Enforce mutual exclusivity of SPI navigation handlers

.github/workflows/ci.yml

@@ -18,7 +18,7 @@ env:
   SIM_DEVICE: iPhone 17
   # Keep in sync with justfile's sim_os default. The Validate / Build & test
   # steps below interpolate $SIM_OS into the xcodebuild -destination string.
-  SIM_OS: "26.1"
+  SIM_OS: "26.2"
 
 jobs:
   ci:
@@ -58,8 +58,8 @@ jobs:
       - name: Install xcresultparser
         run: brew install xcresultparser
 
-      - name: Select Xcode 26.1.1
-        run: sudo xcode-select -s /Applications/Xcode_26.1.1.app/Contents/Developer
+      - name: Select Xcode 26.2
+        run: sudo xcode-select -s /Applications/Xcode_26.2.app/Contents/Developer
 
       # Cache only the SPM source packages, not the whole DerivedData tree.
       # Caching DerivedData also caches Clang's ModuleCache.noindex (.pcm
@@ -73,8 +73,8 @@ jobs:
         uses: actions/cache@v4
         with:
           path: ~/Library/Developer/Xcode/DerivedData/NanoViewController-*/SourcePackages
-          key: spm-${{ runner.os }}-xcode-26.1.1-${{ hashFiles('**/Package.resolved') }}
-          restore-keys: spm-${{ runner.os }}-xcode-26.1.1-
+          key: spm-${{ runner.os }}-xcode-26.2-${{ hashFiles('**/Package.resolved') }}
+          restore-keys: spm-${{ runner.os }}-xcode-26.2-
 
       - name: Runner info
         run: |

Examples/SignUpDemo/App/AppDelegate.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import UIKit
 

Examples/SignUpDemo/App/SceneDelegate.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import NanoViewControllerController
 import UIKit

Examples/SignUpDemo/Sources/AppCoordinator.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import NanoViewControllerController
 import NanoViewControllerNavigation

Examples/SignUpDemo/Sources/Home/HomeCoordinator.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import NanoViewControllerController
 import NanoViewControllerNavigation

Examples/SignUpDemo/Sources/Home/HomeScene.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import NanoViewControllerController
 

Examples/SignUpDemo/Sources/Home/HomeView.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import Combine
 import NanoViewControllerCombine

Examples/SignUpDemo/Sources/Home/HomeViewModel.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import Combine
 import NanoViewControllerController

Examples/SignUpDemo/Sources/Models/SignedUpUser.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import Foundation
 

Examples/SignUpDemo/Sources/Onboarding/OnboardingCoordinator.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import NanoViewControllerController
 import NanoViewControllerNavigation

Examples/SignUpDemo/Sources/Onboarding/SignUpScene.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import NanoViewControllerController
 

Examples/SignUpDemo/Sources/Onboarding/SignUpView.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import Combine
 import NanoViewControllerCombine

Examples/SignUpDemo/Sources/Onboarding/SignUpViewModel.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import Combine
 import Foundation

Examples/SignUpDemo/Sources/Services/DummySignUpService.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import Combine
 import Foundation

Examples/SignUpDemo/Sources/Services/SignUpServicing.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import Combine
 

Sources/NanoViewControllerCombine/Binder.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import Foundation
 

Sources/NanoViewControllerCombine/Publisher+Extras.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import Combine
 import Foundation

Sources/NanoViewControllerCombine/Publisher+Helpers.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import Combine
 import Foundation

Sources/NanoViewControllerCombine/Publisher+Operators.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import Combine
 import UIKit

Sources/NanoViewControllerCombine/UIControl+Publisher.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import Combine
 import UIKit

Sources/NanoViewControllerCombine/UIControl+Publishers.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import Combine
 import UIKit

Sources/NanoViewControllerCombine/UITextField+Publishers.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import Combine
 import UIKit

Sources/NanoViewControllerCombine/UIView+Publishers.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import UIKit
 

Sources/NanoViewControllerController/AbstractController.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import UIKit
 

Sources/NanoViewControllerController/AbstractViewModel.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import Combine
 import Foundation

Sources/NanoViewControllerController/BarButtonContent.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import UIKit
 

Sources/NanoViewControllerController/ContentView.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import NanoViewControllerCore
 import UIKit

Sources/NanoViewControllerController/ControllerConfig.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import Foundation
 

Sources/NanoViewControllerController/Coordinating+Child+ModalPresent.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import Combine
 import NanoViewControllerCombine

Sources/NanoViewControllerController/Coordinating+Child+Start.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import Combine
 import NanoViewControllerCombine

Sources/NanoViewControllerController/Coordinating+NanoViewController+NavigationHelpers.swift

@@ -1,13 +1,15 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import Combine
 import NanoViewControllerCombine
 import NanoViewControllerCore
 import NanoViewControllerNavigation
 
 extension Coordinating {
-    /// Subscribes the coordinator to the controller's navigation publisher and
-    /// stores the resulting cancellable on the coordinator's bag.
+    /// Subscribes to the controller's navigation publisher and stashes the
+    /// cancellable on the scene itself, so re-subscribing through the inverse
+    /// helper (see ``subscribeToModalNavigation(of:handler:)``) cancels this
+    /// subscription instead of letting both sinks fire on every emission.
     ///
     /// Used by the push-style hookup in
     /// ``Coordinating/pushSceneInstance(_:animated:navigationPresentationCompletion:navigationHandler:)``.
@@ -17,37 +19,50 @@ extension Coordinating {
     /// tests can invoke coordinator routing directly without driving the
     /// view-model's Combine pipeline. Production callers don't see this
     /// property unless they opt in via `@_spi(Testing) import`.
+    ///
+    /// Clears ``NanoViewController/modalNavigationHandler`` to keep the two
+    /// SPI hooks mutually exclusive — the live handler is whichever helper
+    /// last subscribed.
     func subscribeToNavigation<S: NanoViewController<V>, V: ContentView>(
         of scene: S,
         handler: @escaping (V.ViewModel.NavigationStep) -> Void
     ) {
         scene.navigationHandler = handler
-        scene.navigation
+        scene.modalNavigationHandler = nil
+        scene.navigationSubscription = scene.navigation
             .sinkOnMain { handler($0) }
-            .store(in: &cancellables)
     }
 
-    /// Subscribes the coordinator to the controller's navigation publisher and
-    /// hands the caller's handler a `DismissScene` callback that dismisses
-    /// the controller with optional animation. Used by the modal-style hookups in
+    /// Subscribes to the controller's navigation publisher and hands the
+    /// caller's handler a `DismissScene` callback that dismisses the
+    /// controller with optional animation. Used by the modal-style hookups in
     /// ``Coordinating/modallyPresent(scene:animated:presentationCompletion:navigationHandler:)``
     /// and ``Coordinating/replaceAllScenes(with:animated:whenReplacingFinished:navigationHandler:)``.
     ///
+    /// Like the push-style variant, the cancellable lives on the scene so
+    /// that re-subscribing through ``subscribeToNavigation(of:handler:)``
+    /// cancels this subscription rather than leaving two live sinks routing
+    /// every emission to both handlers.
+    ///
     /// Side effect: stashes `handler` on
     /// ``NanoViewController/modalNavigationHandler`` (an `@_spi(Testing)` hook).
     /// Tests pass a spy ``DismissScene`` when invoking the handler so the
     /// dismissal side-effect is observable without a real modal presentation.
+    ///
+    /// Clears ``NanoViewController/navigationHandler`` to keep the two SPI
+    /// hooks mutually exclusive — the live handler is whichever helper last
+    /// subscribed.
     func subscribeToModalNavigation<S: NanoViewController<V>, V: ContentView>(
         of scene: S,
         handler: @escaping ModalNavigationHandler<V.ViewModel>
     ) {
         scene.modalNavigationHandler = handler
-        scene.navigation
+        scene.navigationHandler = nil
+        scene.navigationSubscription = scene.navigation
             .sinkOnMain { [weak scene] step in
                 handler(step) { animated, completion in
                     scene?.dismiss(animated: animated, completion: completion)
                 }
             }
-            .store(in: &cancellables)
     }
 }

Sources/NanoViewControllerController/Coordinating+NanoViewController+Present.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import Combine
 import NanoViewControllerCombine

Sources/NanoViewControllerController/Coordinating+NanoViewController+Push.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import Combine
 import NanoViewControllerCombine

Sources/NanoViewControllerController/Coordinating+NanoViewController+Replace.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import Combine
 import NanoViewControllerCombine

Sources/NanoViewControllerController/Coordinating+NavigationStack.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import NanoViewControllerNavigation
 import UIKit

Sources/NanoViewControllerController/Coordinating+Stack.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import NanoViewControllerCore
 import NanoViewControllerNavigation

Sources/NanoViewControllerController/InputFromController.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import Combine
 import Foundation

Sources/NanoViewControllerController/InputType.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import Foundation
 

Sources/NanoViewControllerController/NanoViewController+BarButtonContent.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import NanoViewControllerCore
 import UIKit

Sources/NanoViewControllerController/NanoViewController.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import Combine
 import NanoViewControllerCore
@@ -205,6 +205,18 @@ open class NanoViewController<View: ContentView>: UIViewController {
     @_spi(Testing)
     public internal(set) var modalNavigationHandler: ((ViewModel.NavigationStep, @escaping DismissScene) -> Void)?
 
+    /// The Combine subscription forwarding ``navigation`` into the
+    /// coordinator's routing closure (either ``navigationHandler`` or
+    /// ``modalNavigationHandler``).
+    ///
+    /// Lives on the scene rather than the coordinator's bag so that
+    /// re-subscribing through the inverse helper (push ↔ modal) cancels the
+    /// previous subscription — assigning a fresh `AnyCancellable` releases
+    /// (and cancels) the old one. This enforces "last subscriber wins" on
+    /// the Combine route, matching the mutual-exclusivity invariant the SPI
+    /// hook properties already promise.
+    var navigationSubscription: AnyCancellable?
+
     /// Clock used to auto-dismiss toasts emitted via
     /// ``InputFromController/toastSubject``.
     ///

Sources/NanoViewControllerController/NanoViewControllerWithoutVM.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import NanoViewControllerCore
 import UIKit

Sources/NanoViewControllerController/NavigationBarLayout.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import UIKit
 

Sources/NanoViewControllerController/NavigationBarLayoutingNavigationController.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import UIKit
 

Sources/NanoViewControllerController/Toast.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import NanoViewControllerDIPrimitives
 import NanoViewControllerNavigation

Sources/NanoViewControllerController/ViewModelType.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import Foundation
 import NanoViewControllerCore

Sources/NanoViewControllerController/ViewModelled.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import Combine
 import NanoViewControllerCombine

Sources/NanoViewControllerCore/AbstractTarget.swift

@@ -1,4 +1,4 @@
-// MIT License — Copyright (c) 2018-2026 Alexander Cyon (github.com/sajjon)
+// MIT License — Copyright (c) 2018-2026 Alexander Cyon - https://github.com/sajjon
 
 import Combine
 import Foundation