diff --git a/src/ModulesCore/LegacyCompat.php b/src/ModulesCore/LegacyCompat.php
index d6b1c8ea..415f3840 100644
--- a/src/ModulesCore/LegacyCompat.php
+++ b/src/ModulesCore/LegacyCompat.php
@@ -248,6 +248,61 @@ namespace ModulesCore {
             return PdoFactory::createFromArray($db);
         }
 
+        /**
+         * @return array<int, array<string, mixed>>
+         */
+        public function knownAuthUsers(): array
+        {
+            $pdo = LegacyCompat::app()->basePdo();
+            if (!$pdo instanceof \PDO) {
+                return [];
+            }
+
+            try {
+                $stmt = $pdo->query(
+                    'SELECT sub, username, email, name, groups, last_login_at
+                     FROM nexus_auth_users
+                     ORDER BY COALESCE(NULLIF(name, \'\'), NULLIF(username, \'\'), email, sub)'
+                );
+                if (!$stmt) {
+                    return [];
+                }
+            } catch (\Throwable) {
+                return [];
+            }
+
+            $users = [];
+            foreach ($stmt->fetchAll(\PDO::FETCH_ASSOC) ?: [] as $row) {
+                $groups = json_decode((string) ($row['groups'] ?? '[]'), true);
+                $row['groups'] = is_array($groups)
+                    ? array_values(array_filter(array_map('strval', $groups)))
+                    : [];
+                $users[] = $row;
+            }
+
+            return $users;
+        }
+
+        /**
+         * @return array<int, string>
+         */
+        public function knownAuthGroups(): array
+        {
+            $groups = [];
+            foreach ($this->knownAuthUsers() as $user) {
+                foreach (($user['groups'] ?? []) as $group) {
+                    $group = trim((string) $group);
+                    if ($group !== '') {
+                        $groups[] = $group;
+                    }
+                }
+            }
+
+            sort($groups, SORT_NATURAL | SORT_FLAG_CASE);
+
+            return array_values(array_unique($groups));
+        }
+
         private function modulePath(string $moduleName): string
         {
             return $this->projectRoot . '/modules/' . trim($moduleName, '/');