Extract shared createRateLimiter factory

backend/src/middleware/rate-limiter.middleware.ts

@@ -1,10 +1,22 @@
-import { rateLimit } from 'express-rate-limit';
+import { rateLimit, type Options } from 'express-rate-limit';
 
-export const globalRateLimiter = rateLimit({
+/**
+ * Shared factory to create an express-rate-limit instance with common configuration.
+ * 
+ * @param options Configuration options for express-rate-limit
+ * @returns Express rate limit middleware
+ */
+export function createRateLimiter(options: Partial<Options>) {
+  return rateLimit({
+    standardHeaders: true, // Return rate limit info in the `RateLimit-*` headers
+    legacyHeaders: false, // Disable the `X-RateLimit-*` headers
+    ...options,
+  });
+}
+
+export const globalRateLimiter = createRateLimiter({
   windowMs: 1 * 60 * 1000, // 1 minute
   max: 100, // Limit each IP to 100 requests per `window` (here, per minute)
-  standardHeaders: true, // Return rate limit info in the `RateLimit-*` headers
-  legacyHeaders: false, // Disable the `X-RateLimit-*` headers
   message: {
     message: 'Too many requests, please try again later.',
     status: 429,

backend/src/middleware/stream-rate-limiter.middleware.ts

@@ -1,4 +1,4 @@
-import { rateLimit } from 'express-rate-limit';
+import { createRateLimiter } from './rate-limiter.middleware.js';
 import { type Request, type Response, type NextFunction } from 'express';
 import type { AuthenticatedRequest } from '../types/auth.types.js';
 import logger from '../logger.js';
@@ -22,11 +22,9 @@ export function createStreamRateLimiter(
   // Read from environment variable, default to 10 if not set
   const max = options?.max ?? (process.env.STREAM_CREATE_RATE_LIMIT ? parseInt(process.env.STREAM_CREATE_RATE_LIMIT, 10) : 10);
 
-  return rateLimit({
+  return createRateLimiter({
     windowMs,
     max,
-    standardHeaders: true, // Return rate limit info in the `RateLimit-*` headers
-    legacyHeaders: false, // Disable the `X-RateLimit-*` headers
     message: {
       error: 'Too many stream creation requests - rate limit exceeded',
       message: 'You have exceeded the rate limit for stream creation. Please try again later.',