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

app/api/admin/users/[id]/ban/route.ts

@@ -1,6 +1,7 @@
 import { type NextRequest } from 'next/server';
 import { requireAdminApi } from '@/lib/auth/admin-guard';
 import { getSupabaseAdmin } from '@/lib/supabase/admin';
+import { withAdminRetry } from '@/lib/admin/retry';
 import { logAdminAction } from '@/lib/auth/audit';
 import { isUuid, parseBoolean } from '@/lib/admin/validators';
 import { jsonNoStore } from '@/lib/admin/response';
@@ -44,9 +45,14 @@ export async function POST(
   }
 
   const admin = getSupabaseAdmin();
-  const { error } = await admin.auth.admin.updateUserById(id, {
-    ban_duration: banned ? BAN_DURATION : 'none',
-  } as { ban_duration: string });
+  // Retry transient empty-body / poisoned-keep-alive failures so a burst-load
+  // ban/unban doesn't 500. `updateUserById` is idempotent for our use
+  // (ban_duration set to the same value), so a retry is safe.
+  const { error } = await withAdminRetry(() =>
+    admin.auth.admin.updateUserById(id, {
+      ban_duration: banned ? BAN_DURATION : 'none',
+    } as { ban_duration: string }),
+  );
   if (error) {
     console.error('admin user.ban failed', error);
     return jsonNoStore({ error: 'internal error' }, { status: 500 });

app/api/admin/users/[id]/role/route.ts

@@ -1,6 +1,7 @@
 import { type NextRequest } from 'next/server';
 import { requireAdminApi } from '@/lib/auth/admin-guard';
 import { getSupabaseAdmin } from '@/lib/supabase/admin';
+import { withAdminRetry } from '@/lib/admin/retry';
 import { logAdminAction } from '@/lib/auth/audit';
 import { isUuid } from '@/lib/admin/validators';
 import { jsonNoStore } from '@/lib/admin/response';
@@ -42,17 +43,24 @@ export async function POST(
 
   const admin = getSupabaseAdmin();
 
-  // Merge with existing app_metadata so we don't clobber other keys.
-  const { data: existing, error: getErr } =
-    await admin.auth.admin.getUserById(id);
+  // Merge with existing app_metadata so we don't clobber other keys. Retry the
+  // read on transient empty-body responses so a burst-load flake isn't
+  // misreported as a 404; a genuine not-found still falls through below.
+  const { data: existing, error: getErr } = await withAdminRetry(() =>
+    admin.auth.admin.getUserById(id),
+  );
   if (getErr || !existing.user) {
     return jsonNoStore({ error: 'user not found' }, { status: 404 });
   }
   const merged = { ...(existing.user.app_metadata ?? {}), role };
 
-  const { error } = await admin.auth.admin.updateUserById(id, {
-    app_metadata: merged,
-  });
+  // `updateUserById` is idempotent here (same app_metadata), so retrying a
+  // transient empty-body write is safe.
+  const { error } = await withAdminRetry(() =>
+    admin.auth.admin.updateUserById(id, {
+      app_metadata: merged,
+    }),
+  );
   if (error) {
     console.error('admin user.role failed', error);
     return jsonNoStore({ error: 'internal error' }, { status: 500 });

app/api/admin/users/[id]/route.ts

@@ -119,11 +119,24 @@ export async function DELETE(
 
   // Delete the AUTH USER first. Only if that succeeds do we remove the tunnel
   // row, so a mid-failure never leaves an orphaned auth user with a dangling
-  // tunnel (or half-deletes the tunnel of an already-gone user).
-  const { error: delErr } = await admin.auth.admin.deleteUser(id);
+  // tunnel (or half-deletes the tunnel of an already-gone user). Retry the
+  // delete on transient empty-body / poisoned-keep-alive responses.
+  const { error: delErr } = await withAdminRetry(() =>
+    admin.auth.admin.deleteUser(id),
+  );
   if (delErr) {
-    console.error('admin user.delete: deleteUser failed', delErr);
-    return jsonNoStore({ error: 'internal error' }, { status: 500 });
+    // The delete may have actually succeeded with a truncated/empty response
+    // body (the transient failure mode). Re-check existence before reporting a
+    // 500: if the user is now gone, the deletion is effectively complete.
+    const { data: recheck, error: recheckErr } = await withAdminRetry(() =>
+      admin.auth.admin.getUserById(id),
+    );
+    if (recheckErr || !recheck?.user) {
+      // User is gone -> delete succeeded despite the truncated body.
+    } else {
+      console.error('admin user.delete: deleteUser failed', delErr);
+      return jsonNoStore({ error: 'internal error' }, { status: 500 });
+    }
   }
 
   // The auth user is gone, so no orphaned-user state is possible. Removing the