@debugmcp/mcp-debugger/dist/utils/logger.js

Run-time step-through debugging for LLM agents.

/**
 * Logger utility for the Debug MCP Server.
 */
import * as winston from 'winston';
import path from 'path';
import fs from 'fs';
import { fileURLToPath } from 'url';
let defaultLogger = null;
/**
 * Create a winston logger with the given namespace.
 *
 * @param namespace - The logger namespace
 * @param options - Logger configuration options
 * @returns A configured winston logger instance
 */
export function createLogger(namespace, options = {}) {
    const level = options.level || 'info';
    const transports = [];
    // In stdio mode, we MUST NOT write to stdout as it corrupts the MCP protocol
    // Check if we're running in stdio mode by looking for specific command line args
    const isStdioMode = process.argv.includes('stdio');
    if (!isStdioMode) {
        // Only add console transport when NOT in stdio mode
        transports.push(new winston.transports.Console({
            format: winston.format.combine(winston.format.colorize(), winston.format.timestamp(), winston.format.printf(({ timestamp, level, message, ...rest }) => {
                return `${timestamp} [${level}] [${namespace}]: ${message} ${Object.keys(rest).length ? JSON.stringify(rest, null, 2) : ''}`;
            }))
        }));
    }
    const __filename = fileURLToPath(import.meta.url);
    const __dirname = path.dirname(__filename);
    const projectRootDefaultLogPath = path.resolve(__dirname, '../../logs/debug-mcp-server.log');
    const logFilePath = options.file || projectRootDefaultLogPath;
    try {
        const logDir = path.dirname(logFilePath);
        if (!fs.existsSync(logDir)) {
            fs.mkdirSync(logDir, { recursive: true });
        }
    }
    catch (e) {
        // In stdio mode, we must not write to console as it corrupts MCP protocol
        if (!isStdioMode) {
            console.error(`[Logger Init Error] Failed to ensure log directory for ${logFilePath}:`, e);
        }
    }
    try {
        transports.push(new winston.transports.File({
            filename: logFilePath,
            format: winston.format.combine(winston.format.timestamp(), winston.format.json())
        }));
    }
    catch (fileTransportError) {
        // In stdio mode, we must not write to console as it corrupts MCP protocol
        if (!isStdioMode) {
            console.error(`[Logger Init Error] Failed to create file transport for ${logFilePath}:`, fileTransportError);
        }
    }
    const logger = winston.createLogger({
        level,
        transports,
        defaultMeta: { namespace },
        exitOnError: false
    });
    logger.on('error', (error) => {
        // In stdio mode, we must not write to console as it corrupts MCP protocol
        if (!isStdioMode) {
            console.error('[Winston Logger Internal Error] Failed to write to a transport:', error);
        }
    });
    // If this is the root logger, set it as the default
    if (namespace === 'debug-mcp') {
        defaultLogger = logger;
    }
    return logger;
}
/**
 * Get the default logger instance. If no root logger has been created, a fallback logger is created.
 * @returns The default logger instance.
 */
export function getLogger() {
    if (!defaultLogger) {
        defaultLogger = createLogger('debug-mcp:default-fallback', { level: 'info' });
        defaultLogger.warn('[Logger] getLogger() called before root logger was initialized. Using fallback logger.');
    }
    return defaultLogger;
}
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