import type { PreviewConfig, PreviewDocument } from "./types.js";
export declare function isPdfTextLayerEmpty(doc: PreviewDocument, requestHeaders?: Record<string, string>): Promise<boolean>;
/** Convert legacy Office or scanned PDF via config.conversion when native diff/search needs a text layer. */
export declare function convertDocumentForNativePreview(doc: PreviewDocument, conversion: PreviewConfig["conversion"] | undefined, requestHeaders?: Record<string, string>): Promise<PreviewDocument | null>;
export declare function prepareSplitDiffDocuments(pair: [PreviewDocument, PreviewDocument], conversion: PreviewConfig["conversion"] | undefined, requestHeaders?: Record<string, string>): Promise<[PreviewDocument, PreviewDocument]>;
export declare function canUseNativeSplitDiffAfterConversion(left: PreviewDocument, right: PreviewDocument): boolean;
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