fix: Prevent creating duplicate messages via Instagram echo events (#11535)

Fixes
https://linear.app/chatwoot/issue/CW-4383/copilot-resolution-message-creating-duplicate-conversations-due-to
and
https://linear.app/chatwoot/issue/CW-4287/instagram-channel-missing-existing-source-id-check

When the copilot/system resolves a conversation with a system resolve
message (with `lock_to_single_conversation` disabled), echo events were
creating new conversations instead of using existing ones. This occurred
because we were checking the echo_id in the new conversation rather than
in the resolved conversation. This PR fixes the issue by checking if the
message exists anywhere in the system instead of checking within a
particular conversation.

app/builders/messages/instagram/base_message_builder.rb

@@ -152,11 +152,13 @@ class Messages::Instagram::BaseMessageBuilder < Messages::Messenger::MessageBuil
   end
 
   def message_already_exists?
-    cw_message = conversation.messages.where(
-      source_id: @messaging[:message][:mid]
-    ).first
+    find_message_by_source_id(@messaging[:message][:mid]).present?
+  end
 
-    cw_message.present?
+  def find_message_by_source_id(source_id)
+    return unless source_id
+
+    @message = Message.find_by(source_id: source_id)
   end
 
   def all_unsupported_files?

spec/builders/messages/instagram/message_builder_spec.rb

@@ -79,6 +79,18 @@ describe Messages::Instagram::MessageBuilder do
       expect(instagram_inbox.messages.count).to be 1
     end
 
+    it 'discards duplicate messages from webhook events with the same message_id' do
+      messaging = dm_params[:entry][0]['messaging'][0]
+      described_class.new(messaging, instagram_inbox).perform
+
+      initial_message_count = instagram_inbox.messages.count
+      expect(initial_message_count).to be 1
+
+      described_class.new(messaging, instagram_inbox).perform
+
+      expect(instagram_inbox.messages.count).to eq initial_message_count
+    end
+
     it 'creates message for shared reel' do
       messaging = shared_reel_params[:entry][0]['messaging'][0]
       described_class.new(messaging, instagram_inbox).perform
@@ -151,11 +163,15 @@ describe Messages::Instagram::MessageBuilder do
     end
 
     it 'does not create message for unsupported file type' do
+      conversation
+
+      # try to create a message with unsupported file type
       story_mention_params[:entry][0][:messaging][0]['message']['attachments'][0]['type'] = 'unsupported_type'
       messaging = story_mention_params[:entry][0][:messaging][0]
 
       described_class.new(messaging, instagram_inbox, outgoing_echo: false).perform
 
+      # Conversation should exist but no new message should be created
       expect(instagram_inbox.conversations.count).to be 1
       expect(instagram_inbox.messages.count).to be 0
     end

spec/builders/messages/instagram/messenger/message_builder_spec.rb

@@ -189,19 +189,22 @@ describe Messages::Instagram::Messenger::MessageBuilder do
           profile_pic: 'https://chatwoot-assets.local/sample.png'
         }.with_indifferent_access
       )
+
+      conversation
+
+      # create a message with unsupported file type
       story_mention_params[:entry][0][:messaging][0]['message']['attachments'][0]['type'] = 'unsupported_type'
       messaging = story_mention_params[:entry][0][:messaging][0]
-      contact_inbox
+
       described_class.new(messaging, instagram_messenger_inbox, outgoing_echo: false).perform
 
       instagram_messenger_inbox.reload
 
-      # we would have contact created but message and attachments won't be created
+      # Conversation should exist but no new message should be created
       expect(instagram_messenger_inbox.conversations.count).to be 1
       expect(instagram_messenger_inbox.messages.count).to be 0
 
       contact = instagram_messenger_channel.inbox.contacts.first
-
       expect(contact.name).to eq('Jane Dae')
     end
   end