export interface LineStamperOptions {
    now?: () => Date;
}
/** Returns a stateful function that prefixes `<ISO> ` at every true line start.
 *  A chunk that ends mid-line leaves the next chunk un-prefixed until its line
 *  actually starts, so a partial write is stamped exactly once. */
export declare function createLineStamper(opts?: LineStamperOptions): (chunk: string) => string;
/** Patch process.stdout/stderr `write` so every emitted line is stamped.
 *  Install before any logging runs. String and text-Buffer chunks are stamped;
 *  the arg-shuffle (chunk, encoding?, cb?) is preserved. */
export declare function installTimestampSink(stamp?: (chunk: string) => string): void;
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