Add 10-second test health logger and /_cron/tick endpoint

backend/src/index.ts

@@ -18,18 +18,18 @@ const apiRoot = config.apiPrefix || '/';
 app.use(apiRoot, createHealthRouter(config));
 app.use(apiRoot, createTodosRouter(config, db));
 
-
-// 10-second health check logger
+// 1. Background 10-second health check logger
 setInterval(() => {
   console.log('[Health Check] Sandbox is healthy at ' + new Date().toISOString());
 }, 10000);
 
+// 2. Cloud Run Cron Tick endpoint (No-op to wake up event loop)
 app.post('/_cron/tick', (req, res) => {
   const authHeader = req.headers.authorization;
   if (!authHeader || authHeader !== 'Bearer ' + process.env.CRON_TOKEN) {
     return res.status(401).json({ success: false, error: 'Unauthorized' });
   }
-  console.log('[Tick] Cloud Run cron tick triggered.');
+  console.log('[Tick] Heartbeat received. Waking up event loop.');
   res.status(200).json({ success: true });
 });