Import source: vault/lib/server-redis

Import the existing local project snapshot. This commit organizes existing files; it does not represent newly developed functionality.

vault/lib/server-redis.ts

@@ -0,0 +1,36 @@
+import "server-only";
+
+import { createClient, type RedisClientType } from "redis";
+
+const REDIS_URL = process.env.REDIS_URL ?? "redis://127.0.0.1:6379";
+
+let client: RedisClientType | null = null;
+let connection: Promise<RedisClientType | null> | null = null;
+let disabled = false;
+
+export async function getRedis(): Promise<RedisClientType | null> {
+  if (disabled) return null;
+  if (client?.isOpen) return client;
+  if (connection) return connection;
+
+  connection = (async () => {
+    const redis = createClient({ url: REDIS_URL });
+    redis.on("error", (error) => {
+      console.error("Redis error", error);
+    });
+
+    try {
+      await redis.connect();
+      client = redis as RedisClientType;
+      return client;
+    } catch (error) {
+      console.error("Redis unavailable, using in-memory fallback", error);
+      disabled = true;
+      return null;
+    } finally {
+      connection = null;
+    }
+  })();
+
+  return connection;
+}