import type { SinkWriter } from './spi/token-stream-sink.js';
/**
 * Wraps the turn's stream writer to note when the first `text` frame goes out: the time to first
 * token as the reader sees it (a frame an output gate held back counts when it was released). The
 * clock is this process's, so a run resumed elsewhere measures from its resume.
 */
export declare function observeFirstText(writer: SinkWriter, now?: () => number): {
    writer: SinkWriter;
    firstTextAt: () => number | undefined;
};
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