/**
 * TokensaveMcpClient — long-lived `tokensave serve` subprocess over JSON-RPC 2.0.
 *
 * Responsibilities:
 *   - Spawn and own exactly ONE `tokensave serve` child per instance.
 *   - Multiplex concurrent call() invocations via a numeric-id PendingMap.
 *   - Restart on crash with 3-per-60s circuit breaker (health → 'broken' when
 *     tripped; subsequent call() rejects immediately).
 *   - Reject in-flight call() promises on child exit rather than leaving them
 *     to time out.
 */
import type { GraphSection } from "./types.js";
import type { IncidentLog } from "./incidents.js";
export type EngineHealth = "starting" | "ready" | "restarting" | "broken";
export declare class TokensaveMcpClient {
    private readonly projectRoot;
    private readonly cfg;
    private readonly incidents;
    private readonly binary;
    childPid: number | null;
    private child;
    private handshakeId;
    private healthState;
    private nextId;
    private readonly pending;
    private restartTimestamps;
    private stdoutBuf;
    private stopping;
    constructor(projectRoot: string, cfg: GraphSection, incidents: IncidentLog, binary?: string);
    health(): EngineHealth;
    /**
     * Spawn the child process and wait for the JSON-RPC handshake.
     * Resolves once health flips to 'ready'.
     * Rejects within HANDSHAKE_TIMEOUT_MS if the child exits early or the
     * handshake never arrives.
     */
    start(): Promise<void>;
    /**
     * SIGTERM the child; wait up to 2000ms; SIGKILL if still alive.
     */
    stop(): Promise<void>;
    /**
     * Send a JSON-RPC 2.0 request and await the matching response.
     * Rejects immediately when health is 'broken' or the engine is stopped.
     */
    call<T>(tool: string, params: unknown): Promise<T>;
    private spawnAndHandshake;
    private handleResponse;
    private onExit;
    private rejectAllPending;
}
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