export interface TruncatedText {
    readonly text: string;
    readonly truncated: boolean;
    readonly originalLength: number;
}
/**
 * Longest single log line body any tool returns, in prose or structuredContent. Window budgets
 * keep at least one entry, so without this a single enormous line would be that entry.
 */
export declare const MAX_LOG_LINE_CHARS = 2000;
export declare function truncateText(value: string, limit: number): TruncatedText;
export interface WindowResult<T> {
    readonly kept: T[];
    readonly dropped: number;
}
/** Keep as many trailing entries as fit in `charBudget`; log tails are where failures live. */
export declare function keepTailWithinBudget<T>(entries: readonly T[], charBudget: number, sizeOf: (entry: T) => number): WindowResult<T>;
/** Keep as many leading entries as fit in `charBudget`; used when paging forward. */
export declare function keepHeadWithinBudget<T>(entries: readonly T[], charBudget: number, sizeOf: (entry: T) => number): WindowResult<T>;
/**
 * Accumulates the human-readable summary text for a tool result and stops accepting lines once
 * the character budget is spent, so no tool can return unbounded prose to the model.
 *
 * Overflow is terminal: the line that overflows is cut down to whatever room remains (or dropped
 * when that room is too small to be useful) and every later push is refused, so the rendered
 * text is always a prefix of what was pushed rather than a prefix with holes in it.
 */
export declare class TextBudget {
    private readonly limit;
    private readonly lines;
    private used;
    private overflowed;
    constructor(limit: number);
    push(...lines: string[]): this;
    get didOverflow(): boolean;
    render(): string;
}
export declare function formatCount(count: number, singular: string, plural?: string): string;
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