Fix: only cache successful 2xx responses and validate streams array structure

server/cache.js

@@ -296,8 +296,19 @@ export function cacheMiddleware(ttlSeconds) {
       clearTimeout(safetyTimeout);
       res.json = originalJson; // Restore
       
-      // Save fresh data
-      cache.set(cacheKey, body, ttlMs);
+      // Save fresh data only on successful 2xx responses and check array structure for streams
+      if (res.statusCode >= 200 && res.statusCode < 300) {
+        let shouldCache = true;
+        
+        // If this is the streams list endpoint, ensure the body is a valid array
+        if (req.path === '/api/streams' && !Array.isArray(body)) {
+          shouldCache = false;
+        }
+        
+        if (shouldCache) {
+          cache.set(cacheKey, body, ttlMs);
+        }
+      }
       
       // Resolve the promise to unblock anyone who was coalesced (waiting)
       resolvePending(body);