UX: disable arrow up to edit if last message is not editable (#20729)

plugins/chat/assets/javascripts/discourse/components/chat-live-pane.js

@@ -896,17 +896,20 @@ export default class ChatLivePane extends Component {
   @action
   editLastMessageRequested() {
     const lastUserMessage = this.args.channel.messages.findLast(
-      (message) =>
+      (message) => message.user.id === this.currentUser.id
-        message.user.id === this.currentUser.id &&
-        !message.staged &&
-        !message.error
     );
 
-    if (lastUserMessage) {
+    if (!lastUserMessage) {
+      return;
+    }
+
+    if (lastUserMessage.staged || lastUserMessage.error) {
+      return;
+    }
+
     this.editingMessage = lastUserMessage;
     this._focusComposer();
   }
-  }
 
   @action
   setReplyTo(messageId) {

plugins/chat/spec/system/shortcuts/chat_composer_spec.rb

@@ -70,5 +70,19 @@ RSpec.describe "Shortcuts | chat composer", type: :system, js: true do
 
       expect(page.find(".chat-composer-message-details")).to have_content(message_1.message)
     end
+
+    context "when last message is not editable" do
+      after { page.driver.browser.network_conditions = { offline: false } }
+
+      it "does not edit a message" do
+        chat.visit_channel(channel_1)
+        page.driver.browser.network_conditions = { offline: true }
+        channel_page.send_message("Hello world")
+
+        find(".chat-composer-input").send_keys(:arrow_up)
+
+        expect(page).to have_no_css(".chat-composer-message-details")
+      end
+    end
   end
 end