/**
 * Storage key builders for engine liveness heartbeats and the store-wide
 * lease-fenced single-writer lock.
 *
 * These are spread into `KEYS` in `interface.ts` rather than declared there, so
 * the liveness and lease keyspace can carry its full rationale without pushing
 * that file's documented line ceiling. Callers still reach them through `KEYS`,
 * which keeps one import contract for storage keys.
 *
 * @module storage/lease-keys
 */
/**
 * Engine liveness heartbeat keys plus the lease-fenced single-writer ownership
 * keys (`ownership: 'lease'`).
 *
 * Spread into `KEYS`; not intended to be imported directly by engine code.
 */
export declare const LEASE_KEYS: {
    /** Scan prefix for engine liveness heartbeats (best-effort second-instance detection). */
    readonly livenessPrefix: () => string;
    /** Per-engine liveness heartbeat key. One key per engine instance under the shared store. */
    readonly liveness: (instanceId: string) => string;
    /**
     * Scan/match prefix for the lease-fenced single-writer ownership keys
     * (`leaseEpoch` and `leaseHolder`). Reserved so a caller can recognize
     * lease-owned keys; the lease itself uses the two exact keys below, not a scan.
     */
    readonly leasePrefix: () => string;
    /**
     * The fencing epoch for lease-fenced ownership. A single shared key (one lease
     * per durable store) holding an 8-byte big-endian uint64. It changes ONLY on
     * ownership transfer (initial acquire or a steal after expiry), never on a
     * renewal — so a holder's cached epoch stays stable across heartbeats and can
     * be used unchanged as a `conditionalBatch` fencing condition. Kept separate
     * from `leaseHolder` precisely because `conditionalBatch` compares the whole
     * stored value as bytes: folding the churning holder fields into the fencing
     * token would make every renewal invalidate the fence.
     */
    readonly leaseEpoch: () => string;
    /**
     * The current lease holder record for lease-fenced ownership. A single shared
     * key (one lease per durable store) holding a JSON `{ holderId, expiresAt,
     * epoch }`. Renewed every heartbeat tick (the `expiresAt` field advances), so
     * its bytes churn and it must NOT be used as the fencing token — see
     * `leaseEpoch`.
     */
    readonly leaseHolder: () => string;
};