/**
 * Tool output preview generation.
 * Generates head/tail previews of large tool outputs for context-efficient LLM calls.
 * @module
 */
import type { ToolOutputPreviewOptions, ToolOutputPreviewResult } from "../types/index.js";
/** Default maximum preview size in bytes (50KB) */
export declare const DEFAULT_MAX_PREVIEW_BYTES: number;
/** Default maximum preview lines */
export declare const DEFAULT_MAX_PREVIEW_LINES = 2000;
/** Default head ratio (25% of preview budget) */
export declare const DEFAULT_HEAD_RATIO = 0.25;
/** Tool name referenced in truncation notices for on-demand full-output access */
export declare const RETRIEVE_CONTEXT_TOOL_NAME = "retrieve_context";
/** Default tail ratio (75% of preview budget) */
export declare const DEFAULT_TAIL_RATIO = 0.75;
/**
 * True when `generateToolOutputPreview` would actually shrink this output.
 *
 * Callers gate on this before paying for a preview. It exists so the gate and
 * the generator can never disagree: the budget is expressed in BYTES, and
 * testing it against `String.length` (UTF-16 code units) under-reports every
 * multibyte payload — CJK or emoji tool output would be judged small enough to
 * leave alone while the generator would have truncated it. Line count matters
 * for the same reason: a short-but-tall output exceeds `maxLines` alone.
 */
export declare function exceedsToolOutputPreviewBudget(output: string, options?: ToolOutputPreviewOptions): boolean;
/**
 * Generate a head/tail preview of a tool output string.
 * If the output is within limits, returns it unchanged with truncated: false.
 * If over limits, keeps the first 25% and last 75% with an omission notice.
 *
 * Industry pattern: 25/75 head/tail split. Head captures schema/headers/structure,
 * tail captures the most recent and typically most relevant data.
 */
export declare function generateToolOutputPreview(output: string, options?: ToolOutputPreviewOptions): ToolOutputPreviewResult;