Add native ComfyUI list output converter

tests/test_node_contract.py

@@ -29,16 +29,37 @@ EXPECTED_IDS = {
     "BytesFromListIdx",
     "IntFromListIdx",
     "FloatFromListIdx",
+    "ETKListToComfyList",
 }
 
 
 def test_exact_workflow_ids_are_registered():
     assert set(PACKAGE.NODE_CLASS_MAPPINGS) == EXPECTED_IDS
     assert PACKAGE.NODE_DISPLAY_NAME_MAPPINGS == {
-        "AudioFromListIdx": "Audio From List Index"
+        "AudioFromListIdx": "Audio From List Index",
+        "ETKListToComfyList": "List To ComfyUI List",
     }
 
 
+def test_etk_list_to_comfy_list_uses_native_list_output_contract():
+    node = PACKAGE.ETKListToComfyList
+    source = ["first", {"second": 2}, 3]
+
+    assert node.INPUT_TYPES() == {
+        "required": {"items": ("LIST", {"default": []})}
+    }
+    assert node.RETURN_NAMES == ("items",)
+    assert node.OUTPUT_IS_LIST == (True,)
+    assert node.CATEGORY == "ETK/List"
+    assert node().convert(source) == (source,)
+    assert node().convert(source)[0] is source
+    assert node().convert([]) == ([],)
+    assert (node.RETURN_TYPES[0] != "IMAGE") is False
+
+    with pytest.raises(TypeError, match="items must be a LIST"):
+        node().convert("not-a-list")
+
+
 def test_etk_schema_and_selection_contracts():
     image = PACKAGE.ImageFromListIdx
     latent = PACKAGE.LatentFromListIdx