Expose token usage information in API responses

[davidperezgar]

Currently, the wp-ai-client library does not provide a way to retrieve token usage information (e.g. prompt tokens, completion tokens, total tokens) from API responses.

Having access to token usage is important for:

• Monitoring and controlling costs
• Debugging and optimizing prompts
• Displaying usage metrics in WordPress dashboards or logs

Request

Please consider exposing token usage data returned by the underlying AI provider (when available) as part of the response object, or through an optional accessor/helper method.

For example:

• usage.prompt_tokens
• usage.completion_tokens
• usage.total_tokens

Expected behavior

• Token usage should be returned in a consistent, documented structure.
• If a provider does not support token usage, the field should be null or omitted gracefully.
• This change should be backward-compatible with existing implementations.

Additional context

Many AI SDKs (e.g. OpenAI, Azure OpenAI) already return token usage metadata, and exposing it in wp-ai-client would make the library more useful for production environments where cost awareness is critical.

[felixarntz]

@davidperezgar This should already be present. When you call generate_result, or one of the generate_*_result methods on Prompt_Builder, the result object returned has token usage data. See https://github.com/WordPress/php-ai-client/blob/trunk/src/Results/DTO/GenerativeAiResult.php#L138

So I believe this already works. Please reopen if you meant something different.

[davidperezgar]

Ok! I'll try and give you feedback! This is because we are going to implement it to Plugin Check Plugin!

[jeffpaul]

@davidperezgar check out the work in WordPress/ai#149 for UI around this

[davidperezgar]

Nice, thanks!