fix: guard state reset in GraphNode.reset_executor_state() for MultiAgentBase executors

src/strands/multiagent/graph.py

@@ -193,7 +193,7 @@ def reset_executor_state(self) -> None:
         if hasattr(self.executor, "messages"):
             self.executor.messages = copy.deepcopy(self._initial_messages)
 
-        if hasattr(self.executor, "state"):
+        if hasattr(self.executor, "state") and hasattr(self.executor.state, "get"):
             self.executor.state = AgentState(self._initial_state.get())
 
         if hasattr(self.executor, "_model_state"):

tests/strands/multiagent/test_graph.py

@@ -794,6 +794,32 @@ async def test_node_reset_executor_state():
     assert multi_agent_node.result is None
 
 
+def test_node_reset_executor_state_does_not_corrupt_nested_graph_state():
+    """Test that reset_executor_state does not overwrite a nested Graph's GraphState with AgentState."""
+    inner_agent = create_mock_agent("inner_agent")
+    builder = GraphBuilder()
+    builder.add_node(inner_agent, "inner_a")
+    inner_graph = builder.build()
+
+    # The nested Graph's .state is GraphState, which does not have a .get() method
+    assert isinstance(inner_graph.state, GraphState)
+    assert not hasattr(inner_graph.state, "get")
+
+    # Wrap the nested graph in a GraphNode
+    outer_node = GraphNode("outer", inner_graph)
+    outer_node.execution_status = Status.COMPLETED
+
+    # Before fix: reset_executor_state would call AgentState(self._initial_state.get())
+    # and assign it to inner_graph.state, overwriting GraphState with AgentState.
+    outer_node.reset_executor_state()
+
+    # Verify the nested graph's state was NOT replaced with AgentState
+    assert isinstance(inner_graph.state, GraphState), (
+        "reset_executor_state must not replace a nested Graph's GraphState with AgentState"
+    )
+    assert outer_node.execution_status == Status.PENDING
+
+
 def test_graph_dataclasses_and_enums():
     """Test dataclass initialization, properties, and enum behavior."""
     # Test Status enum