import type { FinishReason, StreamChunk } from '../../types';
import type { TokenUsage } from '../../types/sdk/agent';
export declare class StreamWriterGuard {
    private readonly writer;
    private closed;
    constructor(writer: WritableStreamDefaultWriter<StreamChunk>);
    get isClosed(): boolean;
    write(chunk: StreamChunk): Promise<void>;
    close(): Promise<void>;
    fail(error: unknown, finishReason?: FinishReason, finish?: {
        usage?: TokenUsage;
        model?: string;
    }): Promise<void>;
}