type Env = Record<string, string | undefined>;
export declare function readsPath(env?: Env): string;
/** Record what a read returned. Silent best-effort: a stamp that cannot be
 *  stored must not fail the read that produced it. */
export declare function recordRead(parts: {
    host: string;
    org: string;
    kb: string;
    document: string;
    block: string;
    readAt: string | null | undefined;
}, env?: Env, now?: () => number): void;
/** The stamp a guarded write should carry, or null when nothing was read. */
export declare function lastRead(parts: {
    host: string;
    org: string;
    kb: string;
    document: string;
    block: string;
}, env?: Env): string | null;
export {};