/**
 * A2A email header utilities
 */
/**
 * Build A2A headers for outgoing email
 */
export declare function buildA2AHeaders(myAgentId: string, currentTurn: number): Record<string, string>;
/**
 * Parse A2A headers from incoming email
 */
export declare function parseA2AHeaders(headers: Record<string, string> | undefined): {
    agentId: string | null;
    turn: number;
};
/**
 * Check if text is a stop token
 */
export declare function isStopToken(text: string): boolean;
/**
 * Get next turn number
 */
export declare function getNextTurn(currentTurn: number): number;