prebuilt: allow pydantic model as state schema in create_react_agent

[ianchi]

Inherited attributes where not considered.
Pydantic model can inherit from other pydantic models. In those cases, inherited attributes where not considered in the check and the code fails.

[vercel]

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Name	Status	Preview	Comments	Updated (UTC)
langgraph-docs-preview	⬜️ Ignored (Inspect)	Visit Preview		Mar 7, 2025 3:06pm

[benjamincburns]

Thanks for the contribution @ianchi! Would you mind adding a test for this, please?

[ianchi]

Hi @benjamincburns,

I updated the PR and added the test, but I've run into a problem.
It works ok for v1 but it fails for v2.

It seems that the state that the conditional edge receives is not the full state (but the one in the source node?), so it cannot inject it correctly on the tool.

I don't know if this can be "fixed" somehow.
Any ideas/suggestions??

[ianchi]

Hi @benjamincburns,

I found a "fix" for the v2 problem. Anyhow is more of a hack than a good fix.

Although I couldn't find it clearly in the documentation it seems that currently in Langgraph:

• conditional edges recieve the same state defined in the origin node (either by input, type annotation, or implicit). Type annotation in the conditional function are completely ignored.
• for tools, the type in the InjectedState annotation is ignored. The available state is injected as is, with no convertion (as is the case in nodes)

I couldn't find any other more elegant solution, given these conditions.

[vbarda]

@ianchi thanks for the contribution - i pushed a bunch of updates -- let me know if you have any comments, otherwise will merge shortly