Understanding catalog negotiation

[ISilviu]

Hello,

I'm trying to better understand A2UI's catalog negotiation.
The documentation seems to tie the catalog negotiation to A2A, but I believe this would also apply to projects that don't use A2A.

In my case, I have followed the agent development instructions. In that guide, the A2UI schema is static, and provided as context through the system prompt.

It is hard for me on how one should implement catalog negotiation, considering the provided example uses a static schema.
I have used a Pydantic schema to validate the A2UI schema outputted by the LLM.

If we employ catalog negotation, this means we would essentially need to:

1. Frontend sends the catalog ids in each request.
2. The backend receives it and propagates it to the part of the code that configures the LLM that responds in A2UI.
3. The code will dynamically pick the Pydantic classes to use, as well as pick/re-generate the a2ui_schema that is sent to the system prompt of the LLM.
4. The LLM will respond, with respect to the received catalog ID.

For reference, using LangChain and LangGraph.

Can you please confirm I have correctly understood the flow?

cc @gspencergoog @jacobsimionato