Add iOS lifecycle hardening hooks

apps/ios/TeleTuiIOS/Sources/TeleTuiIOSCore/Lifecycle.swift

@@ -0,0 +1,53 @@
+import Foundation
+
+public enum AppLifecycleState: Equatable, Sendable {
+    case foreground
+    case background
+}
+
+public struct ScopedSessionEvent: Equatable, Sendable {
+    public var accountId: String
+    public var generation: Int
+    public var event: SessionEvent
+
+    public init(accountId: String, generation: Int, event: SessionEvent) {
+        self.accountId = accountId
+        self.generation = generation
+        self.event = event
+    }
+}
+
+@MainActor
+public final class SessionLifecycleCoordinator: ObservableObject {
+    @Published public private(set) var lifecycleState: AppLifecycleState = .foreground
+    @Published public private(set) var activeAccountId: String
+    @Published public private(set) var generation = 0
+
+    public init(activeAccountId: String) {
+        self.activeAccountId = activeAccountId
+    }
+
+    public var shouldPollEvents: Bool {
+        lifecycleState == .foreground
+    }
+
+    public func enterBackground() {
+        lifecycleState = .background
+    }
+
+    public func enterForeground() {
+        lifecycleState = .foreground
+    }
+
+    public func switchAccount(to accountId: String) {
+        guard accountId != activeAccountId else {
+            return
+        }
+        activeAccountId = accountId
+        generation += 1
+    }
+
+    public func accepts(_ event: ScopedSessionEvent) -> Bool {
+        event.accountId == activeAccountId && event.generation == generation
+    }
+}

apps/ios/TeleTuiIOS/Sources/TeleTuiIOSSmokeTests/main.swift

@@ -9,6 +9,7 @@ struct TeleTuiIOSSmokeTests {
         try await chatDetailLoadsAndSendsMessage()
         try await messageActionsCoverEditReplyForwardReactDeleteSearchAndCopy()
         try await platformServicesCoverNotificationsMediaVoiceClipboardAndAccounts()
+        lifecycleCoordinatorDropsStaleAccountEvents()
         try await profileLoadsFromSelectedChat()
         appStorageUsesApplicationSupportStyleAccountPaths()
         print("TeleTuiIOS smoke tests passed")
@@ -141,6 +142,35 @@ struct TeleTuiIOSSmokeTests {
         precondition(switcher.activeAccount.databasePath.path.hasSuffix("/Accounts/work/tdlib"))
     }
 
+    @MainActor
+    private static func lifecycleCoordinatorDropsStaleAccountEvents() {
+        let coordinator = SessionLifecycleCoordinator(activeAccountId: "personal")
+        precondition(coordinator.shouldPollEvents)
+
+        coordinator.enterBackground()
+        precondition(!coordinator.shouldPollEvents)
+
+        coordinator.enterForeground()
+        precondition(coordinator.shouldPollEvents)
+
+        let oldGenerationEvent = ScopedSessionEvent(
+            accountId: "personal",
+            generation: coordinator.generation,
+            event: .authChanged(.ready)
+        )
+        precondition(coordinator.accepts(oldGenerationEvent))
+
+        coordinator.switchAccount(to: "work")
+        precondition(!coordinator.accepts(oldGenerationEvent))
+
+        let newGenerationEvent = ScopedSessionEvent(
+            accountId: "work",
+            generation: coordinator.generation,
+            event: .authChanged(.ready)
+        )
+        precondition(coordinator.accepts(newGenerationEvent))
+    }
+
     @MainActor
     private static func profileLoadsFromSelectedChat() async throws {
         let bridge = FakeSessionBridge(auth: .ready)