[feat] add remote host version checks and update prompts

libs/wire/include/app_version.h

@@ -0,0 +1,43 @@
+/*
+ * @Author: DI JUNKUN
+ * @Date: 2026-09-28
+ * Copyright (c) 2026 by DI JUNKUN, All Rights Reserved.
+ */
+
+#ifndef _APP_VERSION_H_
+#define _APP_VERSION_H_
+
+#include <optional>
+#include <string>
+#include <string_view>
+
+namespace crossdesk {
+
+struct VersionInfo {
+  std::string version;
+  std::string release_name;
+  std::string release_notes;
+  std::string release_date;
+  int patch = -1;
+};
+
+// Shared desktop release parsing and comparison for desktop and iOS controllers.
+std::optional<VersionInfo> ParseVersionInfoJSON(std::string_view json);
+bool IsValidAppVersion(const std::string& version);
+
+bool IsNewerVersion(const std::string& current, const std::string& latest);
+
+// Pass latest_patch < 0 when patch metadata is unavailable.
+bool IsNewerVersionWithMetadata(const std::string& current,
+                                const std::string& latest,
+                                const std::string& latest_date,
+                                int latest_patch);
+
+// Returns the latest release label when the peer is older. Missing or invalid
+// peer versions are treated as legacy; the latest release must still be valid.
+std::optional<std::string> AvailableAppUpdate(const std::string& current,
+                                             const VersionInfo& latest);
+
+}  // namespace crossdesk
+
+#endif

libs/wire/include/remote_action.h

@@ -119,6 +119,8 @@ struct CursorState {
 struct HostInfo {
   char host_name[64];
   std::size_t host_name_size;
+  // Optional; an empty string means the peer version is unknown.
+  char app_version[64];
   char** display_list;
   std::size_t display_num;
   int* left;
@@ -213,9 +215,11 @@ struct HostDisplay {
 // heap-allocated with the same layout the decoder produces; release the
 // result with FreeRemoteAction. An allocation failure yields an empty display
 // list rather than a partially filled one.
+// Missing or oversized app versions are advertised as unknown (empty).
 RemoteAction MakeHostInformation(const std::string& host_name,
                                  const std::vector<HostDisplay>& displays,
-                                 bool supports_privacy_screen);
+                                 bool supports_privacy_screen,
+                                 const std::string& app_version = {});
 
 }  // namespace crossdesk