update

modules/core/src/main/java/com/bytedesk/core/thread/ThreadEntity.java

@@ -150,8 +150,28 @@ public class ThreadEntity extends AbstractThreadEntity {
         return getClient().equals(ClientEnum.WECHAT_MINI.name());
     }
 
+    /**
+     * 检查会话是否曾经处于离线状态
+     */
+    public Boolean wasOffline() {
+        ThreadExtra extra = getThreadExtra();
+        return extra != null && extra.isWasOffline();
+    }
+
+    /**
+     * 将当前会话标记为离线状态
+     */
     public ThreadEntity setOffline() {
         setStatus(ThreadProcessStatusEnum.OFFLINE.name());
+        
+        // 更新extra信息，记录曾经处于离线状态
+        ThreadExtra extra = getThreadExtra();
+        if (extra == null) {
+            extra = new ThreadExtra();
+        }
+        extra.setWasOffline(true);
+        setExtra(JSON.toJSONString(extra));
+        
         return this;
     }
 

modules/core/src/main/java/com/bytedesk/core/thread/ThreadExtra.java

@@ -16,9 +16,19 @@ package com.bytedesk.core.thread;
 import java.io.Serializable;
 
 import lombok.Data;
+import lombok.Builder;
+import lombok.NoArgsConstructor;
+import lombok.AllArgsConstructor;
+import lombok.experimental.Accessors;
 
 @Data
+@Builder
+@NoArgsConstructor
+@AllArgsConstructor
+@Accessors(chain = true)
 public class ThreadExtra implements Serializable {
 
     private static final long serialVersionUID = 1L;
+    
+    private boolean wasOffline; // 标记此会话是否曾经处于离线状态
 }