diff --git a/crates/oxide_kernel/src/builtin.rs b/crates/oxide_kernel/src/builtin.rs
index ed399759..0bf533c3 100644
--- a/crates/oxide_kernel/src/builtin.rs
+++ b/crates/oxide_kernel/src/builtin.rs
@@ -2233,129 +2233,6 @@ impl BuiltinWorld {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::shape_forge::{ShapeForge, EMPTY_SHAPE_ID};
-    use crate::string_forge::PermInterner;
-
-    fn make_world() -> BuiltinWorld {
-        let sf = PermInterner::new();
-        let sh = ShapeForge::new();
-        BuiltinWorld::new(&sf, &sh)
-    }
-
-    #[test]
-    fn test_all_protos_valid() {
-        let w = make_world();
-        let protos = [
-            &w.object_proto,
-            &w.array_proto,
-            &w.function_proto,
-            &w.string_proto,
-            &w.number_proto,
-            &w.boolean_proto,
-            &w.error_proto,
-            &w.symbol_proto,
-        ];
-        for p in protos {
-            assert!(p.shape_id() > EMPTY_SHAPE_ID, "proto should have a non-empty shape");
-        }
-    }
-
-    #[test]
-    fn test_all_constructors_valid() {
-        let w = make_world();
-        assert!(w.object_constructor.is_function());
-        assert!(w.array_constructor.is_function());
-        assert!(w.function_constructor.is_function());
-        assert!(w.string_constructor.is_function());
-        assert!(w.number_constructor.is_function());
-        assert!(w.boolean_constructor.is_function());
-        assert!(w.error_constructor.is_function());
-        assert!(w.symbol_constructor.is_function());
-    }
-
-    #[test]
-    fn test_prototypes_are_not_functions() {
-        let w = make_world();
-        assert!(!w.object_proto.is_function());
-        assert!(!w.array_proto.is_function());
-        assert!(!w.function_proto.is_function());
-        assert!(!w.string_proto.is_function());
-        assert!(!w.number_proto.is_function());
-        assert!(!w.boolean_proto.is_function());
-        assert!(!w.error_proto.is_function());
-        assert!(!w.symbol_proto.is_function());
-    }
-
-    #[test]
-    fn test_protos_have_null_proto() {
-        let w = make_world();
-        // Object.prototype 是根——其 __proto__ 为 null。
-        assert!(w.object_proto.proto().is_null());
-        // 其余构造器原型均继承自 Object.prototype。
-        assert!(w.array_proto.proto().is_object());
-        assert!(w.function_proto.proto().is_object());
-        assert!(w.string_proto.proto().is_object());
-        assert!(w.number_proto.proto().is_object());
-        assert!(w.boolean_proto.proto().is_object());
-        assert!(w.error_proto.proto().is_object());
-        assert!(w.symbol_proto.proto().is_object());
-    }
-
-    #[test]
-    fn test_shapes_populated() {
-        let w = make_world();
-        assert!(
-            w.object_constructor.shape_id() > EMPTY_SHAPE_ID,
-            "constructor should have prototype + name shape"
-        );
-        assert!(w.object_proto.shape_id() > EMPTY_SHAPE_ID, "prototype should have constructor shape");
-    }
-
-    #[test]
-    fn builtin_rebuild_with_dirty_reuses_clean_fields() {
-        let sf = PermInterner::new();
-        let sh = ShapeForge::new();
-        let w = BuiltinWorld::new(&sf, &sh);
-        let rebuilt = BuiltinWorld::rebuild_with_dirty(&w, &sf, &sh, &crate::kernel::BuiltinDirtySet::default());
-
-        assert!(std::ptr::eq(w.object_proto.as_ptr(), rebuilt.object_proto.as_ptr()));
-        assert!(std::ptr::eq(w.array_proto.as_ptr(), rebuilt.array_proto.as_ptr()));
-        assert!(std::ptr::eq(w.function_proto.as_ptr(), rebuilt.function_proto.as_ptr()));
-    }
-
-    #[test]
-    fn builtin_rebuild_with_dirty_replaces_only_dirty_group() {
-        let sf = PermInterner::new();
-        let sh = ShapeForge::new();
-        let w = BuiltinWorld::new(&sf, &sh);
-        let dirty = crate::kernel::BuiltinDirtySet {
-            array: true,
-            ..Default::default()
-        };
-        let rebuilt = BuiltinWorld::rebuild_with_dirty(&w, &sf, &sh, &dirty);
-
-        assert!(!std::ptr::eq(w.array_proto.as_ptr(), rebuilt.array_proto.as_ptr()));
-        assert!(!std::ptr::eq(w.array_constructor.as_ptr(), rebuilt.array_constructor.as_ptr()));
-        assert!(std::ptr::eq(w.object_proto.as_ptr(), rebuilt.object_proto.as_ptr()));
-        assert!(std::ptr::eq(w.function_proto.as_ptr(), rebuilt.function_proto.as_ptr()));
-    }
-
-    #[test]
-    fn builtin_rebuild_with_dirty_repairs_ctor_proto_links() {
-        let sf = PermInterner::new();
-        let sh = ShapeForge::new();
-        let w = BuiltinWorld::new(&sf, &sh);
-        let dirty = crate::kernel::BuiltinDirtySet {
-            array: true,
-            ..Default::default()
-        };
-        let rebuilt = BuiltinWorld::rebuild_with_dirty(&w, &sf, &sh, &dirty);
-
-        let ctor_proto = rebuilt.array_constructor.get_prop_at(0).as_js_object_ptr();
-        let proto_ctor = rebuilt.array_proto.get_prop_at(0).as_js_object_ptr();
-        assert!(std::ptr::eq(ctor_proto, rebuilt.array_proto.as_ptr() as *mut JsObject));
-        assert!(std::ptr::eq(proto_ctor, rebuilt.array_constructor.as_ptr() as *mut JsObject));
-    }
 
     /// 选择性重建的释放 + 重指面动态自测：被替换旧 P 对象属性区恰好释放一次
     /// （置空可断言，含保活钉住对的属性区、本体钉保留），保留字段指针不变且
diff --git a/crates/oxide_kernel/tests/builtin_world_tests.rs b/crates/oxide_kernel/tests/builtin_world_tests.rs
new file mode 100644
index 00000000..91431dde
--- /dev/null
+++ b/crates/oxide_kernel/tests/builtin_world_tests.rs
@@ -0,0 +1,126 @@
+use oxide_kernel::builtin::BuiltinWorld;
+use oxide_kernel::kernel::BuiltinDirtySet;
+use oxide_kernel::shape_forge::{ShapeForge, EMPTY_SHAPE_ID};
+use oxide_kernel::string_forge::PermInterner;
+use oxide_types::object::JsObject;
+
+fn make_world() -> BuiltinWorld {
+    let sf = PermInterner::new();
+    let sh = ShapeForge::new();
+    BuiltinWorld::new(&sf, &sh)
+}
+
+#[test]
+fn test_all_protos_valid() {
+    let w = make_world();
+    let protos = [
+        &w.object_proto,
+        &w.array_proto,
+        &w.function_proto,
+        &w.string_proto,
+        &w.number_proto,
+        &w.boolean_proto,
+        &w.error_proto,
+        &w.symbol_proto,
+    ];
+    for p in protos {
+        assert!(p.shape_id() > EMPTY_SHAPE_ID, "proto should have a non-empty shape");
+    }
+}
+
+#[test]
+fn test_all_constructors_valid() {
+    let w = make_world();
+    assert!(w.object_constructor.is_function());
+    assert!(w.array_constructor.is_function());
+    assert!(w.function_constructor.is_function());
+    assert!(w.string_constructor.is_function());
+    assert!(w.number_constructor.is_function());
+    assert!(w.boolean_constructor.is_function());
+    assert!(w.error_constructor.is_function());
+    assert!(w.symbol_constructor.is_function());
+}
+
+#[test]
+fn test_prototypes_are_not_functions() {
+    let w = make_world();
+    assert!(!w.object_proto.is_function());
+    assert!(!w.array_proto.is_function());
+    assert!(!w.function_proto.is_function());
+    assert!(!w.string_proto.is_function());
+    assert!(!w.number_proto.is_function());
+    assert!(!w.boolean_proto.is_function());
+    assert!(!w.error_proto.is_function());
+    assert!(!w.symbol_proto.is_function());
+}
+
+#[test]
+fn test_protos_have_null_proto() {
+    let w = make_world();
+    // Object.prototype 是根——其 __proto__ 为 null。
+    assert!(w.object_proto.proto().is_null());
+    // 其余构造器原型均继承自 Object.prototype。
+    assert!(w.array_proto.proto().is_object());
+    assert!(w.function_proto.proto().is_object());
+    assert!(w.string_proto.proto().is_object());
+    assert!(w.number_proto.proto().is_object());
+    assert!(w.boolean_proto.proto().is_object());
+    assert!(w.error_proto.proto().is_object());
+    assert!(w.symbol_proto.proto().is_object());
+}
+
+#[test]
+fn test_shapes_populated() {
+    let w = make_world();
+    assert!(
+        w.object_constructor.shape_id() > EMPTY_SHAPE_ID,
+        "constructor should have prototype + name shape"
+    );
+    assert!(w.object_proto.shape_id() > EMPTY_SHAPE_ID, "prototype should have constructor shape");
+}
+
+#[test]
+fn builtin_rebuild_with_dirty_reuses_clean_fields() {
+    let sf = PermInterner::new();
+    let sh = ShapeForge::new();
+    let w = BuiltinWorld::new(&sf, &sh);
+    let rebuilt = BuiltinWorld::rebuild_with_dirty(&w, &sf, &sh, &BuiltinDirtySet::default());
+
+    assert!(std::ptr::eq(w.object_proto.as_ptr(), rebuilt.object_proto.as_ptr()));
+    assert!(std::ptr::eq(w.array_proto.as_ptr(), rebuilt.array_proto.as_ptr()));
+    assert!(std::ptr::eq(w.function_proto.as_ptr(), rebuilt.function_proto.as_ptr()));
+}
+
+#[test]
+fn builtin_rebuild_with_dirty_replaces_only_dirty_group() {
+    let sf = PermInterner::new();
+    let sh = ShapeForge::new();
+    let w = BuiltinWorld::new(&sf, &sh);
+    let dirty = BuiltinDirtySet {
+        array: true,
+        ..Default::default()
+    };
+    let rebuilt = BuiltinWorld::rebuild_with_dirty(&w, &sf, &sh, &dirty);
+
+    assert!(!std::ptr::eq(w.array_proto.as_ptr(), rebuilt.array_proto.as_ptr()));
+    assert!(!std::ptr::eq(w.array_constructor.as_ptr(), rebuilt.array_constructor.as_ptr()));
+    assert!(std::ptr::eq(w.object_proto.as_ptr(), rebuilt.object_proto.as_ptr()));
+    assert!(std::ptr::eq(w.function_proto.as_ptr(), rebuilt.function_proto.as_ptr()));
+}
+
+#[test]
+fn builtin_rebuild_with_dirty_repairs_ctor_proto_links() {
+    let sf = PermInterner::new();
+    let sh = ShapeForge::new();
+    let w = BuiltinWorld::new(&sf, &sh);
+    let dirty = BuiltinDirtySet {
+        array: true,
+        ..Default::default()
+    };
+    let rebuilt = BuiltinWorld::rebuild_with_dirty(&w, &sf, &sh, &dirty);
+
+    let ctor_proto = rebuilt.array_constructor.get_prop_at(0).as_js_object_ptr();
+    let proto_ctor = rebuilt.array_proto.get_prop_at(0).as_js_object_ptr();
+    assert!(std::ptr::eq(ctor_proto, rebuilt.array_proto.as_ptr() as *mut JsObject));
+    assert!(std::ptr::eq(proto_ctor, rebuilt.array_constructor.as_ptr() as *mut JsObject));
+}