submission completed_at

db/migrate/20260701123007_add_submission_completed_at.rb

@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+class AddSubmissionCompletedAt < ActiveRecord::Migration[8.1]
+  def change
+    add_column :submissions, :completed_at, :datetime
+  end
+end