/**
 * Session state machine. Models the lifecycle of a single harness session.
 *
 * Pattern adapted from t3code's `OrchestrationSession`. We use a tiny
 * discriminated-union reducer rather than XState — fewer than 100 lines,
 * zero deps, fully type-checked transitions.
 */
import type { SessionState } from "../contracts/provider-runtime.js";
export type SessionEvent = {
    type: "start";
} | {
    type: "ready";
} | {
    type: "turn.begin";
} | {
    type: "turn.end";
} | {
    type: "interrupt";
} | {
    type: "resume";
} | {
    type: "shutdown";
} | {
    type: "fail";
    reason: string;
};
export interface SessionTransition {
    readonly from: SessionState;
    readonly to: SessionState;
    readonly event: SessionEvent;
    readonly at: string;
}
export declare function nextSessionState(current: SessionState, event: SessionEvent): SessionState;
export declare function canTransition(current: SessionState, event: SessionEvent): boolean;
export declare function isTerminal(state: SessionState): boolean;
export declare class SessionMachine {
    private state;
    private readonly history;
    constructor(initial?: SessionState);
    current(): SessionState;
    send(event: SessionEvent): SessionTransition;
    log(): readonly SessionTransition[];
}