fix(aia,ssa,asl,infra): harden SSE transport and stabilize attachment context

Deliver SSE protocol hardening for SAE/HTTP2 paths, add graceful shutdown health behavior, and improve SSA retry UX for transient stream failures. For AIA, persist attachment extraction results in database with cache read-through fallback, plus production cache safety guard to prevent memory-cache drift in multi-instance deployments; also restore ASL SR page scrolling behavior.

Made-with: Cursor

frontend-v2/src/modules/ssa/hooks/useSSAChat.ts

@@ -77,6 +77,38 @@ export interface UseSSAChatReturn {
   loadHistory: (sessionId: string) => Promise<void>;
   abort: () => void;
   clearMessages: () => void;
+  retryLastMessage: () => Promise<void>;
+}
+
+// ────────────────────────────────────────────
+// Helpers
+// ────────────────────────────────────────────
+
+const MAX_AUTO_RETRY = 2;
+
+function retryDelay(attempt: number): number {
+  return Math.min(1000 * (2 ** attempt), 5000);
+}
+
+function toFriendlyError(err: any): string {
+  const msg = (err?.message || '').toLowerCase();
+
+  if (msg.includes('failed to fetch') || msg.includes('networkerror') || msg.includes('network'))
+    return '网络连接不稳定，请稍后重试。';
+
+  if (msg.includes('http2') || msg.includes('protocol'))
+    return '网络链路出现瞬时波动，请重新发送消息。';
+
+  if (msg.includes('timeout') || msg.includes('timed out'))
+    return '请求超时，服务器响应较慢，请稍后重试。';
+
+  if (msg.includes('502') || msg.includes('503') || msg.includes('504'))
+    return '服务暂时不可用，可能正在更新中，请稍后重试。';
+
+  if (msg.includes('401') || msg.includes('登录'))
+    return '登录已过期，请刷新页面重新登录。';
+
+  return err?.message || '请求失败，请重试。';
 }
 
 // ────────────────────────────────────────────
@@ -95,6 +127,8 @@ export function useSSAChat(): UseSSAChatReturn {
   const [pendingQuestion, setPendingQuestion] = useState<AskUserEventData | null>(null);
 
   const abortRef = useRef<AbortController | null>(null);
+  const lastRequestRef = useRef<{ sessionId: string; content: string; metadata?: Record<string, any> } | null>(null);
+  const retryCountRef = useRef(0);
 
   const ensureFreshToken = useCallback(async (): Promise<string> => {
     if (isTokenExpired()) {
@@ -186,6 +220,7 @@ export function useSSAChat(): UseSSAChatReturn {
    * 发送消息并接收 SSE 流式响应
    */
   const sendChatMessage = useCallback(async (sessionId: string, content: string, metadata?: Record<string, any>) => {
+    lastRequestRef.current = { sessionId, content, metadata };
     setError(null);
     setIsGenerating(true);
     setThinkingContent('');
@@ -454,11 +489,32 @@ export function useSSAChat(): UseSSAChatReturn {
             ? { ...m, content: fullContent || '（已中断）', status: 'complete' }
             : m
         ));
+        retryCountRef.current = 0;
       } else {
-        const errMsg = err.message || '请求失败';
-        setError(errMsg);
+        const isNetworkError = /failed to fetch|networkerror|network|http2|protocol/i.test(err.message || '');
+
+        // 瞬时网络错误自动重试一次
+        if (isNetworkError && retryCountRef.current < MAX_AUTO_RETRY) {
+          retryCountRef.current += 1;
+          const delay = retryDelay(retryCountRef.current);
+          setChatMessages(prev => prev.map(m =>
+            m.id === assistantMsgId
+              ? { ...m, content: `⏳ 网络波动，${(delay / 1000).toFixed(1)}s 后自动重试（第 ${retryCountRef.current}/${MAX_AUTO_RETRY} 次）...`, status: 'generating' }
+              : m
+          ));
+          setIsGenerating(false);
+          abortRef.current = null;
+          await new Promise(r => setTimeout(r, delay));
+          return sendChatMessage(sessionId, content, metadata);
+        }
+
+        retryCountRef.current = 0;
+        const friendlyMsg = toFriendlyError(err);
+        setError(friendlyMsg);
         setChatMessages(prev => prev.map(m =>
-          m.id === assistantMsgId ? { ...m, content: errMsg, status: 'error' } : m
+          m.id === assistantMsgId
+            ? { ...m, content: `⚠️ ${friendlyMsg}`, status: 'error' }
+            : m
         ));
       }
     } finally {
@@ -535,6 +591,20 @@ export function useSSAChat(): UseSSAChatReturn {
     await sendChatMessage(sessionId, '已跳过此问题', { askUserResponse: skipResponse });
   }, [sendChatMessage]);
 
+  const retryLastMessage = useCallback(async () => {
+    const last = lastRequestRef.current;
+    if (!last) return;
+    retryCountRef.current = 0;
+    setChatMessages(prev => {
+      let lastErrIdx = -1;
+      for (let i = prev.length - 1; i >= 0; i--) {
+        if (prev[i].status === 'error') { lastErrIdx = i; break; }
+      }
+      return lastErrIdx >= 0 ? prev.filter((_: ChatMessage, i: number) => i !== lastErrIdx) : prev;
+    });
+    await sendChatMessage(last.sessionId, last.content, last.metadata);
+  }, [sendChatMessage]);
+
   return {
     chatMessages,
     isGenerating,
@@ -552,6 +622,7 @@ export function useSSAChat(): UseSSAChatReturn {
     loadHistory,
     abort,
     clearMessages,
+    retryLastMessage,
   };
 }