feat(core): make locale required on client.fetch()

Make the locale parameter required (not optional) on client.fetch()
to ensure correct channel resolution and Accept-Language header in
all contexts, including inside unstable_cache where getLocale() is
unavailable.

All call sites now explicitly pass locale. Build-time contexts
(next.config.ts, robots.txt, favicon.ico) and proxies pass an empty
string as locale since no request context is available.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: jorgemoya

.changeset/locale-required.md

@@ -0,0 +1,6 @@
+---
+"@bigcommerce/catalyst-client": minor
+"@bigcommerce/catalyst-core": minor
+---
+
+Make `locale` a required parameter on `client.fetch()`. All call sites now explicitly pass locale for correct channel resolution and `Accept-Language` header, including inside `unstable_cache` contexts where `getLocale()` is unavailable.

core/app/[locale]/(default)/(auth)/change-password/_actions/change-password.ts

@@ -3,7 +3,7 @@
 import { BigCommerceGQLError } from '@bigcommerce/catalyst-client';
 import { SubmissionResult } from '@conform-to/react';
 import { parseWithZod } from '@conform-to/zod';
-import { getTranslations } from 'next-intl/server';
+import { getLocale, getTranslations } from 'next-intl/server';
 import { z } from 'zod';
 
 import { client } from '~/client';
@@ -35,6 +35,7 @@ export async function changePassword(
   formData: FormData,
 ) {
   const t = await getTranslations('Auth.ChangePassword');
+  const locale = await getLocale();
   const submission = parseWithZod(formData, { schema });
 
   if (submission.status !== 'success') {
@@ -44,6 +45,7 @@ export async function changePassword(
   try {
     const response = await client.fetch({
       document: ChangePasswordMutation,
+      locale,
       variables: {
         input: {
           token,

core/app/[locale]/(default)/(auth)/change-password/page-data.ts

@@ -1,4 +1,5 @@
 import { unstable_cache } from 'next/cache';
+import { getLocale } from 'next-intl/server';
 import { cache } from 'react';
 
 import { client } from '~/client';
@@ -26,9 +27,10 @@ const ChangePasswordQuery = graphql(`
 `);
 
 const getCachedChangePasswordQuery = unstable_cache(
-  async () => {
+  async (locale: string) => {
     const response = await client.fetch({
       document: ChangePasswordQuery,
+      locale,
       fetchOptions: { cache: 'no-store' },
     });
 
@@ -44,5 +46,7 @@ const getCachedChangePasswordQuery = unstable_cache(
 );
 
 export const getChangePasswordQuery = cache(async () => {
-  return getCachedChangePasswordQuery();
+  const locale = await getLocale();
+
+  return getCachedChangePasswordQuery(locale);
 });

core/app/[locale]/(default)/(auth)/login/forgot-password/_actions/reset-password.ts

@@ -3,7 +3,7 @@
 import { BigCommerceGQLError } from '@bigcommerce/catalyst-client';
 import { SubmissionResult } from '@conform-to/react';
 import { parseWithZod } from '@conform-to/zod';
-import { getTranslations } from 'next-intl/server';
+import { getLocale, getTranslations } from 'next-intl/server';
 
 import { schema } from '@/vibes/soul/sections/forgot-password-section/schema';
 import { client } from '~/client';
@@ -30,6 +30,7 @@ export const resetPassword = async (
   formData: FormData,
 ): Promise<{ lastResult: SubmissionResult | null; successMessage?: string }> => {
   const t = await getTranslations('Auth.Login.ForgotPassword');
+  const locale = await getLocale();
 
   const submission = parseWithZod(formData, { schema });
 
@@ -40,6 +41,7 @@ export const resetPassword = async (
   try {
     const response = await client.fetch({
       document: ResetPasswordMutation,
+      locale,
       variables: {
         input: {
           email: submission.value.email,

core/app/[locale]/(default)/(auth)/register/_actions/register-customer.ts

@@ -373,6 +373,7 @@ export async function registerCustomer<F extends Field>(
     const input = parseRegisterCustomerInput(submission.value, fields);
     const response = await client.fetch({
       document: RegisterCustomerMutation,
+      locale,
       variables: {
         input,
         reCaptchaV2:

core/app/[locale]/(default)/(auth)/register/page-data.ts

@@ -1,3 +1,4 @@
+import { getLocale } from 'next-intl/server';
 import { cache } from 'react';
 
 import { getSessionCustomerAccessToken } from '~/auth';
@@ -63,6 +64,7 @@ interface Props {
 
 export const getRegisterCustomerQuery = cache(async ({ address, customer }: Props) => {
   const customerAccessToken = await getSessionCustomerAccessToken();
+  const locale = await getLocale();
 
   const response = await client.fetch({
     document: RegisterCustomerQuery,
@@ -72,6 +74,7 @@ export const getRegisterCustomerQuery = cache(async ({ address, customer }: Prop
       customerFilters: customer?.filters,
       customerSortBy: customer?.sortBy,
     },
+    locale,
     fetchOptions: { cache: 'no-store' },
     customerAccessToken,
   });

core/app/[locale]/(default)/(faceted)/search/page-data.ts

@@ -1,4 +1,5 @@
 import { unstable_cache } from 'next/cache';
+import { getLocale } from 'next-intl/server';
 import { cache } from 'react';
 
 import { client } from '~/client';
@@ -31,9 +32,10 @@ const SearchPageQuery = graphql(`
 `);
 
 const getCachedSearchPageData = unstable_cache(
-  async () => {
+  async (locale: string) => {
     const response = await client.fetch({
       document: SearchPageQuery,
+      locale,
       fetchOptions: { cache: 'no-store' },
     });
 
@@ -44,5 +46,7 @@ const getCachedSearchPageData = unstable_cache(
 );
 
 export const getSearchPageData = cache(async () => {
-  return getCachedSearchPageData();
+  const locale = await getLocale();
+
+  return getCachedSearchPageData(locale);
 });

core/app/[locale]/(default)/account/addresses/_actions/create-address.ts

@@ -1,7 +1,7 @@
 import { BigCommerceAPIError, BigCommerceGQLError } from '@bigcommerce/catalyst-client';
 import { parseWithZod } from '@conform-to/zod';
 import { revalidateTag } from 'next/cache';
-import { getTranslations } from 'next-intl/server';
+import { getLocale, getTranslations } from 'next-intl/server';
 import { z } from 'zod';
 
 import { Field, FieldGroup } from '@/vibes/soul/form/dynamic-form/schema';
@@ -202,6 +202,7 @@ export async function createAddress(
   formData: FormData,
 ): Promise<State> {
   const t = await getTranslations('Account.Addresses');
+  const locale = await getLocale();
   const customerAccessToken = await getSessionCustomerAccessToken();
 
   const submission = parseWithZod(formData, { schema });
@@ -218,6 +219,7 @@ export async function createAddress(
 
     const response = await client.fetch({
       document: AddCustomerAddressMutation,
+      locale,
       customerAccessToken,
       fetchOptions: { cache: 'no-store' },
       variables: {

core/app/[locale]/(default)/account/addresses/_actions/delete-address.ts

@@ -1,7 +1,7 @@
 import { BigCommerceGQLError } from '@bigcommerce/catalyst-client';
 import { parseWithZod } from '@conform-to/zod';
 import { revalidateTag } from 'next/cache';
-import { getTranslations } from 'next-intl/server';
+import { getLocale, getTranslations } from 'next-intl/server';
 import { z } from 'zod';
 
 import { schema } from '@/vibes/soul/sections/address-list-section/schema';
@@ -46,6 +46,7 @@ function parseDeleteAddressInput(
 
 export async function deleteAddress(prevState: Awaited<State>, formData: FormData): Promise<State> {
   const t = await getTranslations('Account.Addresses');
+  const locale = await getLocale();
   const customerAccessToken = await getSessionCustomerAccessToken();
 
   const submission = parseWithZod(formData, { schema });
@@ -62,6 +63,7 @@ export async function deleteAddress(prevState: Awaited<State>, formData: FormDat
 
     const response = await client.fetch({
       document: DeleteCustomerAddressMutation,
+      locale,
       customerAccessToken,
       fetchOptions: { cache: 'no-store' },
       variables: {

core/app/[locale]/(default)/account/addresses/_actions/update-address.ts

@@ -1,7 +1,7 @@
 import { BigCommerceGQLError } from '@bigcommerce/catalyst-client';
 import { parseWithZod } from '@conform-to/zod';
 import { revalidateTag } from 'next/cache';
-import { getTranslations } from 'next-intl/server';
+import { getLocale, getTranslations } from 'next-intl/server';
 import { z } from 'zod';
 
 import { Field, FieldGroup } from '@/vibes/soul/form/dynamic-form/schema';
@@ -215,6 +215,7 @@ export async function updateAddress(
   formData: FormData,
 ): Promise<State> {
   const t = await getTranslations('Account.Addresses');
+  const locale = await getLocale();
   const customerAccessToken = await getSessionCustomerAccessToken();
 
   const submission = parseWithZod(formData, { schema });
@@ -231,6 +232,7 @@ export async function updateAddress(
 
     const response = await client.fetch({
       document: UpdateCustomerAddressMutation,
+      locale,
       customerAccessToken,
       fetchOptions: { cache: 'no-store' },
       variables: {