feat(facebook): Mark Messenger native-app echoes as external echo message (#13665)

When agents send replies from the native Facebook Messenger app (not
Chatwoot), echo events were created without external_echo metadata and
could be misrepresented in the UI. This change updates Messenger echo
message creation to:

- set content_attributes.external_echo = true for outgoing_echo messages
- set echo message status to delivered
- keep sender as nil for echo messages (existing behavior)

<img width="2614" height="1264" alt="CleanShot 2026-02-26 at 16 32
04@2x"
src="https://github.com/user-attachments/assets/ba61c941-465d-4893-814e-855e6b6c79e8"
/>

app/builders/messages/facebook/message_builder.rb

@@ -105,15 +105,19 @@ class Messages::Facebook::MessageBuilder < Messages::Messenger::MessageBuilder
   end
 
   def message_params
+    content_attributes = {
+      in_reply_to_external_id: response.in_reply_to_external_id
+    }
+    content_attributes[:external_echo] = true if @outgoing_echo
+
     {
       account_id: conversation.account_id,
       inbox_id: conversation.inbox_id,
       message_type: @message_type,
+      status: @outgoing_echo ? :delivered : :sent,
       content: response.content,
       source_id: response.identifier,
-      content_attributes: {
-        in_reply_to_external_id: response.in_reply_to_external_id
-      },
+      content_attributes: content_attributes,
       sender: @outgoing_echo ? nil : @contact_inbox.contact
     }
   end

spec/builders/messages/facebook/message_builder_spec.rb

@@ -59,6 +59,36 @@ describe Messages::Facebook::MessageBuilder do
       expect(contact.name).to eq(default_name)
     end
 
+    it 'marks echo messages as external echo messages' do
+      allow(Koala::Facebook::API).to receive(:new).and_return(fb_object)
+      allow(fb_object).to receive(:get_object).and_return(
+        {
+          first_name: 'Jane',
+          last_name: 'Dae',
+          account_id: facebook_channel.inbox.account_id,
+          profile_pic: 'https://chatwoot-assets.local/sample.png'
+        }.with_indifferent_access
+      )
+
+      echo_message_object = {
+        messaging: {
+          sender: { id: facebook_channel.page_id },
+          recipient: { id: '3383290475046708' },
+          message: { mid: 'm_echo_1', text: 'Echo testing', is_echo: true, app_id: '263902037430900' }
+        }
+      }.to_json
+      echo_message = Integrations::Facebook::MessageParser.new(echo_message_object)
+
+      described_class.new(echo_message, facebook_channel.inbox, outgoing_echo: true).perform
+
+      message = facebook_channel.inbox.messages.find_by(source_id: 'm_echo_1')
+      expect(message).to be_present
+      expect(message.message_type).to eq('outgoing')
+      expect(message.sender).to be_nil
+      expect(message.status).to eq('delivered')
+      expect(message.content_attributes['external_echo']).to be true
+    end
+
     context 'when lock to single conversation' do
       subject(:mocked_message_builder) do
         described_class.new(mocked_incoming_fb_text_message, facebook_channel.inbox).perform