Remove model family from tui (#8488)

- Remove model family from tui

codex-rs/tui2/src/app_backtrack.rs

@@ -338,10 +338,9 @@ impl App {
     ) {
         let conv = new_conv.conversation;
         let session_configured = new_conv.session_configured;
-        let model_family = self.chat_widget.get_model_family();
         let init = crate::chatwidget::ChatWidgetInit {
             config: cfg,
-            model_family: model_family.clone(),
+            model: self.current_model.clone(),
             frame_requester: tui.frame_requester(),
             app_event_tx: self.app_event_tx.clone(),
             initial_prompt: None,
@@ -354,7 +353,6 @@ impl App {
         };
         self.chat_widget =
             crate::chatwidget::ChatWidget::new_from_existing(init, conv, session_configured);
-        self.current_model = model_family.get_model_slug().to_string();
         // Trim transcript up to the selected user message and re-render it.
         self.trim_transcript_for_backtrack(nth_user_message);
         self.render_transcript_once(tui);