import type { Proposal } from "./types.js";
/**
 * Validate a proposal graph.
 *
 * Violations:
 *   - expedition proposal whose missionId does not resolve to a mission proposal
 *   - objective proposal whose expeditionId does not resolve to an expedition proposal
 *   - expedition or objective proposal with no parent reference
 *   - duplicate proposal ids
 */
export declare function validateProposalGraph(proposals: Proposal[]): string[];