/**
 * RenderBuffer batches ANSI operations to minimize syscalls.
 *
 * Node.js stdout.write() is buffered, but batching multiple operations
 * into a single write is still more efficient than multiple small writes.
 */
export declare class RenderBuffer {
    private buffer;
    private readonly stdout;
    constructor(stdout?: NodeJS.WriteStream);
    /**
     * Append data to the buffer (does not write immediately)
     */
    write(data: string): void;
    /**
     * Flush all buffered data to stdout in a single write.
     * This minimizes syscalls and improves performance.
     *
     * Note: process.stdout.write() is synchronous by default (blocks until written),
     * so we don't need writeSync. For tests, we can mock stdout.write.
     */
    flush(): void;
    /**
     * Clear the buffer without writing
     */
    clear(): void;
    /**
     * Get current buffer size (for debugging)
     */
    get size(): number;
}
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