agent_ui: Fix expand message editor button not always working (#41845)

The button could not be clicked whenever the editor was currently not
focused. This PR fixes this and also registers the action on a more
global level, similar to how this is done for all the other agent
actions.

Release Notes:

- Fixed an issue where the `Expand message editor` button would not work
in agent threads if the message editor was not focused.

crates/agent_ui/src/acp/thread_view.rs

@@ -881,6 +881,7 @@ impl AcpThreadView {
         cx: &mut Context<Self>,
     ) {
         self.set_editor_is_expanded(!self.editor_expanded, cx);
+        cx.stop_propagation();
         cx.notify();
     }
 
@@ -3978,8 +3979,12 @@ impl AcpThreadView {
                                             )
                                         }
                                     })
-                                    .on_click(cx.listener(|_, _, window, cx| {
-                                        window.dispatch_action(Box::new(ExpandMessageEditor), cx);
+                                    .on_click(cx.listener(|this, _, window, cx| {
+                                        this.expand_message_editor(
+                                            &ExpandMessageEditor,
+                                            window,
+                                            cx,
+                                        );
                                     })),
                             ),
                     ),

crates/agent_ui/src/agent_panel.rs

@@ -19,7 +19,6 @@ use settings::{
 use zed_actions::OpenBrowser;
 use zed_actions::agent::{OpenClaudeCodeOnboardingModal, ReauthenticateAgent};
 
-use crate::acp::{AcpThreadHistory, ThreadHistoryEvent};
 use crate::context_store::ContextStore;
 use crate::ui::{AcpOnboardingModal, ClaudeCodeOnboardingModal};
 use crate::{
@@ -33,6 +32,10 @@ use crate::{
     text_thread_editor::{AgentPanelDelegate, TextThreadEditor, make_lsp_adapter_delegate},
     ui::{AgentOnboardingModal, EndTrialUpsell},
 };
+use crate::{
+    ExpandMessageEditor,
+    acp::{AcpThreadHistory, ThreadHistoryEvent},
+};
 use crate::{
     ExternalAgent, NewExternalAgentThread, NewNativeAgentThreadFromSummary, placeholder_command,
 };
@@ -106,6 +109,12 @@ pub fn init(cx: &mut App) {
                         }
                     },
                 )
+                .register_action(|workspace, _: &ExpandMessageEditor, window, cx| {
+                    if let Some(panel) = workspace.panel::<AgentPanel>(cx) {
+                        workspace.focus_panel::<AgentPanel>(window, cx);
+                        panel.update(cx, |panel, cx| panel.expand_message_editor(window, cx));
+                    }
+                })
                 .register_action(|workspace, _: &OpenHistory, window, cx| {
                     if let Some(panel) = workspace.panel::<AgentPanel>(cx) {
                         workspace.focus_panel::<AgentPanel>(window, cx);
@@ -944,6 +953,15 @@ impl AgentPanel {
         .detach_and_log_err(cx);
     }
 
+    fn expand_message_editor(&mut self, window: &mut Window, cx: &mut Context<Self>) {
+        if let Some(thread_view) = self.active_thread_view() {
+            thread_view.update(cx, |view, cx| {
+                view.expand_message_editor(&ExpandMessageEditor, window, cx);
+                view.focus_handle(cx).focus(window);
+            });
+        }
+    }
+
     fn open_history(&mut self, window: &mut Window, cx: &mut Context<Self>) {
         if matches!(self.active_view, ActiveView::History) {
             if let Some(previous_view) = self.previous_view.take() {