/**
* Logger — writes to stderr, never stdout.
*
* MCP uses stdout for JSON-RPC communication.
* If we write anything to stdout that isn't valid JSON-RPC,
* the MCP client (Claude Code) will choke. So all debug/info/error
* logging goes to stderr, which Claude Code ignores.
*/
type LogLevel = "debug" | "info" | "warn" | "error";
const LEVEL_PRIORITY: Record<LogLevel, number> = {
debug: 0,
info: 1,
warn: 2,
error: 3,
};
const minLevel: LogLevel = (process.env.HYDRA_LOG_LEVEL as LogLevel) ?? "info";
function log(level: LogLevel, message: string): void {
if (LEVEL_PRIORITY[level] < LEVEL_PRIORITY[minLevel]) return;
const timestamp = new Date().toISOString();
process.stderr.write(`[${timestamp}] [${level.toUpperCase()}] ${message}\n`);
}
export const logger = {
debug: (msg: string) => log("debug", msg),
info: (msg: string) => log("info", msg),
warn: (msg: string) => log("warn", msg),
error: (msg: string) => log("error", msg),
};
