diff --git a/apps/ai-game-creator-shell/tests/assetKindCanonicalMapping.test.ts b/apps/ai-game-creator-shell/tests/assetKindCanonicalMapping.test.ts
index 8ceb8ccc3..40308e594 100644
--- a/apps/ai-game-creator-shell/tests/assetKindCanonicalMapping.test.ts
+++ b/apps/ai-game-creator-shell/tests/assetKindCanonicalMapping.test.ts
@@ -222,6 +222,10 @@ describe('真机出现的 kind 归类口径', () => {
     // 现役写入侧的大写字面量与字体 kind，两者都必须落进明确栏目。
     { kind: 'UI', canonical: 'ui-design', category: 'ui-interaction' },
     { kind: 'font', canonical: 'document', category: 'document' },
+    // `Object.prototype` 上的键不是别名：TS 侧必须用 `Object.hasOwn` 挡住对象字面量的
+    // 原型命中，Rust 侧 match 字面量本来就落 `image`；这类极端输入两侧也必须一致。
+    { kind: 'constructor', canonical: 'image', category: 'unclassified' },
+    { kind: '__proto__', canonical: 'image', category: 'unclassified' },
   ];
 
   test.each(decided)(
diff --git a/packages/shared/src/contracts/gameCreationApp.test.ts b/packages/shared/src/contracts/gameCreationApp.test.ts
index b6ab26444..b187171a7 100644
--- a/packages/shared/src/contracts/gameCreationApp.test.ts
+++ b/packages/shared/src/contracts/gameCreationApp.test.ts
@@ -753,6 +753,25 @@ describe('AI 游戏创作 App 共享契约', () => {
     // 字体资产的现役写入侧写的是 `font`。
     expect(canonicalGameCreationAppAssetKind('font')).toBe('document');
     expect(canonicalGameCreationAppAssetKind('FONT')).toBe('document');
+    /**
+     * `Object.prototype` 上的键不是别名：别名表是对象字面量，直接下标取值会拿到原型上的
+     * 函数/对象（truthy）并被当成 canonical kind 返回；Rust 侧是 `match` 字面量，只会落
+     * `image`。必须用 `Object.hasOwn` 挡掉，两侧对这类输入的归类才一致
+     * （`image → unclassified`）。跨语言对照另见 `assetKindCanonicalMapping.test.ts` 的
+     * `decided` 表。
+     */
+    for (const prototypeKey of [
+      'constructor',
+      '__proto__',
+      'toString',
+      'valueOf',
+      'hasOwnProperty',
+    ]) {
+      expect(canonicalGameCreationAppAssetKind(prototypeKey)).toBe('image');
+      expect(gameCreationAppAssetCategoryForKind(prototypeKey)).toBe(
+        'unclassified',
+      );
+    }
     expect(canonicalGameCreationAppAssetKind('unknown-kind')).toBe('image');
   });
 
diff --git a/packages/shared/src/contracts/gameCreationApp.ts b/packages/shared/src/contracts/gameCreationApp.ts
index 70e82533b..3aee24381 100644
--- a/packages/shared/src/contracts/gameCreationApp.ts
+++ b/packages/shared/src/contracts/gameCreationApp.ts
@@ -547,8 +547,16 @@ export function canonicalGameCreationAppAssetKind(
    * 且派生值本身就是 `unclassified`，读时自愈也救不回来。
    */
   const normalized = value.trim().toLowerCase();
-  const legacyKind = GAME_CREATION_APP_LEGACY_ASSET_KINDS[normalized];
-  if (legacyKind) return legacyKind;
+  /**
+   * `kind` 是外部输入，可能正好是 `Object.prototype` 上的键（`constructor` / `__proto__` /
+   * `toString` / `valueOf` …）。别名表是对象字面量，直接下标取值会拿到原型上的函数/对象
+   * （truthy），被当成 canonical kind 返回；Rust 侧是 `match` 字面量，只会落 `image`。
+   * 必须先确认命中的是**表自己的键**，两侧对这类输入的归类才一致（都落 `image → unclassified`）。
+   */
+  if (Object.hasOwn(GAME_CREATION_APP_LEGACY_ASSET_KINDS, normalized)) {
+    const legacyKind = GAME_CREATION_APP_LEGACY_ASSET_KINDS[normalized];
+    if (legacyKind) return legacyKind;
+  }
   if (
     (GAME_CREATION_APP_CANONICAL_ASSET_KINDS as readonly string[]).includes(
       normalized,
diff --git a/server-rs/crates/shared-contracts/src/game_creation_app.rs b/server-rs/crates/shared-contracts/src/game_creation_app.rs
index 073eae8d9..d210f5e44 100644
--- a/server-rs/crates/shared-contracts/src/game_creation_app.rs
+++ b/server-rs/crates/shared-contracts/src/game_creation_app.rs
@@ -2177,6 +2177,20 @@ mod tests {
             game_creation_app_asset_category_for_kind("font"),
             GameCreationAppAssetCategory::Document
         );
+        // `Object.prototype` 上的键不是别名：Rust 侧是 `match` 字面量，本来就落 `image`；
+        // TS 侧别名表是对象字面量，必须用 `Object.hasOwn` 挡住原型命中，两侧才一致。
+        // 这两条与 TS `gameCreationApp.test.ts` / `assetKindCanonicalMapping.test.ts` 成对。
+        for prototype_key in ["constructor", "__proto__", "toString", "valueOf"] {
+            assert_eq!(
+                canonical_game_creation_app_asset_kind(prototype_key),
+                "image",
+                "{prototype_key} 必须落 image 兜底"
+            );
+            assert_eq!(
+                game_creation_app_asset_category_for_kind(prototype_key),
+                GameCreationAppAssetCategory::Unclassified
+            );
+        }
         assert_eq!(
             game_creation_app_asset_category_for_kind("unknown-kind"),
             GameCreationAppAssetCategory::Unclassified