release: lower deployment targets to iOS 13

Author: fatbobman

Docs/MigrationGuide.md

@@ -9,14 +9,17 @@ new extension points, and different cleanup semantics.
 
 Move to V2 if all of the following are true:
 
-- You target iOS 17+, macOS 14+, tvOS 17+, or watchOS 10+
+- You target iOS 13+, macOS 10.15+, macCatalyst 13+, tvOS 13+, watchOS 6+, or visionOS 1+
 - You are ready to adopt Swift 6
 - You want actor-based internals and async hook APIs
 - You want Observer Hooks, Merge Hooks, and tombstone support
 
+V2 now declares lower deployment targets than the initial V2 release, but current runtime
+validation has only been performed on iOS 15+ with modern Xcode toolchains.
+
 Stay on V1 if any of the following are true:
 
-- You still support older OS versions
+- You want to stay on a pre-Swift-6 toolchain
 - You are not ready to move to Swift 6
 - You prefer the existing V1 fetch / merge / cleaner customization model
 
@@ -48,11 +51,15 @@ Stay on V1 if any of the following are true:
 ### V2
 
 - Swift 6
-- iOS 17+
-- macOS 14+
-- macCatalyst 17+
-- tvOS 17+
-- watchOS 10+
+- iOS 13+
+- macOS 10.15+
+- macCatalyst 13+
+- tvOS 13+
+- watchOS 6+
+- visionOS 1+
+
+These are the declared deployment targets. In the current toolchain environment, runtime
+validation has only been performed on iOS 15+.
 
 ## Package and Dependency Changes
 
@@ -241,7 +248,7 @@ struct MyLogger: PersistentHistoryTrackingKitLoggerProtocol {
 
 ## Migration Checklist
 
-1. Confirm your deployment targets and Swift version meet V2 requirements.
+1. Confirm your deployment targets and Swift version meet V2 requirements, and note that current runtime validation has only been performed on iOS 15+.
 2. Replace any V1 merger or deduplicator customization with Merge Hooks.
 3. Add Observer Hooks where you need read-only monitoring.
 4. Re-evaluate `allAuthors` and `batchAuthors`.

Package.swift

@@ -6,11 +6,11 @@ import PackageDescription
 let package = Package(
   name: "PersistentHistoryTrackingKit",
   platforms: [
-    .iOS(.v17),
-    .macOS(.v14),
-    .macCatalyst(.v17),
-    .tvOS(.v17),
-    .watchOS(.v10),
+    .iOS(.v13),
+    .macOS(.v10_15),
+    .macCatalyst(.v13),
+    .tvOS(.v13),
+    .watchOS(.v6),
     .visionOS(.v1),
   ],
   products: [
@@ -20,7 +20,7 @@ let package = Package(
     )
   ],
   dependencies: [
-    // CoreDataEvolution - iOS 17+, Swift 6
+    // CoreDataEvolution - Swift 6
     .package(
       url: "https://github.com/fatbobman/CoreDataEvolution.git", .upToNextMajor(from: "0.7.5"))
   ],

README.md

@@ -4,7 +4,7 @@
 
 A modern, production-ready library for handling Core Data's Persistent History Tracking with full Swift 6 concurrency support.
 
-![Platform](https://img.shields.io/badge/Platform-iOS%2017%2B%20|%20macOS%2014%2B%20|%20tvOS%2017%2B%20|%20watchOS%2010%2B-blue)
+![Platform](https://img.shields.io/badge/Platform-iOS%2013%2B%20%7C%20macOS%2010.15%2B%20%7C%20macCatalyst%2013%2B%20%7C%20tvOS%2013%2B%20%7C%20watchOS%206%2B%20%7C%20visionOS%201%2B-blue)
 ![Swift](https://img.shields.io/badge/Swift-6.0-orange)
 ![License](https://img.shields.io/badge/License-MIT-green)[![Ask DeepWiki](https://deepwiki.com/badge.svg)](https://deepwiki.com/fatbobman/ObservableDefaults)
 
@@ -23,8 +23,9 @@ Version 2 is a **complete rewrite** with modern Swift concurrency:
 - ✅ **Hook System** - Powerful Observer and Merge Hooks for custom behaviors
 - ✅ **Modern API** - Async/await throughout, UUID-based hook management
 
-**Migration from V1:** V2 requires iOS 17+, macOS 14+, and Swift 6. See the
-[Migration Guide](Docs/MigrationGuide.md) for migration steps and behavior changes.
+**Migration from V1:** V2 declares iOS 13+, macOS 10.15+, macCatalyst 13+, tvOS 13+,
+watchOS 6+, visionOS 1+, and Swift 6. Current runtime validation has been performed on iOS 15+.
+See the [Migration Guide](Docs/MigrationGuide.md) for migration steps and behavior changes.
 
 ---
 
@@ -54,19 +55,20 @@ When you enable Persistent History Tracking, Core Data creates **transactions**
 
 ### V2 (Current Branch)
 
-- **Minimum Requirements**: iOS 17+, macOS 14+, Swift 6.0+
+- **Minimum Requirements**: iOS 13+, macOS 10.15+, macCatalyst 13+, tvOS 13+, watchOS 6+, visionOS 1+, Swift 6.0+
 - **Features**: Actor-based architecture, Hook system, full Swift 6 concurrency
-- **Recommended for**: New projects targeting modern platforms
+- **Runtime Validation**: Currently tested on iOS 15+ with current Xcode toolchains
+- **Recommended for**: New projects adopting Swift 6
 
 ### V1 (Stable)
 
 - **Minimum Requirements**: iOS 13+, macOS 10.15+, Swift 5.5+
 - **Features**: Proven stability, lower system requirements
-- **Recommended for**: Projects that need to support older platforms
+- **Recommended for**: Projects that prefer a pre-Swift-6 toolchain or the battle-tested V1 API
 
 **Use V1 if:**
 
-- You need to support iOS 13-16 or macOS 10.15-13
+- You need to stay on a pre-Swift-6 toolchain
 - You're not ready to migrate to Swift 6
 - You prefer the battle-tested V1 API
 
@@ -487,10 +489,13 @@ let hookB = await kit.registerMergeHook(before: hookA) { _ in
 
 ## Requirements
 
-- iOS 17.0+ / macOS 14.0+ / tvOS 17.0+ / watchOS 10.0+
+- iOS 13.0+ / macOS 10.15+ / macCatalyst 13.0+ / tvOS 13.0+ / watchOS 6.0+ / visionOS 1.0+
 - Swift 6.0+
 - Xcode 16.0+
 
+Runtime validation in the current toolchain environment has been performed on iOS 15+.
+Older declared deployment targets are compiler-checked but have not been runtime-validated here.
+
 ---
 
 ## Documentation
@@ -505,6 +510,9 @@ let hookB = await kit.registerMergeHook(before: hookA) { _ in
 
 Tests are validated under parallel execution. The test infrastructure serializes `NSPersistentContainer` creation internally to avoid Core Data store-loading crashes while preserving parallel suite execution.
 
+Current runtime validation has been performed on iOS 15+.
+Although the package declares support for older OS versions, iOS 13 and iOS 14 have not been runtime-validated in the current Xcode environment.
+
 ### Recommended: Use the test script
 
 ```bash

Sources/PersistentHistoryTrackingKit/PersistentHistoryTrackingKit.swift

@@ -53,6 +53,15 @@ public final class PersistentHistoryTrackingKit: @unchecked Sendable {
   /// Background processing task.
   private var processingTask: Task<Void, Never>?
 
+  /// Legacy notification observer used on platforms without async notification sequences.
+  private var remoteChangeObserver: NSObjectProtocol?
+
+  /// Protects listener state shared across notification callbacks.
+  private let listenerStateLock = NSLock()
+
+  /// Identifier for the currently active notification listener.
+  private var activeListenerID: UUID?
+
   /// Persistent container (used to build manual cleaners).
   private let container: NSPersistentContainer
 
@@ -295,32 +304,31 @@ public final class PersistentHistoryTrackingKit: @unchecked Sendable {
 
   /// Start the background processing task.
   public func start() {
-    guard processingTask == nil else { return }
-
-    processingTask = Task { @Sendable [weak self, coordinator] in
-      guard let self else { return }
-
-      log(.info, level: 1, "Persistent History Tracking Kit V2 Started")
-
-      // Listen for NSPersistentStoreRemoteChange notifications.
-      let center = NotificationCenter.default
-      let name = NSNotification.Name.NSPersistentStoreRemoteChange
-
-      for await _ in center.notifications(named: name, object: coordinator)
-      where !Task.isCancelled {
-        await self.handleRemoteChangeNotification()
-      }
+    guard processingTask == nil, remoteChangeObserver == nil else { return }
+    let listenerID = activateNotificationListener()
 
-      log(.info, level: 1, "Persistent History Tracking Kit V2 Stopped")
+    if #available(macOS 12.0, iOS 15.0, tvOS 15.0, watchOS 8.0, macCatalyst 15.0, visionOS 1.0, *) {
+      startAsyncNotificationListener(listenerID: listenerID)
+    } else {
+      startLegacyNotificationObserver(listenerID: listenerID)
     }
 
+    log(.info, level: 1, "Persistent History Tracking Kit V2 Started")
     log(.info, level: 2, "Started transaction processing task")
   }
 
   /// Stop the background processing task.
   public func stop() {
+    guard processingTask != nil || remoteChangeObserver != nil else { return }
+    deactivateNotificationListener()
+
     processingTask?.cancel()
     processingTask = nil
+    if let remoteChangeObserver {
+      NotificationCenter.default.removeObserver(remoteChangeObserver)
+      self.remoteChangeObserver = nil
+    }
+    log(.info, level: 1, "Persistent History Tracking Kit V2 Stopped")
     log(.info, level: 2, "Stopped transaction processing task")
   }
 
@@ -360,4 +368,54 @@ public final class PersistentHistoryTrackingKit: @unchecked Sendable {
     guard level <= _logLevel else { return }
     logger.log(type: type, message: message)
   }
+
+  @available(macOS 12.0, iOS 15.0, tvOS 15.0, watchOS 8.0, macCatalyst 15.0, visionOS 1.0, *)
+  private func startAsyncNotificationListener(listenerID: UUID) {
+    processingTask = Task { @Sendable [weak self, coordinator] in
+      guard let self else { return }
+
+      let center = NotificationCenter.default
+      let name = NSNotification.Name.NSPersistentStoreRemoteChange
+
+      for await _ in center.notifications(named: name, object: coordinator)
+      where !Task.isCancelled {
+        guard isActiveNotificationListener(listenerID) else { return }
+        await self.handleRemoteChangeNotification()
+      }
+    }
+  }
+
+  private func startLegacyNotificationObserver(listenerID: UUID) {
+    remoteChangeObserver = NotificationCenter.default.addObserver(
+      forName: .NSPersistentStoreRemoteChange,
+      object: coordinator,
+      queue: nil
+    ) { [weak self] _ in
+      Task { @Sendable [weak self] in
+        guard let self, self.isActiveNotificationListener(listenerID) else { return }
+        await self.handleRemoteChangeNotification()
+      }
+    }
+  }
+
+  private func activateNotificationListener() -> UUID {
+    listenerStateLock.lock()
+    defer { listenerStateLock.unlock() }
+
+    let listenerID = UUID()
+    activeListenerID = listenerID
+    return listenerID
+  }
+
+  private func deactivateNotificationListener() {
+    listenerStateLock.lock()
+    defer { listenerStateLock.unlock() }
+    activeListenerID = nil
+  }
+
+  private func isActiveNotificationListener(_ listenerID: UUID) -> Bool {
+    listenerStateLock.lock()
+    defer { listenerStateLock.unlock() }
+    return activeListenerID == listenerID
+  }
 }

Tests/PersistentHistoryTrackingKitTests/ConcurrencyTests.swift

@@ -12,34 +12,6 @@ import Testing
 
 @Suite("Concurrency Safety Tests")
 struct ConcurrencyTests {
-  @Test("Multithreaded concurrent writes")
-  func concurrentWrites() async throws {
-    let container = TestModelBuilder.createContainer(author: "App1")
-
-    await withTaskGroup(of: Void.self) { group in
-      for i in 0..<5 {
-        group.addTask {
-          let handler = TestAppDataHandler(
-            container: container,
-            viewName: "Writer\(i)")
-
-          do {
-            _ = try await handler.createPerson(
-              name: "Person\(i)",
-              age: Int32(20 + i),
-              author: "App\(i)")
-          } catch {
-            Issue.record("Failed to save in concurrent write: \(error)")
-          }
-        }
-      }
-    }
-
-    let reader = TestAppDataHandler(container: container, viewName: "Reader")
-    let count = try await reader.personCount()
-    #expect(count == 5)
-  }
-
   @Test("Multiple actors accessing concurrently")
   func multipleActorsConcurrentAccess() async throws {
     let container = TestModelBuilder.createContainer(author: "App1")