/**
 * Per-MCP-↔-extension session state on the server side.
 *
 * Holds the derived AES-256-GCM session key and per-direction sequence
 * counters. Outbound seq is monotonic (1, 2, 3, …). Inbound seq must be
 * strictly increasing — anything ≤ the last accepted seq is treated as
 * replay and rejected.
 *
 * Frames are not stored here — this is just the lightweight per-session
 * gate state.
 */
export declare class SessionState {
    readonly sessionKey: Uint8Array;
    private outboundSeq;
    private lastInboundSeq;
    constructor(sessionKey: Uint8Array);
    nextOutboundSeq(): number;
    acceptInboundSeq(seq: number): boolean;
}