agentgem-miniapp

agentgem-miniapp is a skill for Claude Code, Codex from ninemindai/agentgem. It costs 85 tokens per session (2,949 once invoked), scanned A, original, MIT.

Instructions for building or editing AgentGem miniapps and mini-games: single-file HTML apps that run inside a restricted browser frame. They explain the required file format, host communication rules, user consent, privacy, and content limits.

In plain words
What is it for?
Creating or modifying a sealed miniapp, keeping JavaScript and CSS inside one HTML file, using data URLs, and working on the AgentGem platform itself.
Why use it?
They prevent changes that would break the miniapp contract, such as adding extra files, using blocked external resources, or ignoring the sandbox restrictions.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Needs its repository: it reads a path above its own folder, which exists only inside the repository. The line is is [`docs/miniapps/spec.md`](../../docs/miniapps/spec.md) — implement against.

Good fit Creating or modifying a sealed miniapp, keeping JavaScript and CSS inside one HTML file, using data URLs, and working on the AgentGem platform itself.

Compare 6 skills from other repositories ↓
Install

Getting it into your agent

It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.

Clone the repo
git clone --depth 1 https://github.com/ninemindai/agentgem
agentmods
npx agentmods add skills/ninemindai/agentgem/agentgem-miniapp

Made for: Claude Code, Codex.

Wrote 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.

agentmods badge for agentgem-miniapp

README.md
[![agentmods](https://agentmods.dev/badge/skills/ninemindai/agentgem/agentgem-miniapp.svg)](https://agentmods.dev/skills/ninemindai/agentgem/agentgem-miniapp)
Your own site
<a href="https://agentmods.dev/skills/ninemindai/agentgem/agentgem-miniapp"><img src="https://agentmods.dev/badge/skills/ninemindai/agentgem/agentgem-miniapp.svg" alt="Measured on agentmods" height="20"></a>
Per session 85 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,949 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 1 finding, 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 Excessive Agency · line 109
    Skill enables autonomous high-impact decisions without human-in-the-loop verification. Critical operations (destructive commands, financial transactions, data deletion) should require explicit user confirmation.
    Fix: Add human-in-the-loop confirmation for destructive, irreversible, or high-impact operations. Never auto-execute commands that modify files, send data, or alter system state.
How audits are shown
Origin original No closer match found 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 5.1 $0.00085 $0.02949
Opus 5 $0.00043 $0.01474
Sonnet 5 $0.00017 $0.00590
Haiku 4.5 $0.00009 $0.00295

Measured 8d ago against content hash 47d6d82c6863, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

agentgem-miniapp 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 8d 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.

skills/agentgem-miniapp/SKILL.md · 205 lines

How it starts

The opening of the file, as written. The whole thing — 205 lines — stays where its author put it; the contents beside it link to each section on GitHub.

agentgem-miniapp

Changing the miniapp platform, not authoring a miniapp? The normative spec is docs/miniapps/spec.md — implement against its conformance checklist, and read docs/miniapps/evolution.md before re-deciding anything it records. If your change touches the authoring contract, edit MINIAPP_BUILDER_BRIEF in packages/play/src/builderBrief.ts — the body below is a byte-for-byte view of that constant (this file must end with it; src/play/__tests__/builderBrief.test.ts guards the mirror), and the Studio agent only ever sees the constant, so a SKILL.md-only edit changes nothing at runtime.

The file

You are editing one file: <name>.html — a single, self-contained HTML document. Never add a second file. If the file has AGENTGEM:GAME-LOGIC start/end markers, keep your changes between them.

It runs in a null-origin sandboxed iframe (sandbox="allow-scripts", no allow-same-origin) under this Content-Security-Policy:

default-src 'none'; style-src 'unsafe-inline'; script-src 'unsafe-inline';
img-src data:; font-src data:; media-src data:;

So inline every byte of JS and CSS, use only data: URIs for images, fonts and media, and make no network calls of any kind.

Theming. The host may supply CSS variables — --color-background-primary, --color-background-secondary, --color-text-primary, --color-border-primary — and sets theme ("light" or "dark") on <html data-theme> automatically. Read them with a fallback, because most hosts send none: background: var(--color-background-primary, #0d1117). On app.agentgem.ai, and any other host that sends no variables, the fallback is what renders.

What Save enforces

Two gates run when the user saves. Both throw a message you will see in the studio.

The seal. Rejects, anywhere in executable code:

  • an external src= or href= (anything other than data: or #)
  • a bare module import (import … from "…")
  • the words fetch, XMLHttpRequest, WebSocket, EventSource, importScripts, navigator.sendBeacon

Read the full file on GitHub · 205 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. 8d ago First seen · 205 lines · 85 tokens per session scan A 47d6d82c6863

Subscribe to this mod's changes

agentgem-miniapp is a skill published in the GitHub repository ninemindai/agentgem (39 stars, last pushed 10d ago), licensed MIT. It adds 85 tokens to every session and 2,949 once invoked, about $0.0004 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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