/**
 * Email signature generation, stripping, and A2A extraction.
 * WS/HTML transport only — SMTP does not use signatures.
 */
/** A2A data embedded in signature link */
export interface SignatureA2AData {
    agentId: string;
    turn: number;
}
/**
 * Build the signature HTML block appended to all WS outgoing emails.
 *
 * @param accountEmail - The account's email address (URL-encoded into the link)
 * @param a2a - Optional A2A metadata to embed as data-* attributes
 * @returns HTML string to append after email body
 */
export declare function buildSignatureHtml(accountEmail: string, a2a?: SignatureA2AData): string;
/**
 * Strip the signature div from HTML.
 * Detection: find `<a>` containing "Mail powered by ClawEmail" and remove its parent div.
 */
export declare function stripSignatureFromHtml(html: string): string;
/**
 * Extract A2A data from the signature link's data-oc-* attributes.
 * Returns null if no signature found or no A2A data present.
 */
export declare function extractA2AFromSignature(html: string): SignatureA2AData | null;