/**
 * Represents token usage metrics from an AI model.
 * Includes support for reasoning tokens (o1/o3 models) and per-turn usage calculation.
 */
export declare class AiUsage {
    promptTokens: number;
    completionTokens: number;
    totalTokens: number;
    cachedTokens: number;
    /**
     * Reasoning tokens used by models like o1/o3.
     * These tokens represent the model's internal reasoning process.
     */
    reasoningTokens: number;
    /**
     * Calculate the usage difference between the current turn and the previous cumulative usage.
     * This is used to extract per-turn metrics from cumulative totals.
     */
    static getUsageDifference(current: AiUsage, previous: AiUsage): AiUsage;
}
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