/** Provider-neutral token counters persisted by the AI invocation ledger. */
export interface NormalizedAiUsage {
    inputTokens: number;
    outputTokens: number;
    cachedInputTokens: number;
    cacheWriteTokens: number;
    reasoningTokens: number;
    toolTokens: number;
}
export type AiUsageChunk = Partial<NormalizedAiUsage>;
export type AiUsageAggregationMode = 'delta' | 'cumulative';
/**
 * Aggregates streaming provider usage without guessing whether chunks are
 * deltas or cumulative snapshots. The caller must select the provider's
 * documented mode; cumulative counters fail loudly if they regress.
 */
export declare class AiUsageAccumulator {
    readonly mode: AiUsageAggregationMode;
    private total;
    constructor(mode: AiUsageAggregationMode);
    observe(chunk: AiUsageChunk): NormalizedAiUsage;
    value(): NormalizedAiUsage;
}