/**
 * Rehydration Helpers — shared utilities for restoring in-memory state
 * from persisted storage during service initialization.
 *
 * Used by ConversationService, GroupService, ChannelService, and ServerService
 * to reconstruct key epoch states and group/sort messages after a restart.
 *
 * Requirements: 6.1, 6.2, 6.3, 2.5, 3.4, 4.6
 */
import { ICommunicationMessage } from '../../interfaces/communication';
import { IKeyEpochState } from './keyEpochManager';
/**
 * Reconstruct an IKeyEpochState<string> from a persisted encryptedSharedKey map.
 *
 * Sets `currentEpoch` to the highest epoch number present, populates
 * `encryptedEpochKeys` with the input map, and leaves `epochKeys` empty
 * (raw symmetric keys are never persisted).
 *
 * Returns `undefined` and logs a warning if the input is null, undefined,
 * or not a Map instance.
 *
 * Requirements: 6.1, 6.2, 6.3
 */
export declare function reconstructKeyEpochState(encryptedSharedKey: Map<number, Map<string, string>> | null | undefined): IKeyEpochState<string> | undefined;
/**
 * Group an array of messages by `contextId` and sort each group
 * by `createdAt` in ascending (chronological) order.
 *
 * Requirements: 2.5, 3.4, 4.6
 */
export declare function groupAndSortMessages(messages: ICommunicationMessage[]): Map<string, ICommunicationMessage[]>;
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