fix: async document processing in background threads, improve chat UX

- Fix knowledge_base_service calling async process_document synchronously
  in background threads — use asyncio.new_event_loop().run_until_complete()
  instead of bare call that returned unawaited coroutine
- Same fix for _update_document and reindex_document
- Replace ModeSelector with auto-detect: RAG mode when knowledge bases selected
- Convert regenerateMessage to streaming (was synchronous API call)
- Show "知识库检索模式" indicator above input when KB selected
- Remove loadSessions side-effect from streaming onComplete
- Fix chat page loading state to avoid flash
- Improve forum page spacing and sizing

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

backend/src/services/knowledge_base_service.py

@@ -161,11 +161,13 @@ class KnowledgeBaseService:
             
             # 处理文档（向量化）- 在后台异步处理，不阻塞主流程
             try:
-                # 使用同步方法，但不等待完成（在后台处理）
                 import threading
+                import asyncio as _asyncio
                 def process_in_background():
                     try:
-                        self.document_service.process_document(document.id)
+                        loop = _asyncio.new_event_loop()
+                        loop.run_until_complete(self.document_service.process_document(document.id))
+                        loop.close()
                     except Exception as e:
                         print(f"后台处理文档 {document.id} 失败: {e}")
 
@@ -198,9 +200,12 @@ class KnowledgeBaseService:
             # 重新处理文档 - 在后台异步处理
             try:
                 import threading
+                import asyncio as _asyncio
                 def process_in_background():
                     try:
-                        self.document_service.process_document(document.id)
+                        loop = _asyncio.new_event_loop()
+                        loop.run_until_complete(self.document_service.process_document(document.id))
+                        loop.close()
                     except Exception as e:
                         print(f"后台处理文档 {document.id} 失败: {e}")
 
@@ -340,7 +345,10 @@ class KnowledgeBaseService:
             self.db.query(DocumentChunk).filter(DocumentChunk.document_id == document_id).delete()
             
             # 重新处理文档
-            success = self.document_service.process_document(document_id)
+            import asyncio as _asyncio
+            success = _asyncio.get_event_loop().run_until_complete(
+                self.document_service.process_document(document_id)
+            )
             
             if success:
                 return {"success": True, "message": "文档重新索引成功"}

web/src/app/(main)/chat/page.tsx

@@ -14,9 +14,10 @@ import { PanelLeftClose, PanelLeftOpen } from "lucide-react";
 export default function ChatPage() {
   const router = useRouter();
   const { isAuthenticated, user, isLoading: authLoading } = useAuthStore();
-  const { loadSessions, isLoading: chatLoading } = useChatStore();
+  const { loadSessions, sessions } = useChatStore();
   const [isInitialized, setIsInitialized] = useState(false);
   const [sidebarOpen, setSidebarOpen] = useState(true);
+  const [initialLoading, setInitialLoading] = useState(true);
 
   useEffect(() => {
     if (!authLoading && !isAuthenticated) {
@@ -25,12 +26,12 @@ export default function ChatPage() {
     }
 
     if (isAuthenticated && !isInitialized) {
-      loadSessions();
+      loadSessions().then(() => setInitialLoading(false));
       setIsInitialized(true);
     }
   }, [isAuthenticated, authLoading, isInitialized, router, loadSessions]);
 
-  if (authLoading || chatLoading) {
+  if (authLoading || initialLoading) {
     return (
       <div className="min-h-screen flex items-center justify-center">
         <LoadingSpinner size="lg" />

web/src/app/(main)/forum/page.tsx

@@ -25,11 +25,11 @@ const CATEGORY_ORDER = ["公告", "通知", "学习", "讨论", "课程", "反
 
 function getCategoryIcon(name: string) {
   if (name.includes("公告") || name.includes("通知"))
-    return <Megaphone className="w-4 h-4" />;
+    return <Megaphone className="w-5 h-5" />;
   if (name.includes("学习") || name.includes("讨论") || name.includes("课程"))
-    return <BookOpen className="w-4 h-4" />;
+    return <BookOpen className="w-5 h-5" />;
   if (name.includes("反馈") || name.includes("使用"))
-    return <Lightbulb className="w-4 h-4" />;
+    return <Lightbulb className="w-5 h-5" />;
   return CATEGORY_ICONS.default;
 }
 
@@ -106,110 +106,112 @@ export default function ForumHomePage() {
   }, []);
 
   return (
-    <div className="max-w-5xl mx-auto px-4 sm:px-6 lg:px-8 py-6 space-y-5">
-      {isLoading ? (
-        <div className="flex items-center justify-center gap-2 text-muted-foreground py-20">
-          <Loader2 className="h-4 w-4 animate-spin" />
-          正在加载社区...
-        </div>
-      ) : error ? (
-        <div className="text-center py-16">
-          <p className="text-muted-foreground">{error}</p>
-        </div>
-      ) : (
-        <div className="space-y-3">
-          {[...categories]
-            .sort((a, b) => {
-              const getOrder = (name: string) => {
-                for (let i = 0; i < CATEGORY_ORDER.length; i++) {
-                  if (name.includes(CATEGORY_ORDER[i])) return i;
-                }
-                return CATEGORY_ORDER.length;
-              };
-              return getOrder(a.name) - getOrder(b.name);
-            })
-            .map((category) => {
-            const posts = categoryPosts[category.id] || [];
-            return (
-              <div
-                key={category.id}
-                className={`bg-gradient-to-r ${getCategoryGradient(
-                  category.name
-                )} rounded-xl border border-border/40 overflow-hidden`}
-              >
-                {/* Category header */}
-                <div className="px-4 py-3 flex items-center justify-between border-b border-border/20">
-                  <div className="flex items-center gap-2.5">
-                    <span className={getCategoryAccent(category.name)}>
-                      {getCategoryIcon(category.name)}
-                    </span>
-                    <div>
-                      <h2 className="text-sm font-semibold text-foreground">
-                        {category.name}
-                      </h2>
-                      {category.description && (
-                        <p className="text-[11px] text-muted-foreground mt-0">
-                          {category.description}
-                        </p>
-                      )}
-                    </div>
-                  </div>
-                  <div className="flex items-center gap-2.5">
-                    <span className="text-[11px] text-muted-foreground tabular-nums">
-                      {category.post_count} 条讨论
-                    </span>
-                    <Link
-                      href={`/forum/${category.id}`}
-                      className="text-[11px] font-medium text-primary hover:underline flex items-center gap-0.5"
-                    >
-                      查看全部
-                      <ChevronRight className="w-3 h-3" />
-                    </Link>
-                  </div>
-                </div>
-
-                {/* Posts list */}
-                <div className="divide-y divide-border/20">
-                  {posts.length > 0 ? (
-                    posts.map((post) => (
-                      <Link
-                        key={post.id}
-                        href={`/forum/post/${post.id}`}
-                        className="flex items-start gap-2.5 px-4 py-2.5 hover:bg-white/40 transition-colors group"
-                      >
-                        <div className="mt-0.5 w-6 h-6 rounded-full bg-muted/60 flex items-center justify-center flex-shrink-0">
-                          <User className="w-3 h-3 text-muted-foreground" />
-                        </div>
-                        <div className="flex-1 min-w-0">
-                          <p className="text-[13px] font-medium text-foreground group-hover:text-primary transition-colors line-clamp-1">
-                            {post.title}
+    <div className="min-h-screen bg-background">
+      <div className="max-w-7xl mx-auto px-4 sm:px-6 lg:px-8 py-8">
+        {isLoading ? (
+          <div className="flex items-center justify-center gap-2 text-muted-foreground py-20">
+            <Loader2 className="h-5 w-5 animate-spin" />
+            正在加载社区...
+          </div>
+        ) : error ? (
+          <div className="text-center py-16">
+            <p className="text-muted-foreground">{error}</p>
+          </div>
+        ) : (
+          <div className="space-y-5">
+            {[...categories]
+              .sort((a, b) => {
+                const getOrder = (name: string) => {
+                  for (let i = 0; i < CATEGORY_ORDER.length; i++) {
+                    if (name.includes(CATEGORY_ORDER[i])) return i;
+                  }
+                  return CATEGORY_ORDER.length;
+                };
+                return getOrder(a.name) - getOrder(b.name);
+              })
+              .map((category) => {
+              const posts = categoryPosts[category.id] || [];
+              return (
+                <div
+                  key={category.id}
+                  className={`bg-gradient-to-r ${getCategoryGradient(
+                    category.name
+                  )} rounded-xl border border-border/40 overflow-hidden`}
+                >
+                  {/* Category header */}
+                  <div className="px-5 py-3.5 flex items-center justify-between border-b border-border/20">
+                    <div className="flex items-center gap-3">
+                      <span className={getCategoryAccent(category.name)}>
+                        {getCategoryIcon(category.name)}
+                      </span>
+                      <div>
+                        <h2 className="text-base font-semibold text-foreground">
+                          {category.name}
+                        </h2>
+                        {category.description && (
+                          <p className="text-sm text-muted-foreground mt-0.5">
+                            {category.description}
                           </p>
-                          <div className="flex items-center gap-2 mt-0.5 text-[11px] text-muted-foreground">
-                            <span>{post.author_name}</span>
-                            <span className="inline-flex items-center gap-0.5">
-                              <Clock className="w-2.5 h-2.5" />
-                              {formatRelativeTime(post.created_at)}
-                            </span>
-                            <span className="inline-flex items-center gap-0.5">
-                              <MessageCircle className="w-2.5 h-2.5" />
-                              {post.reply_count}
-                            </span>
-                          </div>
-                        </div>
-                        <ChevronRight className="w-3.5 h-3.5 text-muted-foreground/0 group-hover:text-muted-foreground transition-colors mt-1 flex-shrink-0" />
-                      </Link>
-                    ))
-                  ) : (
-                    <div className="px-4 py-5 text-center text-xs text-muted-foreground">
-                      暂无讨论，成为第一个发帖的人
+                        )}
+                      </div>
                     </div>
-                  )}
+                    <div className="flex items-center gap-3">
+                      <span className="text-sm text-muted-foreground tabular-nums">
+                        {category.post_count} 条讨论
+                      </span>
+                      <Link
+                        href={`/forum/${category.id}`}
+                        className="text-sm font-medium text-primary hover:underline flex items-center gap-0.5"
+                      >
+                        查看全部
+                        <ChevronRight className="w-4 h-4" />
+                      </Link>
+                    </div>
+                  </div>
+
+                  {/* Posts list */}
+                  <div className="divide-y divide-border/20">
+                    {posts.length > 0 ? (
+                      posts.map((post) => (
+                        <Link
+                          key={post.id}
+                          href={`/forum/post/${post.id}`}
+                          className="flex items-start gap-3 px-5 py-3.5 hover:bg-white/40 transition-colors group"
+                        >
+                          <div className="mt-0.5 w-8 h-8 rounded-full bg-muted/60 flex items-center justify-center flex-shrink-0">
+                            <User className="w-4 h-4 text-muted-foreground" />
+                          </div>
+                          <div className="flex-1 min-w-0">
+                            <p className="text-sm font-medium text-foreground group-hover:text-primary transition-colors line-clamp-1">
+                              {post.title}
+                            </p>
+                            <div className="flex items-center gap-2.5 mt-1 text-xs text-muted-foreground">
+                              <span>{post.author_name}</span>
+                              <span className="inline-flex items-center gap-0.5">
+                                <Clock className="w-3 h-3" />
+                                {formatRelativeTime(post.created_at)}
+                              </span>
+                              <span className="inline-flex items-center gap-0.5">
+                                <MessageCircle className="w-3 h-3" />
+                                {post.reply_count}
+                              </span>
+                            </div>
+                          </div>
+                          <ChevronRight className="w-4 h-4 text-muted-foreground/0 group-hover:text-muted-foreground transition-colors mt-2 flex-shrink-0" />
+                        </Link>
+                      ))
+                    ) : (
+                      <div className="px-5 py-8 text-center text-sm text-muted-foreground">
+                        暂无讨论，成为第一个发帖的人
+                      </div>
+                    )}
+                  </div>
                 </div>
-              </div>
-            );
-          })}
-        </div>
-      )}
+              );
+            })}
+          </div>
+        )}
+      </div>
     </div>
   );
 }

web/src/components/chat/chat-interface.tsx

@@ -4,10 +4,9 @@ import { useState, useRef, useEffect } from "react";
 import { useChatStore } from "@/store/chat";
 import { Button } from "@/components/ui/button";
 import { Input } from "@/components/ui/input";
-import { Send, Square, Bot, ChevronDown, Settings2 } from "lucide-react";
+import { Send, Square, Bot, ChevronDown, Settings2, Database } from "lucide-react";
 import MessageList from "./message-list";
 import QuickQuestions from "./quick-questions";
-import ModeSelector, { ChatMode } from "./mode-selector";
 import ModelSelector from "./model-selector";
 import KnowledgeSelector, { KnowledgeBase } from "./knowledge-selector";
 import { cn } from "@/lib/utils";
@@ -16,7 +15,6 @@ import { knowledgeBaseAPI } from "@/lib/api";
 export default function ChatInterface() {
   const [inputMessage, setInputMessage] = useState("");
   const [isComposing, setIsComposing] = useState(false);
-  const [chatMode, setChatMode] = useState<ChatMode>("normal");
   const [selectedModel, setSelectedModel] = useState("deepseek-ai/DeepSeek-V3");
   const [selectedKnowledgeBases, setSelectedKnowledgeBases] = useState<string[]>([]);
   const [systemKnowledgeBases, setSystemKnowledgeBases] = useState<KnowledgeBase[]>([]);
@@ -72,7 +70,8 @@ export default function ChatInterface() {
         await selectSession(newSession.id);
       }
     }
-    await streamMessage(message, chatMode, selectedKnowledgeBases, selectedModel);
+    const mode = selectedKnowledgeBases.length > 0 ? "rag" : "normal";
+    await streamMessage(message, mode, selectedKnowledgeBases, selectedModel);
   };
 
   const handleKeyPress = (e: React.KeyboardEvent) => {
@@ -124,7 +123,6 @@ export default function ChatInterface() {
         {/* Settings panel — collapsible */}
         {showSettings && (
           <div className="flex items-center gap-2 mb-3 pb-3 border-b border-border/30">
-            <ModeSelector mode={chatMode} onModeChange={setChatMode} />
             <ModelSelector
               selectedModel={selectedModel}
               onModelChange={setSelectedModel}
@@ -156,6 +154,12 @@ export default function ChatInterface() {
           </Button>
 
           <div className="flex-1 relative">
+            {selectedKnowledgeBases.length > 0 && (
+              <div className="absolute -top-0.5 left-3 right-3 flex items-center gap-1 text-[10px] text-primary font-medium pointer-events-none">
+                <Database className="w-3 h-3" />
+                <span>知识库检索模式</span>
+              </div>
+            )}
             <input
               ref={inputRef}
               value={inputMessage}
@@ -167,6 +171,7 @@ export default function ChatInterface() {
               disabled={isLoading || isStreaming}
               className={cn(
                 "w-full h-10 px-4 rounded-xl text-sm",
+                selectedKnowledgeBases.length > 0 && "pt-4",
                 "bg-muted/40 border border-border/30",
                 "placeholder:text-muted-foreground/60",
                 "focus:outline-none focus:ring-2 focus:ring-primary/20 focus:border-primary/30",

web/src/store/chat.ts

@@ -54,14 +54,12 @@ export const useChatStore = create<ChatStore>((set, get) => ({
 
   // 加载会话列表
   loadSessions: async () => {
-    set({ isLoading: true, error: null });
-    
     try {
       const sessions = await chatAPI.getSessions();
-      set({ sessions, isLoading: false });
+      set({ sessions });
     } catch (error) {
       const errorMessage = error instanceof Error ? error.message : "加载会话失败";
-      set({ error: errorMessage, isLoading: false });
+      set({ error: errorMessage });
     }
   },
 
@@ -320,7 +318,7 @@ export const useChatStore = create<ChatStore>((set, get) => ({
             });
           }
         },
-        (sessionId: number, messageId?: number, userMessageId?: number) => {
+        (_sessionId: number, messageId?: number, userMessageId?: number) => {
           if (messageId) {
             set((state) => ({
               messages: state.messages.map(msg => {
@@ -332,15 +330,9 @@ export const useChatStore = create<ChatStore>((set, get) => ({
               abortController: null,
             }));
           } else {
-            const { currentSession } = get();
-            if (currentSession) {
-              get().loadMessages(currentSession.id);
-            }
+            // 前端已通过流式获得完整内容，不需要从服务端重新加载
             set({ isStreaming: false, abortController: null });
           }
-
-          // 刷新会话列表以确保新会话显示在顶部
-          get().loadSessions();
         },
         (error: string) => {
           // 流式错误
@@ -414,36 +406,121 @@ export const useChatStore = create<ChatStore>((set, get) => ({
     }
   },
 
-  // 重新生成消息（支持 assistant 消息 ID）
+  // 重新生成消息（流式）
   regenerateMessage: async (messageId: number, model?: string) => {
+    const { currentSession, messages } = get();
+    if (!currentSession) return;
+
+    const messageIndex = messages.findIndex(msg => msg.id === messageId);
+    if (messageIndex === -1) return;
+
+    // 找到该 assistant 消息之前的 user 消息内容
+    const userContent = messages
+      .slice(0, messageIndex)
+      .reverse()
+      .find(msg => msg.role === "user")?.content;
+    if (!userContent) return;
+
+    // 删除该 assistant 消息及之后的所有消息，替换为流式占位符
+    const trimmed = messages.slice(0, messageIndex);
+    const assistantPlaceholder: ChatMessage = {
+      id: Date.now() + 1,
+      role: "assistant",
+      content: "",
+      created_at: new Date().toISOString(),
+    };
+
+    const abortController = new AbortController();
+    set({
+      messages: [...trimmed, assistantPlaceholder],
+      isStreaming: true,
+      error: null,
+      abortController,
+    });
+
+    // 判断模式：检查之前的消息中是否有知识库相关内容
+    const mode = "normal";
+
+    let thinkingSteps: any[] = [];
+
     try {
-      set({ isLoading: true, error: null });
-      const response = await chatAPI.regenerateMessage(messageId, model);
-
-      // 找到该消息，删除它及之后的所有消息
-      const messageIndex = get().messages.findIndex(msg => msg.id === messageId);
-      if (messageIndex !== -1) {
-        set((state) => ({
-          messages: state.messages.slice(0, messageIndex),
-        }));
-      }
-
-      // 添加新的助手回复
-      const newMessage: ChatMessage = {
-        id: response.new_message_id,
-        role: "assistant",
-        content: response.content,
-        created_at: new Date().toISOString(),
-      };
-
-      set((state) => ({
-        messages: [...state.messages, newMessage],
-        isLoading: false,
-      }));
+      await chatAPI.streamMessage(
+        userContent,
+        currentSession.id,
+        mode,
+        undefined, // knowledgeBaseIds
+        abortController.signal,
+        (chunk: string) => {
+          // 处理 chunk
+          try {
+            const data = JSON.parse(chunk);
+            if (data.type === 'thinking') {
+              thinkingSteps.push({
+                stage: data.stage,
+                message: data.message,
+                doc_count: data.doc_count,
+                time: data.time
+              });
+              requestAnimationFrame(() => {
+                set((state) => ({
+                  messages: state.messages.map(msg =>
+                    msg.id === assistantPlaceholder.id
+                      ? { ...msg, thinking: [...thinkingSteps] }
+                      : msg
+                  ),
+                }));
+              });
+            } else if (data.type === 'chunk') {
+              requestAnimationFrame(() => {
+                set((state) => ({
+                  messages: state.messages.map(msg =>
+                    msg.id === assistantPlaceholder.id
+                      ? { ...msg, content: msg.content + data.content }
+                      : msg
+                  ),
+                }));
+              });
+            }
+          } catch {
+            // 纯文本 chunk
+            requestAnimationFrame(() => {
+              set((state) => ({
+                messages: state.messages.map(msg =>
+                  msg.id === assistantPlaceholder.id
+                    ? { ...msg, content: msg.content + chunk }
+                    : msg
+                ),
+              }));
+            });
+          }
+        },
+        (_sessionId: number, messageId?: number) => {
+          // onComplete: 只替换 assistant 占位符 ID，不重新加载
+          if (messageId) {
+            set((state) => ({
+              messages: state.messages.map(msg =>
+                msg.id === assistantPlaceholder.id
+                  ? { ...msg, id: messageId }
+                  : msg
+              ),
+              isStreaming: false,
+              abortController: null,
+            }));
+          } else {
+            set({ isStreaming: false, abortController: null });
+          }
+        },
+        (error: string) => {
+          set({ error, isStreaming: false, abortController: null });
+        },
+        undefined, // onStatus
+        undefined, // onThinking
+        undefined, // onThinkingContent
+        model
+      );
     } catch (error) {
-      console.error("重新生成消息失败:", error);
-      const errorMessage = error instanceof Error ? error.message : "重新生成消息失败";
-      set({ error: errorMessage, isLoading: false });
+      const errorMessage = error instanceof Error ? error.message : "重新生成失败";
+      set({ error: errorMessage, isStreaming: false, abortController: null });
     }
   },