Fix disconnect notifiers

lib3270j/src/main/java/haus/nightmare/lib3270j/Telnet3270Client.java

@@ -385,6 +385,9 @@ public class Telnet3270Client {
      * Check if connected (any state past TCP pending).
      */
     public boolean isConnected() {
+        if (fsm != null && fsm.getConnectionState() == ConnectionState.NOT_CONNECTED) {
+            return false;
+        }
         return connection != null && connection.isConnected();
     }
 

lib3270j/src/main/java/haus/nightmare/lib3270j/telnet/TelnetConnection.java

@@ -599,7 +599,7 @@ public class TelnetConnection {
      * Check if the socket is connected.
      */
     public boolean isConnected() {
-        return socket != null && socket.isConnected() && !socket.isClosed();
+        return running && socket != null && socket.isConnected() && !socket.isClosed();
     }
 
     /**
@@ -654,7 +654,13 @@ public class TelnetConnection {
                 fsm.onError("Network loop error: " + t.getMessage());
             }
         } finally {
+            running = false;
             stopKeepAlive();
+            try {
+                if (socket != null && !socket.isClosed()) {
+                    socket.close();
+                }
+            } catch (IOException ignored) {}
         }
     }
 

lib3270j/src/test/java/haus/nightmare/lib3270j/testutil/Mock3270ServerIntegrationTest.java

@@ -335,4 +335,24 @@ public class Mock3270ServerIntegrationTest {
         }
         assertTrue(receivedWontOrDontTn3270e, "Server should have received Telnet de-negotiation for TN3270E");
     }
+
+    @Test
+    public void testServerSideDisconnectTransitionsClientToNotConnectedAndClosesSocket() throws Exception {
+        ConnectionConfig config = new ConnectionConfig("127.0.0.1", server.getPort(), TerminalModel.IBM_3279_2);
+        client = new Telnet3270Client(config);
+        assertTrue(client.connect(8000));
+        assertTrue(server.waitForHandshake(5, TimeUnit.SECONDS));
+        waitForState(client, ConnectionState.CONNECTED_TN3270E, 5000);
+        assertTrue(client.isConnected());
+
+        // Server drops connection (host disconnect)
+        server.disconnectClient();
+
+        // Wait for client to detect disconnect
+        waitForState(client, ConnectionState.NOT_CONNECTED, 5000);
+        assertEquals(ConnectionState.NOT_CONNECTED, client.getConnectionState());
+        assertFalse(client.isConnected(), "Client must report isConnected() == false after host disconnect");
+        assertNotNull(client.getConnection());
+        assertFalse(client.getConnection().isConnected(), "TelnetConnection must report isConnected() == false after host disconnect");
+    }
 }