Fix mobile resubscribing

dart/lib/leancode_pipe/pipe_client.dart

@@ -89,6 +89,7 @@ class PipeClient {
             for (final topicSub in _registeredTopicSubscriptions)
               topicSub.close(),
           ]);
+          _registeredTopicSubscriptions.clear();
           onClose?.call(error);
         })
         ..on('subscriptionResult', _onSubscriptionResult)
@@ -120,9 +121,15 @@ class PipeClient {
     Topic<N> topic, {
     void Function()? onReconnect,
   }) async {
-    final thisTopicSubscription =
+    var thisTopicSubscription =
         _registeredTopicSubscriptions.firstWhereOrNull((e) => e.topic == topic);
 
+    // Defensive check: if subscription is closed, remove it and treat as non-existent
+    if (thisTopicSubscription != null && thisTopicSubscription.isClosed) {
+      _registeredTopicSubscriptions.remove(thisTopicSubscription);
+      thisTopicSubscription = null;
+    }
+
     if (thisTopicSubscription != null) {
       final state = thisTopicSubscription.stateSubject.value;
       switch (state) {

dart/test/leancode_pipe/lean_pipe_client_connection_test.dart

@@ -168,5 +168,64 @@ void main() {
         expect(isSubscriptionCanceled, true);
       },
     );
+
+    test(
+      'PipeClient allows subscribing to a topic after disconnect and reconnect',
+      () async {
+        // Prepare general config
+        prepareConnect(connection);
+        prepareTopic(topic);
+        when(() => connection.state)
+            .thenAnswer((_) => HubConnectionState.disconnected);
+
+        // Connect to catch on subscription result method
+        final onSubscriptionResultMethod = await captureOnSubscriptionResult(
+          connect: client.connect,
+          connection: connection,
+        );
+
+        // Prepare connection to simulate backend sending subscription confirmation
+        prepareSubscribeToAnswerWithData(
+          connection: connection,
+          uuid: uuid,
+          answerCallback: (subscribeResult) =>
+              onSubscriptionResultMethod([subscribeResult.toJson()]),
+        );
+
+        // First subscription
+        final subscription1 = await client.subscribe(topic);
+        verifySubscribeCalled(connection);
+        expect(subscription1, isA<PipeSubscription>());
+
+        // Simulate connected state before disconnect
+        when(() => connection.state)
+            .thenAnswer((_) => HubConnectionState.connected);
+
+        // Capture and trigger onClose
+        final onClose = await captureOnClose(
+          connect: client.connect,
+          connection: connection,
+        );
+        when(() => connection.stop()).thenAnswer((_) async {
+          await onClose(null);
+        });
+
+        // Disconnect
+        await client.disconnect();
+        verify(() => connection.stop()).called(1);
+
+        // Simulate disconnected state after disconnect
+        when(() => connection.state)
+            .thenAnswer((_) => HubConnectionState.disconnected);
+
+        // Reconnect
+        await client.connect();
+
+        // Subscribe again to the same topic - this should work
+        final subscription2 = await client.subscribe(topic);
+        verifySubscribeCalled(connection);
+        expect(subscription2, isA<PipeSubscription>());
+      },
+    );
   });
 }