/**
 * Engine Logger
 *
 * Module-level logger interface for the records-validator engine. Lets
 * the engine emit diagnostics without binding directly to the server's
 * Winston logger — a precondition for extracting the engine into a
 * standalone npm package (S-2 in the validation-engine roadmap).
 *
 * ## Wiring
 *
 * Engine modules import the singleton `logger` from this file. By
 * default it forwards only errors to a console-backed implementation. Embedders call
 * `setEngineLogger()` once during boot to route logging through their own
 * Winston/pino/etc. instance:
 *
 * ```ts
 * import { setEngineLogger } from '@records-fhir/validator';
 * setEngineLogger(appLogger);
 * ```
 *
 * The engine never reaches into server code; this file is the entire
 * coupling boundary for logging.
 */
/**
 * Minimal logger contract the engine relies on. Designed to be
 * trivially satisfied by Winston, pino, console, or a noop logger —
 * the second argument is intentionally untyped to accept the variety
 * of meta payloads existing engine call sites emit (Error instances,
 * plain objects, scalars).
 */
export interface EngineLogger {
    debug(message: string, meta?: unknown): void;
    info(message: string, meta?: unknown): void;
    warn(message: string, meta?: unknown): void;
    error(message: string | Error, meta?: unknown): void;
}
export type EngineLogLevel = 'silent' | 'error' | 'warn' | 'info' | 'debug';
/**
 * Replace the engine's underlying logger. Intended to be called once
 * during embedder bootstrap. Calling more than once is supported but
 * not expected in production — later writes simply replace earlier
 * ones.
 */
export declare function setEngineLogger(next: EngineLogger): void;
/**
 * The shared logger every engine module imports. Delegates to whatever
 * `setEngineLogger` last installed (or the filtered console default when an
 * embedder hasn't wired anything up). Set RECORDS_FHIR_VALIDATOR_LOG_LEVEL
 * or RECORDS_VALIDATOR_LOG_LEVEL to silent, error, warn, info, or debug to
 * adjust that default console logger.
 *
 * The wrapper is created once and re-reads `activeLogger` on every
 * call, so installing a logger after engine modules have already
 * captured `logger` still routes correctly.
 */
export declare const logger: EngineLogger;
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