/**
 * bench/auto-reduction.ts — Production-autonomy audit #85, fan-out auto-reduction.
 *
 * Audit quote (production-autonomy-improvements-2026-08-28.md, line 276):
 *
 *   "Automatically reduce fan-out when coordination overhead exceeds
 *    expected benefit."
 *
 * The `recommendFanOut` pure function is the operational rule. It
 * consumes:
 *
 *   - `currentFanOut`: the orchestrator's current fan-out (number of
 *     parallel workers for the next dispatch)
 *   - `historicalCoordinationOverheadRatio`: empirically observed
 *     coordination overhead from prior `runBench` / real-runs data
 *   - `expectedBenefitRatio`: how much parallelism is *expected* to
 *     improve the work, expressed as a fraction of wall-clock saved
 *     vs a single worker. (E.g. 4 independent tasks → 0.75 expected
 *     speedup; `expectedBenefitRatio = 0.75`.)
 *   - `historicalDefectEscapeRate`: fraction of worker outputs that
 *     reviewers missed (0..1). Higher escape rate means reviewers
 *     aren't pulling their weight; the rule widens to compensate.
 *
 * and returns:
 *
 *   - `recommendedFanOut`: 1..currentFanOut
 *   - `reason`: stable, machine-readable justification the orchestrator
 *     can log into its audit trail
 *
 * Decision rule (audit-aligned):
 *
 *   1. If coordination overhead ≥ expected benefit, reduce by 1 each
 *      step until fan-out = 1 (single worker wins).
 *   2. If defect escape rate > 0.20 (audit failure threshold for
 *      "verifier cannot certify"), widen reviewer count rather than
 *      fan-out (out of scope for this function — we surface the
 *      recommendation but leave widening to the reviewer policy).
 *   3. Otherwise, keep current fan-out.
 *
 * Why pure: the rule is consulted from `bizar bench recommend-fan-out`
 * (CLI) and from orchestrator fan-out policy; both contexts want the
 * same answer for the same inputs, with no I/O surprise.
 */
export declare const AUTO_REDUCTION_SCHEMA_VERSION = "1.0.0";
/** Threshold above which coordination overhead is deemed to exceed benefit. */
export declare const DEFAULT_OVERHEAD_VS_BENEFIT_RATIO = 1;
/** Defect escape rate above which the rule recommends widening reviewers. */
export declare const DEFAULT_DEFECT_ESCAPE_RATE_THRESHOLD = 0.2;
/** Hard floor: never recommend fan-out = 0. */
export declare const MIN_FAN_OUT = 1;
/** Hard ceiling: never widen fan-out beyond the input. */
export declare const MAX_FAN_OUT_FLOOR = 1;
export interface FanOutContext {
    readonly currentFanOut: number;
    /**
     * Empirically observed coordination overhead ratio (0..2+). 0.5 =
     * parallel work costs 50% more wall-clock than the theoretical best.
     */
    readonly historicalCoordinationOverheadRatio: number;
    /**
     * Expected wall-clock savings from parallelism (0..1). 0.75 = the
     * work is 75% faster when split into N independent workers.
     */
    readonly expectedBenefitRatio: number;
    /**
     * Fraction of defects reviewers missed across the recent window
     * (0..1). Used to flag a "verifier cannot certify" condition.
     */
    readonly historicalDefectEscapeRate: number;
}
export type FanOutDecisionReason = "single-worker-fan-out" | "coordination-overhead-exceeds-benefit" | "verifier-cannot-certify" | "keep-current";
export interface FanOutDecision {
    readonly recommendedFanOut: number;
    readonly reason: FanOutDecisionReason;
    /** Diagnostic: combined (overheadRatio - expectedBenefitRatio). Positive = reduce. */
    readonly overheadVsBenefitGap: number;
    /** Diagnostic: did the rule trigger a reduction? */
    readonly reduced: boolean;
}
/**
 * Pure fan-out recommendation. See file header for the rule.
 */
export declare function recommendFanOut(ctx: FanOutContext): FanOutDecision;
/**
 * Convenience helper for a batch of context updates (e.g. applied to
 * the last K historical buckets at once). Each context is reduced in
 * turn; the first one that triggers a reduction is returned. Useful
 * when the orchestrator wants the *most aggressive* safe reduction.
 */
export declare function recommendFanOutBatch(contexts: ReadonlyArray<FanOutContext>): FanOutDecision;
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