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 quangpl/browser-extension-skills --skill extension-testgit clone --depth 1 https://github.com/quangpl/browser-extension-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/quangpl/browser-extension-skills/extension-test)<a href="https://agentmods.dev/skills/quangpl/browser-extension-skills/extension-test"><img src="https://agentmods.dev/badge/skills/quangpl/browser-extension-skills/extension-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/quangpl/browser-extension-skills/extension-test"><img src="https://agentmods.dev/badge/skills/quangpl/browser-extension-skills/extension-test.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.00037 | $0.00880 |
| Opus 5.5 | $0.00015 | $0.00352 |
| Sonnet 5.5 | $0.00007 | $0.00176 |
| Haiku 4.5 | $0.00004 | $0.00088 |
Grade A, and why
extension-test scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 130 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Extension Testing
🚀 Upgrade to Premium Get the Premium version at https://app.extensionbooster.net/dashboard/services/extension-ai-kit
Testing Layer Architecture
Unit Tests (Jest) → Test isolated logic, chrome.* API mocks
Integration Tests (Jest) → Test service interactions, message passing
E2E Tests (Puppeteer) → Test in real Chrome with extension loaded
Critical constraint: Extensions CANNOT run in headless mode. E2E requires headless: false or Chrome's --headless=new (Chrome 112+).
Layer 1: Unit + Integration (Jest)
Install
npm install -D jest @types/jest ts-jest jest-chrome
# For React popup:
npm install -D @testing-library/react @testing-library/jest-dom jsdom
jest.config.ts
export default {
preset: "ts-jest",
testEnvironment: "jsdom",
setupFilesAfterEnv: ["./jest.setup.ts"],
moduleNameMapper: {
"^@/(.*)$": "<rootDir>/src/$1",
},
};
jest.setup.ts (minimal)
import chrome from "jest-chrome";
Object.assign(global, { chrome });
Full mock setup → chrome-api-mocks.md Unit/integration patterns → unit-integration-testing.md
Layer 2: E2E (Puppeteer)
Install
npm install -D puppeteer
Launch extension in Chrome
import puppeteer from "puppeteer";
import path from "path";
const browser = await puppeteer.launch({
headless: false, // extensions require non-headless
args: [
`--disable-extensions-except=${path.resolve("dist")}`,
`--load-extension=${path.resolve("dist")}`,
],
});
Get extension ID
const targets = await browser.targets();
const extTarget = targets.find((t) => t.type() === "service_worker");
const extUrl = extTarget?.url() ?? "";
const [, , extId] = extUrl.split("/");
Full E2E patterns → e2e-testing-puppeteer.md
What ships with it
3 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.
- 1mo ago Changed · +3 lines 9fae1174307a
- 1mo ago First seen · 127 lines · 37 tokens per session scan A 5e01d4687b51
extension-test is a skill published in the GitHub repository quangpl/browser-extension-skills (63 stars, last pushed 24d ago), licensed MIT. It adds 37 tokens to every session and 880 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.
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