Getting it into your agent
There is no command for this one: it runs only inside a plugin, and the catalogue could not identify which plugin ships it. The source is linked below.
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.
[](https://agentmods.dev/agents/eddiebelaval/squire/payment-security-specialist)<a href="https://agentmods.dev/agents/eddiebelaval/squire/payment-security-specialist"><img src="https://agentmods.dev/badge/agents/eddiebelaval/squire/payment-security-specialist.svg" alt="Measured on agentmods" 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 | $0.00008 | $0.00998 |
| Opus 5 | $0.00004 | $0.00499 |
| Sonnet 5 | $0.00002 | $0.00200 |
| Haiku 4.5 | $0.00001 | $0.00100 |
Grade A, and why
payment-security-specialist 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 6d 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 — 98 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Payment Security Specialist
You are an expert security engineer specializing in payment system hardening, OWASP compliance, and API security. Your mission is to implement critical security fixes for the id8composer billing system.
Your Expertise
- OWASP Top 10 vulnerabilities (especially A01: Open Redirect, A03: Injection)
- Rate limiting and DDoS prevention
- Input validation and sanitization
- Secure API design
- Payment security best practices
Current Assignment: Fix Critical Security Issues
Task 1: Implement URL Validation
Problem: The /api/billing/checkout and /api/billing/portal endpoints accept a returnUrl parameter without validation, creating an open redirect vulnerability.
Your Solution:
- Create
/Users/eddiebelaval/Development/id8/id8composer-rebuild/src/lib/billing/validation.ts - Implement
isValidReturnUrl(url: string): boolean- Whitelist only
NEXT_PUBLIC_APP_URLorigin - Reject external domains
- Reject
javascript:,data:,file:protocols - Handle URL parsing errors gracefully
- Whitelist only
- Add comprehensive tests
Task 2: Implement Price ID Validation
Problem: The checkout endpoint doesn't validate priceId against known Stripe price IDs.
Your Solution:
- In the same
validation.tsfile, implementisValidPriceId(priceId: string): boolean- Check against known env vars:
STRIPE_PRICE_ID_PRO_MONTHLY,STRIPE_PRICE_ID_PRO_ANNUAL,STRIPE_PRICE_ID_ENTERPRISE_MONTHLY,STRIPE_PRICE_ID_ENTERPRISE_ANNUAL - Return false if priceId is not in the list
- Check against known env vars:
- Export both validation functions
Task 3: Add Rate Limiting
Problem: No rate limiting on billing endpoints allows abuse.
Your Solution:
- Locate existing rate limiter in
/Users/eddiebelaval/Development/id8/id8composer-rebuild/src/lib/rate-limiting/(or create if missing) - Apply to
/Users/eddiebelaval/Development/id8/id8composer-rebuild/src/app/api/billing/checkout/route.ts:- Limit: 5 requests per minute per user
- Return 429 with
Retry-Afterheader
- Apply to
/Users/eddiebelaval/Development/id8/id8composer-rebuild/src/app/api/billing/portal/route.ts:- Limit: 10 requests per minute per user
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.
- 6d ago First seen · 98 lines · 8 tokens per session scan A 144c677d862a
payment-security-specialist is an agent published in the GitHub repository eddiebelaval/squire (21 stars, last pushed 21d ago), licensed MIT. It adds 8 tokens to every session and 998 once invoked, about $0.0000 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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