UX: adds chat send shortcut user preference (#30473)

Users can now decide if they want to send a message on:
- <kbd>enter</kbd>
- <kbd>meta + enter</kbd>

If you choose <kbd>meta + enter</kbd>, <kbd>enter</kbd> will add a
linebreak.

<img width="192" alt="Screenshot 2025-01-21 at 12 57 48"
src="https://github.com/user-attachments/assets/abfd6f8b-83b3-4e6f-be67-8f63d536ca8a"
/>

plugins/chat/spec/system/chat_composer_spec.rb

@@ -104,6 +104,74 @@ RSpec.describe "Chat composer", type: :system do
 
       expect(channel_page.composer.value).to eq("bb")
     end
+
+    context "when user preference is set to send on enter" do
+      before { current_user.user_option.update!(chat_send_shortcut: 0) }
+
+      context "when pressing enter" do
+        it "sends the message" do
+          chat_page.visit_channel(channel_1)
+
+          channel_page.composer.fill_in(with: "testenter").enter_shortcut
+
+          expect(channel_page.messages).to have_message(text: "testenter")
+        end
+      end
+
+      context "when pressing shift + enter" do
+        it "adds a linebreak" do
+          chat_page.visit_channel(channel_1)
+
+          channel_page.composer.fill_in(with: "testenter").shift_enter_shortcut
+
+          expect(channel_page.composer.value).to eq("testenter\n")
+        end
+      end
+
+      context "when pressing meta + enter" do
+        it "sends the message" do
+          chat_page.visit_channel(channel_1)
+
+          channel_page.composer.fill_in(with: "testenter").meta_enter_shortcut
+
+          expect(channel_page.messages).to have_message(text: "testenter")
+        end
+      end
+    end
+
+    context "when user preference is set to send on meta + enter" do
+      before { current_user.user_option.update!(chat_send_shortcut: 1) }
+
+      context "when pressing enter" do
+        it "adds a linebreak" do
+          chat_page.visit_channel(channel_1)
+
+          channel_page.composer.fill_in(with: "testenter").enter_shortcut
+
+          expect(channel_page.composer.value).to eq("testenter\n")
+        end
+      end
+
+      context "when pressing shift + enter" do
+        it "adds a linebreak" do
+          chat_page.visit_channel(channel_1)
+
+          channel_page.composer.fill_in(with: "testenter").shift_enter_shortcut
+
+          expect(channel_page.composer.value).to eq("testenter\n")
+        end
+      end
+
+      context "when pressing meta + enter" do
+        it "sends the message" do
+          chat_page.visit_channel(channel_1)
+
+          channel_page.composer.fill_in(with: "testenter").meta_enter_shortcut
+
+          expect(channel_page.messages).to have_message(text: "testenter")
+        end
+      end
+    end
   end
 
   context "when editing a message with no length" do

plugins/chat/spec/system/page_objects/chat/components/composer.rb

@@ -42,6 +42,7 @@ module PageObjects
 
         def fill_in(**args)
           input.fill_in(**args)
+          self
         end
 
         def value
@@ -105,6 +106,18 @@ module PageObjects
         def focused?
           component.has_css?(".chat-composer.is-focused")
         end
+
+        def enter_shortcut
+          input.send_keys(:enter)
+        end
+
+        def shift_enter_shortcut
+          input.send_keys(%i[shift enter])
+        end
+
+        def meta_enter_shortcut
+          input.send_keys([PLATFORM_KEY_MODIFIER, :enter])
+        end
       end
     end
   end

plugins/chat/spec/system/user_chat_preferences_spec.rb

@@ -62,6 +62,15 @@ RSpec.describe "User chat preferences", type: :system do
     expect(select_kit).to have_selected_value("fullscreen")
   end
 
+  it "can select send shorcut sidebar mode" do
+    visit("/my/preferences")
+    find(".user-nav__preferences-chat", visible: :all).click
+    find("#chat_send_shortcut_meta_enter").click
+    find(".save-changes").click
+
+    expect(page).to have_checked_field("chat_send_shortcut_meta_enter")
+  end
+
   context "as an admin on another user's preferences" do
     fab!(:current_user) { Fabricate(:admin) }
     fab!(:user_1) { Fabricate(:user) }