diff --git a/apps/ai-game-creator-shell/src/features/ui-editor/uiDesignResourceBridge.ts b/apps/ai-game-creator-shell/src/features/ui-editor/uiDesignResourceBridge.ts
index d53c19ab2..459155ee0 100644
--- a/apps/ai-game-creator-shell/src/features/ui-editor/uiDesignResourceBridge.ts
+++ b/apps/ai-game-creator-shell/src/features/ui-editor/uiDesignResourceBridge.ts
@@ -3,11 +3,13 @@ import type {
   GameCreationAppManifest,
 } from '../../../../../packages/shared/src/contracts/gameCreationApp';
 
-/** 一张设计图的输入引用：给已登记资源的 assetId，或给项目内相对路径。 */
-export type UiDesignDocImageReference = {
-  assetId?: string;
-  path?: string;
-};
+/**
+ * 一张设计图的输入引用：给已登记资源的 assetId，或给项目内相对路径。
+ * 两者只能二选一，与 Rust 侧 `每张设计图必须且只能给 assetId 或 path` 的判据一致。
+ */
+export type UiDesignDocImageReference =
+  | { assetId: string; path?: never }
+  | { assetId?: never; path: string };
 
 export type UiDesignDocCreated = {
   asset: GameCreationAppAssetManifestEntry;