assistant2: Add ability to delete past threads (#21607)

This PR adds the ability to delete past threads in Assistant2.

Release Notes:

- N/A

crates/assistant2/src/assistant_panel.rs

@@ -106,6 +106,10 @@ impl AssistantPanel {
         }
     }
 
+    pub(crate) fn local_timezone(&self) -> UtcOffset {
+        self.local_timezone
+    }
+
     fn new_thread(&mut self, cx: &mut ViewContext<Self>) {
         let thread = self
             .thread_store
@@ -147,8 +151,9 @@ impl AssistantPanel {
         self.message_editor.focus_handle(cx).focus(cx);
     }
 
-    pub(crate) fn local_timezone(&self) -> UtcOffset {
-        self.local_timezone
+    pub(crate) fn delete_thread(&mut self, thread_id: &ThreadId, cx: &mut ViewContext<Self>) {
+        self.thread_store
+            .update(cx, |this, cx| this.delete_thread(thread_id, cx));
     }
 }
 

crates/assistant2/src/thread_history.rs

@@ -127,11 +127,23 @@ impl RenderOnce for PastThread {
                     .child(
                         IconButton::new("delete", IconName::TrashAlt)
                             .shape(IconButtonShape::Square)
-                            .icon_size(IconSize::Small),
+                            .icon_size(IconSize::Small)
+                            .on_click({
+                                let assistant_panel = self.assistant_panel.clone();
+                                let id = id.clone();
+                                move |_event, cx| {
+                                    assistant_panel
+                                        .update(cx, |this, cx| {
+                                            this.delete_thread(&id, cx);
+                                        })
+                                        .ok();
+                                }
+                            }),
                     ),
             )
             .on_click({
                 let assistant_panel = self.assistant_panel.clone();
+                let id = id.clone();
                 move |_event, cx| {
                     assistant_panel
                         .update(cx, |this, cx| {

crates/assistant2/src/thread_store.rs

@@ -80,6 +80,10 @@ impl ThreadStore {
             .cloned()
     }
 
+    pub fn delete_thread(&mut self, id: &ThreadId, cx: &mut ModelContext<Self>) {
+        self.threads.retain(|thread| thread.read(cx).id() != id);
+    }
+
     fn register_context_server_handlers(&self, cx: &mut ModelContext<Self>) {
         cx.subscribe(
             &self.context_server_manager.clone(),