/** A DynamoDB `LastEvaluatedKey` / `ExclusiveStartKey`. */
export type DynamoKey = Record<string, string>;
/**
 * The query a cursor must belong to. Every tenant-scoped entity shares the
 * partition key `TENANT#{id}` and is separated only by its sort-key prefix, so
 * the prefix is part of a cursor's identity, not a detail.
 */
export interface CursorQuery {
    /** Partition key value the query filters on. */
    pk: string;
    /** GSI being queried, if any. Its keys are named `{indexName}PK`/`SK`. */
    indexName?: string;
    /** `begins_with` prefix applied to the sort key, if any. */
    skPrefix?: string;
}
/**
 * Encode a `LastEvaluatedKey` into an opaque cursor token suitable for
 * returning as `next` and accepting back as `from`.
 */
export declare function encodeDynamoCursor(key: Record<string, unknown>): string;
/**
 * Decode an opaque cursor token into an `ExclusiveStartKey`, verifying it was
 * minted by the same query that is now presenting it.
 *
 * Returns `null` for anything unusable so a client-supplied `from` degrades to
 * "start from the beginning" rather than throwing — matching `decodeCursor()`
 * in adapter-interfaces.
 *
 * The query check is not decoration. DynamoDB rejects a key that disagrees with
 * the query's key conditions ("The provided starting key does not match the
 * range key predicate", "...is invalid"), so without this an attacker-supplied
 * or merely stale `from` turns into an unhandled ValidationException — a 500
 * driven by a query parameter. Note that this validation is a robustness
 * measure, not a tenant boundary: DynamoDB already refuses a cursor whose
 * partition key differs from the one being queried, so a foreign cursor could
 * never read another tenant's rows. It fails cleanly here instead of loudly
 * there.
 */
export declare function decodeDynamoCursor(token: string, query: CursorQuery): DynamoKey | null;