FEATURE: Log user merge in staff logs

app/services/staff_action_logger.rb

@@ -242,6 +242,16 @@ class StaffActionLogger
     ))
   end
 
+  def log_user_merge(user, source_username, source_email, opts = {})
+    raise Discourse::InvalidParameters.new(:user) unless user
+    UserHistory.create!(params(opts).merge(
+      action: UserHistory.actions[:merge_user],
+      target_user_id: user.id,
+      context: I18n.t("staff_action_logs.user_merged", username: source_username),
+      email: source_email
+    ))
+  end
+
   BADGE_FIELDS ||= %i{id name description long_description icon image badge_type_id
     badge_grouping_id query allow_title multiple_grant listable target_posts
     enabled auto_revoke show_posts system}

app/services/user_merger.rb

@@ -1,7 +1,9 @@
 class UserMerger
-  def initialize(source_user, target_user)
+  def initialize(source_user, target_user, acting_user = nil)
     @source_user = source_user
     @target_user = target_user
+    @acting_user = acting_user
+    @source_primary_email = source_user.email
   end
 
   def merge!
@@ -19,6 +21,7 @@ class UserMerger
 
     delete_source_user
     delete_source_user_references
+    log_merge
   end
 
   protected
@@ -353,7 +356,7 @@ class UserMerger
       email: "#{@source_user.username}_#{SecureRandom.hex}@no-email.invalid"
     )
 
-    UserDestroyer.new(Discourse.system_user).destroy(@source_user)
+    UserDestroyer.new(Discourse.system_user).destroy(@source_user, quiet: true)
   end
 
   def delete_source_user_references
@@ -366,6 +369,11 @@ class UserMerger
     UserAction.where(acting_user_id: @source_user.id).delete_all
   end
 
+  def log_merge
+    logger = StaffActionLogger.new(@acting_user || Discourse.system_user)
+    logger.log_user_merge(@target_user, @source_user.username, @source_primary_email)
+  end
+
   def update_user_id(table_name, opts = {})
     builder = update_user_id_sql_builder(table_name, opts)
     builder.exec(source_user_id: @source_user.id, target_user_id: @target_user.id)