diff --git a/src/funcchain/schema/types.py b/src/funcchain/schema/types.py
index 1c2cf12..0bd26df 100644
--- a/src/funcchain/schema/types.py
+++ b/src/funcchain/schema/types.py
@@ -1,14 +1,12 @@
-from typing import Callable, Optional, Union
+from typing import Callable, Union
 
 from langchain_core.chat_history import BaseChatMessageHistory
 from langchain_core.language_models import BaseChatModel
-from langchain_core.messages import AIMessage, HumanMessage
+from langchain_core.messages import AIMessage, BaseMessage
 from langchain_core.runnables import Runnable
 
 UniversalChatModel = Union[BaseChatModel, str, None]
 
-ChatHandler = Runnable[HumanMessage, AIMessage]
+ChatRunnable = Runnable[list[BaseMessage], AIMessage]
 
 ChatHistoryFactory = Callable[..., BaseChatMessageHistory]
-
-OptionalChatHistoryFactory = Optional[ChatHistoryFactory]