[fix] keep display stream IDs stable after monitor changes

src/common/display_stream_id.h

@@ -0,0 +1,59 @@
+#ifndef CROSSDESK_DISPLAY_STREAM_ID_H_
+#define CROSSDESK_DISPLAY_STREAM_ID_H_
+
+#include <cstddef>
+#include <string>
+
+namespace crossdesk {
+
+// MiniRTC stream identifiers are protocol-facing logical identifiers. Keep
+// them independent from platform display handles and user-visible names, both
+// of which may change or contain duplicate/Unicode text.
+inline std::string MakeDisplayStreamId(size_t display_index) {
+  return "Display" + std::to_string(display_index + 1);
+}
+
+inline bool IsRegisteredDisplayStreamId(const std::string& stream_id,
+                                        size_t display_count) {
+  if (stream_id.empty()) {
+    return false;
+  }
+
+  for (size_t index = 0; index < display_count; ++index) {
+    if (stream_id == MakeDisplayStreamId(index)) {
+      return true;
+    }
+  }
+  return false;
+}
+
+// Resolves a backend-reported identifier to a stream registered with MiniRTC.
+// Backends should report MakeDisplayStreamId(index); the fallbacks keep older
+// capture plugins and hotplug transitions safe.
+inline std::string ResolveDisplayStreamId(
+    const char* reported_id, size_t display_count, int preferred_index = -1,
+    const std::string& previous_id = {}) {
+  const std::string candidate = reported_id ? reported_id : "";
+  if (IsRegisteredDisplayStreamId(candidate, display_count)) {
+    return candidate;
+  }
+
+  if (preferred_index >= 0 &&
+      preferred_index < static_cast<int>(display_count)) {
+    return MakeDisplayStreamId(static_cast<size_t>(preferred_index));
+  }
+
+  if (IsRegisteredDisplayStreamId(previous_id, display_count)) {
+    return previous_id;
+  }
+
+  if (display_count == 1) {
+    return MakeDisplayStreamId(0);
+  }
+
+  return {};
+}
+
+}  // namespace crossdesk
+
+#endif  // CROSSDESK_DISPLAY_STREAM_ID_H_

src/gui/application/gui_application.cpp

@@ -17,6 +17,7 @@
 #include <memory>
 #include <mutex>
 #include <optional>
+#include <random>
 #include <shared_mutex>
 #include <sstream>
 #include <string>
@@ -51,6 +52,15 @@ namespace {
 
 using namespace std::chrono_literals;
 
+std::string CreatePasswordChangeRequestId(uint64_t sequence) {
+  const auto timestamp = std::chrono::system_clock::now()
+                             .time_since_epoch()
+                             .count();
+  std::random_device random;
+  return std::to_string(timestamp) + "-" + std::to_string(random()) + "-" +
+         std::to_string(sequence);
+}
+
 #if defined(__linux__) && !defined(__APPLE__)
 bool HasNonEmptyEnvironmentVariable(const char* name) {
   const char* value = std::getenv(name);
@@ -1356,28 +1366,58 @@ void GuiApplication::BindMainCallbacks() {
       if (password_change_pending_) {
         return true;
       }
-      request_id = std::to_string(++next_password_change_request_id_);
+      request_id =
+          CreatePasswordChangeRequestId(++next_password_change_request_id_);
       password_change_pending_ = true;
       password_change_result_ready_ = false;
       password_change_succeeded_ = false;
+      password_change_result_uncertain_ = false;
       password_change_requested_at_ = std::chrono::steady_clock::now();
       pending_password_change_request_id_ = request_id;
       pending_local_password_ = password;
       password_change_error_.clear();
     }
 
+    const bool self_hosted = config_center_->IsSelfHosted();
+    const std::string server_host =
+        self_hosted ? config_center_->GetSignalServerHost()
+                    : config_center_->GetDefaultServerHost();
+    const int server_port =
+        self_hosted ? config_center_->GetSignalServerPort()
+                    : config_center_->GetDefaultSignalServerPort();
+    const std::string pending_identity =
+        std::string(client_id_) + "@" + password;
+    if (!settings_.StagePendingPasswordChange(
+            pending_identity, self_hosted, server_host, server_port,
+            request_id)) {
+      std::lock_guard<std::mutex> lock(password_change_mutex_);
+      password_change_pending_ = false;
+      pending_password_change_request_id_.clear();
+      pending_local_password_.clear();
+      password_change_error_.clear();
+      offline_warning_text_ = localization::failed[localization_language_index_];
+      show_offline_warning_window_ = true;
+      LOG_ERROR("Could not durably stage password change");
+      return true;
+    }
+
     const nlohmann::json request = {{"type", "change_password"},
                                     {"request_id", request_id},
                                     {"new_password", password}};
     const std::string message = request.dump();
     if (SendSignalMessage(peer_, message.data(), message.size()) != 0) {
-      std::lock_guard<std::mutex> lock(password_change_mutex_);
-      password_change_pending_ = false;
-      pending_password_change_request_id_.clear();
-      pending_local_password_.clear();
-      offline_warning_text_ =
-          localization::signal_disconnected[localization_language_index_];
-      show_offline_warning_window_ = true;
+      {
+        std::lock_guard<std::mutex> lock(password_change_mutex_);
+        password_change_pending_ = false;
+        pending_password_change_request_id_.clear();
+        pending_local_password_.clear();
+        offline_warning_text_ =
+            localization::signal_disconnected[localization_language_index_];
+        show_offline_warning_window_ = true;
+      }
+      if (!settings_.ClearPendingPasswordChange()) {
+        LOG_WARN("Could not clear unsent pending password change");
+      }
     }
     return true;
   });
@@ -1788,6 +1828,7 @@ void GuiApplication::Tick() {
     return;
   }
   HandlePasswordChangeResult();
+  HandleCredentialRecovery();
   if (!peer_) {
     CreateConnectionPeer();
   }
@@ -1864,7 +1905,7 @@ void GuiApplication::Tick() {
 
 void GuiApplication::HandlePasswordChangeResult() {
   bool succeeded = false;
-  std::string new_password;
+  bool uncertain = false;
   std::string error;
 
   {
@@ -1874,6 +1915,7 @@ void GuiApplication::HandlePasswordChangeResult() {
             std::chrono::seconds(10)) {
       password_change_result_ready_ = true;
       password_change_succeeded_ = false;
+      password_change_result_uncertain_ = true;
       password_change_error_ = "Server did not respond";
     }
 
@@ -1882,47 +1924,43 @@ void GuiApplication::HandlePasswordChangeResult() {
     }
 
     succeeded = password_change_succeeded_;
-    new_password = pending_local_password_;
+    uncertain = password_change_result_uncertain_;
     error = password_change_error_;
     password_change_pending_ = false;
     password_change_result_ready_ = false;
     password_change_succeeded_ = false;
+    password_change_result_uncertain_ = false;
     pending_password_change_request_id_.clear();
     pending_local_password_.clear();
     password_change_error_.clear();
   }
 
   if (!succeeded) {
-    LOG_WARN("Password change failed: {}", error);
+    if (uncertain) {
+      LOG_WARN("Password change outcome is unknown: {}; re-authenticating",
+               error);
+    } else {
+      LOG_WARN("Password change failed: {}", error);
+      if (!settings_.ClearPendingPasswordChange()) {
+        LOG_WARN("Could not clear rejected pending password change");
+      }
+    }
     offline_warning_text_ = localization::failed[localization_language_index_];
     if (!error.empty()) {
       offline_warning_text_ += ": " + error;
     }
     show_offline_warning_window_ = true;
+    if (uncertain && peer_) {
+      LeaveConnection(peer_, client_id_);
+      DestroyPeer(&peer_);
+    }
     return;
   }
 
-  std::memset(password_saved_, 0, sizeof(password_saved_));
-  std::strncpy(password_saved_, new_password.c_str(),
-               sizeof(password_saved_) - 1);
-
-  const std::string identity = std::string(client_id_) + "@" + new_password;
-  if (config_center_->IsSelfHosted()) {
-    std::memset(self_hosted_id_, 0, sizeof(self_hosted_id_));
-    std::strncpy(self_hosted_id_, identity.c_str(),
-                 sizeof(self_hosted_id_) - 1);
-  } else {
-    std::memset(client_id_with_password_, 0,
-                sizeof(client_id_with_password_));
-    std::strncpy(client_id_with_password_, identity.c_str(),
-                 sizeof(client_id_with_password_) - 1);
-  }
-
-  if (settings_.Save() != 0) {
-    LOG_ERROR("Password changed on server but could not be saved locally");
-    offline_warning_text_ = localization::failed[localization_language_index_];
-    show_offline_warning_window_ = true;
-    return;
+  if (!settings_.PromotePendingPasswordChange()) {
+    // The pending credential was persisted before the request was sent, so it
+    // remains sufficient for recovery even when promotion cannot be written.
+    LOG_WARN("Password changed on server; pending recovery record retained");
   }
 
   LOG_INFO("Password changed successfully for [{}]", client_id_);
@@ -1932,6 +1970,53 @@ void GuiApplication::HandlePasswordChangeResult() {
   }
 }
 
+void GuiApplication::HandleCredentialRecovery() {
+  bool retry_active = false;
+  bool promote_pending = false;
+  bool clear_pending = false;
+  {
+    std::lock_guard<std::mutex> lock(password_change_mutex_);
+    retry_active = credential_recovery_retry_active_;
+    promote_pending = credential_recovery_promote_pending_;
+    clear_pending = credential_recovery_clear_pending_;
+    credential_recovery_retry_active_ = false;
+    credential_recovery_promote_pending_ = false;
+    credential_recovery_clear_pending_ = false;
+    if (retry_active) {
+      credential_recovery_attempt_pending_ = false;
+    }
+  }
+
+  if (retry_active) {
+    LOG_INFO("Pending credential was not accepted; retrying active credential");
+    if (peer_) {
+      DestroyPeer(&peer_);
+    }
+    return;
+  }
+
+  if (promote_pending) {
+    if (!settings_.PromotePendingPasswordChange()) {
+      LOG_WARN("Recovered credential is active but promotion remains pending");
+    } else {
+      LOG_INFO("Recovered password change with pending credential");
+    }
+  } else if (clear_pending) {
+    if (!settings_.ClearPendingPasswordChange()) {
+      LOG_WARN("Active credential recovered but pending record could not be "
+               "cleared");
+    } else {
+      LOG_INFO("Password change was not committed; retained active credential");
+    }
+  } else {
+    return;
+  }
+
+  std::lock_guard<std::mutex> lock(password_change_mutex_);
+  credential_recovery_in_progress_ = false;
+  credential_recovery_attempt_pending_ = false;
+}
+
 void GuiApplication::UpdateLocalization() {
   const int language =
       localization::detail::ClampLanguageIndex(localization_language_index_);
@@ -2529,8 +2614,10 @@ void GuiApplication::SyncStreamWindow() {
 
   std::vector<slint::SharedString> displays;
   displays.reserve(props->display_info_list_.size());
-  for (const auto& display : props->display_info_list_) {
-    displays.emplace_back(UiText(display.name));
+  for (size_t index = 0; index < props->display_info_list_.size(); ++index) {
+    displays.emplace_back(UiText(localization::FormatDisplayLabel(
+        index, props->display_info_list_[index].name,
+        localization_language_index_)));
   }
   ui_->display_model->set_vector(std::move(displays));
   (*ui_->stream)->set_selected_display(props->selected_display_);

src/gui/application/gui_application.h

@@ -32,6 +32,7 @@ private:
   void BindServerCallbacks();
   void Tick();
   void HandlePasswordChangeResult();
+  void HandleCredentialRecovery();
   void SyncMainWindow();
   void SyncConnectionDialog();
   void SyncPlatformDialogs();

src/gui/assets/localization/localization.h

@@ -6,6 +6,7 @@
 #ifndef _LOCALIZATION_H_
 #define _LOCALIZATION_H_
 
+#include <cstddef>
 #include <string>
 #include <unordered_map>
 #include <vector>
@@ -110,12 +111,26 @@ inline const std::string& GetTranslatedText(const std::string& key,
 
 }  // namespace detail
 
-inline const std::string& LocalizedString::operator[](
-    int language_index) const {
-  return detail::GetTranslatedText(key_, language_index);
-}
-
-#define CROSSDESK_DECLARE_LOCALIZED_STRING(name, zh, en, ru) \
+inline const std::string& LocalizedString::operator[](
+    int language_index) const {
+  return detail::GetTranslatedText(key_, language_index);
+}
+
+inline std::string FormatDisplayLabel(size_t display_index,
+                                      const std::string& display_name,
+                                      int language_index) {
+  const std::string number = std::to_string(display_index + 1);
+  std::string label =
+      detail::GetTranslatedText("display_screen", language_index) + " " +
+      number;
+  const std::string fallback_name = "Display" + number;
+  if (!display_name.empty() && display_name != fallback_name) {
+    label += " (" + display_name + ")";
+  }
+  return label;
+}
+
+#define CROSSDESK_DECLARE_LOCALIZED_STRING(name, zh, en, ru) \
   inline const LocalizedString name(#name);
 CROSSDESK_LOCALIZATION_ALL(CROSSDESK_DECLARE_LOCALIZED_STRING)
 #undef CROSSDESK_DECLARE_LOCALIZED_STRING

src/gui/assets/localization/localization_data.h

@@ -35,6 +35,7 @@ struct TranslationRow {
     u8"Недавние подключения")                                                  \
   X(disconnect, u8"断开连接", "Disconnect", u8"Отключить")                     \
   X(select_display, u8"选择显示器", "Select Display", u8"Выбрать дисплей")     \
+  X(display_screen, u8"显示屏", "Display", u8"Экран")                        \
   X(expand_control_bar, u8"展开控制栏", "Expand Control Bar",                  \
     u8"Развернуть панель управления")                                          \
   X(collapse_control_bar, u8"收起控制栏", "Collapse Control Bar",              \

src/gui/features/devices/session_device_manager.cpp

@@ -3,6 +3,7 @@
 #include <chrono>
 #include <cstdlib>
 
+#include "display_stream_id.h"
 #include "platform.h"
 #include "rd_log.h"
 #include "runtime/gui_runtime.h"
@@ -47,6 +48,10 @@ int SessionDeviceManager::InitializeScreenCapturer() {
                       ? 30
                       : 60;
   LOG_INFO("Init screen capturer with {} fps", fps);
+  display_info_list_.clear();
+  registered_display_stream_count_ = 0;
+  last_video_frame_stream_id_.clear();
+  invalid_video_stream_id_logged_ = false;
 
   const int init_ret = screen_capturer_->Init(
       fps, [this, fps](unsigned char *data, int size, int width, int height,
@@ -80,7 +85,21 @@ int SessionDeviceManager::InitializeScreenCapturer() {
           return;
         }
 
-        const std::string stream_id = display_name ? display_name : "";
+        const std::string stream_id = ResolveDisplayStreamId(
+            display_name, registered_display_stream_count_, -1,
+            last_video_frame_stream_id_);
+        if (stream_id.empty()) {
+          if (!invalid_video_stream_id_logged_) {
+            LOG_ERROR(
+                "Drop captured frames with an empty or unregistered video "
+                "stream id, reported='{}', registered_streams={}",
+                display_name ? display_name : "",
+                registered_display_stream_count_);
+            invalid_video_stream_id_logged_ = true;
+          }
+          return;
+        }
+        invalid_video_stream_id_logged_ = false;
         const bool resumed_after_gap =
             last_frame_time_ != 0 && duration >= kCaptureResumeKeyFrameGapMs;
         const bool stream_changed = !last_video_frame_stream_id_.empty() &&
@@ -113,6 +132,7 @@ int SessionDeviceManager::InitializeScreenCapturer() {
     if (!latest_display_info.empty()) {
       display_info_list_ = latest_display_info;
     }
+    registered_display_stream_count_ = display_info_list_.size();
     return 0;
   }
 

src/gui/features/devices/session_device_manager.h

@@ -77,10 +77,12 @@ private:
   MouseController *mouse_controller_ = nullptr;
   KeyboardCapturer *keyboard_capturer_ = nullptr;
   std::vector<DisplayInfo> display_info_list_;
+  size_t registered_display_stream_count_ = 0;
   std::deque<CapturedKeyboardInput> captured_keyboard_inputs_;
   std::mutex captured_keyboard_inputs_mutex_;
   uint64_t last_frame_time_ = 0;
   std::string last_video_frame_stream_id_;
+  bool invalid_video_stream_id_logged_ = false;
 };
 
 } // namespace crossdesk

src/gui/features/settings/settings_manager.cpp

@@ -1,11 +1,24 @@
 #include "features/settings/settings_manager.h"
 
+#include <chrono>
+#include <cstddef>
+#include <cstdio>
 #include <cstring>
 #include <exception>
 #include <filesystem>
 #include <fstream>
+#include <functional>
 #include <memory>
 #include <string>
+#include <thread>
+
+#if defined(_WIN32)
+#include <io.h>
+#include <windows.h>
+#else
+#include <fcntl.h>
+#include <unistd.h>
+#endif
 
 #include "localization.h"
 #include "rd_log.h"
@@ -14,6 +27,9 @@
 namespace crossdesk {
 namespace {
 
+constexpr uint32_t kCacheV3Magic = 0x33444358;  // "XCD3"
+constexpr uint32_t kCacheV3Version = 3;
+
 template <size_t Size>
 void CopyString(char (&destination)[Size], const char *source) {
   static_assert(Size > 0);
@@ -23,6 +39,99 @@ void CopyString(char (&destination)[Size], const char *source) {
   }
 }
 
+uint32_t CacheChecksum(const void *data, size_t size) {
+  const auto *bytes = static_cast<const unsigned char *>(data);
+  uint32_t hash = 2166136261u;
+  for (size_t i = 0; i < size; ++i) {
+    hash ^= bytes[i];
+    hash *= 16777619u;
+  }
+  return hash;
+}
+
+std::filesystem::path TemporaryPathFor(
+    const std::filesystem::path &target) {
+  const auto timestamp = std::chrono::steady_clock::now()
+                             .time_since_epoch()
+                             .count();
+  const auto thread_id =
+      std::hash<std::thread::id>{}(std::this_thread::get_id());
+  std::filesystem::path temporary = target;
+  temporary += ".tmp-" + std::to_string(timestamp) + "-" +
+               std::to_string(thread_id);
+  return temporary;
+}
+
+bool FlushFileToDisk(FILE *file) {
+  if (!file || std::fflush(file) != 0) {
+    return false;
+  }
+#if defined(_WIN32)
+  return _commit(_fileno(file)) == 0;
+#else
+  return fsync(fileno(file)) == 0;
+#endif
+}
+
+bool ReplaceFileAtomically(const std::filesystem::path &temporary,
+                           const std::filesystem::path &target) {
+#if defined(_WIN32)
+  return MoveFileExW(temporary.c_str(), target.c_str(),
+                     MOVEFILE_REPLACE_EXISTING | MOVEFILE_WRITE_THROUGH) != 0;
+#else
+  if (::rename(temporary.c_str(), target.c_str()) != 0) {
+    return false;
+  }
+
+  const std::filesystem::path parent = target.parent_path().empty()
+                                           ? std::filesystem::path(".")
+                                           : target.parent_path();
+  int directory_flags = O_RDONLY;
+#if defined(O_DIRECTORY)
+  directory_flags |= O_DIRECTORY;
+#endif
+  const int directory = open(parent.c_str(), directory_flags);
+  if (directory >= 0) {
+    const bool synced = fsync(directory) == 0;
+    close(directory);
+    return synced;
+  }
+  return false;
+#endif
+}
+
+bool WriteFileAtomically(const std::filesystem::path &target,
+                         const void *data, size_t size) {
+  std::error_code ec;
+  const std::filesystem::path parent = target.parent_path();
+  if (!parent.empty()) {
+    std::filesystem::create_directories(parent, ec);
+    if (ec) {
+      return false;
+    }
+  }
+
+  const std::filesystem::path temporary = TemporaryPathFor(target);
+#if defined(_WIN32)
+  FILE *file = _wfopen(temporary.c_str(), L"wb");
+#else
+  FILE *file = std::fopen(temporary.c_str(), "wb");
+#endif
+  if (!file) {
+    return false;
+  }
+
+  const bool written = std::fwrite(data, 1, size, file) == size;
+  const bool flushed = written && FlushFileToDisk(file);
+  const bool closed = std::fclose(file) == 0;
+  if (!written || !flushed || !closed ||
+      !ReplaceFileAtomically(temporary, target)) {
+    std::filesystem::remove(temporary, ec);
+    return false;
+  }
+  return true;
+}
+
 } // namespace
 
 SettingsManager::SettingsManager(GuiRuntime &owner) : owner_(owner) {}
@@ -33,36 +142,74 @@ int SettingsManager::Save() {
 }
 
 int SettingsManager::SaveLocked() {
-  std::ofstream cache_v2_file(owner_.cache_path_ + "/secure_cache_v2.enc",
-                              std::ios::binary);
-  if (!cache_v2_file) {
-    return -1;
-  }
-
   CopyString(cache_v2_.client_id_with_password,
              owner_.client_id_with_password_);
   std::memcpy(cache_v2_.key, owner_.aes128_key_, sizeof(owner_.aes128_key_));
   std::memcpy(cache_v2_.iv, owner_.aes128_iv_, sizeof(owner_.aes128_iv_));
   CopyString(cache_v2_.self_hosted_id, owner_.self_hosted_id_);
 
-  cache_v2_file.write(reinterpret_cast<const char *>(&cache_v2_),
-                      sizeof(cache_v2_));
+  cache_v3_.magic = kCacheV3Magic;
+  cache_v3_.version = kCacheV3Version;
+  cache_v3_.base = cache_v2_;
+  cache_v3_.pending_identity[sizeof(cache_v3_.pending_identity) - 1] = '\0';
+  cache_v3_.pending_server_host[sizeof(cache_v3_.pending_server_host) - 1] =
+      '\0';
+  cache_v3_.pending_request_id[sizeof(cache_v3_.pending_request_id) - 1] =
+      '\0';
+  cache_v3_.checksum =
+      CacheChecksum(&cache_v3_, offsetof(CacheV3, checksum));
+
+  if (!WriteFileAtomically(owner_.cache_path_ + "/secure_cache_v3.enc",
+                           &cache_v3_, sizeof(cache_v3_))) {
+    return -1;
+  }
+
+  if (!WriteFileAtomically(owner_.cache_path_ + "/secure_cache_v2.enc",
+                           &cache_v2_, sizeof(cache_v2_))) {
+    LOG_WARN("Failed to update legacy v2 credential cache");
+  }
 
   // Keep writing the legacy cache while older installations may still read it.
-  std::ofstream cache_v1_file(owner_.cache_path_ + "/secure_cache.enc",
-                              std::ios::binary);
-  if (cache_v1_file) {
-    CopyString(cache_v1_.client_id_with_password,
-               owner_.client_id_with_password_);
-    std::memcpy(cache_v1_.key, owner_.aes128_key_, sizeof(owner_.aes128_key_));
-    std::memcpy(cache_v1_.iv, owner_.aes128_iv_, sizeof(owner_.aes128_iv_));
-    cache_v1_file.write(reinterpret_cast<const char *>(&cache_v1_),
-                        sizeof(cache_v1_));
+  CopyString(cache_v1_.client_id_with_password,
+             owner_.client_id_with_password_);
+  std::memcpy(cache_v1_.key, owner_.aes128_key_, sizeof(owner_.aes128_key_));
+  std::memcpy(cache_v1_.iv, owner_.aes128_iv_, sizeof(owner_.aes128_iv_));
+  if (!WriteFileAtomically(owner_.cache_path_ + "/secure_cache.enc",
+                           &cache_v1_, sizeof(cache_v1_))) {
+    LOG_WARN("Failed to update legacy v1 credential cache");
   }
 
   return 0;
 }
 
+bool SettingsManager::ReadV3Locked() {
+  std::ifstream cache_file(owner_.cache_path_ + "/secure_cache_v3.enc",
+                           std::ios::binary);
+  if (!cache_file) {
+    return false;
+  }
+
+  CacheV3 loaded{};
+  cache_file.read(reinterpret_cast<char *>(&loaded), sizeof(loaded));
+  if (cache_file.gcount() != static_cast<std::streamsize>(sizeof(loaded)) ||
+      loaded.magic != kCacheV3Magic ||
+      loaded.version != kCacheV3Version ||
+      loaded.checksum != CacheChecksum(&loaded, offsetof(CacheV3, checksum))) {
+    LOG_WARN("Ignore invalid v3 credential cache");
+    return false;
+  }
+
+  loaded.base.client_id_with_password
+      [sizeof(loaded.base.client_id_with_password) - 1] = '\0';
+  loaded.base.self_hosted_id[sizeof(loaded.base.self_hosted_id) - 1] = '\0';
+  loaded.pending_identity[sizeof(loaded.pending_identity) - 1] = '\0';
+  loaded.pending_server_host[sizeof(loaded.pending_server_host) - 1] = '\0';
+  loaded.pending_request_id[sizeof(loaded.pending_request_id) - 1] = '\0';
+  cache_v3_ = loaded;
+  cache_v2_ = loaded.base;
+  return true;
+}
+
 bool SettingsManager::ReadV2Locked() {
   std::ifstream cache_v2_file(owner_.cache_path_ + "/secure_cache_v2.enc",
                               std::ios::binary);
@@ -84,13 +231,20 @@ bool SettingsManager::ReadV2Locked() {
 int SettingsManager::Load() {
   std::unique_lock<std::mutex> lock(cache_mutex_);
 
-  if (ReadV2Locked()) {
+  const bool loaded_v3 = ReadV3Locked();
+  if (loaded_v3 || ReadV2Locked()) {
     CopyString(owner_.client_id_with_password_,
                cache_v2_.client_id_with_password);
     CopyString(owner_.self_hosted_id_, cache_v2_.self_hosted_id);
     std::memcpy(owner_.aes128_key_, cache_v2_.key, sizeof(cache_v2_.key));
     std::memcpy(owner_.aes128_iv_, cache_v2_.iv, sizeof(cache_v2_.iv));
-    LOG_INFO("Load settings from v2 cache file");
+    if (loaded_v3) {
+      LOG_INFO("Load settings from v3 cache file");
+    } else {
+      cache_v3_ = {};
+      SaveLocked();
+      LOG_INFO("Migrated settings from v2 to v3 cache file");
+    }
   } else {
     std::ifstream cache_v1_file(owner_.cache_path_ + "/secure_cache.enc",
                                 std::ios::binary);
@@ -128,8 +282,9 @@ int SettingsManager::Load() {
     std::memcpy(owner_.aes128_key_, cache_v1_.key, sizeof(cache_v1_.key));
     std::memcpy(owner_.aes128_iv_, cache_v1_.iv, sizeof(cache_v1_.iv));
 
+    cache_v3_ = {};
     SaveLocked();
-    LOG_INFO("Migrated settings from v1 to v2 cache file");
+    LOG_INFO("Migrated settings from v1 to v3 cache file");
   }
 
   lock.unlock();
@@ -186,7 +341,8 @@ int SettingsManager::Load() {
 
 bool SettingsManager::LoadCachedSelfHostedIdentity() {
   std::lock_guard<std::mutex> lock(cache_mutex_);
-  if (!ReadV2Locked() || cache_v2_.self_hosted_id[0] == '\0') {
+  if ((!ReadV3Locked() && !ReadV2Locked()) ||
+      cache_v2_.self_hosted_id[0] == '\0') {
     std::memset(owner_.self_hosted_id_, 0, sizeof(owner_.self_hosted_id_));
     std::memset(owner_.client_id_, 0, sizeof(owner_.client_id_));
     std::memset(owner_.password_saved_, 0, sizeof(owner_.password_saved_));
@@ -227,27 +383,135 @@ bool SettingsManager::ActivateCachedPublicIdentity() {
   return owner_.client_id_[0] != '\0';
 }
 
+void SettingsManager::ActivateIdentity(const char *identity,
+                                       bool self_hosted) {
+  if (!identity) {
+    return;
+  }
+
+  if (self_hosted) {
+    CopyString(owner_.self_hosted_id_, identity);
+  } else {
+    CopyString(owner_.client_id_with_password_, identity);
+  }
+
+  const char *at_pos = std::strchr(identity, '@');
+  if (at_pos == nullptr) {
+    CopyString(owner_.client_id_, identity);
+    std::memset(owner_.password_saved_, 0, sizeof(owner_.password_saved_));
+    return;
+  }
+
+  const std::string id(identity, at_pos - identity);
+  CopyString(owner_.client_id_, id.c_str());
+  CopyString(owner_.password_saved_, at_pos + 1);
+}
+
+bool SettingsManager::StagePendingPasswordChange(
+    const std::string &identity, bool self_hosted,
+    const std::string &server_host, int server_port,
+    const std::string &request_id) {
+  if (identity.empty() || identity.size() >= sizeof(cache_v3_.pending_identity) ||
+      server_host.empty() ||
+      server_host.size() >= sizeof(cache_v3_.pending_server_host) ||
+      server_port <= 0 || request_id.empty() ||
+      request_id.size() >= sizeof(cache_v3_.pending_request_id)) {
+    return false;
+  }
+
+  std::lock_guard<std::mutex> lock(cache_mutex_);
+  if (cache_v3_.pending_identity[0] != '\0' &&
+      (cache_v3_.pending_self_hosted != self_hosted ||
+       cache_v3_.pending_server_port != server_port ||
+       server_host != cache_v3_.pending_server_host ||
+       request_id != cache_v3_.pending_request_id)) {
+    LOG_WARN("Refuse to overwrite an unresolved password change");
+    return false;
+  }
+  const CacheV3 previous = cache_v3_;
+  CopyString(cache_v3_.pending_identity, identity.c_str());
+  CopyString(cache_v3_.pending_server_host, server_host.c_str());
+  cache_v3_.pending_server_port = server_port;
+  cache_v3_.pending_self_hosted = self_hosted;
+  CopyString(cache_v3_.pending_request_id, request_id.c_str());
+  if (SaveLocked() != 0) {
+    cache_v3_ = previous;
+    return false;
+  }
+  return true;
+}
+
+std::string SettingsManager::PendingPasswordChangeIdentity(
+    bool self_hosted, const std::string &server_host, int server_port) const {
+  std::lock_guard<std::mutex> lock(cache_mutex_);
+  if (cache_v3_.pending_identity[0] == '\0' ||
+      cache_v3_.pending_self_hosted != self_hosted ||
+      cache_v3_.pending_server_port != server_port ||
+      server_host != cache_v3_.pending_server_host) {
+    return {};
+  }
+  return cache_v3_.pending_identity;
+}
+
+bool SettingsManager::PromotePendingPasswordChange() {
+  std::lock_guard<std::mutex> lock(cache_mutex_);
+  if (cache_v3_.pending_identity[0] == '\0') {
+    return true;
+  }
+
+  const CacheV3 previous = cache_v3_;
+  const std::string identity = cache_v3_.pending_identity;
+  const bool self_hosted = cache_v3_.pending_self_hosted;
+  ActivateIdentity(identity.c_str(), self_hosted);
+  std::memset(cache_v3_.pending_identity, 0,
+              sizeof(cache_v3_.pending_identity));
+  std::memset(cache_v3_.pending_server_host, 0,
+              sizeof(cache_v3_.pending_server_host));
+  cache_v3_.pending_server_port = 0;
+  cache_v3_.pending_self_hosted = false;
+  std::memset(cache_v3_.pending_request_id, 0,
+              sizeof(cache_v3_.pending_request_id));
+  if (SaveLocked() != 0) {
+    // The already-durable pending credential remains the recovery source on
+    // disk. Keep it in memory as well so a reconnect in this process retries
+    // the credential that the server has accepted.
+    cache_v3_ = previous;
+    return false;
+  }
+  return true;
+}
+
+bool SettingsManager::ClearPendingPasswordChange() {
+  std::lock_guard<std::mutex> lock(cache_mutex_);
+  if (cache_v3_.pending_identity[0] == '\0') {
+    return true;
+  }
+
+  const CacheV3 previous = cache_v3_;
+  std::memset(cache_v3_.pending_identity, 0,
+              sizeof(cache_v3_.pending_identity));
+  std::memset(cache_v3_.pending_server_host, 0,
+              sizeof(cache_v3_.pending_server_host));
+  cache_v3_.pending_server_port = 0;
+  cache_v3_.pending_self_hosted = false;
+  std::memset(cache_v3_.pending_request_id, 0,
+              sizeof(cache_v3_.pending_request_id));
+  if (SaveLocked() != 0) {
+    cache_v3_ = previous;
+    return false;
+  }
+  return true;
+}
+
 void SettingsManager::PersistSelfHostedIdentity(const char *client_id) {
   if (!client_id) {
     return;
   }
 
   std::lock_guard<std::mutex> lock(cache_mutex_);
-  if (!ReadV2Locked()) {
-    cache_v2_ = {};
-  }
-
-  CopyString(cache_v2_.self_hosted_id, client_id);
-  CopyString(cache_v2_.client_id_with_password,
-             owner_.client_id_with_password_);
-  std::memcpy(cache_v2_.key, owner_.aes128_key_, sizeof(owner_.aes128_key_));
-  std::memcpy(cache_v2_.iv, owner_.aes128_iv_, sizeof(owner_.aes128_iv_));
-
-  std::ofstream cache_v2_file(owner_.cache_path_ + "/secure_cache_v2.enc",
-                              std::ios::binary);
-  if (cache_v2_file) {
-    cache_v2_file.write(reinterpret_cast<const char *>(&cache_v2_),
-                        sizeof(cache_v2_));
+  CopyString(owner_.self_hosted_id_, client_id);
+  if (SaveLocked() != 0) {
+    LOG_ERROR("Failed to persist self-hosted identity atomically");
   }
 }
 

src/gui/features/settings/settings_manager.h

@@ -1,6 +1,7 @@
 #ifndef CROSSDESK_GUI_SETTINGS_MANAGER_H_
 #define CROSSDESK_GUI_SETTINGS_MANAGER_H_
 
+#include <cstdint>
 #include <mutex>
 #include <string>
 #include <unordered_map>
@@ -39,6 +40,22 @@ public:
   bool ActivateCachedPublicIdentity();
   void PersistSelfHostedIdentity(const char *client_id);
 
+  // Password rotation is deliberately persisted in two phases. The active
+  // credential remains usable while the pending credential records the value
+  // that may already have been committed by the server. On the next launch the
+  // caller can try the pending credential first and safely fall back to the
+  // active credential when the request never reached the server.
+  bool StagePendingPasswordChange(const std::string &identity,
+                                  bool self_hosted,
+                                  const std::string &server_host,
+                                  int server_port,
+                                  const std::string &request_id);
+  std::string PendingPasswordChangeIdentity(
+      bool self_hosted, const std::string &server_host,
+      int server_port) const;
+  bool PromotePendingPasswordChange();
+  bool ClearPendingPasswordChange();
+
 private:
   struct CacheV1 {
     char client_id_with_password[17];
@@ -67,12 +84,27 @@ private:
     char self_hosted_id[17];
   };
 
+  struct CacheV3 {
+    uint32_t magic;
+    uint32_t version;
+    CacheV2 base;
+    char pending_identity[17];
+    char pending_server_host[256];
+    int pending_server_port;
+    bool pending_self_hosted;
+    char pending_request_id[64];
+    uint32_t checksum;
+  };
+
   int SaveLocked();
+  bool ReadV3Locked();
   bool ReadV2Locked();
+  void ActivateIdentity(const char *identity, bool self_hosted);
 
   GuiRuntime &owner_;
   CacheV1 cache_v1_{};
   CacheV2 cache_v2_{};
+  CacheV3 cache_v3_{};
   mutable std::mutex cache_mutex_;
   std::unordered_map<std::string, std::string> recent_connection_aliases_;
 };

src/gui/runtime/connection_runtime.cpp

@@ -8,6 +8,7 @@
 #include <thread>
 #include <vector>
 
+#include "display_stream_id.h"
 #include "localization.h"
 #include "platform.h"
 #include "rd_log.h"
@@ -381,8 +382,10 @@ int GuiRuntime::ConnectTo(const std::string& remote_id, const char* password,
           return -1;
         }
 
-        for (const auto& display_info : devices_.display_info_list()) {
-          AddVideoStream(props->peer_, display_info.name.c_str());
+        const auto& displays = devices_.display_info_list();
+        for (size_t index = 0; index < displays.size(); ++index) {
+          const std::string stream_id = MakeDisplayStreamId(index);
+          AddVideoStream(props->peer_, stream_id.c_str());
         }
         AddAudioStream(props->peer_, props->audio_label_.c_str());
         AddDataStream(props->peer_, props->data_label_.c_str(), false);

src/gui/runtime/gui_runtime.cpp

@@ -10,6 +10,7 @@
 #include <thread>
 #include <vector>
 
+#include "display_stream_id.h"
 #include "localization.h"
 #include "rd_log.h"
 
@@ -61,6 +62,40 @@ int GuiRuntime::CreateConnectionPeer() {
     params_.user_id = client_id_with_password_;
   }
 
+  const bool self_hosted = config_center_->IsSelfHosted();
+  const std::string pending_identity =
+      settings_.PendingPasswordChangeIdentity(
+          self_hosted, signal_server_ip, signal_server_port);
+  bool try_pending_identity = false;
+  {
+    std::lock_guard<std::mutex> lock(password_change_mutex_);
+    if (pending_identity.empty()) {
+      credential_recovery_in_progress_ = false;
+      credential_recovery_attempt_pending_ = false;
+      credential_recovery_retry_active_ = false;
+      credential_recovery_promote_pending_ = false;
+      credential_recovery_clear_pending_ = false;
+    } else if (!credential_recovery_in_progress_) {
+      credential_recovery_in_progress_ = true;
+      credential_recovery_attempt_pending_ = true;
+      LOG_INFO("Recovering an interrupted password change for [{}]",
+               client_id_);
+    }
+    try_pending_identity = credential_recovery_in_progress_ &&
+                           credential_recovery_attempt_pending_ &&
+                           !pending_identity.empty();
+  }
+
+  const char *active_identity =
+      self_hosted ? self_hosted_user_id_ : client_id_with_password_;
+  const std::string login_identity =
+      try_pending_identity ? pending_identity : std::string(active_identity);
+  std::memset(connection_login_identity_, 0,
+              sizeof(connection_login_identity_));
+  std::strncpy(connection_login_identity_, login_identity.c_str(),
+               sizeof(connection_login_identity_) - 1);
+  params_.user_id = connection_login_identity_;
+
   // self hosted server config
   strncpy(signal_server_ip_self_, config_center_->GetSignalServerHost().c_str(),
           sizeof(signal_server_ip_self_) - 1);
@@ -147,8 +182,10 @@ int GuiRuntime::CreateConnectionPeer() {
   }
 
   if (0 == devices_.InitializeScreenCapturer()) {
-    for (const auto &display_info : devices_.display_info_list()) {
-      AddVideoStream(peer_, display_info.name.c_str());
+    const auto &displays = devices_.display_info_list();
+    for (size_t index = 0; index < displays.size(); ++index) {
+      const std::string stream_id = MakeDisplayStreamId(index);
+      AddVideoStream(peer_, stream_id.c_str());
     }
 
     AddAudioStream(peer_, audio_label_.c_str());

src/gui/runtime/peer_event_handler.cpp

@@ -116,6 +116,7 @@ void PeerEventHandler::OnSignalMessage(const char* message, size_t size,
         j.contains("reason") && j["reason"].is_string()
             ? j["reason"].get<std::string>()
             : "Password change failed";
+    runtime->password_change_result_uncertain_ = false;
     runtime->password_change_result_ready_ = true;
   }
 }
@@ -137,8 +138,21 @@ void PeerEventHandler::OnSignalStatus(SignalStatus status, const char* user_id,
       runtime->signal_connected_ = true;
       runtime->need_to_send_recent_connections_ = true;
       LOG_INFO("[{}] connected to signal server", client_id);
+      std::lock_guard<std::mutex> lock(runtime->password_change_mutex_);
+      if (runtime->credential_recovery_in_progress_) {
+        if (runtime->credential_recovery_attempt_pending_) {
+          runtime->credential_recovery_promote_pending_ = true;
+        } else {
+          runtime->credential_recovery_clear_pending_ = true;
+        }
+      }
     } else if (SignalStatus::SignalFailed == status) {
       runtime->signal_connected_ = false;
+      std::lock_guard<std::mutex> lock(runtime->password_change_mutex_);
+      if (runtime->credential_recovery_in_progress_ &&
+          runtime->credential_recovery_attempt_pending_) {
+        runtime->credential_recovery_retry_active_ = true;
+      }
     } else if (SignalStatus::SignalClosed == status) {
       runtime->signal_connected_ = false;
     } else if (SignalStatus::SignalReconnecting == status) {

src/gui/runtime/runtime_state.h

@@ -116,6 +116,7 @@ struct UserSettingsState {
   char password_saved_[7] = "";
   char self_hosted_id_[17] = "";
   char self_hosted_user_id_[17] = "";
+  char connection_login_identity_[17] = "";
   int language_button_value_ = 0;
   int video_quality_button_value_ = 2;
   int video_frame_rate_button_value_ = 1;
@@ -158,10 +159,16 @@ struct PasswordChangeState {
   bool password_change_pending_ = false;
   bool password_change_result_ready_ = false;
   bool password_change_succeeded_ = false;
+  bool password_change_result_uncertain_ = false;
   std::chrono::steady_clock::time_point password_change_requested_at_;
   std::string pending_password_change_request_id_;
   std::string pending_local_password_;
   std::string password_change_error_;
+  bool credential_recovery_in_progress_ = false;
+  bool credential_recovery_attempt_pending_ = false;
+  bool credential_recovery_retry_active_ = false;
+  bool credential_recovery_promote_pending_ = false;
+  bool credential_recovery_clear_pending_ = false;
 };
 
 struct ConnectionState {

src/gui/ui/stream_window.slint

@@ -167,6 +167,8 @@ export component StreamWindow inherits Window {
 
     private property <bool> control-expanded: true;
     private property <bool> display-menu-open: false;
+    private property <bool> display-menu-animation-enabled: false;
+    private property <float> display-menu-progress: 0.0;
     private property <bool> shortcut-menu-open: false;
     private property <bool> control-docked-left: true;
     private property <bool> control-dragging: false;
@@ -183,6 +185,48 @@ export component StreamWindow inherits Window {
     callback begin-control-drag(length, length);
     callback move-control-drag(length, length);
     callback end-control-drag;
+    pure callback is-local-control-area(length, length) -> bool;
+
+    animate display-menu-progress {
+        duration: 120ms;
+        easing: ease-out;
+        enabled: root.display-menu-animation-enabled;
+    }
+
+    display-menu-open-timer := Timer {
+        interval: 16ms;
+        running: false;
+        triggered => {
+            self.running = false;
+            if root.display-menu-open {
+                root.display-menu-animation-enabled = true;
+                root.display-menu-progress = 1.0;
+            }
+        }
+    }
+
+    is-local-control-area(pointer-x, pointer-y) => {
+        let over-control = pointer-x >= control.x
+            && pointer-x <= control.x + control.width
+            && pointer-y >= control.y
+            && pointer-y <= control.y + control.height;
+        let display-menu-x = control.x + (root.control-docked-left ? 9px : 42px);
+        let display-menu-y = control.y + control.height - 1px;
+        let display-menu-height = min(180px, root.displays.length * 30px + 8px);
+        let over-display-menu = root.display-menu-open
+            && pointer-x >= display-menu-x
+            && pointer-x <= display-menu-x + 180px
+            && pointer-y >= display-menu-y
+            && pointer-y <= display-menu-y + display-menu-height;
+        let shortcut-menu-x = control.x + (root.control-docked-left ? 41px : 74px);
+        let shortcut-menu-y = control.y + 40px;
+        let over-shortcut-menu = root.shortcut-menu-open
+            && pointer-x >= shortcut-menu-x
+            && pointer-x <= shortcut-menu-x + 150px
+            && pointer-y >= shortcut-menu-y
+            && pointer-y <= shortcut-menu-y + 68px;
+        return over-control || over-display-menu || over-shortcut-menu;
+    }
 
     begin-control-drag(press-x, press-y) => {
         // Capture the snapped position before switching x to control-drag-x.
@@ -195,6 +239,9 @@ export component StreamWindow inherits Window {
         // pointer positions remain relative to the stationary video surface.
         root.control-press-x = press-x - current-x;
         root.control-press-y = press-y - current-y;
+        display-menu-open-timer.running = false;
+        root.display-menu-animation-enabled = false;
+        root.display-menu-progress = 0.0;
         root.display-menu-open = false;
         root.shortcut-menu-open = false;
         root.control-dragging = true;
@@ -503,7 +550,9 @@ export component StreamWindow inherits Window {
                             && self.mouse-x <= control.x + control.width
                             && self.mouse-y >= control.y
                             && self.mouse-y <= control.y + control.height;
-                        if event.kind == PointerEventKind.down && !over-control {
+                        let over-local-ui = root.is-local-control-area(
+                            self.mouse-x, self.mouse-y);
+                        if event.kind == PointerEventKind.down && !over-local-ui {
                             input-focus.focus();
                         }
                         if event.kind == PointerEventKind.down
@@ -515,9 +564,9 @@ export component StreamWindow inherits Window {
                                 || event.kind == PointerEventKind.cancel) {
                             root.end-control-drag();
                         // The control bar overlays the remote video. Events in
-                        // its full rectangle (including gaps between buttons)
+                        // it and its attached menus (including padding and gaps)
                         // are local UI input and must never reach the peer.
-                        } else if !root.control-dragging && !over-control {
+                        } else if !root.control-dragging && !over-local-ui {
                             root.pointer-input(event.button, event.kind, self.mouse-x, self.mouse-y);
                         }
                     }
@@ -527,10 +576,7 @@ export component StreamWindow inherits Window {
                         }
                     }
                     scroll-event(event) => {
-                        if self.mouse-x < control.x
-                            || self.mouse-x > control.x + control.width
-                            || self.mouse-y < control.y
-                            || self.mouse-y > control.y + control.height {
+                        if !root.is-local-control-area(self.mouse-x, self.mouse-y) {
                             root.scroll-input(event.delta-x, event.delta-y, self.mouse-x, self.mouse-y);
                         }
                         accept
@@ -565,12 +611,27 @@ export component StreamWindow inherits Window {
                     icon: FontAwesomeIcons.display;
                     badge: root.selected-display + 1;
                     tooltip: StreamStrings.select-display;
-                    clicked => { root.display-menu-open = !root.display-menu-open; root.shortcut-menu-open = false; }
+                    clicked => {
+                        display-menu-open-timer.running = false;
+                        root.display-menu-animation-enabled = false;
+                        root.display-menu-progress = 0.0;
+                        root.display-menu-open = !root.display-menu-open;
+                        root.shortcut-menu-open = false;
+                        if root.display-menu-open {
+                            display-menu-open-timer.running = true;
+                        }
+                    }
                 }
                 if root.control-expanded: shortcut-button := ControlBarButton {
                     x: root.control-docked-left ? 41px : 74px; y: 7px;
                     icon: FontAwesomeIcons.keyboard; tooltip: StreamStrings.send-shortcut;
-                    clicked => { root.shortcut-menu-open = !root.shortcut-menu-open; root.display-menu-open = false; }
+                    clicked => {
+                        display-menu-open-timer.running = false;
+                        root.display-menu-animation-enabled = false;
+                        root.display-menu-progress = 0.0;
+                        root.shortcut-menu-open = !root.shortcut-menu-open;
+                        root.display-menu-open = false;
+                    }
                 }
                 if root.control-expanded: mouse-button := ControlBarButton {
                     x: root.control-docked-left ? 73px : 106px; y: 7px;
@@ -753,18 +814,76 @@ export component StreamWindow inherits Window {
                 }
             }
 
-            if root.display-menu-open: Rectangle {
-                x: control.x + (root.control-docked-left ? 9px : 42px); y: control.y + 40px; width: 180px; height: min(180px, root.displays.length * 30px + 8px);
-                background: white; border-width: 1px; border-color: ImGuiLineStyle.border; border-radius: 5px; z: 11;
+            if root.display-menu-open: display-menu := Rectangle {
+                private property <length> expanded-height: min(180px, root.displays.length * 30px + 8px);
+                private property <int> hovered-index:
+                    display-touch.has-hover && display-touch.mouse-y >= 4px
+                        && floor((display-touch.mouse-y - 4px) / 30px) < root.displays.length
+                    ? floor((display-touch.mouse-y - 4px) / 30px) : -1;
+                x: control.x + (root.control-docked-left ? 9px : 42px);
+                // Overlap the control border by one pixel so the menu reads as
+                // an attached panel growing downward from the display button.
+                y: control.y + control.height - 1px;
+                width: 180px;
+                height: self.expanded-height * root.display-menu-progress;
+                opacity: root.display-menu-progress;
+                background: white;
+                border-width: 1px;
+                border-color: ImGuiLineStyle.border;
+                border-radius: 5px;
+                clip: true;
+                z: 11;
+
                 VerticalLayout {
                     padding: 4px; spacing: 1px;
                     for display[index] in root.displays: Rectangle {
                         height: 29px;
-                        background: display-touch.has-hover || index == root.selected-display ? #e8eef9 : transparent;
-                        Text { x: 8px; text: display; color: #30343b; font-size: ImGuiFontStyle.body; vertical-alignment: center; }
-                        display-touch := TouchArea { clicked => { root.selected-display = index; root.switch-display(index); root.display-menu-open = false; } }
+                        background: index == display-menu.hovered-index && display-touch.pressed ? #bfd4f2
+                                  : index == display-menu.hovered-index ? #d8e6f8
+                                  : index == root.selected-display ? #e8eef9
+                                                                   : transparent;
+                        border-radius: 3px;
+                        Text {
+                            x: 8px;
+                            width: parent.width - 34px;
+                            text: display;
+                            color: #30343b;
+                            font-size: ImGuiFontStyle.body;
+                            overflow: elide;
+                            vertical-alignment: center;
+                        }
+                        if index == root.selected-display: Text {
+                            x: parent.width - 24px;
+                            width: 16px;
+                            text: FontAwesomeIcons.check;
+                            color: #2463c7;
+                            font-family: "Font Awesome 6 Free";
+                            font-weight: 900;
+                            font-size: 10px;
+                            horizontal-alignment: center;
+                            vertical-alignment: center;
+                        }
                     }
                 }
+                // Use one hit target for the whole popup. A single owner keeps
+                // hover stable while still consuming padding, gaps and scroll
+                // events locally instead of forwarding them to the peer.
+                display-touch := TouchArea {
+                    clicked => {
+                        let index = floor((self.mouse-y - 4px) / 30px);
+                        let row-y = self.mouse-y - 4px - index * 30px;
+                        if self.mouse-y >= 4px && row-y < 29px
+                            && index >= 0 && index < root.displays.length {
+                            display-menu-open-timer.running = false;
+                            root.display-menu-animation-enabled = false;
+                            root.display-menu-progress = 0.0;
+                            root.selected-display = index;
+                            root.switch-display(index);
+                            root.display-menu-open = false;
+                        }
+                    }
+                    scroll-event(event) => { accept }
+                }
             }
 
             if root.shortcut-menu-open: Rectangle {

src/gui/views/toolbars/control_bar.cpp

@@ -108,7 +108,10 @@ int GuiApplication::ControlBar(
     if (ImGui::BeginPopup("display")) {
       ImGui::SetWindowFontScale(0.5f);
       for (int i = 0; i < props->display_info_list_.size(); i++) {
-        if (ImGui::Selectable(props->display_info_list_[i].name.c_str())) {
+        const std::string display_label = localization::FormatDisplayLabel(
+            static_cast<size_t>(i), props->display_info_list_[i].name,
+            localization_language_index_);
+        if (ImGui::Selectable(display_label.c_str())) {
           props->selected_display_ = i;
 
           RemoteAction remote_action;

src/screen_capturer/linux/screen_capturer_drm.cpp

@@ -26,6 +26,7 @@
 #include <chrono>
 #include <thread>
 
+#include "display_stream_id.h"
 #include "libyuv.h"
 #include "rd_log.h"
 
@@ -262,6 +263,7 @@ bool ScreenCapturerDrm::DiscoverOutputs() {
       output.height = static_cast<int>(crtc->height);
       output.name = std::string(ConnectorTypeName(connector->connector_type)) +
                     std::to_string(connector->connector_type_id);
+      output.stream_id = MakeDisplayStreamId(outputs_.size());
 
       outputs_.push_back(output);
       display_info_list_.push_back(
@@ -427,7 +429,7 @@ bool ScreenCapturerDrm::CaptureOutputFrame(const DrmOutput& output,
 
   if (emit_callback && callback_) {
     callback_(nv12.data(), static_cast<int>(nv12.size()), capture_width,
-              capture_height, output.name.c_str());
+              capture_height, output.stream_id.c_str());
   }
 
   UnmapFramebuffer(mapped_ptr, mapped_size, prime_fd);

src/screen_capturer/linux/screen_capturer_drm.h

@@ -47,6 +47,7 @@ class ScreenCapturerDrm : public ScreenCapturer {
     uint32_t connector_id = 0;
     uint32_t crtc_id = 0;
     std::string name;
+    std::string stream_id;
     int left = 0;
     int top = 0;
     int width = 0;

src/screen_capturer/linux/screen_capturer_linux.cpp

@@ -6,6 +6,7 @@
 #include <string>
 #include <utility>
 
+#include "display_stream_id.h"
 #include "platform.h"
 #include "rd_log.h"
 #if defined(CROSSDESK_HAS_DRM) && CROSSDESK_HAS_DRM
@@ -49,10 +50,21 @@ int ScreenCapturerLinux::Init(const int fps, cb_desktop_data cb) {
   fps_ = fps;
   callback_orig_ = std::move(cb);
   callback_ = [this](unsigned char* data, int size, int width, int height,
-                     const char* display_name) {
-    const std::string mapped_name = MapDisplayName(display_name);
+                     const char* reported_stream_id) {
+    const std::string mapped_stream_id = MapStreamId(reported_stream_id);
+    if (mapped_stream_id.empty()) {
+      if (!invalid_stream_id_logged_.exchange(true,
+                                              std::memory_order_relaxed)) {
+        LOG_WARN("Linux capturer dropping frame without a registered stream "
+                 "id: reported='{}', size={}x{}, bytes={}",
+                 reported_stream_id ? reported_stream_id : "", width, height,
+                 size);
+      }
+      return;
+    }
+    invalid_stream_id_logged_.store(false, std::memory_order_relaxed);
     if (callback_orig_) {
-      callback_orig_(data, size, width, height, mapped_name.c_str());
+      callback_orig_(data, size, width, height, mapped_stream_id.c_str());
     }
   };
 
@@ -139,10 +151,12 @@ int ScreenCapturerLinux::Destroy() {
   backend_ = BackendType::kNone;
   callback_ = nullptr;
   callback_orig_ = nullptr;
+  current_monitor_index_.store(0, std::memory_order_relaxed);
+  invalid_stream_id_logged_.store(false, std::memory_order_relaxed);
   {
     std::lock_guard<std::mutex> lock(alias_mutex_);
     canonical_displays_.clear();
-    label_alias_.clear();
+    stream_id_alias_.clear();
   }
   return 0;
 }
@@ -153,15 +167,12 @@ int ScreenCapturerLinux::Start(bool show_cursor) {
     return -1;
   }
 
-#if defined(CROSSDESK_HAS_WAYLAND_CAPTURER) && CROSSDESK_HAS_WAYLAND_CAPTURER
-  if (backend_ == BackendType::kWayland) {
-    const int refresh_ret = RefreshWaylandBackend();
-    if (refresh_ret != 0) {
-      LOG_WARN("Linux screen capturer Wayland backend refresh failed: {}",
-               refresh_ret);
-    }
+  // X11 output names, DRM connectors and Wayland stream handles may all change
+  // after an HDMI hotplug, so rebuild the current backend before each session.
+  const int refresh_ret = RefreshCurrentBackend();
+  if (refresh_ret != 0) {
+    LOG_WARN("Linux screen capturer backend refresh failed: {}", refresh_ret);
   }
-#endif
 
   const int ret = impl_->Start(show_cursor);
   if (ret == 0) {
@@ -235,14 +246,23 @@ int ScreenCapturerLinux::SwitchTo(int monitor_index) {
   if (!impl_) {
     return -1;
   }
-  return impl_->SwitchTo(monitor_index);
+  const int ret = impl_->SwitchTo(monitor_index);
+  if (ret == 0) {
+    current_monitor_index_.store(monitor_index, std::memory_order_relaxed);
+  }
+  return ret;
 }
 
 int ScreenCapturerLinux::ResetToInitialMonitor() {
   if (!impl_) {
     return -1;
   }
-  return impl_->ResetToInitialMonitor();
+  const int ret = impl_->ResetToInitialMonitor();
+  if (ret == 0) {
+    current_monitor_index_.store(initial_monitor_index_,
+                                 std::memory_order_relaxed);
+  }
+  return ret;
 }
 
 std::vector<DisplayInfo> ScreenCapturerLinux::GetDisplayInfoList() {
@@ -320,27 +340,55 @@ int ScreenCapturerLinux::InitWayland() {
 #endif
 }
 
-int ScreenCapturerLinux::RefreshWaylandBackend() {
+int ScreenCapturerLinux::RefreshCurrentBackend() {
+  std::unique_ptr<ScreenCapturer> backend;
+  const char* backend_name = "unknown";
+  switch (backend_) {
+    case BackendType::kX11:
+      backend = std::make_unique<ScreenCapturerX11>();
+      backend_name = "X11";
+      break;
+    case BackendType::kDrm:
+#if defined(CROSSDESK_HAS_DRM) && CROSSDESK_HAS_DRM
+      backend = std::make_unique<ScreenCapturerDrm>();
+      backend_name = "DRM";
+      break;
+#else
+      return -1;
+#endif
+    case BackendType::kWayland:
 #if defined(CROSSDESK_HAS_WAYLAND_CAPTURER) && CROSSDESK_HAS_WAYLAND_CAPTURER
-  auto backend = std::make_unique<ScreenCapturerWayland>();
+      backend = std::make_unique<ScreenCapturerWayland>();
+      backend_name = "Wayland";
+      break;
+#else
+      return -1;
+#endif
+    case BackendType::kNone:
+      return -1;
+  }
+
   const int ret = backend->Init(fps_, callback_);
   if (ret != 0) {
     backend->Destroy();
     return ret;
   }
 
+  const int requested_monitor =
+      current_monitor_index_.load(std::memory_order_relaxed);
+  UpdateAliasesFromBackend(backend.get());
+  if (requested_monitor > 0 && backend->SwitchTo(requested_monitor) != 0) {
+    current_monitor_index_.store(0, std::memory_order_relaxed);
+  }
+
   if (impl_) {
     impl_->Destroy();
   }
 
-  UpdateAliasesFromBackend(backend.get());
   impl_ = std::move(backend);
-  backend_ = BackendType::kWayland;
-  LOG_INFO("Linux screen capturer Wayland backend refreshed before start");
+  LOG_INFO("Linux screen capturer {} backend refreshed before start",
+           backend_name);
   return 0;
-#else
-  return -1;
-#endif
 }
 
 bool ScreenCapturerLinux::TryFallbackToDrm(bool show_cursor) {
@@ -447,61 +495,82 @@ void ScreenCapturerLinux::UpdateAliasesFromBackend(ScreenCapturer* backend) {
   }
 
   std::lock_guard<std::mutex> lock(alias_mutex_);
-  label_alias_.clear();
+  stream_id_alias_.clear();
 
   if (canonical_displays_.empty()) {
     canonical_displays_ = backend_displays;
-    for (const auto& display : backend_displays) {
-      label_alias_[display.name] = display.name;
+    for (size_t i = 0; i < backend_displays.size(); ++i) {
+      auto& canonical = canonical_displays_[i];
+      const std::string stream_id = MakeDisplayStreamId(i);
+      if (canonical.name.empty()) {
+        canonical.name = stream_id;
+      }
+      stream_id_alias_[stream_id] = stream_id;
     }
     return;
   }
 
   if (canonical_displays_.size() < backend_displays.size()) {
-    for (size_t i = canonical_displays_.size(); i < backend_displays.size();
-         ++i) {
-      canonical_displays_.push_back(backend_displays[i]);
-    }
+    LOG_WARN("Linux capturer detected {} additional display(s); they remain "
+             "unavailable until peer streams are reinitialized",
+             backend_displays.size() - canonical_displays_.size());
   }
 
-  for (size_t i = 0; i < backend_displays.size(); ++i) {
-    const std::string mapped_name = i < canonical_displays_.size()
-                                        ? canonical_displays_[i].name
-                                        : backend_displays[i].name;
-    label_alias_[backend_displays[i].name] = mapped_name;
+  auto similar = [](const DisplayInfo& current, const DisplayInfo& canonical) {
+    return std::abs(current.left - canonical.left) <= 10 &&
+           std::abs(current.top - canonical.top) <= 10 &&
+           std::abs(current.width - canonical.width) <= 20 &&
+           std::abs(current.height - canonical.height) <= 20;
+  };
+  std::vector<bool> used(canonical_displays_.size(), false);
+  for (size_t current_index = 0; current_index < backend_displays.size();
+       ++current_index) {
+    const auto& backend_display = backend_displays[current_index];
+    int canonical_index = -1;
+    for (size_t i = 0; i < canonical_displays_.size(); ++i) {
+      if (!used[i] && similar(backend_display, canonical_displays_[i])) {
+        canonical_index = static_cast<int>(i);
+        break;
+      }
+    }
+    if (canonical_index < 0 && current_index < canonical_displays_.size() &&
+        !used[current_index]) {
+      canonical_index = static_cast<int>(current_index);
+    }
+    if (canonical_index < 0) {
+      continue;
+    }
 
-    if (i < canonical_displays_.size()) {
-      // Keep original stable names, but refresh geometry from active backend.
-      canonical_displays_[i].handle = backend_displays[i].handle;
-      canonical_displays_[i].is_primary = backend_displays[i].is_primary;
-      canonical_displays_[i].left = backend_displays[i].left;
-      canonical_displays_[i].top = backend_displays[i].top;
-      canonical_displays_[i].right = backend_displays[i].right;
-      canonical_displays_[i].bottom = backend_displays[i].bottom;
-      canonical_displays_[i].width = backend_displays[i].width;
-      canonical_displays_[i].height = backend_displays[i].height;
+    used[canonical_index] = true;
+    const std::string backend_stream_id =
+        MakeDisplayStreamId(current_index);
+    const std::string stable_stream_id =
+        MakeDisplayStreamId(static_cast<size_t>(canonical_index));
+    stream_id_alias_[backend_stream_id] = stable_stream_id;
+
+    // Refresh the user-visible label and geometry. The MiniRTC stream ID is
+    // derived independently from this stable logical index.
+    canonical_displays_[canonical_index] = backend_display;
+    if (canonical_displays_[canonical_index].name.empty()) {
+      canonical_displays_[canonical_index].name = stable_stream_id;
     }
   }
 }
 
-std::string ScreenCapturerLinux::MapDisplayName(
-    const char* display_name) const {
-  std::string input_name = display_name ? display_name : "";
-  if (input_name.empty()) {
-    return input_name;
-  }
-
+std::string ScreenCapturerLinux::MapStreamId(
+    const char* reported_stream_id) const {
+  std::string input_id = reported_stream_id ? reported_stream_id : "";
   std::lock_guard<std::mutex> lock(alias_mutex_);
-  auto it = label_alias_.find(input_name);
-  if (it != label_alias_.end()) {
-    return it->second;
+  auto it = stream_id_alias_.find(input_id);
+  if (it != stream_id_alias_.end()) {
+    input_id = it->second;
+  } else {
+    input_id.clear();
   }
 
-  if (canonical_displays_.size() == 1) {
-    return canonical_displays_[0].name;
-  }
-
-  return input_name;
+  return ResolveDisplayStreamId(
+      input_id.c_str(), canonical_displays_.size(),
+      current_monitor_index_.load(std::memory_order_relaxed));
 }
 
 }  // namespace crossdesk

src/screen_capturer/linux/screen_capturer_linux.h

@@ -7,6 +7,7 @@
 #ifndef _SCREEN_CAPTURER_LINUX_H_
 #define _SCREEN_CAPTURER_LINUX_H_
 
+#include <atomic>
 #include <memory>
 #include <mutex>
 #include <string>
@@ -43,12 +44,12 @@ class ScreenCapturerLinux : public ScreenCapturer {
   int InitX11();
   int InitDrm();
   int InitWayland();
-  int RefreshWaylandBackend();
+  int RefreshCurrentBackend();
   bool TryFallbackToDrm(bool show_cursor);
   bool TryFallbackToX11(bool show_cursor);
   bool TryFallbackToWayland(bool show_cursor);
   void UpdateAliasesFromBackend(ScreenCapturer* backend);
-  std::string MapDisplayName(const char* display_name) const;
+  std::string MapStreamId(const char* reported_stream_id) const;
 
  private:
   std::unique_ptr<ScreenCapturer> impl_;
@@ -58,7 +59,10 @@ class ScreenCapturerLinux : public ScreenCapturer {
   cb_desktop_data callback_orig_;
   std::vector<DisplayInfo> canonical_displays_;
   mutable std::mutex alias_mutex_;
-  std::unordered_map<std::string, std::string> label_alias_;
+  std::unordered_map<std::string, std::string> stream_id_alias_;
+  std::atomic<int> current_monitor_index_{0};
+  int initial_monitor_index_ = 0;
+  mutable std::atomic<bool> invalid_stream_id_logged_{false};
 };
 
 }  // namespace crossdesk

src/screen_capturer/linux/screen_capturer_wayland_pipewire.cpp

@@ -15,6 +15,7 @@
 #include <thread>
 #include <vector>
 
+#include "display_stream_id.h"
 #include "libyuv.h"
 #include "rd_log.h"
 
@@ -831,8 +832,9 @@ void ScreenCapturerWayland::HandlePipeWireBuffer() {
   nv12.insert(nv12.end(), uv_plane_.begin(), uv_plane_.end());
 
   if (callback_) {
+    const std::string stream_id = MakeDisplayStreamId(0);
     callback_(nv12.data(), static_cast<int>(nv12.size()), even_width,
-              even_height, display_name_.c_str());
+              even_height, stream_id.c_str());
   }
   pipewire_last_frame_ms_.store(NowMs());
 

src/screen_capturer/linux/screen_capturer_x11.cpp

@@ -10,6 +10,7 @@
 #include <mutex>
 #include <thread>
 
+#include "display_stream_id.h"
 #include "libyuv.h"
 #include "rd_log.h"
 
@@ -97,12 +98,6 @@ int ScreenCapturerX11::Init(const int fps, cb_desktop_data cb) {
         name = "Display" + std::to_string(i + 1);
       }
 
-      // clean display name, remove non-alphanumeric characters
-      name.erase(
-          std::remove_if(name.begin(), name.end(),
-                         [](unsigned char c) { return !std::isalnum(c); }),
-          name.end());
-
       display_info_list_.push_back(DisplayInfo(
           (void*)display_, name, true, crtc_info->x, crtc_info->y,
           crtc_info->x + crtc_info->width, crtc_info->y + crtc_info->height));
@@ -324,8 +319,9 @@ void ScreenCapturerX11::OnFrame() {
   nv12.insert(nv12.end(), uv_plane_.begin(), uv_plane_.end());
 
   if (callback_) {
+    const std::string stream_id = MakeDisplayStreamId(monitor_index);
     callback_(nv12.data(), width_ * height_ * 3 / 2, width_, height_,
-              display_info_list_[monitor_index].name.c_str());
+              stream_id.c_str());
   }
 
   XDestroyImage(image);

src/screen_capturer/macosx/screen_capturer_sck_impl.mm

@@ -10,21 +10,21 @@
 
 #include "screen_capturer_sck.h"
 
+#include <AppKit/AppKit.h>
 #include <ApplicationServices/ApplicationServices.h>
 #include <CoreGraphics/CoreGraphics.h>
 #include <IOKit/IOKitLib.h>
 #include <IOKit/graphics/IOGraphicsLib.h>
 #include <IOSurface/IOSurface.h>
 #include <ScreenCaptureKit/ScreenCaptureKit.h>
-#include <algorithm>
 #include <atomic>
-#include <cctype>
 #include <cstring>
 #include <limits>
 #include <map>
 #include <mutex>
 #include <vector>
 #include "display_info.h"
+#include "display_stream_id.h"
 #include "rd_log.h"
 
 using namespace crossdesk;
@@ -83,20 +83,23 @@ class API_AVAILABLE(macos(14.0)) ScreenCapturerSckImpl : public ScreenCapturer {
 
   int Resume(int monitor_index) override { return 0; }
 
-  std::vector<DisplayInfo> GetDisplayInfoList() override { return display_info_list_; }
+  std::vector<DisplayInfo> GetDisplayInfoList() override {
+    std::lock_guard<std::mutex> lock(lock_);
+    return display_info_list_;
+  }
   int ResetToInitialMonitor() override;
 
  private:
   std::vector<DisplayInfo> display_info_list_;
   std::map<int, CGDirectDisplayID> display_id_map_;
-  std::map<CGDirectDisplayID, int> display_id_map_reverse_;
-  std::map<CGDirectDisplayID, std::string> display_id_name_map_;
   unsigned char *nv12_frame_ = nullptr;
   size_t nv12_frame_size_ = 0;
   int width_ = 0;
   int height_ = 0;
   int fps_ = 60;
   bool show_cursor_ = false;
+  bool capture_requested_ = false;
+  bool invalid_stream_id_logged_ = false;
 
  public:
   // Called by SckHelper when shareable content is returned by ScreenCaptureKit. `content` will be
@@ -130,9 +133,38 @@ class API_AVAILABLE(macos(14.0)) ScreenCapturerSckImpl : public ScreenCapturer {
   // support full-desktop capture, and will fall back to the first display.
   CGDirectDisplayID current_display_ = 0;
   int initial_monitor_index_ = 0;
+  int current_monitor_index_ = 0;
+  std::string current_stream_id_;
 };
 
+static std::string NSStringToUtf8(NSString *value) {
+  if (!value || value.length == 0) return "";
+  const char *utf8 = value.UTF8String;
+  return utf8 ? utf8 : "";
+}
+
+static std::string GetAppKitDisplayName(CGDirectDisplayID display_id) {
+  if (@available(macOS 10.15, *)) {
+    @autoreleasepool {
+      for (NSScreen *screen in NSScreen.screens) {
+        NSNumber *screen_number = screen.deviceDescription[@"NSScreenNumber"];
+        if (screen_number && screen_number.unsignedIntValue == display_id) {
+          return NSStringToUtf8(screen.localizedName);
+        }
+      }
+    }
+  }
+  return "";
+}
+
 std::string GetDisplayName(CGDirectDisplayID display_id) {
+  // IODisplayConnect is no longer exposed for some external displays on
+  // modern Apple Silicon Macs. NSScreen is the system-owned source for the
+  // user-visible name and maps directly to CGDirectDisplayID.
+  std::string appkit_name = GetAppKitDisplayName(display_id);
+  if (!appkit_name.empty()) return appkit_name;
+
+  // Keep the IOKit path for older macOS versions and display drivers.
   io_iterator_t iter;
   io_service_t serv = 0, matched_serv = 0;
 
@@ -212,8 +244,6 @@ ScreenCapturerSckImpl::~ScreenCapturerSckImpl() {
 
   display_info_list_.clear();
   display_id_map_.clear();
-  display_id_map_reverse_.clear();
-  display_id_name_map_.clear();
 
   if (nv12_frame_) {
     delete[] nv12_frame_;
@@ -232,8 +262,6 @@ int ScreenCapturerSckImpl::Init(const int fps, cb_desktop_data cb) {
   fps_ = fps > 0 ? fps : 60;
   display_info_list_.clear();
   display_id_map_.clear();
-  display_id_map_reverse_.clear();
-  display_id_name_map_.clear();
 
   if (@available(macOS 10.15, *)) {
     bool has_permission = CGPreflightScreenCaptureAccess();
@@ -265,26 +293,18 @@ int ScreenCapturerSckImpl::Init(const int fps, cb_desktop_data cb) {
     return -1;
   }
 
-  CGDirectDisplayID displays[10];
-  uint32_t count;
-  CGGetActiveDisplayList(10, displays, &count);
-
-  int unnamed_count = 1;
   for (SCDisplay *display in content.displays) {
     CGDirectDisplayID display_id = display.displayID;
     CGRect bounds = CGDisplayBounds(display_id);
     bool is_primary = CGDisplayIsMain(display_id);
 
     std::string name = GetDisplayName(display_id);
-
     if (name.empty()) {
-      name = "Display" + std::to_string(unnamed_count++);
+      name = MakeDisplayStreamId(display_info_list_.size());
     }
 
-    // clean display name, remove non-alphanumeric characters
-    name.erase(
-        std::remove_if(name.begin(), name.end(), [](unsigned char c) { return !std::isalnum(c); }),
-        name.end());
+    LOG_INFO("macOS display discovered: index={}, display_id={}, name='{}'",
+             display_info_list_.size(), display_id, name);
 
     DisplayInfo info((void *)(uintptr_t)display_id, name, is_primary,
                      static_cast<int>(bounds.origin.x), static_cast<int>(bounds.origin.y),
@@ -293,11 +313,12 @@ int ScreenCapturerSckImpl::Init(const int fps, cb_desktop_data cb) {
 
     display_info_list_.push_back(info);
     display_id_map_[display_info_list_.size() - 1] = display_id;
-    display_id_map_reverse_[display_id] = display_info_list_.size() - 1;
-    display_id_name_map_[display_id] = name;
   }
 
   initial_monitor_index_ = 0;
+  current_monitor_index_ = initial_monitor_index_;
+  current_display_ = display_id_map_[current_monitor_index_];
+  current_stream_id_ = MakeDisplayStreamId(current_monitor_index_);
   return 0;
 }
 
@@ -307,49 +328,62 @@ int ScreenCapturerSckImpl::Start(bool show_cursor) {
     return -1;
   }
 
-  if (display_info_list_.empty()) {
-    LOG_ERROR("Cannot start capturer: display info not initialized");
-    return -1;
+  {
+    std::lock_guard<std::mutex> lock(lock_);
+    if (display_info_list_.empty()) {
+      LOG_ERROR("Cannot start capturer: display info not initialized");
+      return -1;
+    }
+    show_cursor_ = show_cursor;
+    capture_requested_ = true;
+    invalid_stream_id_logged_ = false;
   }
-
-  show_cursor_ = show_cursor;
   StartOrReconfigureCapturer();
   return 0;
 }
 
 int ScreenCapturerSckImpl::SwitchTo(int monitor_index) {
-  auto display_it = display_id_map_.find(monitor_index);
-  if (display_it == display_id_map_.end()) {
-    LOG_WARN("SwitchTo skipped, invalid monitor_index={}, displays={}",
-             monitor_index, display_id_map_.size());
-    return -1;
-  }
-
-  const CGDirectDisplayID target_display = display_it->second;
+  bool should_reconfigure = false;
   {
     std::lock_guard<std::mutex> lock(lock_);
-    current_display_ = target_display;
+    auto display_it = display_id_map_.find(monitor_index);
+    if (display_it == display_id_map_.end() || monitor_index < 0 ||
+        monitor_index >= static_cast<int>(display_info_list_.size())) {
+      LOG_WARN("SwitchTo skipped, invalid monitor_index={}, displays={}",
+               monitor_index, display_id_map_.size());
+      return -1;
+    }
+    current_monitor_index_ = monitor_index;
+    current_display_ = display_it->second;
+    current_stream_id_ = MakeDisplayStreamId(monitor_index);
+    should_reconfigure = capture_requested_;
+  }
+  if (should_reconfigure) {
+    StartOrReconfigureCapturer();
   }
-  StartOrReconfigureCapturer();
   return 0;
 }
 
 int ScreenCapturerSckImpl::ResetToInitialMonitor() {
   const int target = initial_monitor_index_;
-  if (display_info_list_.empty()) return -1;
-  auto display_it = display_id_map_.find(target);
-  if (display_it == display_id_map_.end()) {
-    LOG_WARN("ResetToInitialMonitor skipped, invalid monitor_index={}", target);
-    return -1;
-  }
-
-  const CGDirectDisplayID target_display = display_it->second;
   bool should_reconfigure = false;
   {
     std::lock_guard<std::mutex> lock(lock_);
-    if (current_display_ == target_display) return 0;
+    if (display_info_list_.empty()) return -1;
+    auto display_it = display_id_map_.find(target);
+    if (display_it == display_id_map_.end()) {
+      LOG_WARN("ResetToInitialMonitor skipped, invalid monitor_index={}", target);
+      return -1;
+    }
+    const CGDirectDisplayID target_display = display_it->second;
+    if (current_display_ == target_display &&
+        current_monitor_index_ == target) {
+      return 0;
+    }
+    current_monitor_index_ = target;
     current_display_ = target_display;
-    should_reconfigure = stream_ != nil;
+    current_stream_id_ = MakeDisplayStreamId(target);
+    should_reconfigure = capture_requested_ && stream_ != nil;
   }
 
   // Resetting session state must not create a capture stream. Preserve the
@@ -369,7 +403,9 @@ int ScreenCapturerSckImpl::Destroy() {
       [stream_ stopCaptureWithCompletionHandler:nil];
       stream_ = nil;
     }
+    capture_requested_ = false;
     current_display_ = 0;
+    current_stream_id_.clear();
     permanent_error_ = false;
     _on_data = nullptr;
     helper_to_release = helper_;
@@ -383,6 +419,7 @@ int ScreenCapturerSckImpl::Destroy() {
 
 int ScreenCapturerSckImpl::Stop() {
   std::lock_guard<std::mutex> lock(lock_);
+  capture_requested_ = false;
   if (stream_) {
     LOG_INFO("Stopping stream");
     [stream_ stopCaptureWithCompletionHandler:nil];
@@ -394,6 +431,14 @@ int ScreenCapturerSckImpl::Stop() {
 }
 
 void ScreenCapturerSckImpl::OnShareableContentCreated(SCShareableContent *content) {
+  {
+    std::lock_guard<std::mutex> lock(lock_);
+    if (!capture_requested_) {
+      LOG_INFO("Ignoring stale ScreenCaptureKit display refresh after stop");
+      return;
+    }
+  }
+
   if (!content) {
     LOG_ERROR("getShareableContent failed");
     permanent_error_ = true;
@@ -407,22 +452,71 @@ void ScreenCapturerSckImpl::OnShareableContentCreated(SCShareableContent *conten
   }
 
   SCDisplay *captured_display = nil;
+  bool show_cursor = false;
   {
     std::lock_guard<std::mutex> lock(lock_);
+    if (!capture_requested_) return;
+
+    int logical_index = current_monitor_index_;
+    if (logical_index < 0 ||
+        logical_index >= static_cast<int>(display_info_list_.size())) {
+      logical_index = 0;
+    }
+
+    SCDisplay *logical_fallback = nil;
+    int display_index = 0;
     for (SCDisplay *display in content.displays) {
+      if (display_index == logical_index) logical_fallback = display;
       if (current_display_ != 0 && current_display_ == display.displayID) {
-        LOG_WARN("current display: {}, name: {}", current_display_,
-                 display_id_name_map_[current_display_]);
         captured_display = display;
         break;
       }
+      ++display_index;
     }
     if (!captured_display) {
-      captured_display = content.displays.firstObject;
-      if (captured_display) {
-        current_display_ = captured_display.displayID;
+      captured_display = logical_fallback ? logical_fallback
+                                          : content.displays.firstObject;
+      if (!logical_fallback) logical_index = 0;
+    }
+
+    if (captured_display) {
+      const CGDirectDisplayID old_display = current_display_;
+      const CGDirectDisplayID new_display = captured_display.displayID;
+      const std::string stable_stream_id = ResolveDisplayStreamId(
+          current_stream_id_.c_str(), display_info_list_.size(), logical_index);
+      if (stable_stream_id.empty()) {
+        LOG_ERROR("Cannot map macOS display {} to a registered video stream",
+                  new_display);
+        return;
+      }
+
+      current_monitor_index_ = logical_index;
+      current_display_ = new_display;
+      current_stream_id_ = stable_stream_id;
+      display_id_map_[logical_index] = new_display;
+
+      CGRect bounds = CGDisplayBounds(new_display);
+      auto& info = display_info_list_[logical_index];
+      info.handle = (void *)(uintptr_t)new_display;
+      info.is_primary = CGDisplayIsMain(new_display);
+      info.left = static_cast<int>(bounds.origin.x);
+      info.top = static_cast<int>(bounds.origin.y);
+      info.right = static_cast<int>(bounds.origin.x + bounds.size.width);
+      info.bottom = static_cast<int>(bounds.origin.y + bounds.size.height);
+      info.width = info.right - info.left;
+      info.height = info.bottom - info.top;
+      const std::string refreshed_name = GetDisplayName(new_display);
+      if (!refreshed_name.empty()) {
+        info.name = refreshed_name;
+      }
+
+      if (old_display != new_display) {
+        LOG_INFO("macOS display mapping refreshed: slot={}, old_id={}, "
+                 "new_id={}, stream='{}'",
+                 logical_index, old_display, new_display, stable_stream_id);
       }
     }
+    show_cursor = show_cursor_;
   }
 
   if (!captured_display) {
@@ -447,13 +541,14 @@ void ScreenCapturerSckImpl::OnShareableContentCreated(SCShareableContent *conten
   }
 
   config.pixelFormat = kCVPixelFormatType_420YpCbCr8BiPlanarVideoRange;
-  config.showsCursor = show_cursor_;
+  config.showsCursor = show_cursor;
   config.width = filter.contentRect.size.width * filter.pointPixelScale;
   config.height = filter.contentRect.size.height * filter.pointPixelScale;
   config.captureResolution = SCCaptureResolutionAutomatic;
   config.minimumFrameInterval = CMTimeMake(1, fps_);
 
   std::lock_guard<std::mutex> lock(lock_);
+  if (!capture_requested_) return;
 
   if (stream_) {
     LOG_INFO("Updating stream configuration");
@@ -523,7 +618,7 @@ void ScreenCapturerSckImpl::OnNewCVPixelBuffer(CVPixelBufferRef pixelBuffer,
   }
 
   std::lock_guard<std::mutex> lock(lock_);
-  if (!_on_data) {
+  if (!_on_data || !capture_requested_) {
     CVPixelBufferUnlockBaseAddress(pixelBuffer, kCVPixelBufferLock_ReadOnly);
     return;
   }
@@ -558,9 +653,22 @@ void ScreenCapturerSckImpl::OnNewCVPixelBuffer(CVPixelBufferRef pixelBuffer,
     memcpy(dst_uv + row * width, static_cast<unsigned char *>(base_uv) + row * stride_uv, width);
   }
 
+  const std::string stream_id = ResolveDisplayStreamId(
+      current_stream_id_.c_str(), display_info_list_.size(),
+      current_monitor_index_);
+  if (stream_id.empty()) {
+    if (!invalid_stream_id_logged_) {
+      LOG_ERROR("Dropping macOS frames without a registered stream id, "
+                "display_id={}",
+                current_display_);
+      invalid_stream_id_logged_ = true;
+    }
+    CVPixelBufferUnlockBaseAddress(pixelBuffer, kCVPixelBufferLock_ReadOnly);
+    return;
+  }
+  invalid_stream_id_logged_ = false;
   _on_data(nv12_frame_, static_cast<int>(required_size), static_cast<int>(width),
-           static_cast<int>(height),
-           display_id_name_map_[current_display_].c_str());
+           static_cast<int>(height), stream_id.c_str());
 
   CVPixelBufferUnlockBaseAddress(pixelBuffer, kCVPixelBufferLock_ReadOnly);
 }

src/screen_capturer/screen_capturer.h

@@ -15,6 +15,8 @@ namespace crossdesk {
 
 class ScreenCapturer {
  public:
+  // The final callback argument is a logical MiniRTC stream ID (DisplayN),
+  // not a platform display name or physical handle.
   typedef std::function<void(unsigned char*, int, int, int, const char*)>
       cb_desktop_data;
 
@@ -34,4 +36,4 @@ class ScreenCapturer {
   virtual int ResetToInitialMonitor() = 0;
 };
 }  // namespace crossdesk
-#endif
+#endif

src/screen_capturer/windows/screen_capturer_dxgi.cpp

@@ -5,6 +5,7 @@
 #include <string>
 #include <vector>
 
+#include "display_stream_id.h"
 #include "libyuv.h"
 #include "rd_log.h"
 
@@ -21,11 +22,12 @@ std::string WideToUtf8(const std::wstring& wstr) {
   return result;
 }
 
-std::string CleanDisplayName(const std::wstring& wide_name) {
+std::string GetDisplayLabel(const std::wstring& wide_name) {
   std::string name = WideToUtf8(wide_name);
-  name.erase(std::remove_if(name.begin(), name.end(),
-                            [](unsigned char c) { return !std::isalnum(c); }),
-             name.end());
+  constexpr char kDevicePrefix[] = "\\\\.\\";
+  if (name.rfind(kDevicePrefix, 0) == 0) {
+    name.erase(0, sizeof(kDevicePrefix) - 1);
+  }
   return name;
 }
 }  // namespace
@@ -207,7 +209,7 @@ void ScreenCapturerDxgi::EnumerateDisplays() {
       if (FAILED(output->GetDesc(&desc))) {
         continue;
       }
-      std::string name = CleanDisplayName(desc.DeviceName);
+      std::string name = GetDisplayLabel(desc.DeviceName);
       MONITORINFOEX mi{};
       mi.cbSize = sizeof(MONITORINFOEX);
       if (GetMonitorInfo(desc.Monitor, &mi)) {
@@ -380,8 +382,9 @@ void ScreenCapturerDxgi::CaptureLoop() {
     if (callback_) {
       int idx = monitor_index_.load();
       if (idx >= 0 && idx < static_cast<int>(display_info_list_.size())) {
+        const std::string stream_id = MakeDisplayStreamId(idx);
         callback_(nv12_frame_, nv12_size, even_width, even_height,
-                  display_info_list_[idx].name.c_str());
+                  stream_id.c_str());
       } else {
         LOG_ERROR("DXGI: CaptureLoop invalid monitor_index {} (list size {})",
                   idx, display_info_list_.size());

src/screen_capturer/windows/screen_capturer_gdi.cpp

@@ -5,6 +5,7 @@
 #include <string>
 #include <vector>
 
+#include "display_stream_id.h"
 #include "libyuv.h"
 #include "rd_log.h"
 
@@ -21,11 +22,12 @@ std::string WideToUtf8(const std::wstring& wstr) {
   return result;
 }
 
-std::string CleanDisplayName(const std::wstring& wide_name) {
+std::string GetDisplayLabel(const std::wstring& wide_name) {
   std::string name = WideToUtf8(wide_name);
-  name.erase(std::remove_if(name.begin(), name.end(),
-                            [](unsigned char c) { return !std::isalnum(c); }),
-             name.end());
+  constexpr char kDevicePrefix[] = "\\\\.\\";
+  if (name.rfind(kDevicePrefix, 0) == 0) {
+    name.erase(0, sizeof(kDevicePrefix) - 1);
+  }
   return name;
 }
 }  // namespace
@@ -42,7 +44,7 @@ BOOL CALLBACK ScreenCapturerGdi::EnumMonitorProc(HMONITOR hMonitor, HDC, LPRECT,
   MONITORINFOEX mi{};
   mi.cbSize = sizeof(MONITORINFOEX);
   if (GetMonitorInfo(hMonitor, &mi)) {
-    std::string name = CleanDisplayName(mi.szDevice);
+    std::string name = GetDisplayLabel(mi.szDevice);
     bool is_primary = (mi.dwFlags & MONITORINFOF_PRIMARY) ? true : false;
     DisplayInfo info((void*)hMonitor, name, is_primary, mi.rcMonitor.left,
                      mi.rcMonitor.top, mi.rcMonitor.right, mi.rcMonitor.bottom);
@@ -209,7 +211,8 @@ void ScreenCapturerGdi::CaptureLoop() {
                        width, height);
 
     if (callback_) {
-      callback_(nv12_frame_, nv12_size, width, height, di.name.c_str());
+      const std::string stream_id = MakeDisplayStreamId(idx);
+      callback_(nv12_frame_, nv12_size, width, height, stream_id.c_str());
     }
 
     SelectObject(mem_dc, old);
@@ -221,4 +224,4 @@ void ScreenCapturerGdi::CaptureLoop() {
   ReleaseDC(nullptr, screen_dc);
 }
 
-}  // namespace crossdesk
+}  // namespace crossdesk

src/screen_capturer/windows/screen_capturer_wgc.cpp

@@ -7,6 +7,7 @@
 
 #include <iostream>
 
+#include "display_stream_id.h"
 #include "libyuv.h"
 #include "rd_log.h"
 
@@ -24,11 +25,12 @@ std::string WideToUtf8(const std::wstring& wstr) {
   return result;
 }
 
-std::string CleanDisplayName(const std::wstring& wide_name) {
+std::string GetDisplayLabel(const std::wstring& wide_name) {
   std::string name = WideToUtf8(wide_name);
-  name.erase(std::remove_if(name.begin(), name.end(),
-                            [](unsigned char c) { return !std::isalnum(c); }),
-             name.end());
+  constexpr char kDevicePrefix[] = "\\\\.\\";
+  if (name.rfind(kDevicePrefix, 0) == 0) {
+    name.erase(0, sizeof(kDevicePrefix) - 1);
+  }
   return name;
 }
 
@@ -38,7 +40,7 @@ BOOL WINAPI EnumMonitorProc(HMONITOR hmonitor, [[maybe_unused]] HDC hdc,
   monitor_info_.cbSize = sizeof(MONITORINFOEX);
 
   if (GetMonitorInfo(hmonitor, &monitor_info_)) {
-    std::string display_name = CleanDisplayName(monitor_info_.szDevice);
+    std::string display_name = GetDisplayLabel(monitor_info_.szDevice);
     if (monitor_info_.dwFlags & MONITORINFOF_PRIMARY) {
       gs_display_list.insert(
           gs_display_list.begin(),
@@ -402,8 +404,9 @@ void ScreenCapturerWgc::OnFrame(const WgcSession::wgc_session_frame& frame,
                        (uint8_t*)(nv12_frame_ + even_width * even_height),
                        even_width, even_width, even_height);
 
+    const std::string stream_id = MakeDisplayStreamId(id);
     on_data_(nv12_frame_, nv12_size, even_width, even_height,
-             display_info_list_[id].name.c_str());
+             stream_id.c_str());
   }
 }
 

src/screen_capturer/windows/screen_capturer_win.cpp

@@ -14,6 +14,7 @@
 #include <utility>
 #include <vector>
 
+#include "display_stream_id.h"
 #include "interactive_state.h"
 #include "rd_log.h"
 #include "screen_capturer_dxgi.h"
@@ -403,37 +404,37 @@ int ScreenCapturerWin::Init(const int fps, cb_desktop_data cb) {
   fps_ = fps;
   cb_orig_ = cb;
   cb_ = [this](unsigned char* data, int size, int w, int h,
-               const char* display_name) {
+               const char* reported_stream_id) {
     if (secure_desktop_capture_active_.load(std::memory_order_relaxed)) {
       return;
     }
 
-    const char* raw_display_name = display_name ? display_name : "";
-    std::string mapped_name;
+    const char* raw_stream_id = reported_stream_id ? reported_stream_id : "";
+    std::string mapped_stream_id;
     {
       std::lock_guard<std::mutex> lock(alias_mutex_);
-      auto it = label_alias_.find(raw_display_name);
-      if (it != label_alias_.end())
-        mapped_name = it->second;
-      else
-        mapped_name = raw_display_name;
-    }
-    {
-      std::lock_guard<std::mutex> lock(alias_mutex_);
-      if (canonical_labels_.find(mapped_name) == canonical_labels_.end()) {
-        if (post_secure_desktop_waiting_for_frame_.load(
-                std::memory_order_relaxed) &&
-            !post_secure_desktop_drop_logged_.exchange(
-                true, std::memory_order_relaxed)) {
-          LOG_WARN(
-              "Windows capturer dropping post-secure-desktop frame from "
-              "unknown display: display='{}', mapped='{}', size={}x{}, "
-              "bytes={}",
-              raw_display_name, mapped_name, w, h, size);
-        }
-        return;
+      auto it = stream_id_alias_.find(raw_stream_id);
+      if (it != stream_id_alias_.end()) {
+        mapped_stream_id = it->second;
+      } else {
+        // Unknown backend labels are presentation data, not protocol IDs.
+        // Resolve them through the selected logical display instead.
+        mapped_stream_id.clear();
       }
+      mapped_stream_id = ResolveDisplayStreamId(
+          mapped_stream_id.c_str(), canonical_displays_.size(),
+          monitor_index_.load(std::memory_order_relaxed));
     }
+    if (mapped_stream_id.empty()) {
+      if (!invalid_stream_id_logged_.exchange(true,
+                                              std::memory_order_relaxed)) {
+        LOG_WARN("Windows capturer dropping frame without a registered stream "
+                 "id: reported='{}', size={}x{}, bytes={}",
+                 raw_stream_id, w, h, size);
+      }
+      return;
+    }
+    invalid_stream_id_logged_.store(false, std::memory_order_relaxed);
     if (post_secure_desktop_waiting_for_frame_.exchange(
             false, std::memory_order_relaxed)) {
       const ULONGLONG start_tick =
@@ -445,10 +446,11 @@ int ScreenCapturerWin::Init(const int fps, cb_desktop_data cb) {
                                              std::memory_order_relaxed);
       LOG_INFO(
           "Windows capturer first normal frame after secure desktop: "
-          "display='{}', mapped='{}', size={}x{}, bytes={}, elapsed_ms={}",
-          raw_display_name, mapped_name, w, h, size, elapsed_ms);
+          "reported_stream='{}', mapped_stream='{}', size={}x{}, bytes={}, "
+          "elapsed_ms={}",
+          raw_stream_id, mapped_stream_id, w, h, size, elapsed_ms);
     }
-    if (cb_orig_) cb_orig_(data, size, w, h, mapped_name.c_str());
+    if (cb_orig_) cb_orig_(data, size, w, h, mapped_stream_id.c_str());
   };
 
   int ret = -1;
@@ -508,9 +510,8 @@ int ScreenCapturerWin::Destroy() {
   }
   {
     std::lock_guard<std::mutex> lock(alias_mutex_);
-    label_alias_.clear();
-    handle_to_canonical_.clear();
-    canonical_labels_.clear();
+    stream_id_alias_.clear();
+    handle_to_canonical_index_.clear();
   }
   return 0;
 }
@@ -523,10 +524,26 @@ int ScreenCapturerWin::Start(bool show_cursor) {
 
   show_cursor_.store(show_cursor, std::memory_order_relaxed);
   paused_.store(false, std::memory_order_relaxed);
+  invalid_stream_id_logged_.store(false, std::memory_order_relaxed);
 
-  int ret = impl_->Start(show_cursor);
+  // Refresh physical monitor identities before every session. HMONITOR and
+  // DXGI output handles may change after an HDMI hotplug while CrossDesk stays
+  // open; logical stream IDs must remain stable.
+  const int requested_monitor =
+      monitor_index_.load(std::memory_order_relaxed);
+  impl_->Destroy();
+  int ret = impl_->Init(fps_, cb_);
+  if (ret == 0) {
+    RebuildAliasesFromImpl();
+    ret = impl_->Start(show_cursor);
+    if (ret == 0 && requested_monitor > 0 &&
+        impl_->SwitchTo(requested_monitor) != 0) {
+      monitor_index_.store(0, std::memory_order_relaxed);
+    }
+  }
   if (ret != 0) {
-    LOG_WARN("Windows capturer: Start failed (ret={}), trying fallback", ret);
+    LOG_WARN("Windows capturer: refresh/start failed (ret={}), trying fallback",
+             ret);
 
     auto try_init_start = [&](std::unique_ptr<ScreenCapturer> cand) -> bool {
       int r = cand->Init(fps_, cb_);
@@ -536,6 +553,10 @@ int ScreenCapturerWin::Start(bool show_cursor) {
         impl_ = std::move(cand);
         impl_is_wgc_plugin_ = false;
         RebuildAliasesFromImpl();
+        if (requested_monitor > 0 &&
+            impl_->SwitchTo(requested_monitor) != 0) {
+          monitor_index_.store(0, std::memory_order_relaxed);
+        }
         return true;
       }
       return false;
@@ -624,25 +645,49 @@ int ScreenCapturerWin::ResetToInitialMonitor() {
 
 std::vector<DisplayInfo> ScreenCapturerWin::GetDisplayInfoList() {
   if (!impl_) return {};
-  return impl_->GetDisplayInfoList();
+  std::lock_guard<std::mutex> lock(alias_mutex_);
+  return canonical_displays_;
 }
 
 void ScreenCapturerWin::BuildCanonicalFromImpl() {
   std::lock_guard<std::mutex> lock(alias_mutex_);
-  handle_to_canonical_.clear();
-  label_alias_.clear();
+  handle_to_canonical_index_.clear();
+  stream_id_alias_.clear();
   canonical_displays_ = impl_->GetDisplayInfoList();
-  canonical_labels_.clear();
-  for (const auto& di : canonical_displays_) {
-    handle_to_canonical_[di.handle] = di.name;
-    canonical_labels_.insert(di.name);
+  std::unordered_map<std::string, size_t> name_counts;
+  for (const auto& display : canonical_displays_) {
+    if (!display.name.empty()) {
+      ++name_counts[display.name];
+    }
+  }
+  for (size_t i = 0; i < canonical_displays_.size(); ++i) {
+    auto& di = canonical_displays_[i];
+    const std::string stream_id = MakeDisplayStreamId(i);
+    if (di.name.empty()) {
+      di.name = stream_id;
+    }
+    handle_to_canonical_index_[di.handle] = i;
+    stream_id_alias_[stream_id] = stream_id;
+    if (name_counts[di.name] == 1) {
+      // Compatibility with an older WGC plugin that reports display names.
+      stream_id_alias_[di.name] = stream_id;
+    }
   }
 }
 
 void ScreenCapturerWin::RebuildAliasesFromImpl() {
   std::lock_guard<std::mutex> lock(alias_mutex_);
-  label_alias_.clear();
+  stream_id_alias_.clear();
   auto current = impl_->GetDisplayInfoList();
+  if (current.empty() || canonical_displays_.empty()) return;
+  const auto previous_handles = handle_to_canonical_index_;
+  handle_to_canonical_index_.clear();
+  std::unordered_map<std::string, size_t> name_counts;
+  for (const auto& display : current) {
+    if (!display.name.empty()) {
+      ++name_counts[display.name];
+    }
+  }
   auto similar = [&](const DisplayInfo& a, const DisplayInfo& b) {
     int dl = std::abs(a.left - b.left);
     int dt = std::abs(a.top - b.top);
@@ -650,21 +695,52 @@ void ScreenCapturerWin::RebuildAliasesFromImpl() {
     int dh = std::abs(a.height - b.height);
     return dl <= 10 && dt <= 10 && dw <= 20 && dh <= 20;
   };
-  for (const auto& di : current) {
-    std::string canonical;
-    auto it = handle_to_canonical_.find(di.handle);
-    if (it != handle_to_canonical_.end()) {
-      canonical = it->second;
-    } else {
-      for (const auto& c : canonical_displays_) {
-        if (similar(di, c) || (di.is_primary && c.is_primary)) {
-          canonical = c.name;
+  std::vector<bool> used(canonical_displays_.size(), false);
+  for (size_t current_index = 0; current_index < current.size();
+       ++current_index) {
+    const auto& di = current[current_index];
+    int canonical_index = -1;
+    auto old_handle = previous_handles.find(di.handle);
+    if (old_handle != previous_handles.end() &&
+        old_handle->second < canonical_displays_.size() &&
+        !used[old_handle->second]) {
+      canonical_index = static_cast<int>(old_handle->second);
+    }
+    if (canonical_index < 0) {
+      for (size_t i = 0; i < canonical_displays_.size(); ++i) {
+        if (!used[i] && (similar(di, canonical_displays_[i]) ||
+                         (di.is_primary && canonical_displays_[i].is_primary))) {
+          canonical_index = static_cast<int>(i);
           break;
         }
       }
     }
-    if (!canonical.empty() && canonical != di.name) {
-      label_alias_[di.name] = canonical;
+    if (canonical_index < 0 && current_index < canonical_displays_.size() &&
+        !used[current_index]) {
+      canonical_index = static_cast<int>(current_index);
+    }
+    if (canonical_index < 0) {
+      LOG_WARN("Windows capturer ignoring unregistered display after topology "
+               "change: display='{}', index={}",
+               di.name, current_index);
+      continue;
+    }
+
+    used[canonical_index] = true;
+    auto& canonical = canonical_displays_[canonical_index];
+    const std::string backend_stream_id =
+        MakeDisplayStreamId(current_index);
+    const std::string stable_stream_id =
+        MakeDisplayStreamId(static_cast<size_t>(canonical_index));
+    stream_id_alias_[backend_stream_id] = stable_stream_id;
+    if (!di.name.empty() && name_counts[di.name] == 1) {
+      stream_id_alias_[di.name] = stable_stream_id;
+    }
+    handle_to_canonical_index_[di.handle] =
+        static_cast<size_t>(canonical_index);
+    canonical = di;
+    if (canonical.name.empty()) {
+      canonical.name = stable_stream_id;
     }
   }
 }
@@ -792,7 +868,7 @@ bool ScreenCapturerWin::GetCurrentCaptureRegion(int* left, int* top, int* width,
   *top = display.top;
   *width = capture_width;
   *height = capture_height;
-  *display_name = display.name;
+  *display_name = MakeDisplayStreamId(static_cast<size_t>(current_monitor));
   return true;
 }
 

src/screen_capturer/windows/screen_capturer_win.h

@@ -10,12 +10,12 @@
 #include <Windows.h>
 
 #include <atomic>
+#include <cstddef>
 #include <cstdint>
 #include <memory>
 #include <mutex>
 #include <thread>
 #include <unordered_map>
-#include <unordered_set>
 #include <vector>
 
 #include "screen_capturer.h"
@@ -48,11 +48,11 @@ class ScreenCapturerWin : public ScreenCapturer {
   cb_desktop_data cb_;
   cb_desktop_data cb_orig_;
 
-  std::unordered_map<void*, std::string> handle_to_canonical_;
-  std::unordered_map<std::string, std::string> label_alias_;
+  std::unordered_map<void*, size_t> handle_to_canonical_index_;
+  std::unordered_map<std::string, std::string> stream_id_alias_;
   std::mutex alias_mutex_;
   std::vector<DisplayInfo> canonical_displays_;
-  std::unordered_set<std::string> canonical_labels_;
+  std::atomic<bool> invalid_stream_id_logged_{false};
   std::atomic<bool> running_{false};
   std::atomic<bool> paused_{false};
   std::atomic<bool> show_cursor_{true};