import winston from 'winston';
import config from './config.js';
/**
* Flag indicating if the application is running in STDIO mode.
* This is determined by checking the command line arguments for '--stdio'.
*/
const useStdio = process.argv.includes('--stdio');
/**
* Custom log format combining timestamp and message.
* Format: `YYYY-MM-DDTHH:mm:ss.sssZ [LEVEL]: message`
*/
const logFormat = winston.format.combine(
winston.format.timestamp(),
winston.format.printf(({ level, message, timestamp }) => {
return `${timestamp} [${level.toUpperCase()}]: ${message}`;
})
);
/**
* List of Winston transports (outputs) for the logger.
* - Always includes file transports for 'error.log' (error level) and 'combined.log' (all levels).
* - Includes Console transport:
* - In STDIO mode: writes to stderr to avoid interfering with MCP protocol on stdout.
* - In HTTP mode: writes to stdout as normal.
*/
const transports: winston.transport[] = [
new winston.transports.File({ filename: 'error.log', level: 'error' }),
new winston.transports.File({ filename: 'combined.log' }),
];
// In STDIO mode, send console output to stderr to avoid interfering with MCP protocol
if (useStdio) {
transports.push(new winston.transports.Console({
stderrLevels: ['error', 'warn', 'info', 'debug', 'verbose', 'silly']
}));
} else {
// In HTTP mode, use normal console output
transports.push(new winston.transports.Console());
}
/**
* Application logger instance configured with timestamped format and multiple transports.
* The log level is determined by the configuration (defaulting to 'info').
*/
const logger = winston.createLogger({
level: config.logger.level,
format: logFormat,
transports: transports,
});
// Add a stream for using with express-winston
logger.stream = {
// @ts-expect-error - express-winston expects a stream-compatible interface
write: (message: string) => {
logger.info(message.trim());
},
};
export default logger;
