fix: preserve knowledge base references

frontend-web/src/pages/AgentChatPage.tsx

@@ -779,7 +779,13 @@ export default function AgentChatPage({
       : "ready";
 
   return (
-    <ThreadContext.Provider value={{ thread: displayThread }}>
+    <ThreadContext.Provider
+      value={{
+        thread: displayThread,
+        knowledgeReferencesEnabled:
+          knowledgeSelectionReady && selectedKnowledgeBaseIds.length > 0,
+      }}
+    >
       {/* Root: fixed-height horizontal split. ChatBox (chat + artifact
           preview) lives in the left flex cell; the agent detail panel is a
           separate flex sibling OUTSIDE ChatBox, so the artifact preview

frontend-web/src/pages/ChatPage.tsx

@@ -688,7 +688,14 @@ export default function ChatPage() {
     !isWujieEnv();
 
   return (
-    <ThreadContext.Provider value={{ thread: displayThread, isMock }}>
+    <ThreadContext.Provider
+      value={{
+        thread: displayThread,
+        isMock,
+        knowledgeReferencesEnabled:
+          knowledgeSelectionReady && selectedKnowledgeBaseIds.length > 0,
+      }}
+    >
       <ChatBox threadId={threadId}>
         <div
           className={cn(