diff --git a/app/Http/Controllers/DutyHallController.php b/app/Http/Controllers/DutyHallController.php
index ab69b04..44745d2 100644
--- a/app/Http/Controllers/DutyHallController.php
+++ b/app/Http/Controllers/DutyHallController.php
@@ -50,17 +50,9 @@ class DutyHallController extends Controller
 
             // ① 在线时长（position_duty_logs）
             $dutyQuery = PositionDutyLog::query()
-                ->selectRaw('
-                    user_id,
-                    SUM(
-                        CASE
-                            WHEN logout_at IS NULL
-                            THEN GREATEST(0, TIMESTAMPDIFF(SECOND, login_at, NOW()))
-                            ELSE duration_seconds
-                        END
-                    ) as total_seconds,
-                    COUNT(*) as checkin_count
-                ');
+                ->selectRaw('user_id, SUM(duration_seconds) as total_seconds, COUNT(*) as checkin_count')
+                // 只统计有离开时间的已完结记录，open session 不计入（防止实时计算偏差）
+                ->whereNotNull('logout_at');
 
             // ② 管理操作（position_authority_logs，排除任命/撤销等人事操作）
             $authQuery = PositionAuthorityLog::query()