diff --git a/backend/src/main/java/com/designhub/service/TaskProgressSnapshotService.java b/backend/src/main/java/com/designhub/service/TaskProgressSnapshotService.java
index 928d6ef..d1d1e1d 100644
--- a/backend/src/main/java/com/designhub/service/TaskProgressSnapshotService.java
+++ b/backend/src/main/java/com/designhub/service/TaskProgressSnapshotService.java
@@ -427,6 +427,13 @@ public class TaskProgressSnapshotService {
         return objectMapper.readValue(json, type);
     }
 
+    private <T> T read(String json, Class<T> type) throws Exception {
+        if (json == null) {
+            return null;
+        }
+        return objectMapper.readValue(json, type);
+    }
+
     private TaskProgressOverviewVO applyFilters(TaskProgressOverviewVO overview, String dateRange, String month, Long deptId) {
         if (overview == null) {
             return null;