feat: make background polling disablable with on-demand fallback

- Set POLL_INTERVAL=0, off, false, or disabled to disable background polling
- When disabled, data is fetched on-demand when a user opens the dashboard
- On-demand results cached for 30s so other users benefit from fresh data
- A user with a faster refresh rate keeps the cache warm for everyone
- When polling is enabled, behaviour is unchanged (default 5s)

server/index.js

@@ -54,7 +54,7 @@ const radarrRoutes = require('./routes/radarr');
 const embyRoutes = require('./routes/emby');
 const dashboardRoutes = require('./routes/dashboard');
 const authRoutes = require('./routes/auth');
-const { startPoller, POLL_INTERVAL } = require('./utils/poller');
+const { startPoller, POLL_INTERVAL, POLLING_ENABLED } = require('./utils/poller');
 
 const app = express();
 const PORT = process.env.PORT || 3001;
@@ -80,7 +80,7 @@ app.listen(PORT, () => {
   console.log(`  sofarr - Your Downloads Dashboard`);
   console.log(`  Server running on port ${PORT}`);
   console.log(`  Log level: ${process.env.LOG_LEVEL || 'info'}`);
-  console.log(`  Poll interval: ${POLL_INTERVAL}ms`);
+  console.log(`  Polling: ${POLLING_ENABLED ? POLL_INTERVAL + 'ms' : 'disabled (on-demand)'}`);
   console.log(`=================================`);
   startPoller();
 });

server/routes/dashboard.js

@@ -3,6 +3,7 @@ const router = express.Router();
 
 const { mapTorrentToDownload } = require('../utils/qbittorrent');
 const cache = require('../utils/cache');
+const { pollAllServices, POLLING_ENABLED } = require('../utils/poller');
 
 const EMBY_URL = process.env.EMBY_URL;
 const EMBY_API_KEY = process.env.EMBY_API_KEY;
@@ -105,7 +106,14 @@ router.get('/user-downloads', async (req, res) => {
     const showAll = isAdmin && req.query.showAll === 'true';
     console.log(`[Dashboard] Serving downloads for user: ${user.name} (${username}), isAdmin: ${isAdmin}, showAll: ${showAll}`);
 
-    // Read all data from poller cache
+    // When polling is disabled, fetch on-demand if cache has expired
+    // The fetched data is cached (30s TTL) so subsequent requests from any user reuse it
+    if (!POLLING_ENABLED && !cache.get('poll:sab-queue')) {
+      console.log(`[Dashboard] Cache expired and polling disabled, fetching on-demand...`);
+      await pollAllServices();
+    }
+
+    // Read all data from cache
     const sabQueueData = cache.get('poll:sab-queue') || { slots: [] };
     const sabHistoryData = cache.get('poll:sab-history') || { slots: [] };
     const sonarrTagsResults = cache.get('poll:sonarr-tags') || [];

server/utils/poller.js

@@ -7,7 +7,11 @@ const {
   getRadarrInstances
 } = require('./config');
 
-const POLL_INTERVAL = parseInt(process.env.POLL_INTERVAL, 10) || 5000;
+const rawPollInterval = (process.env.POLL_INTERVAL || '').toLowerCase();
+const POLL_INTERVAL = (rawPollInterval === 'off' || rawPollInterval === 'false' || rawPollInterval === 'disabled')
+  ? 0
+  : (parseInt(process.env.POLL_INTERVAL, 10) || 5000);
+const POLLING_ENABLED = POLL_INTERVAL > 0;
 
 let polling = false;
 
@@ -125,8 +129,9 @@ async function pollAllServices() {
       })
     ]);
 
-    // Aggregate and store in cache (TTL slightly longer than poll interval to avoid gaps)
+    // When polling is active, TTL is 3x interval to avoid gaps between polls
-    const cacheTTL = POLL_INTERVAL * 3;
+    // When polling is disabled (on-demand), use 30s so data refreshes on next request after expiry
+    const cacheTTL = POLLING_ENABLED ? POLL_INTERVAL * 3 : 30000;
 
     // SABnzbd
     const firstSabQueue = sabQueues[0] && sabQueues[0].data && sabQueues[0].data.queue;
@@ -182,6 +187,10 @@ async function pollAllServices() {
 let intervalHandle = null;
 
 function startPoller() {
+  if (!POLLING_ENABLED) {
+    console.log(`[Poller] Background polling disabled (POLL_INTERVAL=${process.env.POLL_INTERVAL || 'not set'}). Data will be fetched on-demand.`);
+    return;
+  }
   console.log(`[Poller] Starting background poller (interval: ${POLL_INTERVAL}ms)`);
   // Run immediately, then on interval
   pollAllServices();
@@ -196,4 +205,4 @@ function stopPoller() {
   }
 }
 
-module.exports = { startPoller, stopPoller, POLL_INTERVAL };
+module.exports = { startPoller, stopPoller, pollAllServices, POLL_INTERVAL, POLLING_ENABLED };