feat: Add automatic periodic location requests via silent push

- Server sends silent push notifications every 60s (configurable)
- Only requests from rooms with active participants
- Cleans up stale push subscriptions automatically
- Interval configurable via LOCATION_REQUEST_INTERVAL env var

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

sync-server/docker-compose.yml

@@ -9,6 +9,8 @@ services:
       - VAPID_PUBLIC_KEY=BNWACJudUOeHEZKEFB-0Wz086nHYsWzj12LqQ7lsUNT38ThtNUoZTJYEH9lttQitCROE2G3Ob71ZUww47yvCDbk
       - VAPID_PRIVATE_KEY=${VAPID_PRIVATE_KEY:-x3yCse1Q4rbZ1XLgnJ1KpSuRlw2ccHDW0fMcKtQ1qcw}
       - VAPID_SUBJECT=mailto:push@rmaps.online
+      # Automatic location request interval (ms) - 0 to disable
+      - LOCATION_REQUEST_INTERVAL=60000
     labels:
       - "traefik.enable=true"
       # HTTP router (redirects to HTTPS via Cloudflare)

sync-server/server.js

@@ -6,6 +6,7 @@ import webpush from 'web-push';
 
 const PORT = process.env.PORT || 3001;
 const STALE_THRESHOLD_MS = 60 * 60 * 1000; // 1 hour
+const LOCATION_REQUEST_INTERVAL_MS = parseInt(process.env.LOCATION_REQUEST_INTERVAL || '60000', 10); // 60 seconds default
 
 // VAPID keys for push notifications
 // Generate with: npx web-push generate-vapid-keys
@@ -292,6 +293,51 @@ setInterval(() => {
   }
 }, 5 * 60 * 1000); // Every 5 minutes
 
+// Automatic location request - periodically ask all clients for location updates via silent push
+async function requestLocationFromAllRooms() {
+  if (!VAPID_PUBLIC_KEY || !VAPID_PRIVATE_KEY) return;
+
+  for (const [roomSlug, subs] of pushSubscriptions.entries()) {
+    if (subs.size === 0) continue;
+
+    const room = rooms.get(roomSlug);
+    // Only request if room has participants (active room)
+    if (!room || Object.keys(room.participants).length === 0) continue;
+
+    console.log(`[${roomSlug}] Requesting location from ${subs.size} subscribers`);
+
+    const failedEndpoints = [];
+    for (const sub of subs) {
+      try {
+        await webpush.sendNotification(sub, JSON.stringify({
+          silent: true,
+          data: { type: 'location_request', roomSlug }
+        }));
+      } catch (error) {
+        if (error.statusCode === 404 || error.statusCode === 410) {
+          failedEndpoints.push(sub.endpoint);
+        }
+      }
+    }
+
+    // Clean up failed subscriptions
+    for (const endpoint of failedEndpoints) {
+      for (const sub of subs) {
+        if (sub.endpoint === endpoint) {
+          subs.delete(sub);
+          console.log(`[${roomSlug}] Removed stale push subscription`);
+        }
+      }
+    }
+  }
+}
+
+// Start automatic location request interval
+if (VAPID_PUBLIC_KEY && VAPID_PRIVATE_KEY && LOCATION_REQUEST_INTERVAL_MS > 0) {
+  setInterval(requestLocationFromAllRooms, LOCATION_REQUEST_INTERVAL_MS);
+  console.log(`Automatic location requests enabled every ${LOCATION_REQUEST_INTERVAL_MS / 1000}s`);
+}
+
 // Parse JSON body from request
 async function parseJsonBody(req) {
   return new Promise((resolve, reject) => {