fix(core): use get_type_hints for Python 3.14 TypedDict compatibility (#34390)

Replace direct `__annotations__` access with `get_type_hints()` in
`_convert_any_typed_dicts_to_pydantic` to handle [PEP
649](https://peps.python.org/pep-0649/) deferred annotations in Python
3.14:

> [`Changed in version 3.14: Annotations are now lazily evaluated by
default`](https://docs.python.org/3/reference/compound_stmts.html#annotations)

Before:

```python
class MyTool(TypedDict):
    name: str

MyTool.__annotations__  # {'name': 'str'} - string, not type
issubclass('str', ...)  # TypeError: arg 1 must be a class
```

After:

```python
get_type_hints(MyTool)  # {'name': <class 'str'>} - actual type
```

Fixes #34291

Author: mdrxy

libs/core/langchain_core/tools/base.py

@@ -22,6 +22,7 @@
     get_type_hints,
 )
 
+import typing_extensions
 from pydantic import (
     BaseModel,
     ConfigDict,
@@ -94,7 +95,7 @@ def _is_annotated_type(typ: type[Any]) -> bool:
     Returns:
         `True` if the type is an Annotated type, `False` otherwise.
     """
-    return get_origin(typ) is typing.Annotated
+    return get_origin(typ) in (typing.Annotated, typing_extensions.Annotated)
 
 
 def _get_annotation_description(arg_type: type) -> str | None:

libs/core/langchain_core/utils/function_calling.py

@@ -18,8 +18,10 @@
     cast,
     get_args,
     get_origin,
+    get_type_hints,
 )
 
+import typing_extensions
 from pydantic import BaseModel
 from pydantic.v1 import BaseModel as BaseModelV1
 from pydantic.v1 import Field as Field_v1
@@ -232,13 +234,20 @@ def _convert_any_typed_dicts_to_pydantic(
     if is_typeddict(type_):
         typed_dict = type_
         docstring = inspect.getdoc(typed_dict)
-        annotations_ = typed_dict.__annotations__
+        # Use get_type_hints to properly resolve forward references and
+        # string annotations in Python 3.14+ (PEP 649 deferred annotations).
+        # include_extras=True preserves Annotated metadata.
+        try:
+            annotations_ = get_type_hints(typed_dict, include_extras=True)
+        except Exception:
+            # Fallback for edge cases where get_type_hints might fail
+            annotations_ = typed_dict.__annotations__
         description, arg_descriptions = _parse_google_docstring(
             docstring, list(annotations_)
         )
         fields: dict = {}
         for arg, arg_type in annotations_.items():
-            if get_origin(arg_type) is Annotated:  # type: ignore[comparison-overlap]
+            if get_origin(arg_type) in (Annotated, typing_extensions.Annotated):
                 annotated_args = get_args(arg_type)
                 new_arg_type = _convert_any_typed_dicts_to_pydantic(
                     annotated_args[0], depth=depth + 1, visited=visited