MCP ASCII Charts

import { randomUUID } from 'crypto'; export interface LogContext { requestId?: string; toolName?: string; userId?: string; sessionId?: string; [key: string]: unknown; } export interface LogEntry { timestamp: string; level: 'debug' | 'info' | 'warn' | 'error'; message: string; context?: LogContext; duration?: number; error?: { name: string; message: string; stack?: string; }; } export class Logger { private static instance: Logger; private context: LogContext = {}; static getInstance(): Logger { if (!Logger.instance) { Logger.instance = new Logger(); } return Logger.instance; } setContext(context: LogContext): void { this.context = { ...this.context, ...context }; } clearContext(): void { this.context = {}; } generateRequestId(): string { const requestId = randomUUID(); this.setContext({ requestId }); return requestId; } private log(level: LogEntry['level'], message: string, context?: LogContext, error?: Error, duration?: number): void { const entry: LogEntry = { timestamp: new Date().toISOString(), level, message, context: { ...this.context, ...context }, ...(duration && { duration }), ...(error && { error: { name: error.name, message: error.message, stack: error.stack } }) }; // Write to stderr to avoid mixing with MCP protocol on stdout console.error(JSON.stringify(entry)); } debug(message: string, context?: LogContext): void { this.log('debug', message, context); } info(message: string, context?: LogContext): void { this.log('info', message, context); } warn(message: string, context?: LogContext): void { this.log('warn', message, context); } error(message: string, error?: Error, context?: LogContext): void { this.log('error', message, context, error); } logRequest(toolName: string, params: unknown): void { this.info('Tool request received', { toolName, paramsSize: JSON.stringify(params).length, hasData: !!(params && typeof params === 'object' && 'data' in params) }); } logResponse(toolName: string, success: boolean, duration: number): void { this.info('Tool request completed', { toolName, success, duration }); } logPerformance(operation: string, duration: number, context?: LogContext): void { this.info('Performance metric', { operation, duration, ...context }); } } export const logger = Logger.getInstance(); // Performance timing utility export class PerformanceTimer { private startTime: number; private operation: string; private context?: LogContext; constructor(operation: string, context?: LogContext) { this.operation = operation; this.context = context; this.startTime = performance.now(); logger.debug(`Started: ${operation}`, context); } end(): number { const duration = performance.now() - this.startTime; logger.logPerformance(this.operation, duration, this.context); return duration; } } // Request tracking middleware export function withRequestTracking<T extends unknown[], R>( fn: (...args: T) => R | Promise<R>, operationName: string ): (...args: T) => Promise<R> { return async (...args: T): Promise<R> => { const requestId = logger.generateRequestId(); const timer = new PerformanceTimer(operationName, { requestId }); try { logger.debug(`Executing ${operationName}`, { requestId, argsCount: args.length }); const result = await Promise.resolve(fn(...args)); const duration = timer.end(); logger.info(`Completed ${operationName}`, { requestId, duration, success: true }); return result; } catch (error) { const duration = timer.end(); logger.error(`Failed ${operationName}`, error as Error, { requestId, duration, success: false }); throw error; } finally { logger.clearContext(); } }; }