import type { RunStats, StopReason, TranscriptMessage } from "../contracts/turn.js";
import type { ToolLoopState } from "./tool-loop.js";
/** A stopped invocation cannot be represented as a settled checkpoint. */
export declare class UnsettledLoopBoundaryError extends Error {
    constructor();
}
/** A continuation point after the loop has finished all step bookkeeping. */
export type LoopPosition = {
    kind: "ready";
} | {
    kind: "waiting";
    reason: "waiting_for_reply" | "resuming_later";
} | {
    kind: "finished";
    reason: "done" | "iteration_limit" | "aborted";
};
export interface LoopBoundary {
    position: LoopPosition;
    iterationsUsed: number;
    state: ToolLoopState;
    /** Cumulative since invocation start, not a delta since the previous boundary. */
    stats: RunStats;
}
/**
 * Persistence is awaited before more model/tool I/O. The state is borrowed:
 * capture a detached value before storing it. Throwing stops the driver.
 * Unsettled failures do not emit a boundary; reconcile effects before retrying.
 */
export interface LoopControl {
    iterationsUsed: number;
    onBoundary(boundary: LoopBoundary): Promise<"continue" | "checkpoint">;
}
export declare function positionForStop(reason: StopReason): LoopPosition;
/**
 * An ordered protocol check, shared by initial history and checkpoint restore.
 * A waiting checkpoint may leave precisely its suspended call unanswered.
 * History is not provider input: a trailing assistant needs no synthetic turn.
 */
export declare function assertCheckpointTranscript(messages: readonly TranscriptMessage[], openCall: string | null): void;