Programmatically checking if a particular host is still a target.

So I've a situation where I want to delegate_to a host. That host is one
(arbitrarily chosen) of a group.

Rather than

delegate_to: "{{ GROUP[0] }}"

I'd like to confirm that the host is actually up, first - or rather, pick
an arbitrary member of GROUP that's successfully had facts gathered
against it (and no previous play fail on it).

Is that kind of status derivable from any of the information that ansible
currently exposes as a variable to the J2 engine? (Or any other way: if I
need to write a custom filter for this job I have no objection to doing
so.)

Cheers,
jan

I think this may help;

{{ play_hosts[0] }}

That should pick the first host in the current play (so no previous failures)

Hrm, it would, but the group that's being targeted by the top-level
playbook is not the same as the group that contains candidate hosts that
I'd like to delegate to - unless I misunderstand what play_hosts is doing.