Function buildChatCompletionsUsage

packages/openai-base/src/usage.ts:15–75

(
  usage: OpenAI.Chat.Completions.ChatCompletion['usage'] | undefined | null,
)

 * usage object, so callers omit the field rather than fabricating zeroed totals.
 */
export function buildChatCompletionsUsage(
  usage: OpenAI.Chat.Completions.ChatCompletion['usage'] | undefined | null,
): TokenUsage | undefined {
  if (!usage) return undefined

  const result = buildBaseUsage({
    promptTokens: usage.prompt_tokens || 0,
    completionTokens: usage.completion_tokens || 0,
    totalTokens: usage.total_tokens || 0,
  })

  const completionDetails = usage.completion_tokens_details
  const completionTokensDetails = {
    ...(completionDetails?.reasoning_tokens
      ? { reasoningTokens: completionDetails.reasoning_tokens }
      : {}),
    ...(completionDetails?.audio_tokens
      ? { audioTokens: completionDetails.audio_tokens }
      : {}),
  }

  const promptDetails = usage.prompt_tokens_details
  const promptTokensDetails = {
    ...(promptDetails?.cached_tokens
      ? { cachedTokens: promptDetails.cached_tokens }
      : {}),
    ...(promptDetails?.audio_tokens
      ? { audioTokens: promptDetails.audio_tokens }
      : {}),
  }

  if (Object.keys(completionTokensDetails).length > 0) {
    result.completionTokensDetails = completionTokensDetails
  }
  if (Object.keys(promptTokensDetails).length > 0) {
    result.promptTokensDetails = promptTokensDetails
  }

  // Predicted Outputs accepted/rejected counts have no canonical TokenUsage
  // slot but are still billed (rejected tokens included), so surface them under
  // providerUsageDetails — matching how the OpenRouter adapter exposes them.
  const providerUsageDetails = {
    ...(completionDetails?.accepted_prediction_tokens
      ? {
          acceptedPredictionTokens:
            completionDetails.accepted_prediction_tokens,
        }
      : {}),
    ...(completionDetails?.rejected_prediction_tokens
      ? {
          rejectedPredictionTokens:
            completionDetails.rejected_prediction_tokens,
        }
      : {}),
  }
  if (Object.keys(providerUsageDetails).length > 0) {
    result.providerUsageDetails = providerUsageDetails
  }