/**
 * Persistence helpers for the vault-level policy document
 * (`_meta/policy`). Mirrors the bypass-AES pattern used by
 * `_meta/handle` — the policy document is plain JSON, the envelope's
 * `_iv` field is left empty.
 *
 * @see https://github.com/vLannaAi/noy-db-docs/blob/main/content/docs/services/session-tiers.md → Storage location
 *
 * @module
 */
import type { NoydbStore, VaultPolicy } from '../../kernel/types.js';
/** Reserved collection name for vault-level metadata documents. */
export declare const META_COLLECTION = "_meta";
/** Reserved id for the vault-level policy document. */
export declare const POLICY_RECORD_ID = "policy";
/**
 * Read the vault-level policy from `_meta/policy`. Returns `undefined`
 * when no policy has been persisted (fresh vault, or a vault written
 * before the policy module landed). The caller falls back to the
 * default preset.
 *
 * Tolerates corrupted documents the same way `_meta/handle` does: a
 * JSON parse failure surfaces as `undefined`, not a thrown error, so
 * a bad write never permanently locks a vault.
 */
export declare function loadVaultPolicy(store: NoydbStore, vault: string): Promise<VaultPolicy | undefined>;
/**
 * Persist the vault-level policy at `_meta/policy`. Idempotent — call
 * once at vault creation and again on `db.updatePolicy()` invocations.
 */
export declare function saveVaultPolicy(store: NoydbStore, vault: string, policy: VaultPolicy): Promise<void>;