/** Why a run was aborted mid-flight. Extensible — user-initiated cancel will add to this.
 *  `lease_lost`: another worker reclaimed this run (our lease expired + a sweep re-dispatched it),
 *  so we must stop WITHOUT finalizing — the new owner owns the terminal write. */
export type AbortReason = "credit_exhausted" | "cancelled" | "lease_lost";
/** Thrown by WorkflowHost hooks once the run's AbortSignal has fired, so the program unwinds. A plain
 *  Error subclass (no AppError/model coupling) carrying the machine-readable reason. */
export declare class RunAbortedError extends Error {
    readonly reason: AbortReason;
    constructor(reason: AbortReason);
}
/** The reason an aborted signal carries (set via `controller.abort(new RunAbortedError(reason))`), or
 *  null when the signal isn't aborted / wasn't aborted with a RunAbortedError. */
export declare function abortReason(signal: AbortSignal): AbortReason | null;
/** Throw if the signal has already aborted — the guard every WorkflowHost hook calls at entry. Re-uses
 *  the signal's own RunAbortedError when present, so the reason propagates verbatim. */
export declare function throwIfAborted(signal: AbortSignal | undefined): void;