feat: Support perplexity citations

[morloderex]

What:

• Bug Fix
• New Feature

Description:

This adds support for the citations attribute that perplexity adds to their responses and the search_context_size sub attribute under the usage attribute.

Related:

No related

[iBotPeaches]

Hmm. I need to think on this. This might be first time we are introducing a parameter that is not backed by anything in OpenAI. Just a new field that a specific provider will use.

So if we move forward, folks will see the citation property (conditionally) and perhaps confusion. I was discussing this in another thread with someone - #568 (comment)

Is the answer different Response classes backed on the model/provider?

[morloderex]

@iBotPeaches I haven't seen any other provider that adds these attributes.

The perplexity provider is a bit weird in regards to its response, and it's not probably documented.

[morloderex]

It makes me think if we need some kind of extension or decorator pattern that people can hook into?

For custom response.

[iBotPeaches]

@morloderex - Yeah my idea was optional Response classes that are based from the OpenAI one, which then parse custom fields to their provider. Everything else would fallback to existing parsing on OpenAI response class.

[morloderex]

@iBotPeaches do you want me to close this pr and open another one with the above in mind then?

[iBotPeaches]

@morloderex - Looking for more of a POC or a little pseudo code of how we expect this to work. Generally wondering on an elegant way that allows the library to return a different typed response depending on the provider.