RunnableWithMessageHistory: Fix input schema (#14516)

Input schema should not have history key

libs/core/langchain_core/runnables/history.py

@@ -197,8 +197,6 @@ class RunnableWithMessageHistory(RunnableBindingBase):
                 fields[self.input_messages_key] = (Sequence[BaseMessage], ...)
             else:
                 fields["__root__"] = (Sequence[BaseMessage], ...)
-            if self.history_messages_key:
-                fields[self.history_messages_key] = (Sequence[BaseMessage], ...)
             return create_model(  # type: ignore[call-overload]
                 "RunnableWithChatHistoryInput",
                 **fields,

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

@@ -178,7 +178,6 @@ def test_output_dict() -> None:
 def test_get_input_schema_input_dict() -> None:
     class RunnableWithChatHistoryInput(BaseModel):
         input: Union[str, BaseMessage, Sequence[BaseMessage]]
-        history: Sequence[BaseMessage]
 
     runnable = RunnableLambda(
         lambda input: {