live-codes/livecodes is a browser-based code playground for writing and running code in more than 90 languages, frameworks, and processors. It is used to experiment with code, import modules, embed interactive editors in websites, and host playgrounds on a static file server without a backend. The catalogue add-ons support working with LiveCodes.
Borrowing it
Nothing to install: this file belongs to live-codes/livecodes. 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/live-codes/livecodes/develop/.agents/skills/livecodes/headless-mode/SKILL.mdgit clone --depth 1 https://github.com/live-codes/livecodesWrote 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/live-codes/livecodes/headless-mode)<a href="https://agentmods.dev/skills/live-codes/livecodes/headless-mode"><img src="https://agentmods.dev/badge/skills/live-codes/livecodes/headless-mode/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/live-codes/livecodes/headless-mode"><img src="https://agentmods.dev/badge/skills/live-codes/livecodes/headless-mode.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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 | $0.00036 | $0.01044 |
| Opus 5.5 | $0.00014 | $0.00418 |
| Sonnet 5.5 | $0.00007 | $0.00209 |
| Haiku 4.5 | $0.00004 | $0.00104 |
Grade A, and why
headless-mode 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 1mo 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 — 191 lines — stays where its author put it; the contents beside it link to each section on GitHub.
This skill builds on sdk-embedding and sdk-methods. Read them first for foundational concepts.
LiveCodes — Headless Mode
Headless mode runs LiveCodes without any visible UI. Use SDK methods to compile code, get output, and react to events.
Setup
import { createPlayground } from 'livecodes';
// Create headless playground - container is optional
const playground = await createPlayground({
headless: true,
config: {
markup: { language: 'markdown', content: '# Hello World' },
},
});
// Use SDK methods
const code = await playground.getCode();
console.log(code.markup.compiled); // "<h1>Hello World</h1>"
console.log(code.result); // Result page HTML
Core Patterns
Markdown compiler
import { createPlayground } from 'livecodes';
let playground;
async function compileMarkdown(markdown) {
if (!playground) {
playground = await createPlayground({
headless: true,
config: { autoupdate: false },
});
}
await playground.setConfig({
markup: { language: 'markdown', content: markdown },
});
const code = await playground.getCode();
return code.markup.compiled;
}
// Usage
const html = await compileMarkdown('# Hello\n\nWorld');
console.log(html); // "<h1>Hello</h1>\n<p>World</p>"
React/JSX compiler
import { createPlayground } from 'livecodes';
let playground;
async function compileJSX(jsxCode) {
if (!playground) {
playground = await createPlayground({
headless: true,
config: { autoupdate: false },
});
}
await playground.setConfig({
script: { language: 'react', content: jsxCode },
});
const code = await playground.getCode();
return code.script.compiled;
}
const compiled = await compileJSX(`
function App() {
return <h1>Hello</h1>;
}
`);
Python interpreter
import { createPlayground } from 'livecodes';
let playground;
async function runPython(code) {
if (!playground) {
playground = await createPlayground({
headless: true,
config: { autoupdate: true },
});
}
// Set up console listener before running
const outputs = [];
playground.watch('console', ({ method, args }) => {
outputs.push({ method, args });
});
await playground.setConfig({
script: { language: 'python', content: code },
});
// Python runs automatically with autoupdate: true
// Or: await playground.run();
return outputs;
}
// Usage
const outputs = await runPython('print("Hello from Python!")');
// [{ method: 'log', args: ['Hello from Python!'] }]
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.
- 1mo ago Changed · +1 lines · -2 tokens per session 55b94b3bf527
- 2mo ago First seen · 190 lines · 38 tokens per session scan A 86028db7f1c2
headless-mode is a skill published in the GitHub repository live-codes/livecodes (1,525 stars, last pushed 13d ago), licensed MIT. It adds 36 tokens to every session and 1,044 once invoked, about $0.0001 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.
headless-mode compared with skills from other repositories
| Mod | Type | Stars | Last push | Licence | Scan | Tokens | Works with |
|---|---|---|---|---|---|---|---|
| headless-modelive-codes/livecodes | Skill | 1.5k | 13d ago | MIT | A | 36 | Claude Code, Codex |
| create-prprisma/orm | Skill | 48k | yesterday | Apache-2.0 | A | 48 | Claude Code, Codex |
| publish-npm-versionprisma/orm | Skill | 48k | yesterday | Apache-2.0 | A | 182 | Claude Code, Codex |
| contrib-prprisma/orm | Skill | 48k | yesterday | Apache-2.0 | A | 65 | Claude Code, Codex |
| github-review-iterationprisma/orm | Skill | 48k | yesterday | Apache-2.0 | A | 60 | Claude Code |
| review-implement-phaseprisma/orm | Skill | 48k | yesterday | Apache-2.0 | A | 38 | Claude Code |
| angular-developerangular/angular | Skill | 101k | yesterday | MIT | A | 93 | Claude Code, Codex |