feat: run EventSync in background by scoping it to AccountViewModel

Move EventSyncViewModel from a screen-scoped ViewModel to a plain class
held by AccountViewModel (activity-scoped). The sync job now runs on
AccountViewModel's viewModelScope, so it continues when the user
navigates away. The back button no longer cancels the sync.

https://claude.ai/code/session_01U8qF9mK4UBvXsXP1zNMXfX

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/AccountViewModel.kt

@@ -79,6 +79,7 @@ import com.vitorpamplona.amethyst.ui.note.showAmount
 import com.vitorpamplona.amethyst.ui.note.showAmountInteger
 import com.vitorpamplona.amethyst.ui.screen.UiSettingsState
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.notifications.CombinedZap
+import com.vitorpamplona.amethyst.ui.screen.loggedIn.relays.eventsync.EventSyncViewModel
 import com.vitorpamplona.amethyst.ui.stringRes
 import com.vitorpamplona.amethyst.ui.tor.TorSettingsFlow
 import com.vitorpamplona.amethyst.ui.tor.TorType
@@ -175,6 +176,7 @@ class AccountViewModel(
     val toastManager = ToastManager()
     val broadcastTracker = BroadcastTracker()
     val feedStates = AccountFeedContentStates(account, viewModelScope)
+    val eventSyncViewModel = EventSyncViewModel(account, viewModelScope)
 
     val tempManualPaymentCache = LruCache<String, List<ZapPaymentHandler.Payable>>(5)
 

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/relays/eventsync/EventSyncScreen.kt

@@ -48,7 +48,6 @@ import androidx.compose.ui.text.font.FontWeight
 import androidx.compose.ui.text.style.TextOverflow
 import androidx.compose.ui.unit.dp
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
-import androidx.lifecycle.viewmodel.compose.viewModel
 import com.vitorpamplona.amethyst.R
 import com.vitorpamplona.amethyst.ui.navigation.navs.INav
 import com.vitorpamplona.amethyst.ui.navigation.topbars.TopBarWithBackButton
@@ -60,8 +59,7 @@ fun EventSyncScreen(
     accountViewModel: AccountViewModel,
     nav: INav,
 ) {
-    val syncViewModel: EventSyncViewModel =
-        viewModel(factory = EventSyncViewModel.Factory(accountViewModel.account))
+    val syncViewModel = accountViewModel.eventSyncViewModel
 
     val syncState by syncViewModel.syncState.collectAsStateWithLifecycle()
     val isMobileOrMetered by accountViewModel.settings.isMobileOrMeteredConnection.collectAsStateWithLifecycle()
@@ -70,10 +68,7 @@ fun EventSyncScreen(
         topBar = {
             TopBarWithBackButton(
                 caption = stringRes(R.string.event_sync_title),
-                popBack = {
-                    syncViewModel.cancel()
-                    nav.popBack()
-                },
+                popBack = nav::popBack,
             )
         },
     ) { padding ->

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/relays/eventsync/EventSyncViewModel.kt

@@ -21,15 +21,13 @@
  */
 package com.vitorpamplona.amethyst.ui.screen.loggedIn.relays.eventsync
 
-import androidx.lifecycle.ViewModel
-import androidx.lifecycle.ViewModelProvider
-import androidx.lifecycle.viewModelScope
 import com.vitorpamplona.amethyst.model.Account
 import com.vitorpamplona.quartz.nip01Core.core.Event
 import com.vitorpamplona.quartz.nip01Core.relay.client.reqs.IRequestListener
 import com.vitorpamplona.quartz.nip01Core.relay.client.single.newSubId
 import com.vitorpamplona.quartz.nip01Core.relay.filters.Filter
 import com.vitorpamplona.quartz.nip01Core.relay.normalizer.NormalizedRelayUrl
+import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.Job
 import kotlinx.coroutines.channels.Channel
@@ -47,10 +45,14 @@ import kotlinx.coroutines.withTimeoutOrNull
  *
  * The procedure iterates over every relay URL in LocalCache.relayHints.relayDB.
  * Events are deduplicated per destination to avoid redundant sends.
+ *
+ * Scoped to the AccountViewModel so the sync continues in the background while
+ * the user navigates to other screens or away from the app.
  */
 class EventSyncViewModel(
     val account: Account,
-) : ViewModel() {
+    private val scope: CoroutineScope,
+) {
     sealed class SyncState {
         object Idle : SyncState()
 
@@ -81,7 +83,7 @@ class EventSyncViewModel(
     fun start() {
         if (_syncState.value is SyncState.Running) return
         syncJob =
-            viewModelScope.launch(Dispatchers.IO) {
+            scope.launch(Dispatchers.IO) {
                 runSync()
             }
     }
@@ -276,11 +278,4 @@ class EventSyncViewModel(
         account.client.close(subId)
         done.close()
     }
-
-    class Factory(
-        val account: Account,
-    ) : ViewModelProvider.Factory {
-        @Suppress("UNCHECKED_CAST")
-        override fun <T : ViewModel> create(modelClass: Class<T>): T = EventSyncViewModel(account) as T
-    }
 }