/**
 * DefaultMailbox — append-only JSONL inter-agent mailbox (per-session).
 *
 * Stores messages under `<sessionDir>/_mailbox.jsonl`. Every send appends
 * one line. Query reads and filters all lines. Ack rewrites changed
 * messages in-place via atomic write.
 *
 * For cross-session communication, use GlobalMailbox instead.
 *
 * @module DefaultMailbox
 */
import type { Logger } from '../types/logger.js';
import type { AgentHeartbeatInput, AgentRegistrationInput, AutoCompactOptions, AutoCompactResult, ClientHeartbeatInput, ClientRegistrationInput, ClientStatus, Mailbox, MailboxAckBatchInput, MailboxAckInput, MailboxAgentStatus, MailboxMessage, MailboxQuery, MailboxSendInput, PurgeOptions, PurgeResult } from './mailbox-types.js';
export declare class DefaultMailbox implements Mailbox {
    private readonly filePath;
    private _messageCache;
    private _messageCacheMtime;
    private _messageCacheSize;
    /** True when the cache is only the newest MESSAGE_CACHE_MAX_ENTRIES records. */
    private _messageCacheTruncated;
    /** Primary index: recipient → Set of messages (points into _messageCache). */
    private _byTo;
    /** Secondary index: sender → Set of messages (points into _messageCache). */
    private _byFrom;
    /** Counts malformed JSONL lines skipped during parsing for observability. */
    private _corruptionCount;
    private readonly logger;
    constructor(sessionDir: string, opts?: {
        logger?: Logger | undefined;
    });
    get mailboxPath(): string;
    /** Returns the count of malformed JSONL lines encountered during reads. */
    get corruptionCount(): number;
    send(input: MailboxSendInput): Promise<MailboxMessage>;
    query(q: MailboxQuery): Promise<MailboxMessage[]>;
    ack(input: MailboxAckInput): Promise<MailboxMessage | null>;
    softDelete(_mailId: string, _by: string): Promise<MailboxMessage | null>;
    restore(_mailId: string): Promise<MailboxMessage | null>;
    ackMany(input: MailboxAckBatchInput): Promise<MailboxMessage[]>;
    getAgentStatuses(): Promise<MailboxAgentStatus[]>;
    getOnlineAgents(): Promise<MailboxAgentStatus[]>;
    registerAgent(_input: AgentRegistrationInput): Promise<void>;
    deregisterAgent(_agentId: string): Promise<void>;
    heartbeat(_input: AgentHeartbeatInput): Promise<void>;
    unreadCount(forAgentId: string, sessionId?: string): Promise<number>;
    close(): Promise<void>;
    clearAll(): Promise<void>;
    purgeStale(opts?: PurgeOptions): Promise<PurgeResult>;
    autoCompact(_opts?: AutoCompactOptions): Promise<AutoCompactResult>;
    startAutoCompactTimer(_opts?: AutoCompactOptions): () => void;
    registerClient(_input: ClientRegistrationInput): Promise<void>;
    clientHeartbeat(_input: ClientHeartbeatInput): Promise<void>;
    deregisterClient(_clientId: string): Promise<void>;
    getClientStatuses(): Promise<ClientStatus[]>;
    purgeClients(): Promise<number>;
    private _readAll;
    /**
     * Read only newly-appended bytes from the file and append them to the
     * in-memory cache, avoiding a full re-read when the file only grew.
     *
     * Guards against a half-written tail: when the tail doesn't end with
     * LINE_SEPARATOR, another process may be mid-append. Parsing a partial
     * JSON line would throw (caught below), but worse: the NEXT incremental
     * read would skip that same line because the size tracker already advanced.
     */
    private _readNewMessagesOnly;
    private _appendIncrementalLines;
    private _parseLine;
    /** Parse a JSONL string into MailboxMessage[], including migration. */
    private _parseLines;
    /**
     * Stat the mailbox file under the assumption that we are holding the
     * file lock, and that a write to the file has just completed. Returns
     * the (mtimeMs, size) pair, or (-1, -1) if the file does not exist
     * (e.g. ackMany/purgeStale on a session that has never sent a message).
     */
    private _statUnderLockOrAbsent;
    private _readAllCached;
    private _setMessageCache;
    private _pushToCache;
    /** Rebuild both indexes from a full message list. */
    private _buildIndexes;
    /** Add a single message to both indexes. */
    private _indexMsg;
    /** Remove an evicted message from both indexes without rebuilding them. */
    private _unindexMsg;
}
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