Restructure omni services and add Chatwoot research snapshot

research/chatwoot/app/jobs/notification/remove_old_notification_job.rb

@@ -0,0 +1,54 @@
+class Notification::RemoveOldNotificationJob < ApplicationJob
+  queue_as :purgable
+
+  NOTIFICATION_LIMIT = 300
+  OLD_NOTIFICATION_THRESHOLD = 1.month
+
+  def perform
+    remove_old_notifications
+    trim_user_notifications
+  end
+
+  private
+
+  def remove_old_notifications
+    Notification.where('created_at < ?', OLD_NOTIFICATION_THRESHOLD.ago)
+                .delete_all
+  end
+
+  def trim_user_notifications
+    # Find users with more than NOTIFICATION_LIMIT notifications
+    user_ids_exceeding_limit.each do |user_id|
+      trim_notifications_for_user(user_id)
+    end
+  end
+
+  def user_ids_exceeding_limit
+    Notification.group(:user_id)
+                .having('COUNT(*) > ?', NOTIFICATION_LIMIT)
+                .pluck(:user_id)
+  end
+
+  def trim_notifications_for_user(user_id)
+    # Find the cutoff notification (the 301st when we want to keep top 300)
+    # Order by created_at DESC, then id DESC for deterministic ordering
+    cutoff = Notification.where(user_id: user_id)
+                         .order(created_at: :desc, id: :desc)
+                         .offset(NOTIFICATION_LIMIT)
+                         .limit(1)
+                         .pick(:created_at, :id)
+
+    return unless cutoff
+
+    cutoff_time, cutoff_id = cutoff
+
+    # Delete notifications older than cutoff, or same timestamp but lower/equal ID
+    # Since we order by id DESC, higher IDs are kept (come first), lower IDs deleted
+    # This avoids race conditions: notifications created after finding the cutoff
+    # will have timestamps > cutoff_time and won't be incorrectly deleted
+    Notification.where(user_id: user_id)
+                .where('created_at < ? OR (created_at = ? AND id <= ?)',
+                       cutoff_time, cutoff_time, cutoff_id)
+                .delete_all
+  end
+end