/**
 * Import / bootstrap (reverse projection) — walk an existing bucket/prefix in an
 * {@link ObjectProjection} and build a master collection where each record
 * anchors one object, restoring the record-anchoring invariant for objects that
 * pre-date noy-db (or were written by another system). See as-aws-s3 §3.8.
 *
 * Idempotent: re-running re-adopts the same objects under the same record ids.
 */
import type { ObjectProjection } from './object-projection.js';
/** Minimal collection surface this utility needs (avoids importing the kernel). */
export interface ImportableCollection {
    get(id: string): Promise<unknown>;
    put(id: string, record: unknown): Promise<unknown>;
    blob(id: string): {
        adoptExternal(slot: string, ref: {
            key: string;
            size?: number;
            contentType?: string;
            public?: boolean;
            backlink?: string;
        }): Promise<void>;
    };
}
export interface ImportExternalOptions {
    /** Only consider objects under this key prefix. Default `''` (all). */
    prefix?: string;
    /**
     * Derive the record id for an object key. Default: the path segment before
     * the last — i.e. `{collection}/{recordId}/{field}` → `recordId`. Return
     * `null` to skip the object.
     */
    deriveRecordId?: (key: string) => string | null;
    /** Build the anchor record for a new id. Default `{ id }`. */
    makeRecord?: (id: string) => unknown;
}
export interface ImportExternalResult {
    imported: number;
    skipped: number;
    recordIds: string[];
}
/**
 * Build/extend `collection` from the objects under `prefix` in `objectStore`,
 * adopting each as the `field` blob on its derived record.
 */
export declare function importExternalObjects(args: {
    collection: ImportableCollection;
    objectStore: ObjectProjection;
    field: string;
    options?: ImportExternalOptions;
}): Promise<ImportExternalResult>;