more

cmd/order/handlers_checkout.go

@@ -134,11 +134,12 @@ func (s *server) handleFromCheckout(w http.ResponseWriter, r *http.Request) {
 		s.logger.Warn("from-checkout flow failed", "orderId", id.String(), "err", runErr)
 	}
 
-	// Record the idempotency key durably so retries (incl. after a restart) are
-	// safe. We record even on a failed flow: the failed order grain exists, and a
-	// blind retry with the same key should return it rather than place a second
-	// order — the caller is told to retry with a fresh key (402 contract).
-	if req.IdempotencyKey != "" {
+	// Record the idempotency key durably only on success, so retries (incl. after
+	// a restart) return the captured order. A failed flow (402) is deliberately
+	// NOT recorded: the failed grain is terminal, and a retry with the same key
+	// should re-attempt rather than be handed back a dead order as a 409 hit
+	// (which the checkout client treats as a successful, existing order).
+	if req.IdempotencyKey != "" && runErr == nil {
 		if err := s.idem.Put(req.IdempotencyKey, ordID); err != nil {
 			s.logger.Error("idempotency record failed", "key", req.IdempotencyKey, "orderId", id.String(), "err", err)
 		}