// src/logger.ts
//
// Centralized logger with LOG_LEVEL support.
//
// Log levels (from most to least verbose):
// debug - Detailed diagnostic info (text range mapping, request building, etc.)
// info - General operational messages (server started, auth succeeded, etc.)
// warn - Potentially harmful situations (missing content, fallback behavior)
// error - Error conditions (API failures, auth failures, etc.)
//
// Set via the LOG_LEVEL environment variable. Defaults to "info".
// Example: LOG_LEVEL=debug npm start
//
// MCP servers communicate over stdout, so all log output goes to stderr.
const LOG_LEVELS = {
debug: 0,
info: 1,
warn: 2,
error: 3,
silent: 4,
} as const;
type LogLevel = keyof typeof LOG_LEVELS;
function resolveLevel(): LogLevel {
const env = process.env.LOG_LEVEL?.toLowerCase();
if (env && env in LOG_LEVELS) {
return env as LogLevel;
}
return 'info';
}
let currentLevel = resolveLevel();
/** Re-read LOG_LEVEL from the environment (useful for testing). */
export function refreshLogLevel(): void {
currentLevel = resolveLevel();
}
function shouldLog(level: LogLevel): boolean {
return LOG_LEVELS[level] >= LOG_LEVELS[currentLevel];
}
export const logger = {
debug(...args: unknown[]): void {
if (shouldLog('debug')) {
console.error('[DEBUG]', ...args);
}
},
info(...args: unknown[]): void {
if (shouldLog('info')) {
console.error('[INFO]', ...args);
}
},
warn(...args: unknown[]): void {
if (shouldLog('warn')) {
console.error('[WARN]', ...args);
}
},
error(...args: unknown[]): void {
if (shouldLog('error')) {
console.error('[ERROR]', ...args);
}
},
};
