:app

5. Global Tools & CLIs

Use uv's tool management for CLIs that operate independently of the current virtual environment.

• Run an interactive CLI temporarily (run-once): uvx <tool-name>
• Install a tool permanently: uv tool install <tool-name>
• Upgrade installed tools: uv tool upgrade <tool-name> (or uv tool upgrade --all)

6. Temporary Testing via Pip

While uv add is strictly for permanent project management, uv pip install serves a great role in temporary experimentation.

• Test a dependency temporarily: If you are inside a uv project and run uv pip install <package>, it will install the package into the current environment without adding it to pyproject.toml.
• Wipe temporary dependencies: Because it wasn't permanently added, simply running uv sync later will remove the experimental package and return the environment to its official state.
• Create a standard venv manually: uv venv (if you explicitly need a raw virtual environment outside of standard project management).