diff --git a/AttendanceMachineFaceTemplateDAO.cs b/AttendanceMachineFaceTemplateDAO.cs
index 7c1798d..ef3187c 100644
--- a/AttendanceMachineFaceTemplateDAO.cs
+++ b/AttendanceMachineFaceTemplateDAO.cs
@@ -69,6 +69,7 @@ namespace HanvonF710XAttendanceService
 
                 using (var cmd = new MySqlCommand(query, connection))
                 {
+                    cmd.CommandTimeout = 300;
                     for (int i = 0; i < chunk.Length; i++)
                     {
                         cmd.Parameters.AddWithValue(parameterNames[i], chunk[i]);
@@ -178,6 +179,89 @@ namespace HanvonF710XAttendanceService
             return result.ToList();
         }
 
+        /// <summary>
+        /// Active template serial numbers for employees in the given departments (HRMS employees table).
+        /// When department lookup is unavailable, returns an empty list and the caller should fall back.
+        /// </summary>
+        public List<string> GetActiveSerialNumbersByDepartmentIds(
+            MySqlConnection connection,
+            IReadOnlyList<string> departmentIds,
+            IReadOnlyList<string> allowedMachineIds)
+        {
+            var result = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
+            if (departmentIds == null || departmentIds.Count == 0)
+            {
+                return new List<string>();
+            }
+
+            var machineIds = (allowedMachineIds ?? Array.Empty<string>())
+                .Where(id => !string.IsNullOrWhiteSpace(id))
+                .Select(id => id.Trim())
+                .Distinct(StringComparer.OrdinalIgnoreCase)
+                .ToList();
+
+            const int chunkSize = 80;
+            for (int offset = 0; offset < departmentIds.Count; offset += chunkSize)
+            {
+                var deptChunk = departmentIds.Skip(offset).Take(chunkSize).ToArray();
+                var deptParamNames = new List<string>(deptChunk.Length);
+                for (int i = 0; i < deptChunk.Length; i++)
+                {
+                    deptParamNames.Add("@Dept" + i);
+                }
+
+                string deptInClause = string.Join(",", deptParamNames);
+                string machineJoin = "";
+                string machineFilter = "";
+                if (machineIds.Count > 0)
+                {
+                    var machineParamNames = new List<string>(machineIds.Count);
+                    for (int i = 0; i < machineIds.Count; i++)
+                    {
+                        machineParamNames.Add("@Mid" + i);
+                    }
+                    machineJoin = " INNER JOIN hrms.attendance_machine_user u ON u.serial_number = t.serial_no AND u.is_deleted = 0 ";
+                    machineFilter = " AND u.machine_id IN (" + string.Join(",", machineParamNames) + ") ";
+                }
+
+                string query =
+                    "SELECT DISTINCT t.serial_no " +
+                    "FROM hrms.attendance_machine_face_templates t " +
+                    "INNER JOIN hrms.employee e ON CAST(e.emp_id AS CHAR) = t.serial_no " +
+                    machineJoin +
+                    "WHERE t.is_active = 1 AND e.department_id IN (" + deptInClause + ")" +
+                    machineFilter;
+
+                using (var cmd = new MySqlCommand(query, connection))
+                {
+                    cmd.CommandTimeout = 120;
+                    for (int i = 0; i < deptChunk.Length; i++)
+                    {
+                        cmd.Parameters.AddWithValue(deptParamNames[i], deptChunk[i]);
+                    }
+                    for (int i = 0; i < machineIds.Count; i++)
+                    {
+                        cmd.Parameters.AddWithValue("@Mid" + i, machineIds[i]);
+                    }
+
+                    using (var reader = cmd.ExecuteReader())
+                    {
+                        while (reader.Read())
+                        {
+                            if (reader.IsDBNull(0)) continue;
+                            var s = reader.GetString(0);
+                            if (!string.IsNullOrWhiteSpace(s))
+                            {
+                                result.Add(s.Trim());
+                            }
+                        }
+                    }
+                }
+            }
+
+            return result.ToList();
+        }
+
         /// <summary>
         /// Active templates for employees registered on a specific Nedo machine.
         /// Registration-based target selection: attendance_machine_user (is_deleted=0) drives which employees are allowed.