Expose Agent as a CLI for testing during development

[DouweM]

Description

It'd be nice to have the ability to do agent.to_cli() and get an experience similar to https://ai.pydantic.dev/cli/ for testing out an agent without having to build a full chat UI.

References

As discussed in https://pydanticlogfire.slack.com/archives/C083V7PMHHA/p1745525917655549.

[DouweM]

cc @samuelcolvin as you've been working on the CLI

[Kludex]

I want this as well.

[benomahony]

This could be cool inspiration: https://github.com/darrenburns/elia

[AndrewHannigan]

+1 I'm also looking for this

[Kludex]

Maybe the right approach is pai run main:agent?

Just a thought... 🤔

[AndrewHannigan]

This PR is ready for review, it implements this requested feature as a method on Agent. @Kludex any concerns with this approach?

[AndrewHannigan]

I've added a pai --agent flag as well that supports module:variable syntax as you suggested @Kludex. I can see that being helpful to quickly interact with an agent as a CLI without having to modify the module you are importing the agent from.

[samuelcolvin]

We probably need to get #1504 merged first, as it'll conflict.