agent: Fix reinsertion of creases when editing past messages (#30417)

Just noticed this got lost when main was merged in #29828.

Release Notes:

- agent: Fixed the rendering of added context when editing past messages
in a thread.

crates/agent/src/active_thread.rs

@@ -3,9 +3,10 @@ use crate::context::{AgentContextHandle, RULES_ICON};
 use crate::context_picker::{ContextPicker, MentionLink};
 use crate::context_store::ContextStore;
 use crate::context_strip::{ContextStrip, ContextStripEvent, SuggestContextKind};
+use crate::message_editor::insert_message_creases;
 use crate::thread::{
-    LastRestoreCheckpoint, MessageId, MessageSegment, Thread, ThreadError, ThreadEvent,
-    ThreadFeedback,
+    LastRestoreCheckpoint, MessageCrease, MessageId, MessageSegment, Thread, ThreadError,
+    ThreadEvent, ThreadFeedback,
 };
 use crate::thread_store::{RulesLoadingError, TextThreadStore, ThreadStore};
 use crate::tool_use::{PendingToolUseStatus, ToolUse};
@@ -1267,6 +1268,7 @@ impl ActiveThread {
         &mut self,
         message_id: MessageId,
         message_segments: &[MessageSegment],
+        message_creases: &[MessageCrease],
         window: &mut Window,
         cx: &mut Context<Self>,
     ) {
@@ -1286,6 +1288,7 @@ impl ActiveThread {
         );
         editor.update(cx, |editor, cx| {
             editor.set_text(message_text.clone(), window, cx);
+            insert_message_creases(editor, message_creases, &self.context_store, window, cx);
             editor.focus_handle(cx).focus(window);
             editor.move_to_end(&editor::actions::MoveToEnd, window, cx);
         });
@@ -1740,6 +1743,7 @@ impl ActiveThread {
         let Some(message) = self.thread.read(cx).message(message_id) else {
             return Empty.into_any();
         };
+        let message_creases = message.creases.clone();
 
         let Some(rendered_message) = self.rendered_messages_by_id.get(&message_id) else {
             return Empty.into_any();
@@ -2031,6 +2035,7 @@ impl ActiveThread {
                                 this.start_editing_message(
                                     message_id,
                                     &message_segments,
+                                    &message_creases,
                                     window,
                                     cx,
                                 );