export interface ModelPricing {
    inputPerMillion: number;
    outputPerMillion: number;
    cacheReadPerMillion?: number;
    cacheWritePerMillion?: number;
}
export declare class CostTracker {
    private pricing;
    private sessions;
    constructor(customPricing?: Record<string, ModelPricing>);
    /** 记录一次 LLM 调用的 token 用量并计算费用。 */
    record(sessionId: string, model: string, usage: {
        inputTokens: number;
        outputTokens: number;
        cacheReadTokens?: number;
        cacheWriteTokens?: number;
    }): void;
    /** 获取 session 的累计费用。 */
    getCost(sessionId: string): {
        inputTokens: number;
        outputTokens: number;
        cacheRead: number;
        cacheWrite: number;
        cost: number;
    };
    /** 获取所有 session 的总费用。 */
    getTotalCost(): {
        cost: number;
        sessions: number;
    };
    /** 设置/覆盖模型定价。 */
    setPricing(model: string, pricing: ModelPricing): void;
    private getPricing;
}