fix(billing): add StripeIdempotencyError to non-transient set + cover rawType branch

Pre-push review flagged the general isNonTransientStripeError helper omitted
StripeIdempotencyError (400, deterministic — reused key with conflicting params).
Add it. StripeCardError (402) stays excluded since some decline codes
(processing_error, issuer_unavailable) are transient. Add tests for the
rawType-only branch and the card exclusion; drop a mislabeled test.

Author: PierreBrisorgueil

modules/billing/lib/billing.stripe-errors.js

@@ -9,14 +9,17 @@
 
 const NON_TRANSIENT_STRIPE_ERROR_CLASSES = new Set([
   'StripeInvalidRequestError', // 400/404 — bad params, deterministic
+  'StripeIdempotencyError', // 400 — idempotency key reused with conflicting params, deterministic
   'StripeAuthenticationError', // 401 — bad/missing API key, deterministic
   'StripePermissionError', // 403 — key lacks permission for the resource, deterministic
 ]);
 
 /**
  * True when a Stripe error is deterministic and will never succeed on retry
- * (invalid request, authentication, or permission failures). Transient errors
- * (api_error/500, connection, rate_limit/429) return false so they keep retrying.
+ * (invalid request, idempotency, authentication, or permission failures). Transient
+ * errors (api_error/500, connection, rate_limit/429) return false so they keep
+ * retrying. StripeCardError (402) is intentionally excluded — some decline codes
+ * (processing_error, issuer_unavailable) are transient.
  *
  * @param {unknown} err
  * @returns {boolean}

modules/billing/tests/billing.stripe-errors.unit.tests.js

@@ -10,17 +10,19 @@ import { isNonTransientStripeError } from '../lib/billing.stripe-errors.js';
  * across both SDK-wrapped (.type = class name) and raw (.type = wire string) shapes.
  */
 describe('isNonTransientStripeError', () => {
-  test.each(['StripeInvalidRequestError', 'StripeAuthenticationError', 'StripePermissionError'])(
-    'returns true for SDK error class %s (err.type = class name)',
-    (type) => {
-      expect(isNonTransientStripeError({ type })).toBe(true);
-    },
-  );
+  test.each([
+    'StripeInvalidRequestError',
+    'StripeIdempotencyError',
+    'StripeAuthenticationError',
+    'StripePermissionError',
+  ])('returns true for SDK error class %s (err.type = class name)', (type) => {
+    expect(isNonTransientStripeError({ type })).toBe(true);
+  });
 
-  test('returns true for an SDK-wrapped error carrying rawType invalid_request_error', () => {
-    expect(
-      isNonTransientStripeError({ type: 'StripeInvalidRequestError', rawType: 'invalid_request_error' }),
-    ).toBe(true);
+  test('returns true via the rawType branch when the class is not listed', () => {
+    expect(isNonTransientStripeError({ type: 'StripeFutureUnknownError', rawType: 'invalid_request_error' })).toBe(
+      true,
+    );
   });
 
   test('returns true for an unwrapped API error object (type = invalid_request_error)', () => {
@@ -34,6 +36,10 @@ describe('isNonTransientStripeError', () => {
     },
   );
 
+  test('returns false for StripeCardError (402 — some decline codes are transient)', () => {
+    expect(isNonTransientStripeError({ type: 'StripeCardError' })).toBe(false);
+  });
+
   test('returns false for a generic non-Stripe error', () => {
     expect(isNonTransientStripeError(new Error('boom'))).toBe(false);
   });