Remove default model labels from TUI model pickers (#51235)

## What changed

Remove `SelectionItem::is_default` and stop appending `(default)` to model picker entries. Keep the `(current)` marker and explicitly label the workspace owner notification prompt's negative option as `No (default)`.

## Testing

Update the model selection popup snapshot to reflect the removed label and adjusted column spacing.

GitOrigin-RevId: 1f8b85f896541ef7354d5979b4244d7df4b867d6

codex-rs/tui/src/bottom_pane/list_selection_view.rs

@@ -167,7 +167,6 @@ pub(crate) struct SelectionItem {
     pub description: Option<String>,
     pub selected_description: Option<String>,
     pub is_current: bool,
-    pub is_default: bool,
     pub is_disabled: bool,
     pub actions: Vec<SelectionAction>,
     pub secondary_action: Option<SelectionSecondaryAction>,
@@ -666,13 +665,7 @@ impl ListSelectionView {
                     let is_selected = self.state.selected_idx == Some(visible_idx);
                     let prefix = if is_selected { '›' } else { ' ' };
                     let name = item.name.as_str();
-                    let marker = if item.is_current {
-                        " (current)"
-                    } else if item.is_default {
-                        " (default)"
-                    } else {
-                        ""
-                    };
+                    let marker = if item.is_current { " (current)" } else { "" };
                     let name_with_marker = format!("{name}{marker}");
                     let is_disabled = item.is_disabled || item.disabled_reason.is_some();
                     let wrap_prefix = if self.is_searchable {

codex-rs/tui/src/chatwidget/model_popups.rs

@@ -145,7 +145,6 @@ impl ChatWidget {
                     name: preset.display_name.clone(),
                     description,
                     is_current: model.as_str() == current_model,
-                    is_default: preset.is_default,
                     secondary_action: if requires_advanced_selection {
                         None
                     } else {
@@ -267,7 +266,6 @@ impl ChatWidget {
                 name: preset.display_name.clone(),
                 description,
                 is_current,
-                is_default: preset.is_default,
                 secondary_action: direct_effort.and_then(|effort| {
                     self.session_model_selection_action(preset.model.clone(), Some(effort))
                 }),

codex-rs/tui/src/chatwidget/rate_limits.rs

@@ -566,9 +566,8 @@ impl ChatWidget {
                 ..Default::default()
             },
             SelectionItem {
-                name: "No".to_string(),
+                name: "No (default)".to_string(),
                 display_shortcut: Some(key_hint::plain(KeyCode::Char('n')).into()),
-                is_default: true,
                 dismiss_on_select: true,
                 ..Default::default()
             },

codex-rs/tui/src/chatwidget/snapshots/codex_tui__chatwidget__tests__model_selection_popup.snap

@@ -5,13 +5,13 @@ expression: popup
   Select Model and Effort
 
 
-  1. GPT-6.1-Sol (default)  Latest workhorse model for coding and everyday work.
-  2. GPT-6-Astra            Frontier intelligence for the most demanding work.
-  3. GPT-6-Sol              Previous generation workhorse model.
-  4. GPT-6-Luna             Fast and affordable model for easier tasks.
-  5. GPT-5.6-Sol            Older generation workhorse model.
-  6. GPT-5.6-Terra          Older balanced model for straightforward work.
-  7. GPT-5.6-Luna           Older fast and efficient model.
-› 8. GPT-5.5 (current)      Legacy coding model.
+  1. GPT-6.1-Sol        Latest workhorse model for coding and everyday work.
+  2. GPT-6-Astra        Frontier intelligence for the most demanding work.
+  3. GPT-6-Sol          Previous generation workhorse model.
+  4. GPT-6-Luna         Fast and affordable model for easier tasks.
+  5. GPT-5.6-Sol        Older generation workhorse model.
+  6. GPT-5.6-Terra      Older balanced model for straightforward work.
+  7. GPT-5.6-Luna       Older fast and efficient model.
+› 8. GPT-5.5 (current)  Legacy coding model.
 
   enter select · esc back