import type { StreamChunk } from '../types.js';
/**
 * Cross-event state for Anthropic streaming. The protocol splits prompt and
 * completion token counts across two distinct events; we track the prompt
 * count from `message_start` so the later `message_delta` → `finish` chunk can
 * emit a complete usage object.
 */
export interface AnthropicStreamState {
    lastPromptTokens: number;
}
export declare function newAnthropicStreamState(): AnthropicStreamState;
/**
 * Map a single decoded Anthropic stream event to zero-or-more `StreamChunk`s.
 * Shared by the native Anthropic adapter and Bedrock, which wraps Anthropic's
 * events 1:1 in `chunk.bytes`.
 *
 * `state` is mutated across calls: `message_start` captures `lastPromptTokens`,
 * the subsequent `message_delta` reads it back. Without this, the `finish`
 * chunk reports `promptTokens: 0`, the agent loop's last-wins aggregation
 * overwrites the correct earlier value, and consumers (billing, withBudget)
 * silently undercharge for streamed calls.
 */
export declare function mapAnthropicStreamEvent(event: Record<string, any>, state: AnthropicStreamState): Generator<StreamChunk>;
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