From bdf0def7981e0f0b09b439e084245d94a351b5d3 Mon Sep 17 00:00:00 2001
From: Nuno Campos <nuno@langchain.dev>
Date: Tue, 16 Apr 2024 15:05:04 -0700
Subject: [PATCH 1/2] Resolve type annotation forward refs when parsing
 StateGraph schema type

---
 langgraph/graph/state.py | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/langgraph/graph/state.py b/langgraph/graph/state.py
index bc42d0370..86e764504 100644
--- a/langgraph/graph/state.py
+++ b/langgraph/graph/state.py
@@ -1,7 +1,7 @@
 import logging
 from functools import partial
 from inspect import signature
-from typing import Any, Optional, Sequence, Type, Union
+from typing import Any, Optional, Sequence, Type, Union, get_type_hints
 
 from langchain_core.runnables import Runnable, RunnableConfig
 from langchain_core.runnables.base import RunnableLike
@@ -286,15 +286,13 @@ def _coerce_state(schema: Type[Any], input: dict[str, Any]) -> dict[str, Any]:
 
 def _get_channels(schema: Type[dict]) -> dict[str, BaseChannel]:
     if not hasattr(schema, "__annotations__"):
-        return {
-            "__root__": _get_channel(schema),
-        }
+        return {"__root__": _get_channel(schema)}
 
-    channels: dict[str, BaseChannel] = {}
-    for name, typ in schema.__annotations__.items():
-        channels[name] = _get_channel(typ)
-
-    return channels
+    return {
+        name: _get_channel(typ)
+        for name, typ in get_type_hints(schema, include_extras=True).items()
+        if name != "__slots__"
+    }
 
 
 def _get_channel(annotation: Any) -> Optional[BaseChannel]:

From 012bbb961f4736759e7bd14ba9d3adddedaac8e7 Mon Sep 17 00:00:00 2001
From: Nuno Campos <nuno@langchain.dev>
Date: Tue, 16 Apr 2024 15:07:51 -0700
Subject: [PATCH 2/2] Lint

---
 langgraph/graph/state.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/langgraph/graph/state.py b/langgraph/graph/state.py
index 86e764504..fb9380a1c 100644
--- a/langgraph/graph/state.py
+++ b/langgraph/graph/state.py
@@ -295,7 +295,7 @@ def _get_channels(schema: Type[dict]) -> dict[str, BaseChannel]:
     }
 
 
-def _get_channel(annotation: Any) -> Optional[BaseChannel]:
+def _get_channel(annotation: Any) -> BaseChannel:
     if channel := _is_field_binop(annotation):
         return channel
     return LastValue(annotation)