Copy with cached property (#4399)

libs/langgraph/langgraph/pregel/read.py

@@ -192,6 +192,10 @@ class PregelNode(Runnable):
 
     def copy(self, update: dict[str, Any]) -> PregelNode:
         attrs = {**self.__dict__, **update}
+        # Drop the cached properties
+        attrs.pop("flat_writers", None)
+        attrs.pop("node", None)
+        attrs.pop("input_cache_key", None)
         return PregelNode(**attrs)
 
     @cached_property

libs/langgraph/pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "langgraph"
-version = "0.3.33"
+version = "0.3.34"
 description = "Building stateful, multi-actor applications with LLMs"
 authors = []
 license = "MIT"

libs/langgraph/tests/test_pregel.py

@@ -7878,6 +7878,30 @@ def test_bulk_state_updates(
         )
 
 
+def test_pregel_node_copy() -> None:
+    class State(TypedDict):
+        foo: str
+
+    def agent(state: State) -> State:
+        return {"foo": "agent"}
+
+    def tool(state: State) -> State:
+        return {"foo": "tool"}
+
+    graph = (
+        StateGraph(State)
+        .add_node("agent", agent)
+        .add_node("tool", tool)
+        .add_edge(START, "agent")
+        .add_edge("agent", "tool")
+        .compile()
+    )
+
+    graph.invoke({"foo": "input"}, {"configurable": {"thread_id": "1"}})
+    graph.copy()
+    graph.nodes["agent"].copy({})
+
+
 @pytest.mark.parametrize("checkpointer_name", REGULAR_CHECKPOINTERS_SYNC)
 def test_update_as_input(
     request: pytest.FixtureRequest, checkpointer_name: str