context-engine/dist/lib/logger.js

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/**
 * MCP-Compatible Logger
 *
 * A logger specifically designed for MCP servers that:
 * - Writes all output to stderr to avoid breaking stdio protocol
 * - Provides different log levels
 * - Can be controlled via environment variables
 * - Maintains JSON structure for structured logging
 */
export var LogLevel;
(function (LogLevel) {
    LogLevel[LogLevel["ERROR"] = 0] = "ERROR";
    LogLevel[LogLevel["WARN"] = 1] = "WARN";
    LogLevel[LogLevel["INFO"] = 2] = "INFO";
    LogLevel[LogLevel["DEBUG"] = 3] = "DEBUG";
    LogLevel[LogLevel["TRACE"] = 4] = "TRACE";
})(LogLevel || (LogLevel = {}));
class MCPLogger {
    level;
    isStructured;
    constructor() {
        // Get log level from environment or default to INFO
        const envLevel = process.env.MCP_LOG_LEVEL?.toUpperCase();
        this.level = envLevel
            ? (LogLevel[envLevel] ?? LogLevel.INFO)
            : LogLevel.INFO;
        // Enable structured logging if requested
        this.isStructured = process.env.MCP_STRUCTURED_LOGS === "true";
    }
    shouldLog(level) {
        return level <= this.level;
    }
    formatMessage(level, message, context) {
        if (this.isStructured) {
            const entry = {
                timestamp: new Date().toISOString(),
                level,
                message,
                ...(context && { context }),
            };
            return JSON.stringify(entry);
        }
        const timestamp = new Date().toISOString();
        const contextStr = context ? ` ${JSON.stringify(context)}` : "";
        return `[${timestamp}] ${level.toUpperCase()}: ${message}${contextStr}`;
    }
    write(level, levelName, message, context) {
        if (!this.shouldLog(level))
            return;
        const formatted = this.formatMessage(levelName, message, context);
        // Always write to stderr to avoid breaking MCP stdio protocol
        process.stderr.write(formatted + "\n");
    }
    error(message, context) {
        this.write(LogLevel.ERROR, "error", message, context);
    }
    warn(message, context) {
        this.write(LogLevel.WARN, "warn", message, context);
    }
    info(message, context) {
        this.write(LogLevel.INFO, "info", message, context);
    }
    debug(message, context) {
        this.write(LogLevel.DEBUG, "debug", message, context);
    }
    trace(message, context) {
        this.write(LogLevel.TRACE, "trace", message, context);
    }
    // Convenience method for API-related logging
    api(message, context) {
        this.info(`[API] ${message}`, context);
    }
    // Convenience method for MCP-related logging
    mcp(message, context) {
        this.info(`[MCP] ${message}`, context);
    }
}
// Export singleton instance
export const logger = new MCPLogger();
// Export the class for testing
export { MCPLogger };