Stripe API Integration: Webhooks & Subscriptions

1. Deep Architecture

Stripe sends webhook events to notify the system of subscription changes. We verify signatures using HMAC-SHA256 headers. To prevent duplicate billing from duplicate webhook retries, we use transaction locks and track processed message IDs.

2. The Feynman Gatekeeper

[KNOWLEDGE CHECK] Explain how webhook signature checks work, and how to prevent double-processing duplicate webhook events.

3. The Code

import stripe
from django.http import HttpResponse

def handle_stripe_webhook(request):
    payload = request.body
    sig_header = request.META.get('HTTP_STRIPE_SIGNATURE')
    try:
        # Cryptographically verify the webhook payload source signature
        event = stripe.Webhook.construct_event(payload, sig_header, "whsec_secret")
        return HttpResponse(status=200)
    except Exception:
        return HttpResponse(status=400)

4. The Funnel

Stat Level-Up: Billing Engineer (Lvl 1).
Sanjaya Integration: Update team subscription tiers when payments complete.