import type { Message } from '../../types/messages.js';
import type { AgentToolCall } from '../create-agent.js';
/**
 * What the middleware share. Every count here is read from the transcript rather than kept in
 * memory, so it survives a restart, a resumed approval, and a second process, and two threads never
 * share one.
 */
/**
 * The current turn: every message after the latest user message. One `invoke()` is one turn; a run
 * that resumes after an approval is the same turn.
 */
export declare function turnOf(messages: readonly Message[]): readonly Message[];
/** Model calls made in the current turn: its assistant messages. */
export declare function modelCallsInTurn(messages: readonly Message[]): number;
/**
 * Where a call sits among the current turn's calls to the same tool, from 1. Calls the model made in
 * parallel are ordered as the model listed them, so the position never depends on which finished
 * first.
 */
export declare function callPosition(messages: readonly Message[], call: Pick<AgentToolCall, 'id' | 'name'>): number;
/** A message's text: the string, or its text parts joined. */
export declare function textOf(content: Message['content']): string;
/** How long to wait between attempts. */
export interface RetryBackoff {
    /** The wait before the second attempt, in milliseconds. Defaults to 500. */
    initialMs?: number;
    /** The longest wait, in milliseconds. Defaults to 10,000. */
    maxMs?: number;
    /** What each wait is multiplied by. Defaults to 2. */
    factor?: number;
    /** Spreads each wait between half and all of it, so runs that failed together retry apart. Defaults to true. */
    jitter?: boolean;
}
/** The wait before attempt `attempt + 1`, after `attempt` failed. */
export declare function backoffDelay(attempt: number, backoff?: RetryBackoff): number;
/** Waits, or rejects with the signal's reason as soon as it aborts. */
export declare function sleep(ms: number, signal?: AbortSignal): Promise<void>;
/** True for a cancellation: never worth retrying or falling back from. */
export declare function isCancellation(error: unknown, signal?: AbortSignal): boolean;
/** A short, stable hash of a text: cyrb53 as 8 hex digits. Not a security boundary. */
export declare function shortHash(text: string): string;