/**
 * Removes duplicated instructions from a generated system message
 *
 * Commitments are applied one by one, so a commitment used multiple times in one book repeats its whole
 * section, including the shared guidance preamble. For example two `WRITING RULES` commitments emit the
 * `## Writing rules` heading and its guidance paragraph twice. This function merges all sections sharing
 * one heading into the position of their first occurrence and keeps every identical block only once.
 *
 * @param systemMessage The assembled system message which may contain repeated sections and blocks
 * @returns The system message where each section heading and each identical block appears exactly once
 *
 * @private internal utility of `createAgentModelRequirementsWithCommitments`
 */
export declare function deduplicateSystemMessage(systemMessage: string): string;