perf: compact [propId, value] wire format for property events

linux/runner/mpv/mpv_player.cc

@@ -249,7 +249,8 @@ std::string MpvPlayer::GetProperty(const std::string& name) {
 }
 
 void MpvPlayer::ObserveProperty(const std::string& name,
-                                const std::string& format) {
+                                const std::string& format,
+                                int id) {
   if (disposed_ || !mpv_) return;
 
   // Check if already observing.
@@ -257,6 +258,8 @@ void MpvPlayer::ObserveProperty(const std::string& name,
     return;
   }
 
+  name_to_id_[name] = id;
+
   mpv_format mpv_fmt = MPV_FORMAT_NONE;
   if (format == "string") {
     mpv_fmt = MPV_FORMAT_STRING;
@@ -515,22 +518,24 @@ FlValue* MpvPlayer::NodeToFlValue(mpv_node* node) {
 }
 
 void MpvPlayer::SendPropertyChange(const char* name, mpv_node* data) {
-  FlValue* event_map = fl_value_new_map();
-  fl_value_set_string_take(event_map, "type", fl_value_new_string("property"));
-  fl_value_set_string_take(event_map, "name",
-                           fl_value_new_string(name ? name : ""));
+  if (!name) return;
 
+  auto it = name_to_id_.find(name);
+  if (it == name_to_id_.end()) return;
+
+  FlValue* list = fl_value_new_list();
+  fl_value_append_take(list, fl_value_new_int(it->second));
   if (data) {
-    fl_value_set_string_take(event_map, "value", NodeToFlValue(data));
+    fl_value_append_take(list, NodeToFlValue(data));
   } else {
-    fl_value_set_string_take(event_map, "value", fl_value_new_null());
+    fl_value_append_take(list, fl_value_new_null());
   }
 
   std::lock_guard<std::mutex> lock(callback_mutex_);
   if (event_callback_) {
-    event_callback_(event_map);
+    event_callback_(list);
   }
-  fl_value_unref(event_map);
+  fl_value_unref(list);
 }
 
 void MpvPlayer::SendEvent(const std::string& name, FlValue* data) {

linux/runner/mpv/mpv_player.h

@@ -71,7 +71,9 @@ class MpvPlayer {
   /// Changes will be reported via the event callback.
   /// @param name Property name to observe.
   /// @param format Format type ("string", "flag", "int64", "double", "node").
-  void ObserveProperty(const std::string& name, const std::string& format);
+  /// @param id Property ID assigned by Dart for compact event encoding.
+  void ObserveProperty(const std::string& name, const std::string& format,
+                       int id);
 
   /// Renders a frame to the current OpenGL context.
   /// Must be called from the GTK render callback.
@@ -133,6 +135,7 @@ class MpvPlayer {
 
   uint64_t next_reply_userdata_ = 1;
   std::map<std::string, uint64_t> observed_properties_;
+  std::map<std::string, int> name_to_id_;
 
   // Pending async commands: request_id -> callback
   std::map<uint64_t, CommandCallback> pending_commands_;

linux/runner/mpv/mpv_plugin.cc

@@ -411,6 +411,7 @@ static void mpv_plugin_handle_method_call(FlMethodChannel* channel,
     } else {
       FlValue* name_value = fl_value_lookup_string(args, "name");
       FlValue* format_value = fl_value_lookup_string(args, "format");
+      FlValue* id_value = fl_value_lookup_string(args, "id");
 
       if (name_value == nullptr ||
           fl_value_get_type(name_value) != FL_VALUE_TYPE_STRING) {
@@ -420,9 +421,14 @@ static void mpv_plugin_handle_method_call(FlMethodChannel* channel,
                  fl_value_get_type(format_value) != FL_VALUE_TYPE_STRING) {
         response = FL_METHOD_RESPONSE(fl_method_error_response_new(
             "INVALID_ARGS", "Missing 'format'", nullptr));
+      } else if (id_value == nullptr ||
+                 fl_value_get_type(id_value) != FL_VALUE_TYPE_INT) {
+        response = FL_METHOD_RESPONSE(fl_method_error_response_new(
+            "INVALID_ARGS", "Missing 'id'", nullptr));
       } else {
         self->player->ObserveProperty(fl_value_get_string(name_value),
-                                      fl_value_get_string(format_value));
+                                      fl_value_get_string(format_value),
+                                      static_cast<int>(fl_value_get_int(id_value)));
         response = FL_METHOD_RESPONSE(fl_method_success_response_new(nullptr));
       }
     }