/**
 * IndexedDB-backed storage for AG Grid column state.
 *
 * Column states are keyed by a grid identifier + width bucket so that
 * different container widths (monitor switch, sidebar collapse) each
 * get their own persisted layout.
 *
 * Each entry stores `{ state, lastAccessedAt }`. The timestamp is updated
 * on every read and write, enabling time-based cleanup of stale entries.
 */
export declare function loadColumnState(gridKey: string, bucket: number): Promise<unknown[] | null>;
export declare function saveColumnState(gridKey: string, bucket: number, state: unknown[]): Promise<void>;
export declare function getSavedBuckets(gridKey: string): Promise<number[]>;
export declare function deleteColumnState(gridKey: string, bucket: number): Promise<void>;
export declare function deleteAllColumnStates(gridKey: string): Promise<void>;
/**
 * Remove column state entries that haven't been read or written
 * within the specified number of days.
 *
 * Call once at application startup to prevent unbounded growth.
 *
 * @param maxAgeDays - Maximum age in days. Entries older than this are deleted.
 * @returns Number of deleted entries.
 *
 * @example
 * ```ts
 * // main.ts — clean up entries older than 6 months
 * import { cleanupColumnStates } from '@cocoar/vue-data-grid';
 * cleanupColumnStates(180);
 * ```
 */
export declare function cleanupColumnStates(maxAgeDays: number): Promise<number>;
export declare function toBucket(width: number, bucketSize: number): number;
export declare function findNearestBucket(target: number, savedBuckets: number[]): number | null;
export type ColumnStateListener = (state: unknown[], senderId: number) => void;
/** Generate a unique instance ID for a grid builder */
export declare function createPersistenceInstanceId(): number;
/** Subscribe to column state changes from other grids with the same key */
export declare function onColumnStateChanged(gridKey: string, instanceId: number, listener: ColumnStateListener): () => void;
/** Notify other grids with the same key about a column state change */
export declare function broadcastColumnState(gridKey: string, senderId: number, state: unknown[]): void;
//# sourceMappingURL=column-state-storage.d.ts.map