payment-integration

What this skill does

# Payment Integration

Implement payment processing with SePay (Vietnamese payments) and Polar (global SaaS monetization).

## When to Use

Use when implementing:
- Payment gateway integration (checkout, processing)
- Subscription management (trials, upgrades, billing)
- Webhook handling (payment notifications)
- QR code payments (VietQR, NAPAS)
- Usage-based billing (metering, credits)
- Automated benefit delivery (licenses, GitHub access, Discord roles)
- Customer portals (self-service management)
- Bank transfer automation (Vietnamese banks)
- Product catalogs with pricing

## Platform Selection

**Choose SePay for:**
- Vietnamese market (VND currency)
- Bank transfer automation
- VietQR/NAPAS payments
- Local payment methods
- Direct bank account monitoring

**Choose Polar for:**
- Global SaaS products
- Subscription management
- Usage-based billing
- Automated benefits (GitHub, Discord, licenses)
- Merchant of Record (tax compliance)
- Digital product sales

## Quick Reference

### SePay Integration
- **Overview & Auth**: `references/sepay/overview.md` - Platform capabilities, API/OAuth2 auth, supported banks
- **API Reference**: `references/sepay/api.md` - Endpoints, transactions, bank accounts, virtual accounts
- **Webhooks**: `references/sepay/webhooks.md` - Setup, payload structure, verification, retry logic
- **SDK Usage**: `references/sepay/sdk.md` - Node.js, PHP, Laravel implementations
- **QR Codes**: `references/sepay/qr-codes.md` - VietQR generation, templates, integration
- **Best Practices**: `references/sepay/best-practices.md` - Security, patterns, monitoring

### Polar Integration
- **Overview & Auth**: `references/polar/overview.md` - Platform capabilities, authentication methods, MoR concept
- **Products & Pricing**: `references/polar/products.md` - Product types, pricing models, usage-based billing
- **Checkouts**: `references/polar/checkouts.md` - Checkout flows, embedded checkout, links
- **Subscriptions**: `references/polar/subscriptions.md` - Lifecycle, upgrades, downgrades, trials
- **Webhooks**: `references/polar/webhooks.md` - Event types, signature verification, monitoring
- **Benefits**: `references/polar/benefits.md` - Automated delivery (GitHub, Discord, licenses, files)
- **SDK Usage**: `references/polar/sdk.md` - TypeScript, Python, PHP, Go, framework adapters
- **Best Practices**: `references/polar/best-practices.md` - Security, patterns, monitoring

### Integration Scripts
- **SePay Webhook Verification**: `scripts/sepay-webhook-verify.js` - Verify SePay webhook authenticity
- **Polar Webhook Verification**: `scripts/polar-webhook-verify.js` - Verify Polar webhook signatures
- **Checkout Helper**: `scripts/checkout-helper.js` - Generate checkout sessions for both platforms

## Implementation Workflow

### SePay Implementation
1. Load `references/sepay/overview.md` for auth setup
2. Load `references/sepay/api.md` or `references/sepay/sdk.md` for integration
3. Load `references/sepay/webhooks.md` for payment notifications
4. Use `scripts/sepay-webhook-verify.js` for webhook verification
5. Load `references/sepay/best-practices.md` for production readiness

### Polar Implementation
1. Load `references/polar/overview.md` for auth and concepts
2. Load `references/polar/products.md` for product setup
3. Load `references/polar/checkouts.md` for payment flows
4. Load `references/polar/webhooks.md` for event handling
5. Use `scripts/polar-webhook-verify.js` for webhook verification
6. Load `references/polar/benefits.md` if automating delivery
7. Load `references/polar/best-practices.md` for production readiness

## Key Capabilities

**SePay:**
- Payment gateway (QR, bank transfer, cards)
- Bank account monitoring with webhooks
- Order-based virtual accounts
- VietQR generation API
- 44+ Vietnamese banks supported
- Rate limit: 2 calls/second

**Polar:**
- Merchant of Record (global tax compliance)
- Subscription lifecycle management
- Usage-based billing (events, meters)
- Automated benefits (GitHub, Discord, licenses)
- Customer portal (self-service)
- Multi-language SDKs
- Rate limit: 300 req/min

## Instructions

When implementing payment integration:

1. **Identify platform** based on requirements (Vietnamese vs global, payment types)
2. **Load relevant references** progressively as needed
3. **Implement authentication** using platform-specific methods
4. **Set up products/pricing** according to business model
5. **Implement checkout flow** (hosted, embedded, or API-driven)
6. **Configure webhooks** with proper verification
7. **Handle payment events** (success, failure, refund)
8. **Test thoroughly** in sandbox before production
9. **Monitor and optimize** using platform analytics

Load only the references needed for current implementation step to maintain context efficiency.