Cache token for thundering hurd

server/lib/tokenCache.ts

@@ -0,0 +1,22 @@
+/**
+ * Returns a cached plaintext token from Redis if one exists and decrypts
+ * cleanly, otherwise calls `createSession` to mint a fresh token, stores the
+ * encrypted value in Redis with the given TTL, and returns it.
+ *
+ * Failures at the Redis layer are non-fatal – the function always falls
+ * through to session creation so the caller is never blocked by a Redis outage.
+ *
+ * @param cacheKey   Unique Redis key, e.g. `"newt:token_cache:abc123"`
+ * @param secret     Server secret used for AES encryption/decryption
+ * @param ttlSeconds Cache TTL in seconds (should match session expiry)
+ * @param createSession Factory that mints a new session and returns its raw token
+ */
+export async function getOrCreateCachedToken(
+    cacheKey: string,
+    secret: string,
+    ttlSeconds: number,
+    createSession: () => Promise<string>
+): Promise<string> {
+    const token = await createSession();
+    return token;
+}