/**
 * Retroactive duplicate scan across the whole library (#108).
 *
 * `detectDuplicate` answers "is this incoming record a duplicate of anything I already have?" —
 * one item against the library, which is right for `add`. Sweeping an existing library with it
 * would be O(n²): 6,000 references means 18 million normalized comparisons. This module reuses
 * the same normalization rules but groups by key instead, which is O(n).
 *
 * See spec/features/superseded.md.
 */
import type { CslItem } from "../../core/csl-json/types.js";
/** Identifier a scan can group by. */
export type DuplicateKeyType = "doi" | "pmid" | "isbn" | "arxiv" | "eric" | "scopus" | "title";
export declare const DUPLICATE_KEY_TYPES: readonly DuplicateKeyType[];
/**
 * Keys used when `--by` is not given.
 *
 * `title` is excluded: title + authors + year is the noisiest rule in `detector.ts`, and across a
 * whole library it produces false pairs (errata, translations, reprinted chapters) that the
 * identifier-based keys do not. It stays available opt-in.
 */
export declare const DEFAULT_DUPLICATE_KEY_TYPES: readonly DuplicateKeyType[];
/** A set of references that match each other. */
export interface DuplicateGroup {
    /** Every key type that contributed to this group, in DUPLICATE_KEY_TYPES order */
    types: DuplicateKeyType[];
    /** The matched value per contributing type */
    keys: Partial<Record<DuplicateKeyType, string>>;
    /** Two or more references */
    items: CslItem[];
    /** True when the group is already fully linked by superseded pointers */
    resolved: boolean;
}
export interface ScanOptions {
    /** Key types to group by (default: DEFAULT_DUPLICATE_KEY_TYPES) */
    by?: readonly DuplicateKeyType[];
    /** Report groups already linked by superseded pointers (default: false) */
    includeResolved?: boolean;
}
export declare function scanDuplicates(items: CslItem[], options?: ScanOptions): DuplicateGroup[];
/**
 * Suggest which member of a group to keep.
 *
 * Completeness first, then the later publication year. That ordering is what separates an
 * online-first record from its version of record: the VoR is the one that gained volume, issue
 * and page numbers. This is a suggestion — `--fix` presents it as the pre-selected choice, never
 * applies it unattended.
 */
export declare function suggestKeeper(items: CslItem[]): CslItem;
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