Make websocket disconnect codes explicit

lib/phoenix/socket.ex

@@ -556,7 +556,11 @@ defmodule Phoenix.Socket do
   end
 
   def __info__(%Broadcast{event: "disconnect"}, state) do
-    {:stop, {:shutdown, :disconnected}, state}
+    # Close code 1001 ("Going Away") signals the client that the connection
+    # is intentionally closed but a reconnect is expected — phoenix.js gates
+    # reconnects behind a closeCode !== 1000 check.
+    # See https://github.com/mtrudel/bandit/issues/582.
+    {:stop, {:shutdown, :disconnected}, 1001, state}
   end
 
   def __info__(:socket_drain, state) do

lib/phoenix/transports/long_poll_server.ex

@@ -117,6 +117,10 @@ defmodule Phoenix.Transports.LongPoll.Server do
       {:stop, reason, handler_state} ->
         state = %{state | handler: {handler, handler_state}}
         {:stop, reason, state}
+
+      {:stop, reason, _code, handler_state} ->
+        state = %{state | handler: {handler, handler_state}}
+        {:stop, reason, state}
     end
   end
 

test/phoenix/socket/socket_test.exs

@@ -137,4 +137,20 @@ defmodule Phoenix.SocketTest do
       assert DrainerSpecSocket.drainer_spec(drainer: false, endpoint: Endpoint) == :ignore
     end
   end
+
+  describe "__info__/2" do
+    alias Phoenix.Socket.Broadcast
+
+    test "disconnect broadcast emits close code 1001 so phoenix.js reconnects" do
+      # phoenix.js gates reconnects on `closeCode !== 1000`.
+      # Servers might interpret `{:shutdown, :disconnected}`
+      # as code 1000, so we pass 1001 explicitly to force a retry.
+      # See https://github.com/mtrudel/bandit/issues/582.
+      state = make_ref()
+      msg = %Broadcast{topic: "t", event: "disconnect", payload: %{}}
+
+      assert {:stop, {:shutdown, :disconnected}, 1001, ^state} =
+               Phoenix.Socket.__info__(msg, state)
+    end
+  end
 end