import { Etcd3, type IOptions } from 'etcd3';
import { type KernelState, type KernelStateChange, type KernelStateEntry, type KernelStateLease, type KernelStatePrefixWatchObserver, type PutOptions } from '@xemahq/contracts/kernel-state';
export interface EtcdKernelStateOptions {
    endpoints: string[];
    auth?: {
        username: string;
        password: string;
    };
    grpcOptions?: IOptions['grpcOptions'];
    client?: Etcd3;
    keyspacePrefix?: string;
}
export declare const unaryCallDeadline: NonNullable<IOptions['defaultCallOptions']>;
export declare class EtcdKernelState implements KernelState {
    private readonly client;
    private readonly root;
    private readonly leases;
    private readonly leaseTtls;
    readonly backendDescription: string;
    constructor(opts: EtcdKernelStateOptions);
    get(key: string): Promise<KernelStateEntry | null>;
    list(prefix: string): Promise<KernelStateEntry[]>;
    put(key: string, value: unknown, opts?: PutOptions): Promise<void>;
    delete(key: string): Promise<void>;
    watch(prefix: string, cb: (events: KernelStateChange[]) => void): () => void;
    watchPrefix(prefix: string, observer: KernelStatePrefixWatchObserver): () => void;
    private createPrefixSubscription;
    acquireLease(key: string, ttlSeconds: number): Promise<KernelStateLease>;
    renewLease(leaseId: string): Promise<KernelStateLease>;
    lock<T>(key: string, fn: () => T | Promise<T>, options?: {
        readonly waitMs?: number;
    }): Promise<T>;
    close(): void;
    private makePutBuilder;
}
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