import { Transform } from 'stream';
/**
 * A buffer helper that handles splitting UTF-8 characters across chunks.
 *
 * It accumulates incoming chunks (Buffer or string) and pushes complete
 * UTF-8 strings downstream. If a chunk ends in the middle of a multi-byte
 * sequence, the bytes are buffered until the next chunk completes it.
 *
 * This uses the utf8-chunk-buffer package implementation logic but wrapped
 * in a stream.Transform for easy piping.
 */
export declare class Utf8ChunkBuffer {
    private buffer;
    /**
     * Pushes a new chunk into the buffer.
     * Returns an array of complete UTF-8 strings found so far.
     */
    push(chunk: Buffer | string): string[];
    /**
     * Flushes any remaining bytes in the buffer as a string.
     */
    flush(): string[];
}
/**
 * Creates a Node.js Transform stream that ensures chunks emitted are complete UTF-8 strings.
 * This is useful for processing SSE streams where a chunk might split a multi-byte character.
 */
export declare function createUtf8TransformStream(): Transform;