diff --git a/apps/ai-game-creator-shell/src/view/project-development/chat/controller/useDirectProjectChatController.ts b/apps/ai-game-creator-shell/src/view/project-development/chat/controller/useDirectProjectChatController.ts
index 043e5f953..da4941b38 100644
--- a/apps/ai-game-creator-shell/src/view/project-development/chat/controller/useDirectProjectChatController.ts
+++ b/apps/ai-game-creator-shell/src/view/project-development/chat/controller/useDirectProjectChatController.ts
@@ -110,6 +110,11 @@ export function useDirectProjectChatController({
    */
   const [attachmentsImporting, setAttachmentsImporting] = useState(false);
   const attachmentsImportingCountRef = useRef(0);
+  /**
+   * 已经在飞、还没落成正文芯片的附件条数：并发导入各算各的预算时，这些名额必须先占住，
+   * 否则两次并发导入会拿着同一份草稿附件数各自放行，插进正文的芯片就超过上限。
+   */
+  const attachmentsPendingCountRef = useRef(0);
   const [queuedTurns, setQueuedTurns] = useState<QueuedChatTurn[]>([]);
   const queuedTurnsRef = useRef<QueuedChatTurn[]>([]);
   queuedTurnsRef.current = queuedTurns;
@@ -255,6 +260,9 @@ export function useDirectProjectChatController({
    *
    * 控制器不再持有待发附件列表：本轮附件只有「正文芯片」一份事实源，
    * 所以这里不做任何「提交时再拼一次」的事。
+   *
+   * 上限必须是硬上限：草稿里的附件芯片数 + 这次与其它并发导入已经放行、还没落地的条数
+   * 一起算预算，放行的那部分在 `finally` 里还回去。
    */
   async function uploadFiles(
     files: readonly File[],
@@ -267,7 +275,12 @@ export function useDirectProjectChatController({
     }
     const accepted = files.slice(
       0,
-      Math.max(MAX_CHAT_COMPOSER_ATTACHMENTS - draftAttachmentCount, 0),
+      Math.max(
+        MAX_CHAT_COMPOSER_ATTACHMENTS -
+          draftAttachmentCount -
+          attachmentsPendingCountRef.current,
+        0,
+      ),
     );
     if (accepted.length === 0) {
       setAttachmentNotice(
@@ -275,6 +288,7 @@ export function useDirectProjectChatController({
       );
       return [];
     }
+    attachmentsPendingCountRef.current += accepted.length;
     attachmentsImportingCountRef.current += 1;
     setAttachmentsImporting(true);
     setAttachmentNotice('正在上传文件');
@@ -310,6 +324,7 @@ export function useDirectProjectChatController({
       }
       return [];
     } finally {
+      attachmentsPendingCountRef.current -= accepted.length;
       attachmentsImportingCountRef.current -= 1;
       if (attachmentsImportingCountRef.current <= 0) {
         attachmentsImportingCountRef.current = 0;
diff --git a/apps/ai-game-creator-shell/tests/chatComposerAttachmentCap.test.tsx b/apps/ai-game-creator-shell/tests/chatComposerAttachmentCap.test.tsx
new file mode 100644
index 000000000..9698af429
--- /dev/null
+++ b/apps/ai-game-creator-shell/tests/chatComposerAttachmentCap.test.tsx
@@ -0,0 +1,73 @@
+// @vitest-environment jsdom
+import { act, cleanup, renderHook, waitFor } from '@testing-library/react';
+import { afterEach, describe, expect, it, vi } from 'vitest';
+
+import {
+  MAX_CHAT_COMPOSER_ATTACHMENTS,
+  useDirectProjectChatController,
+} from '../src/view/project-development/chat/controller/useDirectProjectChatController';
+import type { DirectCodexTurnAttachment } from '../src/view/project-development/chat/conversation/directCodexTurnAttachments';
+
+// jsdom 的 Blob/File 没实现 `arrayBuffer`，而附件导入链路要按字节读文件。
+if (typeof Blob.prototype.arrayBuffer !== 'function') {
+  Blob.prototype.arrayBuffer = () =>
+    Promise.resolve(new Uint8Array([120]).buffer);
+}
+
+function files(count: number, prefix: string) {
+  return Array.from(
+    { length: count },
+    (_, index) =>
+      new File(['x'], `${prefix}-${index}.png`, { type: 'image/png' }),
+  );
+}
+
+afterEach(() => {
+  cleanup();
+  vi.restoreAllMocks();
+  window.__TAURI__ = undefined;
+});
+
+describe('聊天输入盒的附件上限', () => {
+  it('并发导入也守得住上限：在飞的条数先占名额', async () => {
+    let uploadSeq = 0;
+    const invoke = vi.fn(async (command: string, args?: unknown) => {
+      if (command !== 'upload_local_asset') {
+        throw new Error(`unexpected invoke ${command}`);
+      }
+      const fileName = (args as { fileName?: string }).fileName ?? 'file';
+      return { localPath: `assets/upload-${(uploadSeq += 1)}-${fileName}` };
+    });
+    window.__TAURI__ = { core: { invoke: invoke as never } };
+
+    const { result } = renderHook(() =>
+      useDirectProjectChatController({
+        assets: [],
+        enabled: false,
+        ensureConversationReadAllowed: async () => true,
+        ensureConversationWriteAllowed: async () => true,
+        onRuntimeError: () => undefined,
+        projectId: 'project-1',
+        projectPath: 'C:/project',
+        refreshManifest: () => undefined,
+      }),
+    );
+
+    // 两次并发导入各带 5 个文件：第一次占住 5 个名额，第二次只剩 3 个名额。
+    const imported: DirectCodexTurnAttachment[][] = [[], []];
+    await act(async () => {
+      const first = result.current.uploadFiles(files(5, 'first'), 0);
+      const second = result.current.uploadFiles(files(5, 'second'), 0);
+      [imported[0], imported[1]] = await Promise.all([first, second]);
+    });
+
+    await waitFor(() => {
+      expect(result.current.attachmentsImporting).toBe(false);
+    });
+    expect(imported[0]).toHaveLength(5);
+    expect(imported[1]).toHaveLength(3);
+    expect(imported[0].length + imported[1].length).toBe(
+      MAX_CHAT_COMPOSER_ATTACHMENTS,
+    );
+  });
+});