import type { TraceCallback, TraceLine } from "./types.js";
export type TraceSink = {
    writeLine(line: TraceLine): Promise<void> | void;
    close?(): Promise<void> | void;
    /** What this sink already holds from an earlier writer in the same run,
     *  so the new writer skips a second header and the chunks already
     *  there. A sink that keeps nothing leaves this out. */
    existing?(): Promise<{
        hasHeader: boolean;
        chunkHashes: Set<string>;
    }>;
};
export declare class CallbackSink implements TraceSink {
    private callback;
    private runId;
    constructor(runId: string, callback: TraceCallback);
    writeLine(line: TraceLine): Promise<void>;
}