Function insert_rejected_exercise_task_submission_files 

async fn insert_rejected_exercise_task_submission_files(
    conn: &mut PgConnection,
    rejected_exercise_task_submission_id: Uuid,
    file_upload_ids: &[Uuid],
) -> ModelResult<()>

Records which files a rejected file answer named.

The files themselves are not spared from the exercise_answer_uploads reaper, so this is what a later diagnosis has to work from: the ids still resolve to soft-deleted file_uploads rows carrying each file’s name, type and size.

order_number must stay encoded exactly as exercise_task_submission_files::insert_many encodes it, so a rejection can be compared against an accepted answer.