[fix] move connection cleanup off the UI thread

apps/desktop/src/common/task_queue_lock_free.cpp

@@ -0,0 +1,79 @@
+#include "task_queue_lock_free.h"
+
+#include <exception>
+#include <new>
+#include <stdexcept>
+#include <utility>
+
+namespace crossdesk {
+
+TaskQueueLockFree::TaskQueueLockFree()
+    : producer_(task_queue_), worker_([this] { WorkerThread(); }) {}
+
+TaskQueueLockFree::~TaskQueueLockFree() { Stop(); }
+
+std::future<void> TaskQueueLockFree::PostTask(std::function<void()> task) {
+  TaskItem item;
+  item.run = std::move(task);
+  auto result = item.completion.get_future();
+  {
+    std::lock_guard lock(mutex_);
+    if (stopping_) {
+      throw std::runtime_error("Cannot post to a stopped task queue");
+    }
+
+    // Count before publishing: the worker may dequeue as soon as enqueue returns.
+    ++pending_tasks_;
+    if (!task_queue_.enqueue(producer_, std::move(item))) {
+      --pending_tasks_;
+      throw std::bad_alloc();
+    }
+  }
+  wake_.notify_one();
+  return result;
+}
+
+void TaskQueueLockFree::Stop() {
+  // Concurrent Stop callers all wait for the same worker shutdown to finish.
+  std::call_once(stop_once_, [this] {
+    {
+      std::lock_guard lock(mutex_);
+      stopping_ = true;
+    }
+    wake_.notify_all();
+    worker_.join();
+  });
+}
+
+void TaskQueueLockFree::WorkerThread() {
+  while (true) {
+    TaskItem item;
+    while (task_queue_.try_dequeue(item)) {
+      --pending_tasks_;
+
+      std::exception_ptr error;
+      try {
+        item.run();
+      } catch (...) {
+        error = std::current_exception();
+      }
+
+      // Release captured resources before marking the task complete.
+      item.run = nullptr;
+      if (error) {
+        item.completion.set_exception(error);
+      } else {
+        item.completion.set_value();
+      }
+    }
+
+    std::unique_lock lock(mutex_);
+    wake_.wait(lock, [this] { return stopping_ || pending_tasks_ > 0; });
+    // A stop request must not discard tasks submitted while the worker was idle.
+    if (stopping_ && pending_tasks_ == 0) {
+      return;
+    }
+  }
+}
+
+}  // namespace crossdesk

apps/desktop/src/common/task_queue_lock_free.h

@@ -0,0 +1,57 @@
+/*
+ * @Author: DI JUNKUN
+ * @Date: 2026-09-07
+ * Copyright (c) 2026 by DI JUNKUN, All Rights Reserved.
+ */
+
+#ifndef _TASK_QUEUE_LOCK_FREE_H_
+#define _TASK_QUEUE_LOCK_FREE_H_
+
+#include <atomic>
+#include <condition_variable>
+#include <cstddef>
+#include <functional>
+#include <future>
+#include <mutex>
+#include <thread>
+
+#include <concurrentqueue.h>
+
+namespace crossdesk {
+
+// A single worker executes tasks in submission order. The concurrent queue
+// stores tasks; a mutex coordinates submissions, worker wakeups and shutdown.
+class TaskQueueLockFree {
+ public:
+  TaskQueueLockFree();
+  ~TaskQueueLockFree();
+
+  // Returns completion or the task's exception. Throws if the queue is stopped.
+  std::future<void> PostTask(std::function<void()> task);
+
+  // Rejects new tasks, finishes accepted tasks and joins the worker.
+  // May be called repeatedly, but never from the queue's own tasks.
+  void Stop();
+
+ private:
+  struct TaskItem {
+    std::function<void()> run;
+    std::promise<void> completion;
+  };
+
+  void WorkerThread();
+
+  moodycamel::ConcurrentQueue<TaskItem> task_queue_;
+  // All submissions share one producer so different caller threads keep FIFO.
+  moodycamel::ProducerToken producer_;
+  std::atomic<std::size_t> pending_tasks_{0};
+  std::mutex mutex_;
+  std::condition_variable wake_;
+  bool stopping_ = false;
+  std::once_flag stop_once_;
+  std::thread worker_;
+};
+
+}  // namespace crossdesk
+
+#endif