diff --git a/packages/plugins/@nocobase/plugin-ai/src/client-v2/ai-employees/chatbox/components/Sender.tsx b/packages/plugins/@nocobase/plugin-ai/src/client-v2/ai-employees/chatbox/components/Sender.tsx
index 864c6712111..3f4d41fd1ad 100644
--- a/packages/plugins/@nocobase/plugin-ai/src/client-v2/ai-employees/chatbox/components/Sender.tsx
+++ b/packages/plugins/@nocobase/plugin-ai/src/client-v2/ai-employees/chatbox/components/Sender.tsx
@@ -477,7 +477,7 @@ const UploadFiles: React.FC<{ disabled?: boolean }> = observer(({ disabled }) =>
 
   return (
     <Attachments
-      getDropContainer={() => chatBoxRef?.current ?? document.body}
+      getDropContainer={() => chatBoxRef?.current}
       styles={{
         placeholder: {
           opacity: 0.8,
diff --git a/packages/plugins/@nocobase/plugin-ai/src/client-v2/ai-employees/chatbox/components/__tests__/SenderInput.test.tsx b/packages/plugins/@nocobase/plugin-ai/src/client-v2/ai-employees/chatbox/components/__tests__/SenderInput.test.tsx
index e05f9bf4f68..b760ab41ca0 100644
--- a/packages/plugins/@nocobase/plugin-ai/src/client-v2/ai-employees/chatbox/components/__tests__/SenderInput.test.tsx
+++ b/packages/plugins/@nocobase/plugin-ai/src/client-v2/ai-employees/chatbox/components/__tests__/SenderInput.test.tsx
@@ -21,6 +21,9 @@ const mocks = vi.hoisted(() => {
         nickname: 'Sales',
       },
       readonly: false,
+      chatBoxRef: {
+        current: null as HTMLDivElement | null,
+      },
     },
     chatConversationModel: {
       currentConversation: undefined as string | undefined,
@@ -44,6 +47,7 @@ const mocks = vi.hoisted(() => {
 
   return {
     runtime,
+    attachmentsGetDropContainer: undefined as (() => HTMLElement | null | undefined) | undefined,
     send: vi.fn(),
     cancelRequest: vi.fn(),
     finishEditingMessage: vi.fn(),
@@ -58,7 +62,16 @@ vi.mock('@ant-design/x', async () => {
   MockButton.displayName = 'MockButton';
 
   return {
-    Attachments: ({ children }: { children?: React.ReactNode }) => <div>{children}</div>,
+    Attachments: ({
+      children,
+      getDropContainer,
+    }: {
+      children?: React.ReactNode;
+      getDropContainer?: () => HTMLElement | null | undefined;
+    }) => {
+      mocks.attachmentsGetDropContainer = getDropContainer;
+      return <div>{children}</div>;
+    },
     Sender: React.forwardRef<
       { nativeElement?: HTMLTextAreaElement },
       {
@@ -167,9 +180,24 @@ describe('Sender input state', () => {
     mocks.runtime.chatSenderModel.setSenderValue.mockClear();
     mocks.runtime.chatSenderModel.setSenderRef.mockClear();
     mocks.runtime.chatSenderModel.setShowSenderHint.mockClear();
+    mocks.runtime.chatBoxModel.chatBoxRef.current = null;
+    mocks.attachmentsGetDropContainer = undefined;
     mocks.send.mockClear();
   });
 
+  it('limits attachment drops to the mounted chat box', () => {
+    const dropContainer = document.createElement('div');
+    mocks.runtime.chatBoxModel.chatBoxRef.current = dropContainer;
+
+    render(
+      <Sender showContextSelector={false} showWebSearch={false} showEmployeeSelect={false} showModelSelect={false} />,
+    );
+
+    expect(mocks.attachmentsGetDropContainer?.()).toBe(dropContainer);
+    mocks.runtime.chatBoxModel.chatBoxRef.current = null;
+    expect(mocks.attachmentsGetDropContainer?.()).toBeNull();
+  });
+
   it('keeps typing local until blur', () => {
     const { getByTestId } = render(
       <Sender
diff --git a/packages/plugins/@nocobase/plugin-ai/src/client-v2/block/ai-chat-box/__tests__/AIChatBoxCoreView.test.tsx b/packages/plugins/@nocobase/plugin-ai/src/client-v2/block/ai-chat-box/__tests__/AIChatBoxCoreView.test.tsx
index 69764e0d101..a2ad4f5dc49 100644
--- a/packages/plugins/@nocobase/plugin-ai/src/client-v2/block/ai-chat-box/__tests__/AIChatBoxCoreView.test.tsx
+++ b/packages/plugins/@nocobase/plugin-ai/src/client-v2/block/ai-chat-box/__tests__/AIChatBoxCoreView.test.tsx
@@ -23,6 +23,7 @@ const mocks = vi.hoisted(() => ({
   getAIEmployees: vi.fn(),
   refreshAITools: vi.fn(),
   setRoles: vi.fn(),
+  setChatBoxRef: vi.fn(),
   aiEmployees: [] as Array<{ username: string; nickname?: string; category?: string }>,
   currentEmployee: { username: 'legacy', nickname: 'Legacy' },
   currentConversation: undefined as string | undefined,
@@ -60,6 +61,7 @@ vi.mock('../../../ai-employees/chatbox/stores/runtime', () => ({
       roles: {},
       senderValue: mocks.senderValue,
       setRoles: mocks.setRoles,
+      setChatBoxRef: mocks.setChatBoxRef,
       setSenderValue: mocks.setSenderValue,
     },
     chatConversationModel: {
@@ -132,6 +134,23 @@ const createAIChatBoxCoreViewNode = (props: AIChatBoxBlockProps) => {
 };
 
 describe('AIChatBoxCoreView', () => {
+  it('registers its root as the attachment drop container', () => {
+    mocks.setChatBoxRef.mockReset();
+    mocks.currentConversation = undefined;
+    mocks.draftMessages = [];
+    mocks.getAIEmployees.mockResolvedValue([]);
+
+    const { container, unmount } = render(createAIChatBoxCoreViewNode({ showMessages: false, showDisclaimer: false }));
+
+    const root = container.firstElementChild;
+    const registeredRef = mocks.setChatBoxRef.mock.calls[0][0] as React.MutableRefObject<HTMLDivElement | null>;
+    expect(registeredRef.current).toBe(root);
+    expect(root).toHaveStyle({ position: 'relative' });
+
+    unmount();
+    expect(mocks.setChatBoxRef).toHaveBeenLastCalledWith(null);
+  });
+
   it('keeps messages in a bounded flex region above the sender', () => {
     mocks.messagesRendered = false;
     mocks.currentConversation = undefined;
diff --git a/packages/plugins/@nocobase/plugin-ai/src/client-v2/block/ai-chat-box/components/AIChatBoxCoreView.tsx b/packages/plugins/@nocobase/plugin-ai/src/client-v2/block/ai-chat-box/components/AIChatBoxCoreView.tsx
index 71a1ec3bd49..73118f75d9b 100644
--- a/packages/plugins/@nocobase/plugin-ai/src/client-v2/block/ai-chat-box/components/AIChatBoxCoreView.tsx
+++ b/packages/plugins/@nocobase/plugin-ai/src/client-v2/block/ai-chat-box/components/AIChatBoxCoreView.tsx
@@ -46,6 +46,7 @@ export const AIChatBoxCoreView: React.FC = observer(() => {
   const hasDraftUserMessage = draftMessages.some((message) => message.role === 'user');
 
   const { switchAIEmployee } = useChatBoxActions(runtime);
+  const chatBoxRef = useRef<HTMLDivElement | null>(null);
   const defaultUserMessageStateRef = useRef<{
     draftKey?: string;
     value?: string;
@@ -54,6 +55,13 @@ export const AIChatBoxCoreView: React.FC = observer(() => {
 
   useChatBoxEffect(runtime);
 
+  useEffect(() => {
+    chatBoxModel.setChatBoxRef(chatBoxRef);
+    return () => {
+      chatBoxModel.setChatBoxRef(null);
+    };
+  }, [chatBoxModel]);
+
   useEffect(() => {
     if (currentConversation) {
       return;
@@ -140,12 +148,14 @@ export const AIChatBoxCoreView: React.FC = observer(() => {
 
   return (
     <div
+      ref={chatBoxRef}
       style={{
         height: '100%',
         maxHeight: '100%',
         minHeight: 0,
         display: 'flex',
         flexDirection: 'column',
+        position: 'relative',
         overflow: 'hidden',
         backgroundColor: 'transparent',
       }}