type LogLevel = "info" | "warn" | "error" | "debug";
export let logLevel: LogLevel = (process.env.LOG_LEVEL as LogLevel) || "info";
type ConsoleParams = Parameters<Console["log"]>;
abstract class Logger {
abstract log(level: LogLevel, ...args: ConsoleParams): void;
error(...args: ConsoleParams): void {
this.log("error", ...args);
}
warn(...args: ConsoleParams): void {
this.log("warn", ...args);
}
info(...args: ConsoleParams): void {
this.log("info", ...args);
}
debug(...args: ConsoleParams): void {
this.log("debug", ...args);
}
set logLevel(level: LogLevel) {
logLevel = level;
}
get console(): Console {
return console;
}
protected shouldLog(level: LogLevel): boolean {
const levels: LogLevel[] = ["debug", "info", "warn", "error"];
return levels.indexOf(level) >= levels.indexOf(logLevel);
}
}
class ConsoleLogger extends Logger {
log(level: LogLevel, ...args: ConsoleParams): void {
if (this.shouldLog(level)) {
const timestamp = new Date().toISOString();
if (level === "error") {
// Errors should be output to stderr (2)
console.error(`[${timestamp}] [${level.toUpperCase()}]`, ...args);
return;
}
if (level === "warn") {
// Warnings should be output to stderr (2)
console.warn(`[${timestamp}] [${level.toUpperCase()}]`, ...args);
return;
}
console.log(`[${timestamp}] [${level.toUpperCase()}]`, ...args);
}
}
}
const loggerInstance = new ConsoleLogger();
export const logger = loggerInstance;
export class McpStdioLogger extends Logger {
log(level: LogLevel, ...args: ConsoleParams): void {
if (this.shouldLog(level)) {
const timestamp = new Date().toISOString();
// MCP logging should be output to stderr (2) as stdout (1) is reserved for machine-readable output
console.error(`[${timestamp}] [${level.toUpperCase()}]`, ...args);
}
}
}
const mcpLoggerInstance = new McpStdioLogger();
export const mcpLogger = mcpLoggerInstance;
