统一组件图标布局并完善选择吸附交互

tests/test_reactflow_project_medium_reference.py

@@ -66,5 +66,39 @@ class ReactFlowProjectMediumReferenceVersionTests(unittest.TestCase):
         self.assertIn('<Parameter name="property_model" value="0.0"', xml)
 
 
+class ReactFlowPresentationLayoutVersionTests(unittest.TestCase):
+    def test_layout_version_is_preserved_but_not_written_to_xml(self) -> None:
+        project = ReactFlowProjectPayload(
+            name="versioned-presentation-layout",
+            presentationLayoutVersion=1,
+        )
+
+        self.assertEqual(project.presentationLayoutVersion, 1)
+        self.assertEqual(
+            pydantic_to_jsonable(project)["presentationLayoutVersion"],
+            1,
+        )
+        xml = build_reactflow_system_xml(project).decode("utf-8")
+        self.assertNotIn("presentationLayoutVersion", xml)
+
+    def test_layout_version_rejects_unsupported_values(self) -> None:
+        for version in (0, 2, -1, "1"):
+            with self.subTest(version=version):
+                with self.assertRaises(ValueError):
+                    ReactFlowProjectPayload(
+                        name="unsupported-presentation-layout",
+                        presentationLayoutVersion=version,
+                    )
+
+    def test_legacy_layout_version_remains_missing(self) -> None:
+        project = ReactFlowProjectPayload(name="legacy-presentation-layout")
+
+        self.assertIsNone(project.presentationLayoutVersion)
+        self.assertNotIn(
+            "presentationLayoutVersion",
+            pydantic_to_jsonable(project),
+        )
+
+
 if __name__ == "__main__":
     unittest.main()