Reproducer for Airflow 3 issue: Missing tasks in DAG runs for dynamic DAGs when the DAG's end_date is changed.

airflow3-dynamic-dag-dagrun-missing-tasks-repro.py

"""
Reproducer for Airflow 3 issue:
Missing tasks in DAG runs for dynamic DAGs when the DAG's end_date is changed.

Expected:
Each DagRun contains one task instance: 'noop'.

Observed:
Some DagRuns exist but have zero task instances.

Tested with:
- Apache Airflow 3.0.6
"""

import logging
from pathlib import Path

import pendulum
import yaml

from airflow import DAG
from airflow.providers.standard.operators.empty import EmptyOperator


logger = logging.getLogger(__name__)

CONFIG_FILE = Path(__file__).parent / "airflow3-dynamic-dag-dagrun-missing-tasks-repro.yaml"

with open(CONFIG_FILE) as f:
    parsed_config = yaml.safe_load(f)

for dag_config in parsed_config.get("dags", []):
    dag_id = dag_config["dag_id"]
    start_date = pendulum.parse(dag_config["start_date"], tz="UTC")
    end_date = pendulum.parse(dag_config["end_date"], tz="UTC") if "end_date" in dag_config else None

    logger.info(
        "Creating DAG %s with start_date=%s end_date=%s",
        dag_id,
        start_date,
        end_date,
    )

    dag = DAG(
        dag_id=dag_id,
        start_date=start_date,
        end_date=end_date,
        schedule="@daily",
        catchup=True,
        max_active_runs=16,
    )

    with dag:
        EmptyOperator(task_id="noop")

    globals()[dag_id] = dag

airflow3-dynamic-dag-dagrun-missing-tasks-repro.yaml

dags:
  - dag_id: dag_x
    start_date: "2026-02-01"
    end_date: "2026-02-15"
  - dag_id: dag_y
    start_date: "2026-02-01"
    end_date: "2026-02-15"