import type { ButtonHTMLAttributes } from 'react';
export type FoldButtonProps = Omit<ButtonHTMLAttributes<HTMLButtonElement>, 'children'>;
export type FoldRegion = {
    /** Unique identifier for this fold region */
    id: string;
    /** Inclusive start line number (1-based) */
    startLine: number;
    /** Inclusive end line number */
    endLine: number;
    /** Optional label for the collapsed summary. When omitted, auto-generated from line count. */
    label?: string;
    /** Whether the fold starts collapsed. Default: false */
    defaultCollapsed?: boolean;
    /** Props forwarded to the fold gutter toggle button. */
    toggleProps?: FoldButtonProps;
    /** Props forwarded to the collapsed fold summary button. */
    summaryProps?: FoldButtonProps;
};
export type DisplayItem = {
    type: 'line';
    index: number;
    lineNumber: number;
} | {
    type: 'fold-summary';
    fold: FoldRegion;
    lineCount: number;
};
export declare function getFoldSummaryLabel(fold: FoldRegion, lineCount: number): string;
/**
 * Validates fold regions and returns a clean, sorted list.
 * Dev: logs warnings for invalid folds. Prod: silently filters them out.
 */
export declare function validateFolds(folds: FoldRegion[], totalLines: number, startingLineNumber?: number): FoldRegion[];
export declare function buildDisplayItems(totalLines: number, folds: FoldRegion[], collapsedFolds: Set<string>, startingLineNumber: number): DisplayItem[];