core[patch]: pydantic 2.11 compat (#30554)

Release notes: https://pydantic.dev/articles/pydantic-v2-11-release

Covered here:

- We no longer access `model_fields` on class instances (that is now
deprecated);
- Update schema normalization for Pydantic version testing to reflect
changes to generated JSON schema (addition of `"additionalProperties":
True` for dict types with value Any or object).

## Considerations:

### Changes to JSON schema generation

#### Tool-calling / structured outputs

This may impact tool-calling + structured outputs for some providers,
but schema generation only changes if you have parameters of the form
`dict`, `dict[str, Any]`, `dict[str, object]`, etc. If dict parameters
are typed my understanding is there are no changes.

For OpenAI for example, untyped dicts work for structured outputs with
default settings before and after updating Pydantic, and error both
before/after if `strict=True`.

### Use of `model_fields`

There is one spot where we previously accessed `super(cls,
self).model_fields`, where `cls` is an object in the MRO. This was done
for the purpose of tracking aliases in secrets. I've updated this to
always be `type(self).model_fields`-- see comment in-line for detail.

---------

Co-authored-by: Sydney Runkle <54324534+sydney-runkle@users.noreply.github.com>

libs/core/tests/unit_tests/prompts/test_prompt.py

@@ -237,8 +237,8 @@ def test_mustache_prompt_from_template(snapshot: SnapshotAssertion) -> None:
     is a test."""
     )
     assert prompt.input_variables == ["foo"]
-    assert prompt.get_input_jsonschema() == {
-        "properties": {"foo": {"default": None, "title": "Foo", "type": "object"}},
+    assert _normalize_schema(prompt.get_input_jsonschema()) == {
+        "properties": {"foo": {"title": "Foo", "type": "object"}},
         "title": "PromptInput",
         "type": "object",
     }

libs/core/tests/unit_tests/pydantic_utils.py

@@ -1,4 +1,4 @@
-from typing import Any
+from typing import Any, Union
 
 from pydantic import BaseModel
 
@@ -97,6 +97,39 @@ def _schema(obj: Any) -> dict:
     return schema_
 
 
+def _remove_additionalproperties_from_untyped_dicts(schema: dict) -> dict[str, Any]:
+    """Remove `"additionalProperties": True` from dicts in the schema.
+
+    Pydantic 2.11 and later versions include `"additionalProperties": True` when
+    generating JSON schemas for dict properties with `Any` or `object` values.
+    """
+
+    def _remove_dict_additional_props(
+        obj: Union[dict[str, Any], list[Any]], inside_properties: bool = False
+    ) -> None:
+        if isinstance(obj, dict):
+            if (
+                inside_properties
+                and obj.get("type") == "object"
+                and obj.get("additionalProperties") is True
+            ):
+                obj.pop("additionalProperties", None)
+
+            # Recursively scan children
+            for key, value in obj.items():
+                # We are "inside_properties" if the *current* key is "properties",
+                # or if we were already inside properties in the caller.
+                next_inside_properties = inside_properties or (key == "properties")
+                _remove_dict_additional_props(value, next_inside_properties)
+
+        elif isinstance(obj, list):
+            for item in obj:
+                _remove_dict_additional_props(item, inside_properties)
+
+    _remove_dict_additional_props(schema, inside_properties=False)
+    return schema
+
+
 def _normalize_schema(obj: Any) -> dict[str, Any]:
     """Generate a schema and normalize it.
 
@@ -117,4 +150,5 @@ def _normalize_schema(obj: Any) -> dict[str, Any]:
     remove_all_none_default(data)
     replace_all_of_with_ref(data)
     _remove_enum(data)
+    _remove_additionalproperties_from_untyped_dicts(data)
     return data

libs/core/tests/unit_tests/runnables/__snapshots__/test_graph.ambr

@@ -30,41 +30,6 @@
   
   '''
 # ---
-# name: test_triple_nested_subgraph_mermaid[mermaid]
-  '''
-  ---
-  config:
-    flowchart:
-      curve: linear
-  ---
-  graph TD;
-  	__start__([<p>__start__</p>]):::first
-  	parent_1(parent_1)
-  	parent_2(parent_2)
-  	__end__([<p>__end__</p>]):::last
-  	__start__ --> parent_1;
-  	child_child_2 --> parent_2;
-  	parent_1 --> child_child_1_grandchild_1;
-  	parent_2 --> __end__;
-  	subgraph child
-  	child_child_2(child_2)
-  	child_child_1_grandchild_2 --> child_child_2;
-  	subgraph child_1
-  	child_child_1_grandchild_1(grandchild_1)
-  	child_child_1_grandchild_2(grandchild_2<hr/><small><em>__interrupt = before</em></small>)
-  	child_child_1_grandchild_1_greatgrandchild --> child_child_1_grandchild_2;
-  	subgraph grandchild_1
-  	child_child_1_grandchild_1_greatgrandchild(greatgrandchild)
-  	child_child_1_grandchild_1 --> child_child_1_grandchild_1_greatgrandchild;
-  	end
-  	end
-  	end
-  	classDef default fill:#f2f0ff,line-height:1.2
-  	classDef first fill-opacity:0
-  	classDef last fill:#bfb6fc
-  
-  '''
-# ---
 # name: test_graph_mermaid_duplicate_nodes[mermaid]
   '''
   graph TD;
@@ -2148,3 +2113,38 @@
     ]),
   })
 # ---
+# name: test_triple_nested_subgraph_mermaid[mermaid]
+  '''
+  ---
+  config:
+    flowchart:
+      curve: linear
+  ---
+  graph TD;
+  	__start__([<p>__start__</p>]):::first
+  	parent_1(parent_1)
+  	parent_2(parent_2)
+  	__end__([<p>__end__</p>]):::last
+  	__start__ --> parent_1;
+  	child_child_2 --> parent_2;
+  	parent_1 --> child_child_1_grandchild_1;
+  	parent_2 --> __end__;
+  	subgraph child
+  	child_child_2(child_2)
+  	child_child_1_grandchild_2 --> child_child_2;
+  	subgraph child_1
+  	child_child_1_grandchild_1(grandchild_1)
+  	child_child_1_grandchild_2(grandchild_2<hr/><small><em>__interrupt = before</em></small>)
+  	child_child_1_grandchild_1_greatgrandchild --> child_child_1_grandchild_2;
+  	subgraph grandchild_1
+  	child_child_1_grandchild_1_greatgrandchild(greatgrandchild)
+  	child_child_1_grandchild_1 --> child_child_1_grandchild_1_greatgrandchild;
+  	end
+  	end
+  	end
+  	classDef default fill:#f2f0ff,line-height:1.2
+  	classDef first fill-opacity:0
+  	classDef last fill:#bfb6fc
+  
+  '''
+# ---

libs/core/tests/unit_tests/runnables/test_history.py

@@ -1,6 +1,7 @@
 from collections.abc import Sequence
 from typing import Any, Callable, Optional, Union
 
+import pydantic
 import pytest
 from pydantic import BaseModel
 
@@ -19,6 +20,8 @@ from langchain_core.runnables.utils import ConfigurableFieldSpec, Input, Output
 from langchain_core.tracers import Run
 from tests.unit_tests.pydantic_utils import _schema
 
+PYDANTIC_VERSION = tuple(map(int, pydantic.__version__.split(".")))
+
 
 def test_interfaces() -> None:
     history = InMemoryChatMessageHistory()
@@ -484,10 +487,13 @@ def test_get_output_schema() -> None:
     )
     output_type = with_history.get_output_schema()
 
-    assert _schema(output_type) == {
+    expected_schema: dict = {
         "title": "RunnableWithChatHistoryOutput",
         "type": "object",
     }
+    if PYDANTIC_VERSION >= (2, 11):
+        expected_schema["additionalProperties"] = True
+    assert _schema(output_type) == expected_schema
 
 
 def test_get_input_schema_input_messages() -> None: