feat: 标签管理功能 + 问答前缀对用户隐藏

标签管理:
- 新增 tags/tag_assignments 持久化层、迁移、/api/tags 路由
- 标签分智能体/技能/定时任务三类, 仅同类型可互打, 仅 admin 可增删改与打标签
- 三类资源列表支持按名称模糊检索与按标签筛选(走后端查询参数)
- 前端新增标签管理页、TagPickerDialog(点击即时绑定)、彩色标签 chip

问答前缀:
- 前缀不再拼入消息 content, 改存 additional_kwargs 由 PromptPrefixMiddleware
  在调模型前临时注入, 用户界面看不到前缀但模型仍收到
- 修正 thread_existed 闸门导致首轮前缀被跳过的问题

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend-web/src/pages/ChatPage.tsx

@@ -93,7 +93,9 @@ export default function ChatPage() {
 
   const handleSubmit = useCallback(
     (message: PromptInputMessage) => {
+      // Only the opening turn of a brand-new thread may carry the prefix.
       const shouldApplyPrefix =
+        isNewThread &&
         !hasStartedConversation &&
         promptPrefixOn &&
         promptPrefixSettings?.enabled === true;
@@ -101,19 +103,17 @@ export default function ChatPage() {
       window.dispatchEvent(
         new CustomEvent("workspace:sandbox-resume-autoscroll"),
       );
-      const messageToSend = shouldApplyPrefix
-        ? {
-            ...message,
-            text: `${promptPrefixSettings?.prompt_prefix ?? ""}\n\n${message.text}`,
-          }
-        : message;
+      // The prefix is intentionally NOT concatenated into the message text:
+      // doing so would make the user see it. We only flag the request via
+      // context; the backend tags the message and PromptPrefixMiddleware
+      // injects the prefix into the LLM request only.
       void sendMessage(
         threadId,
-        messageToSend,
+        message,
         shouldApplyPrefix ? { prompt_prefix_enabled: true } : undefined,
       );
     },
-    [sendMessage, threadId, hasStartedConversation, promptPrefixOn, promptPrefixSettings],
+    [sendMessage, threadId, isNewThread, hasStartedConversation, promptPrefixOn, promptPrefixSettings],
   );
 
   const handleClarificationSubmit = useCallback(
@@ -129,13 +129,14 @@ export default function ChatPage() {
 
   const promptPrefixProp = useMemo(() => {
     if (!promptPrefixSettings?.enabled) return undefined;
-    if (hasStartedConversation) return undefined;
+    // The prefix toggle is offered only on the opening turn of a new thread.
+    if (!isNewThread || hasStartedConversation) return undefined;
     return {
       label: promptPrefixSettings.switch_label || "前缀",
       on: promptPrefixOn,
       onToggle: () => setPromptPrefixOn((v) => !v),
     };
-  }, [promptPrefixSettings, hasStartedConversation, promptPrefixOn]);
+  }, [promptPrefixSettings, isNewThread, hasStartedConversation, promptPrefixOn]);
 
   const messageListPaddingBottom = showFollowups
     ? MESSAGE_LIST_DEFAULT_PADDING_BOTTOM +

frontend-web/src/pages/ScheduledTasksPage.tsx

@@ -15,6 +15,7 @@ import {
   Play,
   Plus,
   RefreshCw,
+  TagsIcon,
   Trash2,
 } from "lucide-react";
 import { useRouteNavigate as useNavigate } from "@/core/route-base";
@@ -35,7 +36,11 @@ import {
   WorkspaceContainer,
   WorkspaceHeader,
 } from "@/components/workspace/workspace-container";
+import { TagChipList } from "@/components/workspace/tags/tag-chip";
+import { TagPickerDialog } from "@/components/workspace/tags/tag-picker-dialog";
+import { TagSearchBar } from "@/components/workspace/tags/tag-search-bar";
 import { useAgents } from "@/core/agents";
+import { getStoredAuth } from "@/core/auth";
 import {
   downloadScheduledTaskRun,
   type PublishedScheduledTask,
@@ -283,7 +288,10 @@ const emptyForm = {
 
 export default function ScheduledTasksPage() {
   const navigate = useNavigate();
-  const { data: tasks = [], isLoading } = useScheduledTasks();
+  const [search, setSearch] = useState("");
+  const [tagId, setTagId] = useState<string | null>(null);
+  // Name + tag filtering is resolved server-side via the /api/scheduled-tasks query.
+  const { data: tasks = [], isLoading } = useScheduledTasks({ search, tagId });
   const { data: deliveryProfile } = useScheduledTaskDeliveryProfile();
   const { agents } = useAgents();
   const actions = useScheduledTaskActions();
@@ -299,6 +307,8 @@ export default function ScheduledTasksPage() {
   const [runsTimeFilter, setRunsTimeFilter] = useState<"all" | "today" | "7d" | "30d">("all");
   const [subscribeTarget, setSubscribeTarget] = useState<PublishedScheduledTask | null>(null);
   const [subscribeNotify, setSubscribeNotify] = useState(false);
+  const [tagPickerTask, setTagPickerTask] = useState<ScheduledTask | null>(null);
+  const isAdmin = useMemo(() => getStoredAuth()?.system_role === "admin", []);
 
   const sortedTasks = useMemo(
     () =>
@@ -466,6 +476,14 @@ export default function ScheduledTasksPage() {
                   <TabsTrigger value="plaza" className="flex-1">广场</TabsTrigger>
                 </TabsList>
               </Tabs>
+              {activeTab === "mine" && (
+                <TagSearchBar
+                  targetType="scheduled_task"
+                  onSearchChange={setSearch}
+                  tagId={tagId}
+                  onTagIdChange={setTagId}
+                />
+              )}
             </CardHeader>
             <CardContent className="min-h-0 flex-1 p-0">
               <ScrollArea className="size-full">
@@ -527,7 +545,23 @@ export default function ScheduledTasksPage() {
                               </div>
                             )}
                           </div>
+                          {(task.tags?.length ?? 0) > 0 && (
+                            <TagChipList tags={task.tags!} className="mt-3" />
+                          )}
                           <div className="mt-3 flex flex-wrap gap-2">
+                            {isAdmin && (
+                              <Button
+                                size="icon"
+                                variant="outline"
+                                title="编辑标签"
+                                onClick={(event) => {
+                                  event.stopPropagation();
+                                  setTagPickerTask(task);
+                                }}
+                              >
+                                <TagsIcon className="size-4" />
+                              </Button>
+                            )}
                             {isOwner ? (
                               <>
                                 <Button
@@ -934,6 +968,16 @@ export default function ScheduledTasksPage() {
           </DialogFooter>
         </DialogContent>
       </Dialog>
+
+      {isAdmin && tagPickerTask && (
+        <TagPickerDialog
+          open={!!tagPickerTask}
+          onOpenChange={(open) => !open && setTagPickerTask(null)}
+          targetType="scheduled_task"
+          targetId={tagPickerTask.task_id}
+          currentTags={tagPickerTask.tags ?? []}
+        />
+      )}
     </WorkspaceContainer>
   );
 }

frontend-web/src/pages/TagsPage.tsx

@@ -0,0 +1,5 @@
+import { TagManagementPage } from "@/components/workspace/admin/tag-management-page";
+
+export default function TagsPage() {
+  return <TagManagementPage />;
+}

frontend-web/src/pages/WorkspaceRoutes.tsx

@@ -25,6 +25,7 @@ import PromptPrefixSettingsPage from "./PromptPrefixSettingsPage";
 import SkillEvolutionPage from "./SkillEvolutionPage";
 import SkillsPage from "./SkillsPage";
 import UsersPage from "./UsersPage";
+import TagsPage from "./TagsPage";
 import RecommendedQuestionsPage from "./RecommendedQuestionsPage";
 
 export function WorkspaceLayout({
@@ -183,6 +184,18 @@ export default function WorkspaceRoutes({
           </WorkspaceLayout>
         }
       />
+      <Route
+        path="admin/tags"
+        element={
+          getStoredAuth()?.system_role === "admin" ? (
+            <WorkspaceLayout {...layoutProps}>
+              <TagsPage />
+            </WorkspaceLayout>
+          ) : (
+            <Navigate to="/page/workspace/chats/new" replace />
+          )
+        }
+      />
       <Route
         path="settings/recommended-questions"
         element={