block sending emails on limits (#216)

apps/web/src/server/redis.ts

@@ -11,3 +11,40 @@ export const getRedis = () => {
   }
   return connection;
 };
+
+/**
+ * Simple Redis caching helper. Stores JSON-serialized values under `key` for `ttlSeconds`.
+ * If the key exists, returns the parsed value; otherwise, runs `fetcher`, caches, and returns it.
+ */
+export async function withCache<T>(
+  key: string,
+  fetcher: () => Promise<T>,
+  options?: { ttlSeconds?: number; disable?: boolean }
+): Promise<T> {
+  const { ttlSeconds = 120, disable = false } = options ?? {};
+
+  const redis = getRedis();
+
+  if (!disable) {
+    const cached = await redis.get(key);
+    if (cached) {
+      try {
+        return JSON.parse(cached) as T;
+      } catch {
+        // fallthrough to refresh cache
+      }
+    }
+  }
+
+  const value = await fetcher();
+
+  if (!disable) {
+    try {
+      await redis.setex(key, ttlSeconds, JSON.stringify(value));
+    } catch {
+      // ignore cache set errors
+    }
+  }
+
+  return value;
+}