修复延迟问题

server/index.js

@@ -910,13 +910,12 @@ app.put('/api/latency-routes/:id', requireAuth, async (req, res) => {
 app.get('/api/metrics/latency', async (req, res) => {
   try {
     const [routes] = await db.query(`
-      SELECT r.*, s.url 
+      SELECT r.*, s.url, s.type as source_type
       FROM latency_routes r 
       JOIN prometheus_sources s ON r.source_id = s.id
     `);
     
     if (routes.length === 0) {
-      // Return empty routes array instead of null for consistency
       return res.json({ routes: [] });
     }
 
@@ -924,8 +923,8 @@ app.get('/api/metrics/latency', async (req, res) => {
       // Try to get from Valkey first (filled by background latencyService)
       let latency = await cache.get(`latency:route:${route.id}`);
       
-      // Fallback if not in cache (maybe service just started or failed)
-      if (latency === null) {
+      // Fallback if not in cache (only for prometheus sources, blackbox sources rely on the background service)
+      if (latency === null && route.source_type === 'prometheus') {
         latency = await prometheusService.getLatency(route.url, route.latency_target);
       }