Going live checklist

When sandbox testing is complete, this is the runbook for going live. Work top to bottom. Don't skip the verification steps — each one represents a class of mistake we've seen real merchants make.

1. Credentials

• Live keys (pk_live_… / sk_live_…) issued by your account manager
• Secret key stored in your secrets manager — never in source control
• Test keys removed from production config (no fallback to sandbox)
• Old test-mode webhook URL retired or pointed at a no-op handler

2. Webhook endpoint

• Live webhook URL registered with your account manager
• Endpoint is HTTPS, public, and responds inside 10 seconds
• Signature verification implemented with crypto.timingSafeEqual — see Verify webhook signatures
• Endpoint rejects mismatched environment field (live handler refuses "test" events)
• Deduplication on eventId is in place — handlers are idempotent
• Handler returns 2xx promptly; heavy processing happens asynchronously

3. Idempotency

• Every POST /payments, POST /subscriptions, and POST /refund includes an externalId you control
• externalId is unique per intent — orders, invoices, refund batches
• No accidental reuse across customers or environments

4. Final dress rehearsal

Before flipping traffic:

• Run one live charge with a real card you control — confirm payment.succeeded
• Verify funds appear in your settlement account
• Refund the same charge — confirm payment.refunded and money returns
• Subscribe yourself to a recurring plan — confirm the renewal cron fires
• Cancel the subscription — confirm subscription.cancelled

What to monitor in the first week

• Webhook delivery success rate — should be near 100%; we retry, but persistent failures need investigation
• payment.failed rate by error code — sudden spikes usually mean a config drift
• Subscription churn at the past_due → cancelled boundary — early signal of dunning issues
• requestId correlation between application errors and MintCash failures

If anything looks off, your support channel goes both ways. We see your traffic too — flag anything anomalous and we'll dig in together.