Fix: prevent mobile web remote desktop freeze on Safari app-switch

by forcing clean WS reconnect on foreground return;

add 30-second grace period on server to avoid cold-start on quick reconnects

server/2015Remote/WebService.cpp

@@ -1814,6 +1814,16 @@ bool CWebService::StartRemoteDesktop(uint64_t device_id) {
     context* ctx = m_pParentDlg->FindHost(device_id);
     if (!ctx) return false;
 
+    // Cancel any pending grace-period close so the existing session stays alive.
+    {
+        std::lock_guard<std::mutex> lk(m_PendingCloseMutex);
+        auto it = m_PendingCloseTimers.find(device_id);
+        if (it != m_PendingCloseTimers.end()) {
+            it->second->store(true);
+            m_PendingCloseTimers.erase(it);
+        }
+    }
+
     // Check if there's already a Web session for this device
     // Only reuse if Web has already triggered AND a Web dialog exists
     // This ensures MFC and Web have independent dialogs
@@ -1854,11 +1864,36 @@ void CWebService::StopRemoteDesktop(uint64_t device_id) {
         }
     }
 
-    // If no more web clients watching, close only the Web session dialog
-    // MFC dialogs remain open
+    // If no more web clients watching, defer close by 30 s so a quick
+    // mobile reconnect (e.g. switching to a TOTP app) reuses the existing
+    // CScreenSpyDlg without a full cold-start.
     if (watchingCount == 0) {
-        ClearWebTriggered(device_id);
-        m_pParentDlg->CloseWebRemoteDesktopByClientID(device_id);
+        auto cancelled = std::make_shared<std::atomic<bool>>(false);
+        {
+            std::lock_guard<std::mutex> lk(m_PendingCloseMutex);
+            auto it = m_PendingCloseTimers.find(device_id);
+            if (it != m_PendingCloseTimers.end())
+                it->second->store(true);
+            m_PendingCloseTimers[device_id] = cancelled;
+        }
+        std::thread([this, device_id, cancelled]() {
+            std::this_thread::sleep_for(std::chrono::seconds(30));
+            if (cancelled->load()) return;
+            {
+                std::lock_guard<std::mutex> lk(m_PendingCloseMutex);
+                m_PendingCloseTimers.erase(device_id);
+            }
+            int count = 0;
+            {
+                std::lock_guard<std::mutex> lock(m_ClientsMutex);
+                for (const auto& [ws, client] : m_Clients)
+                    if (client.watch_device_id == device_id) count++;
+            }
+            if (count == 0 && m_pParentDlg) {
+                ClearWebTriggered(device_id);
+                m_pParentDlg->CloseWebRemoteDesktopByClientID(device_id);
+            }
+        }).detach();
     }
 }
 

server/2015Remote/WebService.h

@@ -5,6 +5,8 @@
 #include <vector>
 #include <map>
 #include <set>
+#include <atomic>
+#include <chrono>
 #include <mutex>
 #include <thread>
 #include <memory>
@@ -231,6 +233,13 @@ private:
     std::set<uint64_t> m_OfflineDevices;  // Devices that went offline since last flush
     std::mutex m_DirtyDevicesMutex;
 
+    // Grace-period timers: delay CloseWebRemoteDesktopByClientID by 30 s after
+    // the last web viewer disconnects to allow quick mobile reconnects (e.g.
+    // switching to a TOTP app briefly). Cancelled by StartRemoteDesktop when a
+    // viewer reconnects within the window.
+    std::map<uint64_t, std::shared_ptr<std::atomic<bool>>> m_PendingCloseTimers;
+    std::mutex m_PendingCloseMutex;
+
 public:
     // Check if a device session was triggered by web (should be hidden)
     bool IsWebTriggered(uint64_t device_id);