/**
 * Skew detector. Identifies patterns where one slot value dominates
 * (>= min_concentration of events). Used by `log10x_find_skew` to
 * surface sampling opportunities: "this slot is `get` 78% of events,
 * sample the get case at 1/N and save volume without losing signal."
 *
 * Algorithm:
 *   1. Run aggregateSlotsBySymbolMessage on the input patterns
 *      (Option B merge by precedingToken / semantic slot name).
 *   2. For each aggregated pattern, find slots where dominantPct >= min.
 *   3. Rank findings by (dominantPct × bytesShare) so strong skew on
 *      a big-spend pattern surfaces first.
 *   4. Surface up to top_n patterns; for each, the skewed-slot list
 *      and an estimated savings opportunity at 1/N sampling of the
 *      dominant value.
 *
 * Sampling-opportunity math: if a pattern has `count` events and
 * `dominantPct` of them carry the dominant value, sampling those at
 * 1/N drops (1 - 1/N) × dominantPct of total events. Translated to
 * bytes: (1 - 1/N) × dominantPct × bytes. At a typical N=10 and
 * dominantPct=0.78, that is 0.7 × bytes — i.e. 70% volume savings on
 * this pattern alone.
 */
import type { ExtractedPattern } from '../pattern-extraction.js';
import { type AggregatedSlot } from './slot-aggregation.js';
import type { Template } from '../cli-output-parser.js';
export interface SkewFinding {
    patternIdentity: string;
    templateHashes: string[];
    costPerMonthUsd?: number;
    totalEvents: number;
    totalBytes: number;
    skewedSlots: Array<{
        slotName: string;
        precedingToken?: string;
        dominantValue: string;
        dominantPct: number;
        distinctCount: number;
        aggregationStatus: AggregatedSlot['aggregationStatus'];
    }>;
    /** Projected savings as a fraction of pattern bytes if dominant case is sampled 1/sampleN. */
    samplingOpportunityPct: number;
}
export interface FindSkewOptions {
    minConcentration?: number;
    topN?: number;
    minEvents?: number;
    sampleN?: number;
    costPerMonthByIdentity?: (identity: string) => number | undefined;
    templates?: Map<string, Template>;
}
export declare function findSkew(patterns: ExtractedPattern[], opts?: FindSkewOptions): SkewFinding[];