fix: set checkout languageCode to ensure emails are sent in correct language

- Add CHECKOUT_LANGUAGE_CODE_UPDATE mutation to update checkout language
- Call language code update before completing checkout
- Language code (SR, EN, DE, FR) is now set on checkout before order creation
- This ensures order confirmation emails are sent in the customer's language
- Update step numbering in checkout flow (now 6 steps total)

src/app/[locale]/checkout/page.tsx

@@ -18,6 +18,8 @@ import {
   CHECKOUT_EMAIL_UPDATE,
   CHECKOUT_METADATA_UPDATE,
   CHECKOUT_SHIPPING_METHOD_UPDATE,
+  ORDER_METADATA_UPDATE,
+  CHECKOUT_LANGUAGE_CODE_UPDATE,
 } from "@/lib/saleor/mutations/Checkout";
 import { PaymentSection } from "./components/PaymentSection";
 import { DEFAULT_PAYMENT_METHOD } from "@/lib/config/paymentMethods";
@@ -313,7 +315,17 @@ export default function CheckoutPage() {
         }
         console.log("Step 1: Email updated successfully");
 
-        console.log("Step 2: Updating billing address...");
+        console.log("Step 2: Updating language code...");
+        await saleorClient.mutate({
+          mutation: CHECKOUT_LANGUAGE_CODE_UPDATE,
+          variables: {
+            checkoutId: checkout.id,
+            languageCode: locale.toUpperCase(),
+          },
+        });
+        console.log("Step 2: Language code updated to", locale.toUpperCase());
+
+        console.log("Step 3: Updating billing address...");
         const billingResult = await saleorClient.mutate<BillingAddressUpdateResponse>({
           mutation: CHECKOUT_BILLING_ADDRESS_UPDATE,
           variables: {
@@ -334,9 +346,9 @@ export default function CheckoutPage() {
         if (billingResult.data?.checkoutBillingAddressUpdate?.errors && billingResult.data.checkoutBillingAddressUpdate.errors.length > 0) {
           throw new Error(`Billing address update failed: ${billingResult.data.checkoutBillingAddressUpdate.errors[0].message}`);
         }
-        console.log("Step 2: Billing address updated successfully");
+        console.log("Step 3: Billing address updated successfully");
 
-        console.log("Step 3: Setting shipping method...");
+        console.log("Step 4: Setting shipping method...");
         const shippingMethodResult = await saleorClient.mutate<ShippingMethodUpdateResponse>({
           mutation: CHECKOUT_SHIPPING_METHOD_UPDATE,
           variables: {
@@ -348,9 +360,9 @@ export default function CheckoutPage() {
         if (shippingMethodResult.data?.checkoutShippingMethodUpdate?.errors && shippingMethodResult.data.checkoutShippingMethodUpdate.errors.length > 0) {
           throw new Error(`Shipping method update failed: ${shippingMethodResult.data.checkoutShippingMethodUpdate.errors[0].message}`);
         }
-        console.log("Step 3: Shipping method set successfully");
+        console.log("Step 4: Shipping method set successfully");
 
-        console.log("Step 4: Saving metadata...");
+        console.log("Step 5: Saving metadata...");
         const metadataResult = await saleorClient.mutate<MetadataUpdateResponse>({
           mutation: CHECKOUT_METADATA_UPDATE,
           variables: {
@@ -367,10 +379,10 @@ export default function CheckoutPage() {
         if (metadataResult.data?.updateMetadata?.errors && metadataResult.data.updateMetadata.errors.length > 0) {
           console.warn("Failed to save phone metadata:", metadataResult.data.updateMetadata.errors);
         } else {
-          console.log("Step 4: Phone number saved successfully");
+          console.log("Step 5: Phone number saved successfully");
         }
 
-        console.log("Step 5: Completing checkout...");
+        console.log("Step 6: Completing checkout...");
         const completeResult = await saleorClient.mutate<CheckoutCompleteResponse>({
           mutation: CHECKOUT_COMPLETE,
           variables: {

src/lib/saleor/mutations/Checkout.ts

@@ -173,3 +173,40 @@ export const CHECKOUT_METADATA_UPDATE = gql`
     }
   }
 `;
+
+export const ORDER_METADATA_UPDATE = gql`
+  mutation OrderMetadataUpdate($orderId: ID!, $metadata: [MetadataInput!]!) {
+    updateMetadata(id: $orderId, input: $metadata) {
+      item {
+        ... on Order {
+          id
+          metadata {
+            key
+            value
+          }
+        }
+      }
+      errors {
+        field
+        message
+        code
+      }
+    }
+  }
+`;
+
+export const CHECKOUT_LANGUAGE_CODE_UPDATE = gql`
+  mutation CheckoutLanguageCodeUpdate($checkoutId: ID!, $languageCode: LanguageCodeEnum!) {
+    checkoutLanguageCodeUpdate(checkoutId: $checkoutId, languageCode: $languageCode) {
+      checkout {
+        id
+        languageCode
+      }
+      errors {
+        field
+        message
+        code
+      }
+    }
+  }
+`;