/**
 * Parses OpenAI usage data into a standardized structure.
 * Supports Chat Completions API (prompt_tokens/completion_tokens) and
 * Responses API (input_tokens/output_tokens) plus detailed breakdowns
 * (reasoning_tokens, cached_tokens) for o1/o3/o4 models.
 */
export interface ParsedUsage {
    inputTokens: number;
    outputTokens: number;
    totalTokens: number | null;
    reasoningTokens: number;
    cachedTokens: number;
    rejectedPredictionTokens: number;
}
/**
 * Safely parse usage data from OpenAI responses.
 * Handles both legacy (prompt_tokens/completion_tokens) and modern
 * (input_tokens/output_tokens) formats, plus input_tokens_details and
 * output_tokens_details for reasoning and cached tokens.
 */
export declare function parseUsage(usageData: unknown): ParsedUsage;