feat: enhance offline support with improved network management and sync handling

src/hooks/useSyncOnReconnect.js

@@ -10,6 +10,7 @@ import { networkManager } from './NetworkManager'
 
 const PENDING_POLL_MS = 30_000 // retry pending commands every 30s
 const CACHE_REFRESH_MS = 5 * 60_000 // refresh IDB cache every 5 min while online
+const SERVER_PROBE_MS = 15_000 // probe server when marked unreachable but device has network
 
 export function useSyncOnReconnect() {
   const queryClient = useQueryClient()
@@ -18,6 +19,7 @@ export function useSyncOnReconnect() {
   useEffect(() => {
     let pendingPollInterval
     let cacheRefreshInterval
+    let serverProbeInterval
     let resumeListener
     let networkListener
     const handleVisibilityChange = () => {
@@ -77,13 +79,27 @@ export function useSyncOnReconnect() {
       cacheRefreshInterval = setInterval(() => {
         runSync()
       }, CACHE_REFRESH_MS)
+
+      // 6. Probe server every 15s when server is unreachable but device has network
+      serverProbeInterval = setInterval(async () => {
+        if (!networkManager.isOnline && networkManager.deviceOnline) {
+          await runSync()
+        }
+      }, SERVER_PROBE_MS)
     }
 
     const runSync = async () => {
       if (!isOfflineFeatureEnabled()) return
+      const wasOffline = !networkManager.isOnline
       const didSync = await syncEngine.sync()
       if (didSync) {
         queryClient.invalidateQueries()
+        // After recovery from server-unreachable, run a second pass to flush
+        // any commands that were skipped while offline
+        if (wasOffline && networkManager.isOnline) {
+          const didSync2 = await syncEngine.sync()
+          if (didSync2) queryClient.invalidateQueries()
+        }
       }
     }
 
@@ -98,6 +114,10 @@ export function useSyncOnReconnect() {
         clearInterval(cacheRefreshInterval)
       }
 
+      if (serverProbeInterval) {
+        clearInterval(serverProbeInterval)
+      }
+
       if (networkListener) {
         networkManager.unregisterNetworkListener(networkListener)
       }