assistant: Add model names in alternative inline tooltips (#20350)

Closes https://github.com/zed-industries/zed/issues/18826

This PR adds the model name to the tooltips on the alternative inline
assistant icon buttons. The default model should be the first, so every
other one set as an alternative appears after.


https://github.com/user-attachments/assets/46faccaa-447c-45a4-b927-49ea3c4f3be1


Release Notes:

- Improve knowledge of which model is used when with alternative inline
models turned on

crates/assistant/src/inline_assistant.rs

@@ -53,7 +53,9 @@ use telemetry_events::{AssistantEvent, AssistantKind, AssistantPhase};
 use terminal_view::terminal_panel::TerminalPanel;
 use text::{OffsetRangeExt, ToPoint as _};
 use theme::ThemeSettings;
-use ui::{prelude::*, text_for_action, CheckboxWithLabel, IconButtonShape, Popover, Tooltip};
+use ui::{
+    prelude::*, text_for_action, CheckboxWithLabel, IconButtonShape, KeyBinding, Popover, Tooltip,
+};
 use util::{RangeExt, ResultExt};
 use workspace::{notifications::NotificationId, ItemHandle, Toast, Workspace};
 
@@ -1899,21 +1901,58 @@ impl PromptEditor {
         let codegen = self.codegen.read(cx);
         let disabled = matches!(codegen.status(cx), CodegenStatus::Idle);
 
+        let model_registry = LanguageModelRegistry::read_global(cx);
+        let default_model = model_registry.active_model();
+        let alternative_models = model_registry.inline_alternative_models();
+
+        let get_model_name = |index: usize| -> String {
+            let name = |model: &Arc<dyn LanguageModel>| model.name().0.to_string();
+
+            match index {
+                0 => default_model.as_ref().map_or_else(String::new, name),
+                index if index <= alternative_models.len() => alternative_models
+                    .get(index - 1)
+                    .map_or_else(String::new, name),
+                _ => String::new(),
+            }
+        };
+
+        let total_models = alternative_models.len() + 1;
+
+        if total_models <= 1 {
+            return div().into_any_element();
+        }
+
+        let current_index = codegen.active_alternative;
+        let prev_index = (current_index + total_models - 1) % total_models;
+        let next_index = (current_index + 1) % total_models;
+
+        let prev_model_name = get_model_name(prev_index);
+        let next_model_name = get_model_name(next_index);
+
         h_flex()
             .child(
                 IconButton::new("previous", IconName::ChevronLeft)
                     .icon_color(Color::Muted)
-                    .disabled(disabled)
+                    .disabled(disabled || current_index == 0)
                     .shape(IconButtonShape::Square)
                     .tooltip({
                         let focus_handle = self.editor.focus_handle(cx);
                         move |cx| {
-                            Tooltip::for_action_in(
-                                "Previous Alternative",
-                                &CyclePreviousInlineAssist,
-                                &focus_handle,
-                                cx,
-                            )
+                            cx.new_view(|cx| {
+                                let mut tooltip = Tooltip::new("Previous Alternative").key_binding(
+                                    KeyBinding::for_action_in(
+                                        &CyclePreviousInlineAssist,
+                                        &focus_handle,
+                                        cx,
+                                    ),
+                                );
+                                if !disabled && current_index != 0 {
+                                    tooltip = tooltip.meta(prev_model_name.clone());
+                                }
+                                tooltip
+                            })
+                            .into()
                         }
                     })
                     .on_click(cx.listener(|this, _, cx| {
@@ -1937,17 +1976,25 @@ impl PromptEditor {
             .child(
                 IconButton::new("next", IconName::ChevronRight)
                     .icon_color(Color::Muted)
-                    .disabled(disabled)
+                    .disabled(disabled || current_index == total_models - 1)
                     .shape(IconButtonShape::Square)
                     .tooltip({
                         let focus_handle = self.editor.focus_handle(cx);
                         move |cx| {
-                            Tooltip::for_action_in(
-                                "Next Alternative",
-                                &CycleNextInlineAssist,
-                                &focus_handle,
-                                cx,
-                            )
+                            cx.new_view(|cx| {
+                                let mut tooltip = Tooltip::new("Next Alternative").key_binding(
+                                    KeyBinding::for_action_in(
+                                        &CycleNextInlineAssist,
+                                        &focus_handle,
+                                        cx,
+                                    ),
+                                );
+                                if !disabled && current_index != total_models - 1 {
+                                    tooltip = tooltip.meta(next_model_name.clone());
+                                }
+                                tooltip
+                            })
+                            .into()
                         }
                     })
                     .on_click(cx.listener(|this, _, cx| {