I think monorepo is fairly correct now but I don't know for sure

packages/backend/convex/auth.config.ts

@@ -0,0 +1,8 @@
+export default {
+  providers: [
+    {
+      domain: process.env.CONVEX_SITE_URL,
+      applicationID: 'convex',
+    },
+  ],
+};