World of ClaudeCraft is a browser-based classic-style multiplayer online game with a persistent shared world that can also run locally or be controlled through a Python reinforcement-learning interface. Players can quest and raid in the online world, while developers can host it themselves and train AI agents to play. The catalogue skills, agents, instructions, hooks, and setting support workflows for interacting with and developing the game.
Borrowing it
Nothing to install: this file belongs to levy-street/world-of-claudecraft. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/levy-street/world-of-claudecraft/main/.claude/skills/extract-and-test/SKILL.mdgit clone --depth 1 https://github.com/levy-street/world-of-claudecraftWrote 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/levy-street/world-of-claudecraft/extract-and-test)<a href="https://agentmods.dev/skills/levy-street/world-of-claudecraft/extract-and-test"><img src="https://agentmods.dev/badge/skills/levy-street/world-of-claudecraft/extract-and-test/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/levy-street/world-of-claudecraft/extract-and-test"><img src="https://agentmods.dev/badge/skills/levy-street/world-of-claudecraft/extract-and-test.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 5 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 MCP Rug Pull · line 139 npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.Fix: Pin the version: npx @scope/[email protected]
- medium MCP Rug Pull · line 140 npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.Fix: Pin the version: npx @scope/[email protected]
- medium MCP Rug Pull · line 141 npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.Fix: Pin the version: npx @scope/[email protected]
- medium MCP Rug Pull · line 146 npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.Fix: Pin the version: npx @scope/[email protected]
- medium MCP Rug Pull · line 150 npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.Fix: Pin the version: npx @scope/[email protected]
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 | $0.00137 | $0.02867 |
| Opus 5 | $0.00068 | $0.01434 |
| Sonnet 5 | $0.00027 | $0.00573 |
| Haiku 4.5 | $0.00014 | $0.00287 |
Grade A, and why
extract-and-test 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 13d 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 — 182 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Extract and test: module-first features, test-first fixes
This repo is built and maintained almost entirely by AI agents and grows by many small contributions. The thing that keeps it scalable, and keeps open-source merge conflicts small, is that new behavior lands as a focused module behind a known seam, not as another block appended to an already huge coordinator. This skill is the detailed how-to behind the root CLAUDE.md "Modularity" section. Apply it whenever you implement a feature or fix a bug.
The one decision: sibling module or monolith edit
The four logic monoliths (src/ui/hud.ts, src/sim/sim.ts, src/main.ts,
src/render/renderer.ts) are coordinators, not a license to grow them: do
not split them to hit a line count, and do not rewrite them as a side effect of your task,
but never GROW one either. src/main.ts especially is a firewall, not a home (its
client-bootstrap helpers belong in src/game/ or src/ui/ siblings). Before you add a
block of new logic to one, ask:
Does this behavior need the monolith's private mutable state (the live
Simentity loop, theHudDOM and per-frame state, the renderer's scene graph)?
- No: it is a sibling module. Write it as its own file with a named export and a Vitest, then wire it in with a few lines (a call, a registration, a consume).
- Yes, partly: extract the pure part (the math, the formatting, the id/state
resolution) into a host-agnostic module a test imports directly, and leave the
stateful side a thin consumer that calls it. This is the pure-core + thin-consumer
split (reference:
src/ui/unit_portrait.tscore +src/ui/unit_portrait_painter.ts, shared by the player and target frames;src/ui/xp_bar.tsis a purexpBarView()that a snapshot test drives with no DOM).
If your edit to a monolith is more than a thin wiring of something defined elsewhere, you are probably appending behavior that wants its own module.
The enforcement backstop: the monolith line-count ratchet
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.
- 13d ago First seen · 182 lines · 137 tokens per session scan A ab19eb798402
extract-and-test is a skill published in the GitHub repository levy-street/world-of-claudecraft (2,251 stars, last pushed yesterday), licensed MIT. It adds 137 tokens to every session and 2,867 once invoked, about $0.0007 per session on Opus 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.
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