Fix inclusion of message when counting tokens from message editor (#29443)

Accidentally omitted this in #29233

Release Notes:

- N/A

crates/agent/src/message_editor.rs

@@ -20,7 +20,9 @@ use gpui::{
     Task, TextStyle, WeakEntity, linear_color_stop, linear_gradient, point, pulsating_between,
 };
 use language::{Buffer, Language};
-use language_model::{ConfiguredModel, LanguageModelRegistry, LanguageModelRequestMessage};
+use language_model::{
+    ConfiguredModel, LanguageModelRegistry, LanguageModelRequestMessage, MessageContent,
+};
 use language_model_selector::ToggleModelSelector;
 use multi_buffer;
 use project::Project;
@@ -1089,6 +1091,12 @@ impl MessageEditor {
                     loaded_context.add_to_request_message(&mut request_message);
                 }
 
+                if !message_text.is_empty() {
+                    request_message
+                        .content
+                        .push(MessageContent::Text(message_text));
+                }
+
                 let request = language_model::LanguageModelRequest {
                     thread_id: None,
                     prompt_id: None,