import type { UsageStats } from '@mastra/core/observability';
/**
 * BraintrustUsageMetrics
 *
 * Canonical metric keys expected by Braintrust for LLM usage accounting.
 */
export interface BraintrustUsageMetrics {
    prompt_tokens?: number;
    completion_tokens?: number;
    tokens?: number;
    completion_reasoning_tokens?: number;
    prompt_cached_tokens?: number;
    prompt_cache_creation_tokens?: number;
}
/**
 * Formats UsageStats to Braintrust's expected metric format.
 */
export declare function formatUsageMetrics(usage?: UsageStats): BraintrustUsageMetrics;
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