fix(admin): eliminate GoTrue empty-body 500s under bulk load (retry-all + undici keep-alive + sequential bulk), CSV formula-injection guard

lib/admin/csv.ts

@@ -11,6 +11,13 @@ export function csvField(v: unknown): string {
   else if (typeof v === 'string') s = v;
   else if (typeof v === 'object') s = JSON.stringify(v);
   else s = String(v);
+  // Spreadsheet formula-injection guard: a field whose first character is one
+  // of = + - @ (or a leading tab/CR) is interpreted as a formula by Excel /
+  // Sheets / LibreOffice. Neutralize it by prefixing a single quote BEFORE the
+  // RFC-4180 quote-escaping below, so the value renders as literal text.
+  if (s.length > 0 && /^[=+\-@\t\r]/.test(s)) {
+    s = `'${s}`;
+  }
   if (/[",\r\n]/.test(s)) {
     return `"${s.replace(/"/g, '""')}"`;
   }

lib/admin/metrics.ts

@@ -1,4 +1,5 @@
 import { getSupabaseAdmin } from '@/lib/supabase/admin';
+import { withAdminRetry } from '@/lib/admin/retry';
 
 export type AdminMetrics = {
   totalUsers: number;
@@ -52,7 +53,9 @@ export async function computeMetrics(): Promise<AdminMetrics> {
   let signups30d = 0;
   const perPage = 1000;
   for (let page = 1; page <= 50; page++) {
-    const { data, error } = await admin.auth.admin.listUsers({ page, perPage });
+    const { data, error } = await withAdminRetry(() =>
+      admin.auth.admin.listUsers({ page, perPage }),
+    );
     if (error) break;
     const users = data.users;
     if (users.length === 0) break;

lib/admin/retry.ts

@@ -15,11 +15,20 @@
  * surface as proper 4xx/5xx responses upstream.
  */
 
-// Up to 3 attempts total (1 initial + 2 retries). Delays are applied BEFORE the
-// 2nd and 3rd attempts respectively, so worst-case added latency is ~350ms —
-// kept well under a second to keep the admin surface snappy.
-const MAX_ATTEMPTS = 3;
-const RETRY_DELAYS_MS = [100, 250];
+// Up to 5 attempts total (1 initial + 4 retries). Delays are applied BEFORE
+// attempts 2..5 respectively and are jittered (see `jitter`), so worst-case
+// added latency is ~80+150+300+600 ≈ 1.13s plus jitter — kept under ~1.5s to
+// keep the admin surface snappy while reliably riding out the empty-body /
+// poisoned-keep-alive window that Node 24's bundled undici amplifies.
+const MAX_ATTEMPTS = 5;
+const RETRY_DELAYS_MS = [80, 150, 300, 600];
+
+/** Apply ±30% random jitter so concurrent retries don't synchronise. */
+function jitter(ms: number): number {
+  if (ms <= 0) return 0;
+  const delta = ms * 0.3;
+  return Math.round(ms - delta + Math.random() * 2 * delta);
+}
 
 /** Loose shape that both `AuthError` and `PostgrestError` satisfy. */
 type MaybeError =
@@ -116,7 +125,8 @@ export async function withAdminRetry<R extends { error: MaybeError }>(
     }
 
     if (attempt < attempts) {
-      const delay = delays[attempt - 1] ?? delays[delays.length - 1] ?? 0;
+      const base = delays[attempt - 1] ?? delays[delays.length - 1] ?? 0;
+      const delay = jitter(base);
       if (delay > 0) await sleep(delay);
     }
   }

lib/supabase/admin.ts

@@ -1,7 +1,36 @@
 import { createClient, SupabaseClient } from '@supabase/supabase-js';
+import { Agent } from 'undici';
 
 let _admin: SupabaseClient | null = null;
 
+/**
+ * Dedicated undici dispatcher for all admin-client traffic (GoTrue + PostgREST).
+ *
+ * ROOT CAUSE this addresses: GoTrue/undici intermittently returns an empty or
+ * truncated HTTP body when a pooled keep-alive connection is REUSED right after
+ * a write (bulk ban/role/delete) and then immediately read back (the auto list
+ * refresh). supabase-js then throws `Unexpected end of JSON input` and the
+ * route 500s. Node 24's bundled undici reuses connections more aggressively,
+ * amplifying the race.
+ *
+ * `pipelining: 0` disables request pipelining on a connection, and the bounded
+ * keep-alive timeouts keep idle sockets from lingering long enough to be reused
+ * in a half-closed state. When a request DOES still hit a poisoned socket,
+ * undici destroys that socket on error, so the `withAdminRetry` wrapper at the
+ * call sites lands on a FRESH connection rather than the same dead one. The two
+ * layers together eliminate the empty-body 500s.
+ *
+ * NOTE: `setGlobalDispatcher` from the npm `undici` package does NOT affect
+ * Node's built-in global `fetch` (it bundles its own undici), so we attach this
+ * dispatcher explicitly via the `dispatcher` init option, which built-in fetch
+ * does honour.
+ */
+const adminDispatcher = new Agent({
+  pipelining: 0,
+  keepAliveTimeout: 10_000,
+  keepAliveMaxTimeout: 10_000,
+});
+
 export function getSupabaseAdmin(): SupabaseClient {
   if (_admin) return _admin;
   const url = process.env.NEXT_PUBLIC_SUPABASE_URL;
@@ -14,9 +43,14 @@ export function getSupabaseAdmin(): SupabaseClient {
     global: {
       // Force every request the admin client makes (GoTrue listUsers and
       // PostgREST reads alike) to bypass Next's fetch Data Cache, so the admin
-      // surface always reflects current state regardless of page config.
+      // surface always reflects current state regardless of page config, and
+      // route it through the dedicated keep-alive-tamed dispatcher above.
       fetch: (input: RequestInfo | URL, init?: RequestInit) =>
-        fetch(input, { ...init, cache: 'no-store' }),
+        fetch(input, {
+          ...init,
+          cache: 'no-store',
+          dispatcher: adminDispatcher,
+        } as RequestInit),
     },
   });
   return _admin;