/**
 * @name session/redis-session-store
 * @description Redis-backed persistent session store for production SAP MCP deployments.
 *
 * Features:
 * - Persistent sessions across server restarts
 * - Multi-instance support (distributed deployments)
 * - Automatic TTL-based expiration
 * - Memory-safe (no local storage)
 *
 * @flow
 *   1. `createSessionStore` checks `SAP_MCP_USE_REDIS` env var and creates a `RedisSessionStore`
 *      or returns `null` for in-memory development mode.
 *   2. `RedisSessionStore` manages session CRUD with automatic TTL based on session expiry.
 *   3. A background cleanup interval removes expired sessions periodically.
 *
 * @env `SAP_MCP_USE_REDIS` — Set to `true` to enable Redis session storage.
 * @env `SAP_MCP_REDIS_URL` — Redis connection URL (default `redis://localhost:6379`).
 *
 * @module session/redis-session-store
 */
import { Redis } from 'ioredis';
import type { SapAgentSession } from '../../core/src/types.js';
/**
 * @name RedisSessionStoreConfig
 * @description Configuration for the Redis-backed session store.
 *
 * @property redisUrl          — Redis connection URL.
 * @property keyPrefix         — Optional prefix for session keys in Redis (default `sap-mcp:session:`).
 * @property cleanupIntervalMs — Optional cleanup interval in milliseconds (default 3600000 / 1 hour).
 *
 * @usedBy `RedisSessionStore`, `createSessionStore`
 */
export interface RedisSessionStoreConfig {
    redisUrl: string;
    keyPrefix?: string;
    cleanupIntervalMs?: number;
}
/**
 * @name RedisSessionStore
 * @description Persistent session store backed by Redis with TTL-based expiration and periodic cleanup.
 *
 * @method connect   — Establish the Redis connection.
 * @method set        — Store a session with TTL derived from its expiry.
 * @method get        — Retrieve a session by id.
 * @method delete     — Remove a session by id.
 * @method getAll     — Retrieve all active sessions (for debugging/admin).
 * @method getCount   — Get the total number of stored sessions.
 * @method cleanup    — Manually remove expired sessions.
 * @method getStats   — Get session statistics (total, active, expired).
 * @method shutdown   — Gracefully close the Redis connection and cleanup interval.
 * @method getClient  — Get the raw Redis client for advanced operations.
 *
 * @usedBy `createSessionStore`, distributed SAP MCP deployments.
 */
export declare class RedisSessionStore {
    private redis;
    private keyPrefix;
    private cleanupInterval?;
    private isShuttingDown;
    /**
     * @name RedisSessionStore.constructor
     * @description Creates a new Redis session store with merged config and starts the cleanup interval.
     *
     * @param config — Optional configuration overriding defaults.
     */
    constructor(config?: RedisSessionStoreConfig);
    /**
     * @name RedisSessionStore.connect
     * @description Connects to the Redis server.
     *
     * @usedBy `createSessionStore`.
     */
    connect(): Promise<void>;
    /**
     * @name RedisSessionStore.set
     * @description Stores a session in Redis with a TTL derived from its expiry timestamp.
     *
     * @param sessionId — Unique session identifier.
     * @param session   — The agent session to store.
     */
    set(sessionId: string, session: SapAgentSession): Promise<void>;
    /**
     * @name RedisSessionStore.get
     * @description Retrieves a session by id from Redis.
     *
     * @param sessionId — Unique session identifier.
     * @returns The session if found and parseable, `null` otherwise.
     */
    get(sessionId: string): Promise<SapAgentSession | null>;
    /**
     * @name RedisSessionStore.delete
     * @description Deletes a session from Redis by id.
     *
     * @param sessionId — Unique session identifier.
     * @returns `true` if the session was deleted, `false` if it did not exist.
     */
    delete(sessionId: string): Promise<boolean>;
    /**
     * @name RedisSessionStore.getAll
     * @description Retrieves all active sessions from Redis (for debugging/admin).
     *
     * @returns Array of all stored agent sessions.
     */
    /**
     * @name RedisSessionStore.scanKeys
     * @description Iterates session keys with `SCAN` instead of `KEYS` to avoid
     *   blocking Redis on large key spaces. `KEYS` is O(N) and can stall a
     *   production instance; `SCAN` is incremental and safe under load.
     *
     * @returns The full list of session keys matching the store prefix.
     */
    private scanKeys;
    getAll(): Promise<SapAgentSession[]>;
    /**
     * @name RedisSessionStore.getCount
     * @description Returns the total number of stored sessions.
     *
     * @returns Count of session keys in Redis.
     */
    getCount(): Promise<number>;
    /**
     * @name RedisSessionStore.cleanup
     * @description Manually removes expired sessions from Redis.
     */
    cleanup(): Promise<void>;
    /**
     * @name RedisSessionStore.getStats
     * @description Returns session statistics (total, active, expired).
     *
     * @returns Object with `totalSessions`, `activeSessions`, and `expiredSessions` counts.
     */
    getStats(): Promise<{
        totalSessions: number;
        activeSessions: number;
        expiredSessions: number;
    }>;
    /**
     * @name RedisSessionStore.shutdown
     * @description Gracefully shuts down the Redis connection and clears the cleanup interval.
     */
    shutdown(): Promise<void>;
    /**
     * @name RedisSessionStore.getClient
     * @description Returns the raw Redis client instance for advanced operations.
     *
     * @returns The underlying `ioredis` Redis instance.
     */
    getClient(): InstanceType<typeof Redis>;
    /** @description Builds the full Redis key from the prefix and session id. */
    private getKey;
    /** @description Starts the periodic cleanup interval for expired sessions. */
    private startCleanup;
}
/**
 * @name createSessionStore
 * @description Creates a session store based on environment configuration.
 *
 * Uses Redis in production (when `SAP_MCP_USE_REDIS=true`) and in-memory
 * storage in development (returns `null`).
 *
 * @returns A connected `RedisSessionStore` if Redis is enabled, `null` otherwise.
 * @throws If Redis connection fails after retries.
 *
 * @env `SAP_MCP_USE_REDIS` — Set to `true` to enable Redis.
 * @env `SAP_MCP_REDIS_URL` — Redis connection URL (default `redis://localhost:6379`).
 *
 * @usedBy Server initialization in the SAP MCP runtime.
 */
export declare function createSessionStore(): Promise<RedisSessionStore | null>;
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