/**
 * RPC failover: automatic switch to a backup Solana RPC endpoint on
 * infrastructure errors, with 120 s cooldown recovery to primary.
 *
 * Mirrors rust/src/rpc_failover.rs.
 */
export declare const FAST_RETRY_DELAY_MS = 100;
export declare const COOLDOWN_DURATION_MS = 120000;
export declare enum ActiveRpc {
    Primary = "primary",
    Backup = "backup"
}
export declare class RpcFailoverState {
    active: ActiveRpc;
    private flippedToBackupAt?;
    maybeRecoverToPrimary(): void;
    flipToBackup(): void;
    flipToPrimary(): void;
}
export declare function isInfrastructureError(err: unknown): boolean;
export declare function sleep(ms: number): Promise<void>;
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