Credit-Based Payment Architecture

Credit system with Stripe integration, usage tracking, and idempotent payment processing for SaaS monetization.

Production implementation used in AuthorAI for credit purchases and usage tracking.

Key Design Decisions

Idempotency keys: Every payment request includes an idempotency key to prevent duplicate charges on retries.
Webhook verification: All webhooks are verified using signatures to prevent replay attacks and ensure authenticity.
Error recovery: Failed payments are logged with full context, and retry logic handles transient failures.