Missing cached_tokens_details property in RealtimeResponseUsage.InputTokenDetails

[ericleib]

Confirm this is a Node library issue and not an underlying OpenAI API issue

• This is an issue with the Node library

Describe the bug

The OpenAI.Beta.Realtime.RealtimeResponseUsage.InputTokenDetails type has 3 properties:

• text_tokens
• audio_tokens
• cached_tokens

But in fact, the API returns a fourth property (which is indeed very important):

• cached_tokens_details, an object with 2 properties text_tokens and audio_tokens.

This information is needed to accurately evaluate the cost of generating the response.

To Reproduce

1. Open a websocket connection with the realtime API at wss://api.openai.com/v1/realtime.
2. Send a session.update and a response.create event.
3. Inspect the content of the response.done event sent by the server, in particular response.usage.input_token_details

Code snippets

OS

Windows

Node version

Node v20

Library version

openai 5.11.0