Use internal origin for runtime locale state

middleware.ts

@@ -28,6 +28,20 @@ type SiteRuntimeState = {
   maintenanceEnabled: boolean;
 };
 
+function getSiteRuntimeStateOrigin(request: NextRequest): string {
+  const configuredOrigin = process.env.SITE_RUNTIME_ORIGIN?.trim();
+
+  if (configuredOrigin) {
+    return configuredOrigin;
+  }
+
+  if (process.env.NODE_ENV === "production") {
+    return "http://127.0.0.1:3000";
+  }
+
+  return request.nextUrl.origin;
+}
+
 function getPathLocale(pathname: string, fallbackLocale: (typeof appLocales)[number]) {
   const locale = pathname.split("/")[1];
 
@@ -40,8 +54,8 @@ function isComingSoonPath(pathname: string) {
 
 async function getSiteRuntimeState(request: NextRequest): Promise<SiteRuntimeState> {
   try {
-    const runtimeStateUrl = new URL("/api/site/default-locale", request.url);
-    const response = await fetch(new URL("/api/site/default-locale", request.url), {
+    const runtimeStateUrl = new URL("/api/site/default-locale", getSiteRuntimeStateOrigin(request));
+    const response = await fetch(runtimeStateUrl, {
       headers: {
         "x-middleware-request": "1",
       },
@@ -74,8 +88,8 @@ async function getSiteRuntimeState(request: NextRequest): Promise<SiteRuntimeSta
       defaultLocale: isSupportedLocale(data.defaultLocale) ? data.defaultLocale : FALLBACK_LOCALE,
       maintenanceEnabled: data.maintenanceEnabled === true,
     };
-  } catch {
-    console.error("middleware:getSiteRuntimeState:failed");
+  } catch (error) {
+    console.error("middleware:getSiteRuntimeState:failed", error);
     return {
       defaultLocale: FALLBACK_LOCALE,
       maintenanceEnabled: false,