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-paymentgit 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-payment)<a href="https://agentmods.dev/skills/quangpl/browser-extension-skills/extension-payment"><img src="https://agentmods.dev/badge/skills/quangpl/browser-extension-skills/extension-payment/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-payment"><img src="https://agentmods.dev/badge/skills/quangpl/browser-extension-skills/extension-payment.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 | $0.00049 | $0.00904 |
| Opus 5 | $0.00024 | $0.00452 |
| Sonnet 5 | $0.00010 | $0.00181 |
| Haiku 4.5 | $0.00005 | $0.00090 |
Grade A, and why
extension-payment 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 10d 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 — 85 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Extension Payment Integration
Integrate payment/subscription into a Chrome extension. Ask user for provider, then fetch docs and implement.
Workflow (Execute This)
Step 1: Ask user for payment requirements
Ask the user to confirm:
- Payment model: One-time purchase / Subscription / Freemium / Credits-based
- Provider category: Payment Gateway or Merchant of Record (MoR)?
- Preferred provider (or let us recommend)
- Required info: API keys, product/price IDs, webhook URL
Recommend MoR for solo/indie developers — handles tax, compliance, billing portal. No need to register as a business in every country.
Step 2: Provider selection guide
| Category | Provider | Best For | Docs |
|---|---|---|---|
| MoR | Paddle | SaaS subscriptions, global tax | https://developer.paddle.com |
| MoR | Lemon Squeezy | Indie/solo devs, simple setup | https://docs.lemonsqueezy.com |
| MoR | Polar | Open source monetization | https://docs.polar.sh |
| MoR | Creem | Extension-focused MoR | https://docs.creem.io |
| MoR | Dodo Payments | Simple digital products | https://docs.dodopayments.com |
| MoR | FastSpring | Enterprise digital commerce | https://developer.fastspring.com |
| MoR | Gumroad | Creators, digital products | https://help.gumroad.com |
| Gateway | Stripe | Full control, most flexible | https://docs.stripe.com |
| Gateway | PayPal | Wide user base, easy checkout | https://developer.paypal.com/docs |
| Gateway | Razorpay | India-focused payments | https://razorpay.com/docs |
| Gateway | Square | POS + online | https://developer.squareup.com/docs |
| Gateway | Adyen | Enterprise, multi-currency | https://docs.adyen.com |
| Gateway | Braintree | PayPal-owned, cards + PayPal | https://developer.paypal.com/braintree/docs |
| Gateway | Authorize.Net | US legacy, reliable | https://developer.authorize.net |
llms.txt for AI-assisted docs (use docs-seeker skill):
- Stripe:
https://docs.stripe.com/llms.txt - Polar:
https://docs.polar.sh/llms-full.txt
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.
- 10d ago First seen · 85 lines · 49 tokens per session scan A 46213586dd72
extension-payment is a skill published in the GitHub repository quangpl/browser-extension-skills (49 stars, last pushed 3mo ago), licensed MIT. It adds 49 tokens to every session and 904 once invoked, about $0.0002 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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