fix(billing): address reviewer nits — narrow comment + improve log wording

- Narrow shouldRetry JSDoc comment to only mention invalid_request_error
  (not auth errors) — matches what the predicate actually checks
  (Copilot thread PRRT_kwDOBss37M6EM5HL)
- Change failure log from "failed after retries" to "failed (retries
  exhausted or skipped)" to reflect short-circuit path
  (CodeRabbit thread PRRT_kwDOBss37M6EM5c1)
- Update billing.refund-correlation tests to match new log wording

Author: PierreBrisorgueil

modules/billing/services/billing.webhook.service.js

@@ -326,16 +326,16 @@ const handleCheckoutPaymentCompleted = async (session) => {
           {
             attempts: 3,
             baseMs: 200,
-            // Skip retries on deterministic Stripe client errors (bad params / auth) — they
-            // never succeed on retry and only delay the dead-letter path. Same classification
-            // as billing.admin.controller.js.
+            // Skip retries on Stripe invalid-request errors (invalid_request_error /
+            // StripeInvalidRequestError) — these are deterministic client errors that never
+            // succeed on retry and only delay the dead-letter path.
             shouldRetry: (err) =>
               err?.type !== 'StripeInvalidRequestError' && err?.type !== 'invalid_request_error',
           },
         );
       } catch (err) {
         logger.error(
-          '[billing.webhook] PI metadata backfill failed after retries — refund correlation at risk',
+          '[billing.webhook] PI metadata backfill failed (retries exhausted or skipped) — refund correlation at risk',
           { paymentIntentId, stripeSessionId, error: err?.message ?? String(err), stack: err?.stack },
         );
         try {

modules/billing/tests/billing.refund-correlation.unit.tests.js

@@ -158,7 +158,7 @@ describe('checkout.session.completed — metadata backfill retry:', () => {
 
     // logger.error should be called for the final failure.
     expect(mockLogger.error).toHaveBeenCalledWith(
-      expect.stringContaining('backfill failed after retries'),
+      expect.stringContaining('backfill failed (retries exhausted or skipped)'),
       expect.objectContaining({ paymentIntentId }),
     );
 
@@ -185,7 +185,7 @@ describe('checkout.session.completed — metadata backfill retry:', () => {
     // Both error paths should be logged.
     expect(mockLogger.error).toHaveBeenCalledTimes(2);
     expect(mockLogger.error).toHaveBeenCalledWith(
-      expect.stringContaining('backfill failed after retries'),
+      expect.stringContaining('backfill failed (retries exhausted or skipped)'),
       expect.objectContaining({ paymentIntentId }),
     );
     expect(mockLogger.error).toHaveBeenCalledWith(