import type { Package } from '@mdgate/containers';
import { type Relationships } from '@mdgate/containers';
import type { Asset, AssetId, ImageSource } from '@mdgate/document';
export declare class AssetSink {
    assets: Asset[];
    private readonly byPart;
    total: number;
    add(mediaType: string, originPart: string, bytes: Uint8Array): AssetId;
}
/**
 * Resolve an image relationship to its source. Failures degrade to
 * `undefined`; fatal errors propagate.
 */
export declare function relImageSource(pkg: Package, rels: Relationships, basePart: string, assets: AssetSink, relId: string): ImageSource | undefined;
/** MIME type from a part path's extension. */
export declare function mediaTypeFor(part: string): string;