fix(query-handler): allow QueryOutput without type var (#1041)

Author: georgeh0

pyproject.toml

@@ -10,6 +10,7 @@ authors = [{ name = "CocoIndex", email = "[email protected]" }]
 readme = "README.md"
 requires-python = ">=3.11"
 dependencies = [
+    "typing-extensions>=4.12; python_version < '3.13'",
     "click>=8.1.8",
     "rich>=14.0.0",
     "python-dotenv>=1.1.0",

python/cocoindex/query_handler.py

@@ -1,8 +1,14 @@
 import dataclasses
 import numpy as np
 from numpy import typing as npt
-from typing import Generic, TypeVar
+from typing import Generic, Any
 from .index import VectorSimilarityMetric
+import sys
+
+if sys.version_info >= (3, 13):
+    from typing import TypeVar
+else:
+    from typing_extensions import TypeVar  # PEP 696 backport
 
 
 @dataclasses.dataclass
@@ -35,7 +41,7 @@ class QueryInfo:
     similarity_metric: VectorSimilarityMetric | None = None
 
 
-R = TypeVar("R")
+R = TypeVar("R", default=Any)
 
 
 @dataclasses.dataclass