import type { SessionStatus } from "./types.js";
import { PreconditionError } from "./errors.js";
/**
 * Legal session state transitions, encoding the documented lifecycle diagram.
 *
 * Extended from the docs-site diagram with pragmatic additions:
 * pending and suspended sessions must be killable (→ stopped).
 */
export declare const SESSION_TRANSITIONS: ReadonlyMap<SessionStatus, ReadonlySet<SessionStatus>>;
/** Whether transitioning from `from` to `to` is legal per the session lifecycle. */
export declare function isValidTransition(from: SessionStatus, to: SessionStatus): boolean;
/** Thrown when code attempts an illegal session state transition. */
export declare class InvalidSessionTransitionError extends PreconditionError {
    readonly from: SessionStatus;
    readonly to: SessionStatus;
    constructor(from: SessionStatus, to: SessionStatus);
}
/**
 * Assert that transitioning from `from` to `to` is legal.
 * Same-state transitions are no-ops. Illegal transitions throw
 * {@link InvalidSessionTransitionError}.
 */
export declare function assertTransition(from: SessionStatus, to: SessionStatus): void;
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