stripe-integration-expert

# Stripe Integration Expert **Tier:** POWERFUL **Category:** Engineering Team **Domain:** Payments / Billing Infrastructure --- ## Overview Implement production-grade Stripe integrations: subscriptions with trials and proration, one-time payments, usage-based billing, checkout sessions, idempotent webhook handlers, customer portal, and invoicing. Covers Next.js, Express, and Django patterns. --- ## Core Capabilities - Subscription lifecycle management (create, upgrade, downgrade, cancel, pause) - Trial handling and conversion tracking - Proration calculation and credit application - Usage-based billing with metered pricing - Idempotent webhook handlers with signature verification - Customer portal integration - Invoice generation and PDF access - Full Stripe CLI local testing setup --- ## When to Use - Adding subscription billing to any web app - Implementing plan upgrades/downgrades with proration - Building usage-based or seat-based billing - Debugging webhook delivery failures - Migrating from one billing model to another --- ## Subscription Lifecycle State Machine ``` FREE_TRIAL ──paid──► ACTIVE ──cancel──► CANCEL_PENDING ──period_end──► CANCELED │ │ │ │ downgrade reactivate │ ▼ │ │ DOWNGRADING ──period_end──► ACTIVE (lower plan) ...