/**
* MCP STDIO Handler
*
* This module ensures that only valid JSON is sent to stdout for MCP communication.
* All other output (logs, debug messages, etc.) is redirected to stderr.
*
* It should be imported at the very beginning of the application.
*/
// Store original console methods
const originalConsoleLog = console.log;
const originalConsoleError = console.error;
const originalConsoleWarn = console.warn;
const originalConsoleInfo = console.info;
const originalConsoleDebug = console.debug;
/**
* Format a log message for stderr
*/
function formatLogForStderr(prefix: string, message: unknown, ...args: unknown[]): string {
const timestamp = new Date().toISOString();
const msgStr = typeof message === 'string' ? message : JSON.stringify(message);
const argsStr =
args.length > 0
? ' ' + args.map((arg) => (typeof arg === 'string' ? arg : JSON.stringify(arg))).join(' ')
: '';
return `[${timestamp}] [${prefix}] ${msgStr}${argsStr}\n`;
}
// Override console methods to use stderr directly
console.log = function (message: unknown, ...args: unknown[]): void {
process.stderr.write(formatLogForStderr('LOG', message, ...args));
};
console.error = function (message: unknown, ...args: unknown[]): void {
process.stderr.write(formatLogForStderr('ERROR', message, ...args));
};
console.warn = function (message: unknown, ...args: unknown[]): void {
process.stderr.write(formatLogForStderr('WARN', message, ...args));
};
console.info = function (message: unknown, ...args: unknown[]): void {
process.stderr.write(formatLogForStderr('INFO', message, ...args));
};
console.debug = function (message: unknown, ...args: unknown[]): void {
process.stderr.write(formatLogForStderr('DEBUG', message, ...args));
};
// Create a special function for MCP-safe JSON output
export function mcpSafeOutput(data: unknown): void {
try {
// Ensure data is serializable
const jsonString = JSON.stringify(data);
// Write directly to stdout
process.stdout.write(jsonString + '\n');
} catch (error) {
console.error('Failed to serialize data for MCP output:', error);
}
}
// Export a function to restore original console methods
export function restoreConsole(): void {
console.log = originalConsoleLog;
console.error = originalConsoleError;
console.warn = originalConsoleWarn;
console.info = originalConsoleInfo;
console.debug = originalConsoleDebug;
}
