import type { AgentSession } from "../../core/agent-session.js";
import type { SessionStats } from "../../core/agent-session-types.js";
import type { RpcClient } from "../rpc/rpc-client.ts";
/** The engine's latest session stats for an isolated host session, or undefined before the first reply. */
export declare function getEngineSessionStats(session: AgentSession): SessionStats | undefined;
/**
 * Caches the engine's `get_session_stats` reply for the host footer. One request
 * is in flight at a time; triggers that arrive meanwhile share one trailing
 * request. `reset()` drops the cache and discards every reply already in flight.
 */
export declare class EngineSessionStats {
    private stats;
    private epoch;
    private inFlight;
    private refreshQueued;
    private readonly listeners;
    private readonly client;
    constructor(client: Pick<RpcClient, "requestInternal" | "getGeneration">);
    get current(): SessionStats | undefined;
    track(session: AgentSession): void;
    onChange(listener: () => void): () => void;
    reset(): void;
    refresh(): void;
    private request;
}
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