/**
 * Logger - Structured logging for RPG-MCP
 *
 * Hygiene Improvement: Replaces raw console statements with structured logging.
 *
 * Features:
 * - Log levels (debug, info, warn, error)
 * - Environment-based log level control (RPG_LOG_LEVEL)
 * - Module prefixes for easy filtering
 * - Silent mode for tests
 * - MCP-compatible stderr output (stdout reserved for MCP protocol)
 *
 * Usage:
 *   import { createLogger } from '../utils/logger.js';
 *   const log = createLogger('Combat');
 *
 *   log.debug('Detailed info');  // Only shown when RPG_LOG_LEVEL=debug
 *   log.info('Normal operation');
 *   log.warn('Potential issue');
 *   log.error('Something broke');
 *
 * Environment:
 *   RPG_LOG_LEVEL=debug|info|warn|error|silent (default: info)
 *   NODE_ENV=test automatically sets silent
 */
export type LogLevel = 'debug' | 'info' | 'warn' | 'error' | 'silent';
export interface Logger {
    debug(message: string, ...args: unknown[]): void;
    info(message: string, ...args: unknown[]): void;
    warn(message: string, ...args: unknown[]): void;
    error(message: string, ...args: unknown[]): void;
    /** Create a child logger with additional prefix */
    child(prefix: string): Logger;
    /** Check if a log level is enabled */
    isEnabled(level: LogLevel): boolean;
}
/**
 * Reset the cached level (useful for tests)
 */
export declare function resetLogLevel(): void;
/**
 * Override the log level programmatically
 */
export declare function setLogLevel(level: LogLevel): void;
/**
 * Create a logger instance with the given module prefix
 *
 * @example
 * const log = createLogger('Combat');
 * log.info('Combat started');
 * // Output: [12:34:56.789] [INFO ] [Combat] Combat started
 *
 * const childLog = log.child('Initiative');
 * childLog.debug('Rolling initiative');
 * // Output: [12:34:56.790] [DEBUG] [Combat:Initiative] Rolling initiative
 */
export declare function createLogger(prefix: string): Logger;
/**
 * Global logger instance for quick access
 * Prefer creating module-specific loggers with createLogger()
 */
export declare const logger: Logger;
/**
 * Log a structured object with pretty formatting
 */
export declare function logObject(logger: Logger, level: LogLevel, label: string, obj: unknown): void;
/**
 * Create a timer for performance logging
 *
 * @example
 * const timer = createTimer(log);
 * // ... do work ...
 * timer.done('Operation completed'); // Logs with duration
 */
export declare function createTimer(logger: Logger): {
    done: (message: string) => void;
};
/**
 * Wrap an async function with entry/exit logging
 */
export declare function withLogging<TArgs extends unknown[], TResult>(logger: Logger, name: string, fn: (...args: TArgs) => Promise<TResult>): (...args: TArgs) => Promise<TResult>;
/**
 * Safely extract error message from unknown error type
 */
export declare function getErrorMessage(error: unknown): string;
/**
 * Log an error with stack trace if available
 */
export declare function logError(logger: Logger, message: string, error: unknown): void;
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