For the ARC client implementation I am determining if the job is complete using the Pulsar state rather than the ARC job state.

    def full_status(self):
        pulsar_state = self.get_status()
        return {
            "status": pulsar_state,
            "complete": "true" if manager_status.is_job_done(pulsar_state) else "false",
            # ancient John, what were you thinking? 👀
            "outputs_directory_contents": [],
            # it needs to be defined, otherwise `PulsarOutputs.has_outputs` fails; it is ok that it is empty because
            # ARC is responsible for staging the outputs (Galaxy does not have to collect any outputs)
        }

I get the Pulsar state via a mapping too (similar to gcp_state_to_pulsar_status()). What would be the advantage of using two mappings gcp_state_to_pulsar_status(), gcp_state_is_complete() as you are doing for the GCP client implementation? (or what is my mistake?)

Would I need to use something akin to gcp_state_is_complete()

The client manager is generated by Galaxy calling pulsar.client.manager.build_client_manager(). For the ARC client implementation I was forced to define a kwarg arc_enabled (and do some extra trickery). I assume this is not how things work. How are you managing to make Galaxy create a PollingJobClientManager rather than a ClientManager when you want to use the polling job client?

def build_client_manager(**kwargs: Dict[str, Any]) -> ClientManagerInterface:
    if 'job_manager' in kwargs:
        return ClientManager(**kwargs)  # TODO: Consider more separation here.
    elif kwargs.get('amqp_url', None):
        return MessageQueueClientManager(**kwargs)
    elif kwargs.get("k8s_enabled") or kwargs.get("tes_url") or kwargs.get("arc_enabled"):
        return PollingJobClientManager(**kwargs)
    else:
        return ClientManager(**kwargs)

I've gone this route also more or less - the matching Pulsar client code looks something like https://github.com/galaxyproject/galaxy/compare/dev...jmchilton:galaxy:pulsar_2025?expand=1#diff-8232d66b380f49f27bbfbe089dad63ea193e3710939463c6294ee28d09fc0bafR1087.

I did galaxyproject/galaxy@6b65775, which is almost the same. However, I find your approach more attractive.

Could you mention me when you open a PR for this? I'd like to suggest something (merging self.client_manager_kwargs with the superclass' client_manager_kwargs) and adapt galaxyproject/galaxy#20598 to your PR.

Will do. I'm sorry I have not been very responsive but I do appreciate your attention to the details.