preserve auth headers in json proxies

frontend/app/api/ops/subscriptions/extend/route.ts

@@ -1,5 +1,5 @@
 import { NextRequest, NextResponse } from "next/server";
-import { applyAuthResponseCookies, buildBackendRequestHeaders } from "@/lib/backend-auth";
+import { applyAuthResponseCookies, buildBackendRequestHeaders, buildJsonBackendRequestHeaders } from "@/lib/backend-auth";
 import { buildProxyExceptionResponse } from "@/lib/api-proxy";
 import { requireOpsProxyAuth } from "@/lib/ops-proxy-auth";
 
@@ -14,9 +14,9 @@ export async function POST(req: NextRequest) {
     if (authError) return authError;
 
     const body = await req.text();
-    const headers: Record<string, string> = { ...auth.headers as Record<string, string>, "Content-Type": "application/json" };
+    const headers = buildJsonBackendRequestHeaders(auth.headers);
     if (ENTITLEMENT_TOKEN) {
-      headers.Authorization = `Bearer ${ENTITLEMENT_TOKEN}`;
+      headers.set("Authorization", `Bearer ${ENTITLEMENT_TOKEN}`);
     }
     const res = await fetch(`${API_BASE}/api/ops/subscriptions/extend`, {
       method: "POST", headers, body, cache: "no-store",

frontend/app/api/ops/subscriptions/grant/route.ts

@@ -2,6 +2,7 @@ import { NextRequest, NextResponse } from "next/server";
 import {
   applyAuthResponseCookies,
   buildBackendRequestHeaders,
+  buildJsonBackendRequestHeaders,
 } from "@/lib/backend-auth";
 import { buildProxyExceptionResponse } from "@/lib/api-proxy";
 import { requireOpsProxyAuth } from "@/lib/ops-proxy-auth";
@@ -166,7 +167,7 @@ export async function POST(req: NextRequest) {
 
     const res = await fetch(`${API_BASE}/api/ops/subscriptions/grant`, {
       method: "POST",
-      headers: { ...(auth.headers as Record<string, string>), "Content-Type": "application/json" },
+      headers: buildJsonBackendRequestHeaders(auth.headers),
       body,
       cache: "no-store",
     });