/**
 * Debug Utility for MCP Server
 *
 * This module provides debug logging that only outputs when DEBUG mode is enabled.
 * This prevents console.log from interfering with MCP STDIO communication.
 */
import type { DebugInfo } from "../types/index.js";
export type LogLevel = "debug" | "info" | "warn" | "error";
export interface Logger {
    log(...args: unknown[]): void;
    info(...args: unknown[]): void;
    warn(...args: unknown[]): void;
    error(...args: unknown[]): void;
}
export interface StructuredLogger extends Logger {
    logStructured(info: DebugInfo): void;
    child(context: Record<string, unknown>): StructuredLogger;
}
/**
 * Debug logger that only outputs in debug mode
 */
export declare const debug: Logger;
/**
 * Silent logger for production use
 */
export declare const silent: Logger;
/**
 * Create a structured logger instance
 */
export declare const createStructuredLogger: (context?: Record<string, unknown>) => StructuredLogger;
/**
 * Default logger instance
 */
export declare const logger: Logger;
/**
 * Create a logger with context
 */
export declare const createLogger: (context?: Record<string, unknown>) => StructuredLogger;
/**
 * Performance measurement utility
 */
export interface PerformanceTimer {
    end(): number;
    endWithLog(message?: string): number;
}
export declare const startTimer: (label?: string) => PerformanceTimer;
/**
 * Log error with stack trace
 */
export declare const logError: (error: Error | string, context?: Record<string, unknown>) => void;
/**
 * Conditional logging
 */
export declare const logIf: (condition: boolean, level?: LogLevel) => Logger | ((...args: unknown[]) => void);
/**
 * Type-safe environment variable getter with security logging
 */
export declare const getEnvVar: (key: string, defaultValue?: string) => string | undefined;
/**
 * Validate required environment variables with secure error messages
 */
export declare const validateEnvVars: (required: string[]) => void;
/**
 * Sanitize environment variable for logging
 */
export declare const sanitizeEnvValue: (key: string, value: string) => string;
/**
 * Get sanitized environment summary for debugging
 */
export declare const getEnvSummary: (keys: string[]) => Record<string, string>;
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