/**
 * Cost / token accumulation helpers for RunHandleImpl.
 *
 * Pure functions extracted so the main run-handle implementation stays
 * focused on orchestration (state machine, iterators, thenable). No behavior
 * change — these are the exact mutations previously inlined in
 * RunHandleImpl._accumulate and RunHandleImpl._buildResult.
 */
import type { CostEvent, TokenUsageEvent } from './events.js';
import type { TokenUsageSummary } from './run-handle.js';
export interface CostAccumulator {
    totalUsd: number;
    inputTokens: number;
    outputTokens: number;
    thinkingTokens: number;
    cachedTokens: number;
    cacheCreationTokens: number;
    cacheReadTokens: number;
}
export interface TokenAccumulator {
    inputTokens: number;
    outputTokens: number;
    thinkingTokens: number;
    cachedTokens: number;
    cacheCreationTokens: number;
    cacheReadTokens: number;
}
/** Fold a `token_usage` event into the running accumulator. */
export declare function accumulateTokenUsage(acc: TokenAccumulator, event: TokenUsageEvent): void;
/**
 * Fold a `cost` event into the running accumulator. Returns the new
 * accumulator (which may be a freshly allocated record on the first call).
 */
export declare function accumulateCost(current: CostAccumulator | null, event: CostEvent): CostAccumulator;
/** Build the token usage summary, or null when no usage was seen. */
export declare function buildTokenUsageSummary(acc: TokenAccumulator): TokenUsageSummary | null;