preserve state in singleton managers

backend/test/backend/node_cluster_integration_test.exs

@@ -30,6 +30,29 @@ defmodule Backend.NodeClusterIntegrationTests do
       assert length(peer_nodes -- [owner_node]) == 3,
              "Expected 3 non-owner peer nodes, got #{inspect(peer_nodes -- [owner_node])}"
     end
+
+    test "crashing GameRunner gets picked up on other node" do
+      peers = start_cluster(2)
+
+      game_runner_pid =
+        :peer.call(hd(peers) |> elem(0), :global, :whereis_name, [Backend.GameRunner])
+
+      assert is_pid(game_runner_pid), "Could not find GameRunner in :global registry"
+
+      first_node = node(game_runner_pid)
+
+      GameRunner.crash_game()
+
+      :timer.sleep(100)
+
+      new_pid = GameRunner.get_pid()
+      assert is_pid(new_pid), "GameRunner did not restart after crash "
+
+      restarted_node = node(new_pid)
+
+      assert restarted_node != first_node,
+             "GameRunner restarted on the same node after 10 crash attempts"
+    end
   end
 
   defp start_cluster(count) do