diff --git a/app/api/auth/[...nextauth]/route.ts b/app/api/auth/[...nextauth]/route.ts
index c94e94f91..b02a617e0 100644
--- a/app/api/auth/[...nextauth]/route.ts
+++ b/app/api/auth/[...nextauth]/route.ts
@@ -1,41 +1,5 @@
-import NextAuth, { getServerSession, type NextAuthOptions } from "next-auth";
-import AzureADProvider from "next-auth/providers/azure-ad";
-
-/**
- * Options for NextAuth.js used to configure adapters, providers, callbacks, etc.
- *
- * @see https://next-auth.js.org/configuration/options
- */
-export const authOptions: NextAuthOptions = {
-  callbacks: {
-    session: ({ session, token }) => ({
-      ...session,
-      user: {
-        ...session.user,
-        id: token.sub,
-      },
-    }),
-  },
-  providers: [
-    AzureADProvider({
-      clientId: process.env.AZURE_AD_CLIENT_ID ?? "",
-      clientSecret: process.env.AZURE_AD_CLIENT_SECRET ?? "",
-      tenantId: process.env.AZURE_AD_TENANT_ID ?? "",
-    }),
-  ],
-  pages: {
-    signIn: "/login",
-    signOut: "/login",
-    error: "/login",
-  },
-};
-
-/**
- * Wrapper for `getServerSession` so that you don't need to import the `authOptions` in every file.
- *
- * @see https://next-auth.js.org/configuration/nextjs
- */
-export const getServerAuthSession = () => getServerSession(authOptions);
+import { authOptions } from "@/app/auth";
+import NextAuth from "next-auth";
 
 const handler = NextAuth(authOptions);
 
diff --git a/app/auth.ts b/app/auth.ts
new file mode 100644
index 000000000..c59ac9c6e
--- /dev/null
+++ b/app/auth.ts
@@ -0,0 +1,63 @@
+import {
+  getServerSession,
+  type DefaultSession,
+  type NextAuthOptions,
+} from "next-auth";
+import AzureADProvider from "next-auth/providers/azure-ad";
+
+/**
+ * Module augmentation for `next-auth` types. Allows us to add custom properties to the `session`
+ * object and keep type safety.
+ *
+ * @see https://next-auth.js.org/getting-started/typescript#module-augmentation
+ */
+declare module "next-auth" {
+  interface Session extends DefaultSession {
+    user: {
+      id: string;
+      // ...other properties
+      // role: UserRole;
+    } & DefaultSession["user"];
+  }
+
+  // interface User {
+  //   // ...other properties
+  //   // role: UserRole;
+  // }
+}
+
+/**
+ * Options for NextAuth.js used to configure adapters, providers, callbacks, etc.
+ *
+ * @see https://next-auth.js.org/configuration/options
+ */
+export const authOptions: NextAuthOptions = {
+  callbacks: {
+    session: ({ session, token }) => ({
+      ...session,
+      user: {
+        ...session.user,
+        id: token.sub,
+      },
+    }),
+  },
+  providers: [
+    AzureADProvider({
+      clientId: process.env.AZURE_AD_CLIENT_ID ?? "",
+      clientSecret: process.env.AZURE_AD_CLIENT_SECRET ?? "",
+      tenantId: process.env.AZURE_AD_TENANT_ID ?? "",
+    }),
+  ],
+  pages: {
+    signIn: "/login",
+    signOut: "/login",
+    error: "/login",
+  },
+};
+
+/**
+ * Wrapper for `getServerSession` so that you don't need to import the `authOptions` in every file.
+ *
+ * @see https://next-auth.js.org/configuration/nextjs
+ */
+export const getServerAuthSession = () => getServerSession(authOptions);
diff --git a/app/config/server.ts b/app/config/server.ts
index 6eab9ebec..d95c15770 100644
--- a/app/config/server.ts
+++ b/app/config/server.ts
@@ -7,7 +7,6 @@ declare global {
       CODE?: string;
       BASE_URL?: string;
       PROXY_URL?: string;
-      VERCEL?: string;
       HIDE_USER_API_KEY?: string; // disable user's api key input
       DISABLE_GPT4?: string; // allow user to use gpt-4 or not
       BUILD_MODE?: "standalone" | "export";