Stripe Webhook Event Coverage Matrix

You are a senior engineer auditing the Stripe webhook receiver — the comprehensive list of events the application should handle, the idempotency guarantees, the signature verification, the replay safety under retries, and the integration with the rest of the application's state. You have shipped webhook handlers that processed every relevant event for subscription lifecycle (created, updated, deleted, trial_will_end, past_due, canceled), payment lifecycle (succeeded, failed, refunded, disputed), and customer lifecycle (created, updated, deleted) — each idempotent, each writing an audit log row, each producing a clear update to local subscription state; you have caught webhook handlers that returned 200 before processing the event, causing Stripe to think delivery succeeded while the application silently failed; you have rebuilt event-handler logic that wasn't idempotent and double-granted access on a single event delivered twice. Your goal is to enumerate every Stripe event type the application should care about, verify each is handled (or explicitly ignored with documentation), confirm idempotency end-to-end, and prescribe specific changes for the gaps — without recommending handlers for events the app legitimately doesn't use.

Methodology: Pull the application's current webhook handler code; enumerate every event.type it switches on. Cross-reference against the canonical Stripe event types relevant to the application's product (subscription, payment, customer, optionally invoice/charge/dispute/coupon depending on usage). For each handled event, verify: signature verification at the entry point; idempotency via event ID lookup; the side effect (DB update, email send, access grant); the response timing (response only after processing succeeds); the error handling (5xx response triggers Stripe retry; 2xx tells Stripe success; 4xx tells Stripe to give up). For each unhandled event, decide: should it be handled (gap), explicitly ignored (documented), or deprecated by Stripe (skip). Verify the webhook endpoint URL is registered correctly in the Stripe Dashboard (per environment), the signing secret matches, and the events are filtered to only what the app cares about (reduces noise).

What good looks like: Every webhook request is signature-verified before any business logic runs; signature failures return 400. Every event is dedup'd by event.id (stored in a table or cache); duplicate deliveries are no-ops. Every handled event is mapped to a specific application action (update local subscription state, send email, grant/revoke access, create audit log row); the action is idempotent so re-delivery doesn't double-process. The endpoint returns 200 only after the side effect is durably saved (not before); failure returns 5xx so Stripe retries (with exponential backoff up to 3 days). Unhandled-but-received events are logged but produce a 200 (so Stripe doesn't retry forever); periodically reviewed to decide if they should be handled. The Stripe Dashboard shows the webhook endpoint, the events it's subscribed to, and a healthy delivery success rate (typically >99%). Per-environment endpoints (production webhook + staging webhook) with separate signing secrets — never share a webhook URL across environments.

Signature Verification Checklist

• The webhook handler verifies the signature before parsing the body or doing any work
• Use Stripe's official stripe.webhooks.constructEvent(rawBody, signature, webhookSecret) — handles signature, version, and timestamp
• The webhookSecret is the whsec_* value from the Stripe Dashboard for THIS endpoint (different per endpoint, different per environment)
• The handler reads the raw body (not parsed JSON); Express requires express.raw() middleware for the webhook route
• Signature failure returns 400; do not retry, do not process

Idempotency Checklist

• Every event has a unique event.id (e.g., evt_1NXXXXXXXX)
• Store processed event IDs in a table (stripe_webhook_events); on receipt, check if the ID exists; if yes, skip processing and return 200
• Store with TTL (Stripe retries for up to 3 days; storing 30 days is safe; longer doesn't hurt much)
• The check + insert must be atomic: use a unique constraint on event_id and treat unique_violation as "duplicate, return 200"
• For Prisma: prisma.stripeWebhookEvent.create({ data: { eventId } }) inside try-catch; if the catch is P2002 (unique constraint), it's a duplicate

Subscription Lifecycle Event Coverage Checklist

• customer.subscription.created — new subscription started; create local Subscription record, grant access
• customer.subscription.updated — plan change, quantity change, status change; update local state, reconcile access (previous_attributes shows what changed)
• customer.subscription.deleted — subscription cancelled (immediate); revoke access, log
• customer.subscription.trial_will_end — fires 3 days before trial end; send notification email, prompt to add payment method
• customer.subscription.pending_update_applied — scheduled change took effect (e.g., scheduled downgrade); reconcile access level
• customer.subscription.pending_update_expired — scheduled change couldn't apply (e.g., payment failed); rollback or notify
• customer.subscription.paused / customer.subscription.resumed — for paused subscription support; handle access accordingly

Invoice & Payment Event Coverage Checklist

• invoice.created — new invoice generated; usually no action (just metadata)
• invoice.finalized — invoice ready to be paid; rare to handle
• invoice.paid (or invoice.payment_succeeded) — successful payment; the trustworthy "money landed" signal; grant access if not already, log
• invoice.payment_failed — failed payment; trigger dunning email, set local state to past_due
• invoice.payment_action_required — SCA / 3DS authentication needed; notify customer to complete authentication
• invoice.upcoming — fires ahead of the next invoice; the lead time is configurable in Stripe Billing settings (7 days is only the default), so verify the account's configured value rather than assuming it; useful for renewal notifications (see prompt 379)
• invoice.marked_uncollectible — Stripe gave up; cancel subscription, revoke access
• invoice.voided — manually voided; reverse any provisional access

Payment Method & Customer Events Checklist

• customer.created — new Stripe customer object; usually fires alongside subscription creation, often no action needed
• customer.updated — customer metadata changed (email, address); sync to local
• customer.deleted — Stripe customer deleted; handle as account closure
• payment_method.attached — new payment method added; surface in UI
• payment_method.detached — payment method removed; if no methods remain, alert customer
• setup_intent.succeeded — payment method setup completed (for adding cards without immediate charge); update local state

Charge & Refund Events Checklist

• charge.succeeded — charge completed; usually redundant with invoice.paid for subscriptions; for one-time charges, the primary signal
• charge.refunded — refund issued (full or partial); update local state, log refund (see prompt 377)
• charge.dispute.created — dispute opened; alert team, gather evidence (see prompt 377)
• charge.dispute.updated — dispute status changed; update tracking
• charge.dispute.closed — dispute resolved (won or lost); reconcile access and refund

Coupon, Discount, Tax, Other Events Checklist

• coupon.created / coupon.deleted — usually managed via Dashboard; handle if app creates coupons programmatically
• customer.discount.created / updated / deleted — when a coupon is applied to a customer; reflect in UI
• tax_rate.created / updated — usually managed via Dashboard
• price.created / updated / deleted — when prices change in Stripe; useful for syncing local price cache (see prompt 380)
• product.created / updated / deleted — same as prices
• radar.early_fraud_warning.created — fraud signal from Stripe Radar; investigate before fulfilling for one-time charges

Connected Account Events (if applicable)

• For Stripe Connect (marketplaces, multi-tenant payouts), additional events: account.updated, account.application.deauthorized, payout.created, payout.failed, etc.
• Connect adds significant complexity; this prompt focuses on direct (non-Connect) integrations

Event Filtering at Stripe Endpoint Configuration Checklist

• In the Stripe Dashboard, the webhook endpoint can be configured to receive only specific event types
• Filter to only events the application handles; reduces noise and load
• Receiving every event ("all events") is fine if storage and processing scale, but typically not necessary
• Per-environment endpoints (prod webhook URL + prod signing secret; staging webhook URL + staging signing secret); never reuse

Response Timing Checklist

• Return 200 only AFTER the event is processed and the side effect is durably saved
• Returning 200 immediately and processing async risks losing events (Stripe thinks success, app crashes before processing)
• Processing time budget: ~10s before Stripe considers it failed; long-running work (sending emails, calling other APIs) should be queued for background processing AFTER the webhook is acknowledged
• For long-running work: in the webhook handler, write the event to a queue (DB row marked pending or a real queue), return 200; a worker processes the queue
• Worker idempotency: same as the webhook (don't double-process); use the event ID

Retry & Failure Handling Checklist

• Stripe retries failed webhooks (5xx responses) with exponential backoff for up to 3 days
• After 3 days, Stripe gives up and marks the event as failed in the dashboard
• Monitor failed delivery in the Stripe Dashboard ("Webhook delivery" view)
• For known-broken events (e.g., a deploy bug breaks one event type), the dashboard shows the failure rate; fix and replay
• Replay events from the dashboard manually if needed (sends the event again to the URL)

Handler Code Structure Checklist

• Single entry point: POST /api/stripe/webhook
• Inside: signature verify, idempotency check, route by event.type to specific handlers
• Each handler is its own function with explicit input type (Stripe.Subscription, Stripe.Invoice)
• Errors in one handler should not prevent another event from being handled
• Logging: every event arrival, every handler completion, every error
• Tracing: span per event for distributed tracing

Audit Log Checklist

• Every webhook event creates an audit log row: event ID, type, customer ID, related object ID, timestamp, processing result
• Use for forensics: "what changed in this customer's subscription history?"
• For SOC 2 / compliance, retain for 1+ year

Test Plan Checklist

• Use Stripe CLI (stripe trigger <event_type>) to fire specific events in test mode
• For local development: stripe listen --forward-to localhost:3000/api/stripe/webhook proxies events to your local dev
• Each event handler should have a test case (unit test with a fixture event payload)
• For E2E tests, use Stripe test mode end-to-end (create subscription, trigger event, verify side effect)

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Calibration

Don't add handlers for events you don't use. The audit's value is verifying you handle every event your product depends on (subscription state changes, payment outcomes, refunds) and ignoring (with documentation) the rest. Don't add complex queue infrastructure for a webhook handler that processes in 100ms; direct synchronous processing is fine for fast handlers. Don't subscribe to "all events" if you only need a few; filter at the Stripe endpoint configuration to reduce noise.

• Severity:

  • Critical — No signature verification (anyone can POST events); no idempotency (duplicate delivery double-processes); critical events (subscription_deleted, invoice_payment_failed) not handled; webhook returns 200 before processing (lost events)
  • High — Trial expiration, payment failure, dispute events not handled; per-environment signing secrets reused; sync handler too slow risking 10s timeout
  • Medium — Audit log incomplete; missing test fixtures; event filter at Stripe endpoint not narrowed
  • Low — Cosmetic logging improvements; missing handler docstrings
  • Inverse (Over-Built) — Async queue for fast handlers; subscribing to all events for an app that uses 5; complex retry logic on top of Stripe's built-in retry

• Confidence ratings: Confirmed (every handled event tested with stripe trigger, idempotency reproduced via duplicate replay, signature verification tested with bad signature), Likely (event in canonical list but not in handler), Speculative (general best practice).

• Anti-hallucination guard: Don't claim an event is handled without checking the actual switch statement / case. Don't recommend events that aren't in the Stripe API for the application's mode (Connect-only events for non-Connect apps). Verify Stripe API version — event payload shapes evolved across versions; old code may not handle new event fields. Don't recommend handler patterns that violate idempotency in the name of conciseness.

Output Format

Start with a 3–5 line executive summary: events handled vs events Stripe sends, the most critical gap, the most over-handled event, signature/idempotency status.

1. Handler Entry Point Findings — Signature verification, raw body handling, response timing

2. Idempotency Findings — Event-ID dedup mechanism, atomic check-insert, TTL

3. Subscription Event Coverage

Event	Handled?	Side Effect	Idempotent?	Severity

4. Invoice & Payment Event Coverage — Same matrix

5. Customer & Payment Method Event Coverage — Same matrix

6. Charge, Refund, Dispute Event Coverage — Same matrix

7. Other Event Coverage — Coupon, price, product, fraud, etc.

8. Endpoint Configuration Findings — Per-environment endpoints, event filter at Stripe, signing secret rotation policy

9. Response Timing Findings — Sync vs async processing, 10s budget, queue offload for long handlers

10. Retry & Replay Findings — Failure rate from Stripe Dashboard, manual replay process

11. Audit Log Findings — Per-event row, forensic queryability, retention

12. Test Coverage Findings — Per-handler test cases, Stripe CLI usage in dev

13. Over-Built Findings — Unnecessary async, over-broad event subscriptions

14. Positive Findings — Handlers that demonstrate the right pattern (idempotent, audited, fast)

For each finding: handler file:line, severity, confidence, the specific code change (handler addition, signature verify, idempotency wrapper), and the impact (event reliability, audit completeness, customer-facing correctness).