[fix] disable privacy screen for legacy and web clients

apps/desktop/src/gui/runtime/privacy_session_policy.h

@@ -0,0 +1,61 @@
+/*
+ * @Author: DI JUNKUN
+ * @Date: 2026-09-15
+ * Copyright (c) 2026 by DI JUNKUN, All Rights Reserved.
+ */
+
+#ifndef _PRIVACY_SESSION_POLICY_H_
+#define _PRIVACY_SESSION_POLICY_H_
+
+#include <algorithm>
+#include <string>
+#include <unordered_map>
+
+namespace crossdesk {
+
+// Guarded by GuiRuntime's connection_status_mutex_. Privacy covers the shared
+// desktop, so every connected controller must explicitly support it.
+class PrivacySessionPolicy {
+ public:
+  void Connected(const std::string& remote_id, bool automatic_privacy) {
+    const auto [entry, inserted] = controllers_.try_emplace(remote_id, false);
+    if (inserted && controllers_.size() == 1 && automatic_privacy) {
+      automatic_controller_ = remote_id;
+    }
+  }
+
+  void Disconnected(const std::string& remote_id) {
+    controllers_.erase(remote_id);
+    if (automatic_controller_ == remote_id) automatic_controller_.clear();
+  }
+
+  // Consume automatic activation once, on the first controller's host info.
+  // Repeated metadata or a later join must not undo an explicit privacy exit.
+  bool SetSupported(const std::string& remote_id, bool supported) {
+    const auto entry = controllers_.find(remote_id);
+    if (entry == controllers_.end()) return false;
+    entry->second = supported && remote_id.find("web") == std::string::npos;
+    if (automatic_controller_ != remote_id) return false;
+    automatic_controller_.clear();
+    return CanEnable();
+  }
+
+  bool Supports(const std::string& remote_id) const {
+    const auto entry = controllers_.find(remote_id);
+    return entry != controllers_.end() && entry->second;
+  }
+
+  bool CanEnable() const {
+    return !controllers_.empty() &&
+           std::all_of(controllers_.begin(), controllers_.end(),
+                       [](const auto& entry) { return entry.second; });
+  }
+
+ private:
+  std::unordered_map<std::string, bool> controllers_;
+  std::string automatic_controller_;
+};
+
+}  // namespace crossdesk
+
+#endif