feat: spark emergency exit

Bitkit/AppScene.swift

@@ -609,6 +609,23 @@ struct AppScene: View {
                 await pubkyProfile.retrySessionRestoration()
             }
             .task(id: [scenePhase == .active, network.isConnected, wipeCoordinator.isGateUp]) { await pollIncomingPaykitPaymentRequests() }
+            .task(id: [scenePhase == .active, SparkExitManager.shared.needsDriving]) {
+                guard scenePhase == .active else { return }
+                await SparkExitManager.shared.runWhileActive()
+            }
+            .task(id: [
+                SparkExitManager.shared.opensProgress,
+                SparkExitManager.shared.showsResult,
+                isLockedForDeepLinks,
+                wallet.walletExists == true,
+            ]) {
+                // A tapped exit notification opens the exit once the wallet is unlocked and its record is loaded.
+                let exit = SparkExitManager.shared
+                guard exit.opensProgress, exit.showsResult, wallet.walletExists == true, !isLockedForDeepLinks else { return }
+                exit.opensProgress = false
+                navigation.reset()
+                navigation.navigate(.sparkExitProgress)
+            }
             .task(id: foregroundContactSession) {
                 shopContactImport?.task.cancel()
                 shopContactImport = nil

Bitkit/BitkitApp.swift

@@ -73,6 +73,7 @@ class AppDelegate: NSObject, UIApplicationDelegate {
     func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]? = nil) -> Bool
     {
         UNUserNotificationCenter.current().delegate = self
+        SparkExitManager.registerBackgroundTask()
 
         // Check notification authorization status at launch and re-register with APN if granted
         UNUserNotificationCenter.current().getNotificationSettings { settings in
@@ -163,6 +164,8 @@ extension AppDelegate: UNUserNotificationCenterDelegate {
                 PaykitSubscriptionNotificationTargetStore.save(target)
             }
             NotificationCenter.default.post(name: .paykitSubscriptionPaymentDue, object: nil, userInfo: userInfo)
+        } else if userInfo["bitkit_action"] as? String == SparkExitManager.notificationAction {
+            Task { @MainActor in SparkExitManager.shared.opensProgress = true }
         } else {
             PushNotificationManager.shared.handleNotification(userInfo)
         }

Bitkit/Constants/Env.swift

@@ -295,6 +295,20 @@ enum Env {
             .appendingPathComponent("wallet\(walletIndex)/spark-exit-restore.json")
     }
 
+    /// The running Spark emergency exit, if any: its signed recovery and how far it got.
+    static func sparkExitRecord(walletIndex: Int) -> URL {
+        appStorageUrl
+            .appendingPathComponent(networkName)
+            .appendingPathComponent("wallet\(walletIndex)/spark-exit.json")
+    }
+
+    /// The leaves an older state of the wallet claimed in an earlier Spark exit, kept out of every later one.
+    static func sparkExitLostLeaves(walletIndex: Int) -> URL {
+        appStorageUrl
+            .appendingPathComponent(networkName)
+            .appendingPathComponent("wallet\(walletIndex)/spark-exit-lost-leaves.json")
+    }
+
     /// Breez SDK API key, set with the `BREEZ_API_KEY` build setting. Spark on mainnet needs it; its regtest does not.
     static var breezApiKey: String? {
         infoPlistValue("BREEZ_API_KEY")

Bitkit/Info.plist

@@ -2,6 +2,16 @@
 <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
 <plist version="1.0">
 <dict>
+	<key>BGTaskSchedulerPermittedIdentifiers</key>
+	<array>
+		<string>to.bitkit.spark-exit</string>
+		<string>to.bitkit.spark-exit.processing</string>
+	</array>
+	<key>UIBackgroundModes</key>
+	<array>
+		<string>fetch</string>
+		<string>processing</string>
+	</array>
 	<key>UIDesignRequiresCompatibility</key>
 	<true/>
 	<key>USDT_BRIDGE_NETWORKS</key>

Bitkit/MainNavView.swift

@@ -705,6 +705,12 @@ struct MainNavView: View {
                 case .connections: LightningConnectionsView()
                 case let .connectionDetail(channelId): LightningConnectionDetailView(channelId: channelId)
                 case .sparkConnectionDetail: SparkConnectionDetailView()
+                case .sparkExitIntro: SparkExitIntroView()
+                case .sparkExitQuote: SparkExitQuoteView()
+                case .sparkExitFunding: SparkExitFundingView()
+                case .sparkExitConfirm: SparkExitConfirmView()
+                case .sparkExitProgress: SparkExitProgressView()
+                case .sparkExitFeeBump: SparkExitFeeBumpView()
                 case let .closeConnection(channel: channel): CloseConnectionConfirmation(channel: channel)
                 case .node: NodeStateView()
                 case .electrumSettings: ElectrumSettingsScreen()

Bitkit/Managers/BalanceManager.swift

@@ -144,6 +144,11 @@ class BalanceManager {
         var pendingAmount: UInt64 = 0
 
         for transfer in transfers.filter({ $0.type.isToSavings() }) {
+            // A Spark exit has no channel: it is in transfer until its sweep confirms and the exit settles it.
+            if transfer.type == .sparkExit {
+                pendingAmount += transfer.amountSats
+                continue
+            }
             guard let channelId = transfer.channelId else { continue }
 
             let balanceFromLdk = balanceDetails.lightningBalances