feat: 全新智能体功能

- 基于先进智能体框架，增加智能体编排功能
- 增加智能体聊天，并对接持久化

easyflow-commons/easyflow-common-chat-protocol/src/main/java/tech/easyflow/core/chat/protocol/ChatType.java

@@ -6,6 +6,8 @@ public enum ChatType {
     TOOL_CALL,
     TOOL_RESULT,
     STATUS,
+    CITATIONS,
+    SESSION_CREATED,
     ERROR,
     FORM_REQUEST,
     FORM_CANCEL,

easyflow-commons/easyflow-common-chat-protocol/src/main/java/tech/easyflow/core/chat/protocol/sse/ChatSseEmitter.java

@@ -4,9 +4,10 @@ import com.alibaba.fastjson.JSON;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;
+import org.springframework.web.context.request.async.AsyncRequestNotUsableException;
 import org.springframework.web.servlet.mvc.method.annotation.SseEmitter;
-import tech.easyflow.common.util.StringUtil;
 import tech.easyflow.common.util.SpringContextUtil;
+import tech.easyflow.common.util.StringUtil;
 import tech.easyflow.core.chat.protocol.ChatEnvelope;
 
 import java.io.IOException;
@@ -90,15 +91,21 @@ public class ChatSseEmitter {
                             .data(json)
             );
             return true;
-        } catch (IllegalStateException e) {
-            closed.compareAndSet(false, true);
-            LOG.error("ChatSseEmitter send failed(event={}), message={}, exception={}", event, e.getMessage(), e.toString(), e);
+        } catch (AsyncRequestNotUsableException e) {
+            markDisconnected(event, e);
             return false;
         } catch (IOException e) {
-            LOG.error("ChatSseEmitter send io failed(event={}), message={}, exception={}", event, e.getMessage(), e.toString(), e);
-            safeCompleteWithError(e);
+            markDisconnected(event, e);
+            return false;
+        } catch (IllegalStateException e) {
+            closed.compareAndSet(false, true);
+            LOG.warn("ChatSseEmitter send failed(event={}), message={}, exception={}", event, e.getMessage(), e.toString());
             return false;
         } catch (Exception e) {
+            if (isClientDisconnected(e)) {
+                markDisconnected(event, e);
+                return false;
+            }
             LOG.error("ChatSseEmitter send unexpected failed(event={}), message={}, exception={}", event, e.getMessage(), e.toString(), e);
             safeCompleteWithError(e);
             return false;
@@ -165,4 +172,31 @@ public class ChatSseEmitter {
             }
         }
     }
+
+    private void markDisconnected(String event, Throwable ex) {
+        closed.compareAndSet(false, true);
+        LOG.warn("ChatSseEmitter client disconnected(event={}), message={}, exception={}",
+                event, ex == null ? null : ex.getMessage(), ex == null ? null : ex.toString());
+    }
+
+    private boolean isClientDisconnected(Throwable ex) {
+        Throwable current = ex;
+        while (current != null) {
+            if (current instanceof AsyncRequestNotUsableException || current instanceof IOException) {
+                return true;
+            }
+            String message = current.getMessage();
+            if (message != null) {
+                String lowerMessage = message.toLowerCase();
+                if (lowerMessage.contains("broken pipe")
+                        || lowerMessage.contains("connection reset")
+                        || lowerMessage.contains("disconnected client")
+                        || lowerMessage.contains("response not usable")) {
+                    return true;
+                }
+            }
+            current = current.getCause();
+        }
+        return false;
+    }
 }