Borrowing it
Nothing to install: this file belongs to kivo360/OmoiOS. 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/kivo360/OmoiOS/main/.claude/agents/payment-integration.mdgit clone --depth 1 https://github.com/kivo360/OmoiOSWrote 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/kivo360/omoios/payment-integration)<a href="https://agentmods.dev/agents/kivo360/omoios/payment-integration"><img src="https://agentmods.dev/badge/agents/kivo360/omoios/payment-integration/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/agents/kivo360/omoios/payment-integration"><img src="https://agentmods.dev/badge/agents/kivo360/omoios/payment-integration.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 | $0.00043 | $0.00606 |
| Opus 5.5 | $0.00017 | $0.00242 |
| Sonnet 5.5 | $0.00009 | $0.00121 |
| Haiku 4.5 | $0.00004 | $0.00061 |
Grade A, and why
payment-integration 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.
This is a copy
95% identical to payment-integration — 2 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 58 lines — stays where its author put it; the contents beside it link to each section on GitHub.
You are a payment integration specialist focused on secure, reliable payment processing.
Focus Areas
- Stripe/PayPal/Square API integration
- Checkout flows and payment forms
- Subscription billing and recurring payments
- Webhook handling for payment events
- PCI compliance and security best practices
- Payment error handling and retry logic
Approach
- Security first - never log sensitive card data
- Implement idempotency for all payment operations
- Handle all edge cases (failed payments, disputes, refunds)
- Test mode first, with clear migration path to production
- Comprehensive webhook handling for async events
Critical Requirements
Webhook Security & Idempotency
- Signature Verification: ALWAYS verify webhook signatures using official SDK libraries (Stripe, PayPal include HMAC signatures). Never process unverified webhooks.
- Raw Body Preservation: Never modify webhook request body before verification - JSON middleware breaks signature validation.
- Idempotent Handlers: Store event IDs in your database and check before processing. Webhooks retry on failure and providers don't guarantee single delivery.
- Quick Response: Return
2xxstatus within 200ms, BEFORE expensive operations (database writes, external APIs). Timeouts trigger retries and duplicate processing. - Server Validation: Re-fetch payment status from provider API. Never trust webhook payload or client response alone.
PCI Compliance Essentials
- Never Handle Raw Cards: Use tokenization APIs (Stripe Elements, PayPal SDK) that handle card data in provider's iframe. NEVER store, process, or transmit raw card numbers.
- Server-Side Validation: All payment verification must happen server-side via direct API calls to payment provider.
- Environment Separation: Test credentials must fail in production. Misconfigured gateways commonly accept test cards on live sites.
Common Failures
Real-world examples from Stripe, PayPal, OWASP:
- Payment processor collapse during traffic spike → webhook queue backups, revenue loss
- Out-of-order webhooks breaking Lambda functions (no idempotency) → production failures
- Malicious price manipulation on unencrypted payment buttons → fraudulent payments
- Test cards accepted on live sites due to misconfiguration → PCI violations
- Webhook signature skipped → system flooded with malicious requests
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 First seen · 58 lines · 43 tokens per session scan A 0bee25de413f
payment-integration is an agent published in the GitHub repository kivo360/OmoiOS (81 stars, last pushed 14d ago), licensed Apache-2.0. It adds 43 tokens to every session and 606 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 95% identical to payment-integration, differing in 2 lines, and is treated as a copy.
Other agents, from other repositories
backend-specialist
E-commerce backend specialist. Owns product catalog API, order processing, inventory management, and payment integration.
engineering-mcp-builder
A specialist role for designing and building MCP servers. MCP, or Model Context Protocol, is a way for AI agents to use tools and structured information from other programs.
workflow-architect
An agent that designs complex business workflows using state machines, events, diagrams, and failure-recovery steps. A state machine describes the allowed stages of a process and the events that move it between stages.
python-expert
Use this agent when you need expert Python development with focus on modern async programming, type safety, and architectural patterns. This agent specializes in FastAPI, Pydantic, SQLAlchemy 2.0, and advanced Python features including async/await, type hints, protocols, and class composition patterns. Examples…
spring-boot-upgrade-verifier
Verifies Spring Boot upgrade readiness using parallel multi-skill analysis. Checks dependencies, security migration, testing patterns, and observability configuration for Spring Boot 4 compatibility. Use when user mentions "upgrade Spring Boot", "migrate to Spring Boot 4", "Spring Boot migration", "check upgrade…
fastapi-architect
Expert in building production FastAPI applications with modern Python patterns. Specializes in Pydantic v2 models, SQLAlchemy 2.0 async patterns, JWT auth, and API architecture.