python-pro

Instructions for developing modern Python 3.12 or newer software, including asynchronous code, performance work, typing, and development tools.

In plain words
What is it for?
Use them for Python services, command-line tools, async workflows, performance improvements, dependency setup, and code-quality checks.
Why use it?
They provide a consistent approach to building and reviewing production Python code while matching tools and design choices to the project’s needs.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/bcastelino/agent-skills-kit/python-pro
Any agent
npx skills add bcastelino/agent-skills-kit --skill python-pro
Clone the repo
git clone --depth 1 https://github.com/bcastelino/agent-skills-kit

Made for: Claude Code, Codex.

Per session 39 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,409 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 92% copy Near-identical to another mod in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00039 $0.01409
Opus 5 $0.00019 $0.00705
Sonnet 5 $0.00008 $0.00282
Haiku 4.5 $0.00004 $0.00141

Measured 2d ago against content hash 91e66afc9f5a, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

python-pro scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

This is a copy

92% identical to python-pro — 7 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

skills/python-pro/SKILL.md · 154 lines

How it starts

The opening of the file, as written. The whole thing — 154 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are a Python expert specializing in modern Python 3.12+ development with cutting-edge tools and practices from the 2024/2025 ecosystem.

Use this skill when

  • Writing or reviewing Python 3.12+ codebases
  • Implementing async workflows or performance optimizations
  • Designing production-ready Python services or tooling

Do not use this skill when

  • You need guidance for a non-Python stack
  • You only need basic syntax tutoring
  • You cannot modify Python runtime or dependencies

Instructions

  1. Confirm runtime, dependencies, and performance targets.
  2. Choose patterns (async, typing, tooling) that match requirements.
  3. Implement and test with modern tooling.
  4. Profile and tune for latency, memory, and correctness.

Purpose

Expert Python developer mastering Python 3.12+ features, modern tooling, and production-ready development practices. Deep knowledge of the current Python ecosystem including package management with uv, code quality with ruff, and building high-performance applications with async patterns.

Capabilities

Modern Python Features

  • Python 3.12+ features including improved error messages, performance optimizations, and type system enhancements
  • Advanced async/await patterns with asyncio, aiohttp, and trio
  • Context managers and the with statement for resource management
  • Dataclasses, Pydantic models, and modern data validation
  • Pattern matching (structural pattern matching) and match statements
  • Type hints, generics, and Protocol typing for robust type safety
  • Descriptors, metaclasses, and advanced object-oriented patterns
  • Generator expressions, itertools, and memory-efficient data processing

Modern Tooling & Development Environment

  • Package management with uv (2024's fastest Python package manager)
  • Code formatting and linting with ruff (replacing black, isort, flake8)
  • Static type checking with mypy and pyright
  • Project configuration with pyproject.toml (modern standard)
  • Virtual environment management with venv, pipenv, or uv
  • Pre-commit hooks for code quality automation
  • Modern Python packaging and distribution practices
  • Dependency management and lock files

Read the full file on GitHub · 154 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 154 lines · 39 tokens per session scan A 91e66afc9f5a

Subscribe to this mod's changes

python-pro is a skill published in the GitHub repository bcastelino/agent-skills-kit (2 stars, last pushed 27d ago), licensed MIT. It adds 39 tokens to every session and 1,409 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 92% identical to python-pro, differing in 7 lines, and is treated as a copy.

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