Add unit test

Author: henry3260

airflow-core/src/airflow/api_fastapi/core_api/routes/public/xcom.py

@@ -361,7 +361,7 @@ def update_xcom_entry(
             status.HTTP_400_BAD_REQUEST, f"Couldn't serialise the XCom with key: `{xcom_key}`"
         ) from e
 
-    # Re-fetch after set (delete + insert) to get fresh object for response
+    # Fetch after setting, to get fresh object for response
     xcom_entry = session.scalar(xcom_query)
     return XComResponseNative.model_validate(xcom_entry)
 

airflow-core/tests/unit/api_fastapi/core_api/routes/public/test_xcom.py

@@ -845,3 +845,21 @@ def test_patch_xcom_entry_with_slash_key(self, test_client, session):
         assert response.json()["key"] == slash_key
         assert response.json()["value"] == new_value
         check_last_log(session, dag_id=TEST_DAG_ID, event="update_xcom_entry", logical_date=None)
+
+    def test_patch_xcom_preserves_int_type(self, test_client, session):
+        """Test scenario described in #59032: if existing XCom value type is int,
+        after patching with different value, it should still be int in the API response.
+        """
+        key = "int_type_xcom"
+        # Create with int value
+        self._create_xcom(key, 42)
+        patch_value = 100
+        response = test_client.patch(
+            f"/dags/{TEST_DAG_ID}/dagRuns/{run_id}/taskInstances/{TEST_TASK_ID}/xcomEntries/{key}",
+            json={"value": patch_value},
+        )
+        assert response.status_code == 200
+        data = response.json()
+        assert data["value"] == patch_value
+        assert isinstance(data["value"], int), f"Expected int type but got {type(data['value'])}"
+        check_last_log(session, dag_id=TEST_DAG_ID, event="update_xcom_entry", logical_date=None)