/**
 * LocalBackend — the default backend, and the reference implementation.
 *
 * LocalBackend is not a special case bolted next to the pipeline: it **is** the
 * pipeline's per-trial core (`runEval()` + grading) packaged as a {@link Backend}.
 * It runs every trial on this host, owns the cross-trial prepared-workspace
 * cache, and attaches per-attempt workspace preservation to successful envelopes.
 *
 * The surrounding harness (planning, pool admission, retry, session-log
 * lifecycle, scoring, reporting) stays in core; LocalBackend never sees it.
 */
import type { Executor } from "../executor/types.js";
import type { EnvironmentConfig } from "../eval/types.js";
import type { Backend, DisposableTrialResult, GradeTrialOptions, TrialIdentity, TrialOptions } from "./types.js";
/**
 * Whether a stimulus is eligible for the cross-trial prepared-workspace cache.
 *
 * This is the single source of truth for the gate; {@link LocalBackend} owns the
 * cache and any related progress events.
 */
export declare function isPreparedWorkspaceEligible(args: {
    executor: Executor;
    totalTrials: number;
    environment?: EnvironmentConfig;
}): boolean;
export declare class LocalBackend implements Backend {
    readonly name = "local";
    private readonly slots;
    private disposed;
    runTrial(item: TrialIdentity, options: TrialOptions): Promise<DisposableTrialResult>;
    gradeTrial(options: GradeTrialOptions): Promise<DisposableTrialResult>;
    shutdown(): Promise<void>;
    private getOrCreateSlot;
}
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