/**
 * @license
 * Copyright 2026 Steven Roussey <sroussey@gmail.com>
 * SPDX-License-Identifier: Apache-2.0
 */
import type { Usage } from "@workglow/ai";
/**
 * Collects Anthropic's token accounting off a raw Messages event stream.
 *
 * Anthropic splits usage across two frames: `message_start` carries the prompt
 * side (`input_tokens`, `cache_read_input_tokens`, `cache_creation_input_tokens`)
 * while `message_delta` carries the running completion side. Both report
 * **cumulative** figures, so each field is last-reported-wins rather than summed
 * — the collector never adds counts of its own, it only keeps the newest number
 * the SDK stated.
 *
 * `message_delta.usage` nulls the prompt-side fields on older API versions; a
 * `null` is "not restated here", so it leaves the earlier value intact rather
 * than erasing it. A field no frame ever reported stays `undefined`.
 */
export interface IAnthropicUsageCollector {
    /** Feed one raw SDK stream event. Non-usage events are ignored. */
    readonly observe: (event: unknown) => void;
    /** The collected usage, or `undefined` when the stream reported none. */
    readonly result: () => Usage | undefined;
}
/**
 * Map one Anthropic usage payload into {@link Usage}.
 *
 * Anthropic already reports the three prompt buckets disjointly — `input_tokens`
 * excludes both cache reads and cache writes — so nothing is subtracted here.
 * Used directly for non-streaming calls (a checkpoint warm-up) and per frame by
 * {@link createAnthropicUsageCollector} for streams.
 */
export declare function mapAnthropicUsage(raw: unknown): Usage | undefined;
export declare function createAnthropicUsageCollector(): IAnthropicUsageCollector;