I couldn't find any official documentation specifying what each parameter to a `sla_miss_callback` callable are. This would be a great addition to know how to properly format the messages sent.
airflow/models/dag.py
return
        log.info("Sync %s DAGs", len(dags))
        dag_by_ids = {dag.dag_id: dag for dag in dags}
        dag_ids = set(dag_by_ids.keys())
        query = (
            session.query(DagModel)
            .options(joinedload(DagModel.tags, innerjoin=False))
            .filter(DagModel.dag_id.in_(dag_ids))
        )
        orm_dags: List[DagModel] = with_row_locks(query, of=DagModel, session=session).all()
        existing_dag_ids = {orm_dag.dag_id for orm_dag in orm_dags}
        missing_dag_ids = dag_ids.difference(existing_dag_ids)
        for missing_dag_id in missing_dag_ids:
            orm_dag = DagModel(dag_id=missing_dag_id)
            dag = dag_by_ids[missing_dag_id]
            if dag.is_paused_upon_creation is not None:
                orm_dag.is_paused = dag.is_paused_upon_creation
            orm_dag.tags = []
            log.info("Creating ORM DAG for %s", dag.dag_id)
            session.add(orm_dag)
            orm_dags.append(orm_dag)
        
        most_recent_subq = (
            session.query(DagRun.dag_id, func.max(DagRun.execution_date).label("max_execution_date"))
            .filter(
                DagRun.dag_id.in_(existing_dag_ids),
                or_(DagRun.run_type == DagRunType.BACKFILL_JOB, DagRun.run_type == DagRunType.SCHEDULED),
            )
            .group_by(DagRun.dag_id)
            .subquery()