Persist state between Sensor pokes

[Desdroid]

I am trying to persist state in-between sensor pokes of a sensor in reschedule mode.
I tried using XCOMs for this, but even though I can see the XCOM for the Sensor in the UI, pulling it always returns None.
Is this just something that's not possible, or a potential bug?
Is there a supported way to persist state in between sensor runs?
My code looks like this:

@task.sensor(
    poke_interval=timedelta(minutes=5), timeout=timedelta(minutes=120), mode="reschedule"
)
def wait_for_file_count_to_not_increase(ti: RuntimeTaskInstanceProtocol)
    previous_file_count = ti.xcom_pull(key="file_count", default=0)
    # Code to get the current file count
    current_file_count = 100
    if previous_file_count == current_file_count:
        return True
    ti.xcom_push(key="file_count", value=current_file_count)
    return False

[Desdroid]

Seems like this is not possible and I need to use Variables or Files instead.
I now came to this conclusion after I found this SO post:
https://stackoverflow.com/questions/67258269/use-xcom-pull-to-pull-a-keys-value-that-same-task-pushed-airflow

[Desdroid]

PR to clarify this in the docs is here: #57577

[potiuk]

Also - there is a discussion about the need for persisting state in Airflow - which might lead to adding such a feature https://lists.apache.org/thread/vftpzrwb34xr2xbfsx7qtbxn5w6h3f2b - so feel free to take part in that discussion.