Merge pull request #430 from langchain-ai/harrison/expose-messages-state

add messages state

langgraph/graph/__init__.py

@@ -1,5 +1,12 @@
 from langgraph.graph.graph import END, Graph
-from langgraph.graph.message import MessageGraph, add_messages
+from langgraph.graph.message import MessageGraph, MessagesState, add_messages
 from langgraph.graph.state import StateGraph
 
-__all__ = ["END", "Graph", "StateGraph", "MessageGraph", "add_messages"]
+__all__ = [
+    "END",
+    "Graph",
+    "StateGraph",
+    "MessageGraph",
+    "add_messages",
+    "MessagesState",
+]

langgraph/graph/message.py

@@ -1,5 +1,5 @@
 import uuid
-from typing import Annotated, Union
+from typing import Annotated, TypedDict, Union
 
 from langchain_core.messages import (
     AnyMessage,
@@ -136,3 +136,7 @@ class MessageGraph(StateGraph):
 
     def __init__(self) -> None:
         super().__init__(Annotated[list[AnyMessage], add_messages])
+
+
+class MessagesState(TypedDict):
+    messages: Annotated[list[AnyMessage], add_messages]