agent: Improve end of trial card display (#35789)

Now rendering the backdrop behind the card to clean up the UI, bring
focus to the card's content, and direct the user to act on it, either by
ignoring it or upgrading.

<img width="500" height="1242" alt="CleanShot 2025-08-07 at 10  30
58@2x"
src="https://github.com/user-attachments/assets/8c6b9c34-eb22-4f01-b3fa-158ac78b7439"
/>

Release Notes:

- N/A

crates/agent_ui/src/agent_panel.rs

@@ -2343,6 +2343,16 @@ impl AgentPanel {
         )
     }
 
+    fn render_backdrop(&self, cx: &mut Context<Self>) -> impl IntoElement {
+        div()
+            .size_full()
+            .absolute()
+            .inset_0()
+            .bg(cx.theme().colors().panel_background)
+            .opacity(0.8)
+            .block_mouse_except_scroll()
+    }
+
     fn render_trial_end_upsell(
         &self,
         _window: &mut Window,
@@ -2352,15 +2362,24 @@ impl AgentPanel {
             return None;
         }
 
-        Some(EndTrialUpsell::new(Arc::new({
-            let this = cx.entity();
-            move |_, cx| {
-                this.update(cx, |_this, cx| {
-                    TrialEndUpsell::set_dismissed(true, cx);
-                    cx.notify();
-                });
-            }
-        })))
+        Some(
+            v_flex()
+                .absolute()
+                .inset_0()
+                .size_full()
+                .bg(cx.theme().colors().panel_background)
+                .opacity(0.85)
+                .block_mouse_except_scroll()
+                .child(EndTrialUpsell::new(Arc::new({
+                    let this = cx.entity();
+                    move |_, cx| {
+                        this.update(cx, |_this, cx| {
+                            TrialEndUpsell::set_dismissed(true, cx);
+                            cx.notify();
+                        });
+                    }
+                }))),
+        )
     }
 
     fn render_empty_state_section_header(
@@ -3210,9 +3229,10 @@ impl Render for AgentPanel {
         // - Scrolling in all views works as expected
         // - Files can be dropped into the panel
         let content = v_flex()
-            .key_context(self.key_context())
-            .justify_between()
+            .relative()
             .size_full()
+            .justify_between()
+            .key_context(self.key_context())
             .on_action(cx.listener(Self::cancel))
             .on_action(cx.listener(|this, action: &NewThread, window, cx| {
                 this.new_thread(action, window, cx);
@@ -3255,14 +3275,12 @@ impl Render for AgentPanel {
             .on_action(cx.listener(Self::toggle_burn_mode))
             .child(self.render_toolbar(window, cx))
             .children(self.render_onboarding(window, cx))
-            .children(self.render_trial_end_upsell(window, cx))
             .map(|parent| match &self.active_view {
                 ActiveView::Thread {
                     thread,
                     message_editor,
                     ..
                 } => parent
-                    .relative()
                     .child(
                         if thread.read(cx).is_empty() && !self.should_render_onboarding(cx) {
                             self.render_thread_empty_state(window, cx)
@@ -3299,21 +3317,10 @@ impl Render for AgentPanel {
                     })
                     .child(h_flex().relative().child(message_editor.clone()).when(
                         !LanguageModelRegistry::read_global(cx).has_authenticated_provider(cx),
-                        |this| {
-                            this.child(
-                                div()
-                                    .size_full()
-                                    .absolute()
-                                    .inset_0()
-                                    .bg(cx.theme().colors().panel_background)
-                                    .opacity(0.8)
-                                    .block_mouse_except_scroll(),
-                            )
-                        },
+                        |this| this.child(self.render_backdrop(cx)),
                     ))
                     .child(self.render_drag_target(cx)),
                 ActiveView::ExternalAgentThread { thread_view, .. } => parent
-                    .relative()
                     .child(thread_view.clone())
                     .child(self.render_drag_target(cx)),
                 ActiveView::History => parent.child(self.history.clone()),
@@ -3352,7 +3359,8 @@ impl Render for AgentPanel {
                         ))
                 }
                 ActiveView::Configuration => parent.children(self.configuration.clone()),
-            });
+            })
+            .children(self.render_trial_end_upsell(window, cx));
 
         match self.active_view.which_font_size_used() {
             WhichFontSize::AgentFont => {