/**
 * Fastify error handler — translates known typed errors to stable HTTP status
 * codes and uniform `{ ok: false, error: { code, message } }` payloads.
 *
 * Codes (cross-referenced with `nat/types.ts`, `update/types.ts`,
 * `hosted/types.ts`):
 *   - NatError
 *       invalid_config, ddns_provider_unknown,
 *       ddns_credentials_missing                 → 400
 *       unknown_node                             → 404
 *       secrets_unavailable, storage_error,
 *       mapping_failed, router_unreachable,
 *       ip_detection_failed, ddns_update_failed  → 500
 *   - UpdateErrorException
 *       manifest_invalid, no_update_available,
 *       min_previous_version                     → 400
 *       apply_in_progress                        → 409
 *       signature_invalid, unsupported_state_version,
 *       apply_failed, rollback_failed, storage_error → 500
 *   - HostedNodeError
 *       invalid_request                          → 400
 *       not_found                                → 404
 *       invalid_state                            → 409
 *       orchestrator_error, storage_error        → 500
 *       node_unavailable                         → 503
 *   - everything else                            → 500 (code "internal")
 */
import type { FastifyInstance } from 'fastify';
export declare function registerErrorHandler(app: FastifyInstance): void;