/**
 * Lightweight helpers for detecting whether a PDF already contains a
 * signature placeholder (`/FT /Sig` widget reachable from `/AcroForm`).
 *
 * Used by:
 *   - `sign_pdf` (Phase 3) to decide whether to call `addSignaturePlaceholder`
 *     before signing when `autoInjectPlaceholder` is enabled.
 *   - `inspect_pdf` (Phase 6) to expose `hasSignaturePlaceholder` to AI agents
 *     so they can pick between "sign" and "re-sign" workflows.
 *
 * Implementation goes through pdfnative's hardened `openPdf()` reader so that
 * CWE-674 / CWE-400 mitigations are inherited automatically.
 */
import { type ParsedDict as PdfDict, type PdfReader } from 'pdfnative';
/** Resolve the `/AcroForm` dictionary, or `null` when absent / malformed. */
export declare function getAcroForm(reader: PdfReader): PdfDict | null;
/** Count signature widgets (`/FT /Sig`) reachable from the AcroForm fields. */
export declare function countSignatureWidgets(reader: PdfReader): number;
/** True when the PDF already exposes at least one signature widget. */
export declare function hasSignaturePlaceholder(reader: PdfReader): boolean;
/**
 * Materialised view of a single signature widget useful to `verify_pdf`.
 * `contentsRaw` is the literal byte string parsed from `/Contents <...>` (one
 * JS-string char per byte — pdfnative stores PDF strings as Latin-1) and is
 * converted to a `Uint8Array` of the underlying CMS SignedData by
 * `signatureWidgetContentsBytes()`.
 */
export interface SignatureWidget {
    readonly fieldName: string | null;
    readonly byteRange: readonly [number, number, number, number] | null;
    readonly contentsRaw: string | null;
    readonly subFilter: string | null;
    readonly filter: string | null;
    readonly signingTimeRaw: string | null;
    readonly reason: string | null;
    readonly signerName: string | null;
    readonly location: string | null;
    readonly contactInfo: string | null;
}
/** Decode a `/Contents` literal byte-string into the underlying byte array. */
export declare function contentsToBytes(raw: string): Uint8Array;
/** Enumerate every `/FT /Sig` widget, materialising its `/V` signature dict. */
export declare function collectSignatureWidgets(reader: PdfReader): SignatureWidget[];
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