/**
 * Kernel Runtime — Phantom backend.
 *
 * PhantomRuntimeBackend wraps SubAgentRuntime so the kernel execution service
 * never imports SubAgentRuntime directly. This is the PR 3 shim; PR 4 can
 * refactor SubAgentRuntime internals without touching kernel contracts.
 */
import type { RuntimeBackend } from './contracts.js';
import type { PreparedStep, ExecutedStep, InspectedStep, RuntimeExecuteInput } from './types.js';
import type { SubAgentRuntime } from '../../phantom/runtime.js';
export declare class PhantomRuntimeBackend implements RuntimeBackend {
    private readonly runtime;
    constructor(runtime: SubAgentRuntime);
    prepareStep(input: RuntimeExecuteInput): Promise<PreparedStep>;
    executeStep(input: RuntimeExecuteInput): Promise<ExecutedStep>;
    inspectStep(input: RuntimeExecuteInput): Promise<InspectedStep>;
    cleanupStep(_input: RuntimeExecuteInput): Promise<void>;
}
/** Convenience factory so callers don't import SubAgentRuntime. */
export declare function createPhantomBackend(runtime: SubAgentRuntime): PhantomRuntimeBackend;
