fix(sse): 优化SSE保活机制并添加自动重试逻辑

1. 后端调整心跳间隔为5秒，改用带时间戳的结构化ping心跳替代简单注释
2. 前端重构SSE连接逻辑，添加重试计数器，支持连接失败自动重试
3. 前端仅在首次连接时获取学员画像，避免重试时重复调用
4. 前端新增ping事件监听器处理服务端保活消息

backend/generation-service/src/main/java/com/artedu/generation/controller/GenerationController.java

@@ -350,14 +350,17 @@ public class GenerationController {
                 emitter.onCompletion(() -> generationFuture.cancel(true));
                 emitter.onTimeout(() -> generationFuture.cancel(true));
 
-                // 等待生成结果，每 10s 发送一次心跳，防止 nginx/移动网络因 30s 空闲超时而断开
+                // 等待生成结果，每 5s 发送一次心跳，防止 nginx/移动网络因空闲超时而断开
                 while (!generationFuture.isDone()) {
                     try {
-                        generationFuture.get(10, TimeUnit.SECONDS);
+                        generationFuture.get(5, TimeUnit.SECONDS);
                         break;
                     } catch (TimeoutException e) {
                         try {
-                            emitter.send(SseEmitter.event().comment("keep-alive"));
+                            Map<String, Object> ping = new HashMap<>();
+                            ping.put("type", "ping");
+                            ping.put("time", System.currentTimeMillis());
+                            emitter.send(SseEmitter.event().name("ping").data(ping));
                         } catch (IOException ioe) {
                             log.warn("SSE 心跳发送失败，连接已断开");
                             generationFuture.cancel(true);

frontend/sidebar/src/components/ScriptRecommendStream.tsx

@@ -35,6 +35,7 @@ export default function ScriptRecommendStream({ userInfo, customerId: propCustom
   const [utterances, setUtterances] = useState<UtteranceItem[]>([])
   const [error, setError] = useState('')
   const sseRef = useRef<EventSource | null>(null)
+  const retryCountRef = useRef(0)
 
   const customerId = propCustomerId || localStorage.getItem('current_customer_id') || ''
   const staffId = userInfo?.userId || ''
@@ -103,12 +104,16 @@ export default function ScriptRecommendStream({ userInfo, customerId: propCustom
 
     setGenerating(true)
     setLoading(false)
+    setError('')
+    retryCountRef.current = 0
 
+    const attempt = () => {
       try {
-      // 单聊才获取画像标签
-      if (!isGroupChat && customerId) {
-        const profileRes = await fetch(`/api/v1/intent/profile/${encodeURIComponent(customerId)}?corpId=${corpId}`)
-        const profileData = await profileRes.json()
+        // 仅首次连接时获取画像标签，重试时不重复调用
+        if (retryCountRef.current === 0 && !isGroupChat && customerId) {
+          fetch(`/api/v1/intent/profile/${encodeURIComponent(customerId)}?corpId=${corpId}`)
+            .then(res => res.json())
+            .then(profileData => {
               if (profileData.code === 0 && profileData.data) {
                 const p = profileData.data
                 const tags: string[] = []
@@ -120,6 +125,8 @@ export default function ScriptRecommendStream({ userInfo, customerId: propCustom
                 if (p.decisionStage) tags.push(p.decisionStage)
                 setProfileTags(tags)
               }
+            })
+            .catch(e => console.error('获取学员画像失败:', e))
         }
 
         // 构建 SSE URL：群聊传 roomid，单聊传 fromUser+toUser+staffName
@@ -135,7 +142,7 @@ export default function ScriptRecommendStream({ userInfo, customerId: propCustom
         }
 
         const url = `/api/v1/generation/utterance-stream?${params.toString()}`
-      console.log('SSE connect:', url)
+        console.log('SSE connect (attempt', retryCountRef.current + 1, '):', url)
         const es = new EventSource(url)
         sseRef.current = es
 
@@ -148,6 +155,10 @@ export default function ScriptRecommendStream({ userInfo, customerId: propCustom
           } catch (e) { console.error('SSE start error:', e) }
         })
 
+        es.addEventListener('ping', (_event: MessageEvent) => {
+          // 服务端心跳保活，无需处理
+        })
+
         es.addEventListener('item-start', (event: MessageEvent) => {
           try {
             const data = JSON.parse(event.data)
@@ -187,19 +198,30 @@ export default function ScriptRecommendStream({ userInfo, customerId: propCustom
             if (data.type === 'done') {
               setGenerating(false)
               es.close()
+              retryCountRef.current = 0
             }
           } catch (e) { console.error('SSE done error:', e) }
         })
 
         es.addEventListener('error', (event: MessageEvent) => {
+          es.close()
           try {
             const data = JSON.parse(event.data)
             setError(data.message || '生成失败')
-        } catch (e) {
-          setError('连接中断')
-        }
             setGenerating(false)
-        es.close()
+            retryCountRef.current = 0
+          } catch (e) {
+            // 连接类错误自动重试一次，避免网络抖动导致用户看到"连接中断"
+            if (retryCountRef.current < 2) {
+              retryCountRef.current += 1
+              console.warn(`SSE 连接中断，第 ${retryCountRef.current} 次重试...`)
+              setTimeout(attempt, 1000)
+            } else {
+              setError('连接中断')
+              setGenerating(false)
+              retryCountRef.current = 0
+            }
+          }
         })
 
       } catch (e) {
@@ -207,6 +229,9 @@ export default function ScriptRecommendStream({ userInfo, customerId: propCustom
         setError('网络错误，请重试')
         setGenerating(false)
       }
+    }
+
+    attempt()
   }, [canStartGeneration, isGroupChat, customerId, staffId, chatId, corpId])
 
   useEffect(() => {