perf: cache Supabase admin client as module-level singleton

src/lib/supabase/admin.ts

@@ -2,13 +2,22 @@ import { createClient } from "@supabase/supabase-js";
 import { requireServerEnv } from "@/lib/env";
 import type { Database } from "./database.types";
 
-export function createAdminClient() {
-  const { NEXT_PUBLIC_SUPABASE_URL: url, SUPABASE_SERVICE_ROLE_KEY: key } = requireServerEnv();
+// Cache the admin client as a module-level singleton so that every API request
+// reuses the same instance (and its underlying HTTP agent) rather than allocating
+// a fresh one on every call. Mirrors the openAIClient singleton in openai.ts.
+// The service-role client carries no user-specific session state, so sharing it
+// across requests is safe.
+let adminClient: ReturnType<typeof createClient<Database>> | null = null;
 
-  return createClient<Database>(url, key, {
-    auth: {
-      autoRefreshToken: false,
-      persistSession: false,
-    },
-  });
+export function createAdminClient() {
+  if (!adminClient) {
+    const { NEXT_PUBLIC_SUPABASE_URL: url, SUPABASE_SERVICE_ROLE_KEY: key } = requireServerEnv();
+    adminClient = createClient<Database>(url, key, {
+      auth: {
+        autoRefreshToken: false,
+        persistSession: false,
+      },
+    });
+  }
+  return adminClient;
 }