sanyuan-skills is a collection of reusable instructions, called agent skills, that extend Claude Code and other AI coding terminals with defined workflows. Developers use it for code review, learning, skill quality checks, skill creation, and organizing knowledge into wikis or study materials. The catalogue entries are individual skills from this collection.
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.
npx skills add sanyuan0704/sanyuan-skills --skill sigmagit clone --depth 1 https://github.com/sanyuan0704/sanyuan-skillsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/sanyuan0704/sanyuan-skills/sigma)<a href="https://agentmods.dev/skills/sanyuan0704/sanyuan-skills/sigma"><img src="https://agentmods.dev/badge/skills/sanyuan0704/sanyuan-skills/sigma/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/sanyuan0704/sanyuan-skills/sigma"><img src="https://agentmods.dev/badge/skills/sanyuan0704/sanyuan-skills/sigma.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- Socket pass
- Snyk pass
- NVIDIA SkillSpector warn
SkillSpector: 2 findings, up to medium
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- medium Rogue Agent · line 16 Skill establishes unauthorized persistence across sessions via cron jobs, startup scripts, or state files. Session persistence allows an attacker to maintain access beyond the current interaction.Fix: Remove any persistence mechanisms (cron jobs, startup scripts, state files). Skills should not maintain state across sessions without explicit user consent.
- medium Rogue Agent · line 26 Skill establishes unauthorized persistence across sessions via cron jobs, startup scripts, or state files. Session persistence allows an attacker to maintain access beyond the current interaction.Fix: Remove any persistence mechanisms (cron jobs, startup scripts, state files). Skills should not maintain state across sessions without explicit user consent.
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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00124 | $0.05825 |
| Opus 5.5 | $0.00050 | $0.02330 |
| Sonnet 5.5 | $0.00025 | $0.01165 |
| Haiku 4.5 | $0.00012 | $0.00583 |
Grade A, and why
sigma 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 2mo 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.
How it starts
The opening of the file, as written. The whole thing — 500 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Sigma Tutor
Personalized 1-on-1 mastery tutor. Bloom's 2-Sigma method: diagnose, question, advance only on mastery.
Usage
/sigma Python decorators
/sigma 量子力学 --level beginner
/sigma React hooks --level intermediate --lang zh
/sigma linear algebra --resume # Resume previous session
Arguments
| Argument | Description |
|---|---|
<topic> |
Subject to learn (required, or prompted) |
--level <level> |
Starting level: beginner, intermediate, advanced (default: diagnose) |
--lang <code> |
Language override (default: follow user's input language) |
--resume |
Resume previous session from sigma/{topic-slug}/ |
--visual |
Force rich visual output every round |
Core Rules (NON-NEGOTIABLE)
- NEVER give answers directly. Only ask questions, give minimal hints, request explanations/examples/derivations.
- Diagnose first. Always start by probing the learner's current understanding.
- Mastery gate. Advance to next concept ONLY when learner demonstrates ~80% correct understanding.
- 1-2 questions per round. No more. Use AskUserQuestion for structured choices; use plain text for open-ended questions.
- Patience + rigor. Encouraging tone, but never hand-wave past gaps.
- Language follows user. Match the user's language. Technical terms can stay in English with translation.
Output Directory
sigma/
├── learner-profile.md # Cross-topic learner model (created on first session, persists across topics)
└── {topic-slug}/
├── session.md # Learning state: concepts, mastery scores, misconceptions, review schedule
├── roadmap.html # Visual learning roadmap (generated at start, updated on progress)
├── concept-map/ # Excalidraw concept maps (generated as topics connect)
├── visuals/ # HTML explanations, diagrams, image files
└── summary.html # Session summary (generated at milestones or end)
Slug: Topic in kebab-case, 2-5 words. Example: "Python decorators" -> python-decorators
What ships with it
4 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 2mo ago First seen · 500 lines · 124 tokens per session scan A 727d69e9a679
sigma is a skill published in the GitHub repository sanyuan0704/sanyuan-skills (3,973 stars, last pushed 5mo ago), licensed MIT. It adds 124 tokens to every session and 5,825 once invoked, about $0.0005 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
sigma compared with skills from other repositories
| Mod | Type | Stars | Last push | Licence | Scan | Tokens | Works with |
|---|---|---|---|---|---|---|---|
| sigmasanyuan0704/sanyuan-skills | Skill | 4.0k | 5mo ago | MIT | A | 124 | Claude Code, Codex |
| hr-onboardingnexu-io/open-design | Skill | 106k | today | Apache-2.0 | A | 62 | Claude Code, Codex |
| book-mirrorgarrytan/gbrain | Skill | 32k | today | MIT | A | 138 | Claude Code |
| exam-forecastanthropics/claude-for-legal | Skill | 9.9k | 3d ago | Apache-2.0 | A | 73 | Claude Code |
| lean-formalizewanshuiyin/Auto-claude-code-research-in-sleep | Skill | 19k | 3d ago | MIT | A | 81 | Claude Code |
| eli5companion-inc/feynman | Skill | 10k | 6d ago | MIT | A | 63 | Claude Code, Codex |
| deck-course-modulenexu-io/html-anything | Skill | 9.4k | 24d ago | Apache-2.0 | A | 25 | Claude Code, Codex |