Function slowResponseTracker

server/src/middleware/slow-response.ts:78–106

(req: Request, res: Response, next: NextFunction)

 * Only tracks /api/* paths to avoid noise from static assets.
 */
export function slowResponseTracker(req: Request, res: Response, next: NextFunction): void {
  if (!req.path.startsWith("/api/")) {
    return next();
  }

  const start = process.hrtime.bigint();

  res.on("finish", () => {
    const durationMs = Number(process.hrtime.bigint() - start) / 1e6;

    if (durationMs > WARN_THRESHOLD_MS) {
      logger.warn(
        {
          method: req.method,
          path: req.path.slice(0, 200),
          status: res.statusCode,
          duration_ms: Math.round(durationMs),
        },
        "Slow API response"
      );

      if (durationMs > ALERT_THRESHOLD_MS && shouldAlert(normalizeAlertKey(req.method, req.path))) {
        notifySlack(req.method, req.path, durationMs, res.statusCode);
      }
    }
  });

  next();
}