feat: add cost details to chat completion usage

[akicool]

• Extend ChatGenerationTokenUsage with cost, isByok, and costDetails fields to expose pricing information returned by the OpenRouter API. Matches the actual API response shape (upstream_inference_prompt_cost / upstream_inference_completions_cost).

[the-dream-machine]

Is it possible to extend this to return costs for the embedding endpoints as well?

[akicool]

Is it possible to extend this to return costs for the embedding endpoints as well?

Yep, it make sense btw, I'll try to add this

[akicool]

Is it possible to extend this to return costs for the embedding endpoints as well?

As far as I understand, we can't get information about costs_details in the response data, but we do have a cost field in the response from the embeddings endpoint.

[the-dream-machine]

As far as I understand, we can't get information about costs_details in the response data, but we do have a cost field in the response from the embeddings endpoint.

Yes, this is true. The cost_details contains information about the upstream provider cost for BYOK. I don't think BYOK is supported yet for embedding providers.