Initial working commit

src/lib/rateLimiter.ts

@@ -0,0 +1,31 @@
+/**
+ * In-memory sliding window rate limiter.
+ * Single-instance, single-user container — no need for Redis.
+ */
+
+interface RateLimitEntry {
+  timestamps: number[];
+}
+
+const store = new Map<string, RateLimitEntry>();
+
+const WINDOW_MS = 60 * 1000; // 1 minute
+const MAX_REQUESTS = 10;
+
+export function checkRateLimit(ip: string): { allowed: boolean; retryAfterMs: number } {
+  const now = Date.now();
+  const entry = store.get(ip) ?? { timestamps: [] };
+
+  // Remove timestamps outside the window
+  entry.timestamps = entry.timestamps.filter((t) => now - t < WINDOW_MS);
+
+  if (entry.timestamps.length >= MAX_REQUESTS) {
+    const oldestInWindow = entry.timestamps[0];
+    const retryAfterMs = WINDOW_MS - (now - oldestInWindow);
+    return { allowed: false, retryAfterMs };
+  }
+
+  entry.timestamps.push(now);
+  store.set(ip, entry);
+  return { allowed: true, retryAfterMs: 0 };
+}