After obtaining a HostAgent authentication, do multiple agents communicate with each other directly?

[hotdogarea]

For example, in a simple communication and collaboration scenario between two agents, according to the A2A protocol, the two agents must be routed through a unified hostagent, I am curious whether the hostagent will support multiple collaboration modes in the future to cope with more scenarios, and if in a simple two-agent scenario, can it support direct communication between the two after authentication? Or does it have to be forwarded by hostagent?

[hotdogarea]

I am very optimistic about the future of A2A, so I am actively learning about it.
In the demo, we know that there are three kinds of agents developed by different frameworks, which can be developed by different vendors. They can't work directly with each other on their own. In this case, the host agent must go through for collaboration. And the message must be forwarded by the host agent. It doesn't count as direct communication.
Another scenario is that if both agents are developed based on the A2A protocol, whether the host agent is required in this scenario. I don't know if my understanding is rigorous or not, but I'm still learning, thanks to the efforts and contributions of the google team