Send new photos from iPhone with the app off screen

.github/workflows/ci.yml

@@ -4,6 +4,11 @@ on:
     branches: [main]
   pull_request:
   workflow_call:
+    inputs:
+      ios:
+        type: boolean
+        default: true
+        description: "Compile the iOS app (macOS runner)"
 concurrency:
   group: ci-${{ github.ref }}
   cancel-in-progress: true
@@ -41,3 +46,37 @@ jobs:
           dart pub get
           dart analyze --fatal-infos
           dart test --exclude-tags perf
+
+  # The Swift side (the background keep-alive engine) is only ever compiled
+  # here: there is no macOS in the development setup, so without this a build
+  # error would not show up until a release tag.
+  ios:
+    if: ${{ inputs.ios == null || inputs.ios }}
+    runs-on: macos-15
+    timeout-minutes: 45
+    steps:
+      - uses: actions/checkout@v4
+      - uses: subosito/flutter-action@v2
+        with:
+          channel: stable
+          flutter-version: "3.47.4"
+          cache: true
+      - uses: dtolnay/rust-toolchain@stable
+        with:
+          targets: aarch64-apple-ios
+      - uses: Swatinem/rust-cache@v2
+        with: { workspaces: packages/pepo_native/rust }
+      - name: Newest Xcode on the runner (plugins use the iOS 18.4+ SDK)
+        run: |
+          sudo xcode-select -s "$(ls -d /Applications/Xcode_*.app | sort -V | tail -n1)"
+          xcodebuild -version
+      - run: flutter pub get
+      - run: flutter build ios --release --no-codesign
+      - name: The background keys have to survive into the bundle
+        run: |
+          set -eu
+          plist=build/ios/iphoneos/Runner.app/Info.plist
+          read_key() { /usr/libexec/PlistBuddy -c "Print :$1" "$plist"; }
+          read_key UIBackgroundModes | grep -q audio
+          read_key BGTaskSchedulerPermittedIdentifiers | grep -q org.pepoconnect.app.sync
+          read_key NSBonjourServices | grep -q _pepoconnect._tcp

.github/workflows/release.yml

@@ -13,6 +13,9 @@ env:
 jobs:
   check:
     uses: ./.github/workflows/ci.yml
+    # This workflow builds iOS itself right below.
+    with:
+      ios: false
 
   windows:
     if: github.event_name == 'push' || inputs.windows

README.en.md

@@ -38,7 +38,12 @@ sideloading and is not an App Store download.
 ## What you can do
 
 - Browse your phone's gallery from your computer and download original files.
-- See newly taken photos while the devices are connected.
+- See newly taken photos as they happen, with the app closed. On Android a
+  foreground service keeps the engine alive; on iPhone the system audio mode
+  does (an inaudible silent loop that leaves your music alone). Whatever cannot
+  be sent right away — computer asleep, Wi-Fi gone — is kept and sent on
+  reconnect. Closing the app from the iPhone app switcher stops the engine
+  until you open it again.
 - Send files in both directions, resume interrupted transfers and connect
   several devices at once.
 - Share clipboard text. Android background clipboard restrictions still apply;

README.md

@@ -73,10 +73,16 @@ Capturas de la aplicación real.
   dispositivo (`Fotos/`, `Vídeos/`, `Archivos/`) o unificado desde Ajustes.
 - **Emparejamiento por QR** (móvil) o por código de 6 dígitos (PC↔PC), con
   reconexión automática.
-- **Sigue conectado con la app cerrada** (Android): con «Servicio en segundo
-  plano» activado, un servicio en primer plano mantiene vivo el motor aunque
-  cierres la ventana o la quites de recientes, y lo rearranca solo si Android
-  mata el proceso o reinicias el móvil.
+- **Sigue conectado con la app cerrada**: con «Servicio en segundo plano»
+  activado, haces una foto y llega al PC sin abrir PepoConnect. En Android, un
+  servicio en primer plano mantiene vivo el motor aunque cierres la ventana o
+  la quites de recientes, y lo rearranca solo si Android mata el proceso o
+  reinicias el móvil. En iPhone, PepoConnect se mantiene en marcha con el modo
+  de audio del sistema (un bucle de silencio inaudible que no interrumpe tu
+  música); si cierras la app desde el selector de apps o reinicias el iPhone,
+  las fotos pendientes esperan en cola y salen al volver a abrirla. Lo que no
+  se puede enviar en el momento —el PC apagado, la Wi-Fi caída— queda guardado
+  y se envía solo al reconectar.
 - **Portapapeles compartido**: un solo interruptor por pareja de dispositivos
   (se activa en cualquiera de los dos y vale para ambos sentidos). El PC lo
   envía al instante; Android no deja leer el portapapeles en segundo plano,
@@ -177,8 +183,12 @@ Segunda instancia en el mismo PC para probar: `flutter run -d windows --dart-ent
 2. Instálalo con Sideloadly (Windows) o AltStore con tu Apple ID.
 3. Con Apple ID gratuito la app caduca cada 7 días (AltServer la renueva
    sola si está en la misma Wi-Fi) y puedes tener 3 apps así a la vez.
-4. La primera vez, acepta el permiso de "Red local"; en iPhone las fotos
-   llegan al PC mientras PepoConnect está en pantalla.
+4. La primera vez, acepta el permiso de "Red local" y da acceso **completo** a
+   las fotos: con «Acceso limitado» iOS oculta las fotos nuevas y el envío
+   automático se queda sin nada que enviar (Ajustes › Este móvil avisa si pasa).
+5. Para que las fotos salgan con la app cerrada, deja activado «Servicio en
+   segundo plano» en Ajustes › Este móvil. «Estado del segundo plano» dice si
+   el motor está vivo y desde cuándo.
 
 ## Estructura
 

docs/packaging.md

@@ -213,8 +213,20 @@ vacío al lado.
   El proyecto usa Swift Package Manager para los plugins (no hay `Podfile`).
 - `ios/Runner/Info.plist`: `CFBundleDisplayName` PepoConnect, textos de uso de fototeca (leer y
   guardar), cámara y red local, `NSBonjourServices` (`_pepoconnect._tcp`), `UIBackgroundModes`
-  (`processing`), `UIFileSharingEnabled`, `LSSupportsOpeningDocumentsInPlace`,
-  `ITSAppUsesNonExemptEncryption=false` y el esquema de URL `pepoconnect`.
+  (`audio`, `fetch`, `processing`), `BGTaskSchedulerPermittedIdentifiers`
+  (`org.pepoconnect.app.refresh`, `org.pepoconnect.app.sync`), `UIFileSharingEnabled`,
+  `LSSupportsOpeningDocumentsInPlace`, `ITSAppUsesNonExemptEncryption=false` y el esquema de URL
+  `pepoconnect`. Ninguna de esas claves necesita entitlements, así que sobreviven a la refirma de
+  AltStore o Sideloadly con un Apple ID gratuito. El job `ios` de `ci.yml` comprueba que siguen en
+  el bundle compilado.
+- Segundo plano (`ios/Runner/PepoBackground.swift`): iOS no despierta una app suspendida al hacer
+  una foto —`PHPhotoLibraryChangeObserver` solo entrega a un proceso vivo y las `BGTask` son
+  oportunistas—, así que `KeepAlive` reproduce un bucle de silencio con la sesión de audio en
+  `.playback` + `.mixWithOthers` para que el proceso no llegue a suspenderse. `BackgroundHold`
+  envuelve las transferencias en un `beginBackgroundTask` y `BackgroundTasks` registra las dos
+  `BGTask` como red de seguridad. Todo se controla desde Dart por el canal `org.pepoconnect/native`
+  (`keepAliveStart`, `keepAliveStop`, `backgroundHold`, `backgroundStatus`, `backgroundReady`,
+  `backgroundTaskDone`, y `backgroundTask` en sentido contrario).
 - `ios/ExportOptions.plist`: exportación ad-hoc con firma manual; `packaging/ios/sign-and-export.sh`
   sustituye `TEAM_ID` y `PROFILE_NAME` con los secretos `IOS_TEAM_ID` y el nombre del perfil, y
   ejecuta `flutter build ipa --export-options-plist=ios/ExportOptions.plist`.
@@ -228,6 +240,10 @@ vacío al lado.
 - `linux/runner/my_application.cc`: título `PepoConnect`, tamaño por defecto 1100x700.
 - Scripts en `packaging/linux/`: `make-tarball.sh`, `make-appimage.sh`, `make-flatpak.sh`,
   `bundle-extra-libs.sh` (indicador de bandeja y libnotify), `install-desktop-entry.sh`.
+- Descubrimiento mDNS: `bonsoir_linux` habla con Avahi por el bus **de sistema**, así que el
+  manifiesto Flatpak lleva `--system-talk-name=org.freedesktop.Avahi`. Sin `avahi-daemon` no hay
+  anuncio ni exploración y queda solo el beacon UDP, que en Linux sigue activo; el iPhone, que no
+  puede usar UDP, dejaría de encontrar ese equipo.
 - Iconos: `flutter_launcher_icons` no soporta Linux. Los scripts copian a mano
   `assets/icon/pepoconnect-256.png` y `assets/icon/pepoconnect-512.png` como
   `org.pepoconnect.PepoConnect.png`; genera esos dos PNG junto con el resto.

integration_test/e2e_test.dart

@@ -101,4 +101,39 @@ void main() {
     await settle(tester);
     await pumpUntilFound(tester, find.text('Guion PepoTech.txt'));
   });
+
+  testWidgets('auto-send: photos leave the phone on their own, offline ones too', (tester) async {
+    final w = await E2eWorld.start(tester);
+    await tester.tap(find.text('Añadir móvil'));
+    await settle(tester);
+    final pc = await w.pairThroughQr(tester);
+    await pumpUntilFound(tester, find.text('Emparejado'), timeout: const Duration(seconds: 15));
+    await tester.tap(find.text('Empezar'));
+    await settle(tester);
+
+    // The phone forwards every new photo to this PC, with nobody watching.
+    await w.phone.setAutoSend(pc.deviceId, true);
+
+    final first = await w.takePhoto('IMG_AUTO_0001.jpg', r: 30, g: 200, b: 90);
+    final arrived = await waitForFile(tester, w.hubDownloads, 'IMG_AUTO_0001.jpg');
+    expect(await arrived.length(), await first.length());
+
+    // Taken with the PC away: it has to wait in the queue and go out when
+    // the connection comes back, not be dropped on the floor.
+    await w.phone.sessions.disconnect(pc.deviceId);
+    final offline = await w.takePhoto('IMG_AUTO_0002.jpg', r: 200, g: 40, b: 40);
+    await waitFor(tester, () {
+      final queue = w.phone.mediaServer?.autoSend;
+      return queue != null && queue.pendingCount > 0 ? true : null;
+    }, what: 'the offline photo waiting in the queue');
+
+    w.phone.reconnectAll();
+    final drained = await waitForFile(
+      tester,
+      w.hubDownloads,
+      'IMG_AUTO_0002.jpg',
+      timeout: const Duration(seconds: 60),
+    );
+    expect(await drained.length(), await offline.length());
+  });
 }

integration_test/support.dart

@@ -68,6 +68,8 @@ class E2eWorld {
         cacheDir: p.join(hubData, 'cache'),
       ),
       options: const LaunchOptions(profile: 'e2e', port: hubPort),
+      // Keep the test off the real network.
+      bonjour: false,
     );
 
     final phone = PepoEngine(

ios/Runner.xcodeproj/project.pbxproj

@@ -12,6 +12,7 @@
 		3B3967161E833CAA004F5970 /* AppFrameworkInfo.plist in Resources */ = {isa = PBXBuildFile; fileRef = 3B3967151E833CAA004F5970 /* AppFrameworkInfo.plist */; };
 		74858FAF1ED2DC5600515810 /* AppDelegate.swift in Sources */ = {isa = PBXBuildFile; fileRef = 74858FAE1ED2DC5600515810 /* AppDelegate.swift */; };
 		7884E8682EC3CC0700C636F2 /* SceneDelegate.swift in Sources */ = {isa = PBXBuildFile; fileRef = 7884E8672EC3CC0400C636F2 /* SceneDelegate.swift */; };
+		7B10A4022F1A55B000C636F2 /* PepoBackground.swift in Sources */ = {isa = PBXBuildFile; fileRef = 7B10A4012F1A55B000C636F2 /* PepoBackground.swift */; };
 		78A318202AECB46A00862997 /* FlutterGeneratedPluginSwiftPackage in Frameworks */ = {isa = PBXBuildFile; productRef = 78A3181F2AECB46A00862997 /* FlutterGeneratedPluginSwiftPackage */; };
 		97C146FC1CF9000F007C117D /* Main.storyboard in Resources */ = {isa = PBXBuildFile; fileRef = 97C146FA1CF9000F007C117D /* Main.storyboard */; };
 		97C146FE1CF9000F007C117D /* Assets.xcassets in Resources */ = {isa = PBXBuildFile; fileRef = 97C146FD1CF9000F007C117D /* Assets.xcassets */; };
@@ -50,6 +51,7 @@
 		74858FAD1ED2DC5600515810 /* Runner-Bridging-Header.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = "Runner-Bridging-Header.h"; sourceTree = "<group>"; };
 		74858FAE1ED2DC5600515810 /* AppDelegate.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = AppDelegate.swift; sourceTree = "<group>"; };
 		7884E8672EC3CC0400C636F2 /* SceneDelegate.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SceneDelegate.swift; sourceTree = "<group>"; };
+		7B10A4012F1A55B000C636F2 /* PepoBackground.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = PepoBackground.swift; sourceTree = "<group>"; };
 		78E0A7A72DC9AD7400C4905E /* FlutterGeneratedPluginSwiftPackage */ = {isa = PBXFileReference; lastKnownFileType = wrapper; name = FlutterGeneratedPluginSwiftPackage; path = Flutter/ephemeral/Packages/FlutterGeneratedPluginSwiftPackage; sourceTree = "<group>"; };
 		7AFA3C8E1D35360C0083082E /* Release.xcconfig */ = {isa = PBXFileReference; lastKnownFileType = text.xcconfig; name = Release.xcconfig; path = Flutter/Release.xcconfig; sourceTree = "<group>"; };
 		9740EEB21CF90195004384FC /* Debug.xcconfig */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.xcconfig; name = Debug.xcconfig; path = Flutter/Debug.xcconfig; sourceTree = "<group>"; };
@@ -123,6 +125,7 @@
 				1498D2331E8E89220040F4C2 /* GeneratedPluginRegistrant.m */,
 				74858FAE1ED2DC5600515810 /* AppDelegate.swift */,
 				7884E8672EC3CC0400C636F2 /* SceneDelegate.swift */,
+				7B10A4012F1A55B000C636F2 /* PepoBackground.swift */,
 				74858FAD1ED2DC5600515810 /* Runner-Bridging-Header.h */,
 			);
 			path = Runner;
@@ -284,6 +287,7 @@
 				74858FAF1ED2DC5600515810 /* AppDelegate.swift in Sources */,
 				1498D2341E8E89220040F4C2 /* GeneratedPluginRegistrant.m in Sources */,
 				7884E8682EC3CC0700C636F2 /* SceneDelegate.swift in Sources */,
+				7B10A4022F1A55B000C636F2 /* PepoBackground.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};

ios/Runner/AppDelegate.swift

@@ -10,6 +10,10 @@ import UIKit
     _ application: UIApplication,
     didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
   ) -> Bool {
+    // iOS refuses identifiers registered after launch finishes, so this has
+    // to happen before anything else asks for time.
+    PepoTasks.shared.register()
+    PepoTasks.shared.schedule()
     return super.application(application, didFinishLaunchingWithOptions: launchOptions)
   }
 
@@ -21,9 +25,10 @@ import UIKit
   }
 }
 
-/// The `org.pepoconnect/native` channel on iOS. Only `playWav` exists here:
-/// it plays a short 16-bit mono WAV (the transfer chime). Everything else
-/// answers "not implemented", which the Dart side treats as a no-op.
+/// The `org.pepoconnect/native` channel on iOS: the transfer chime and the
+/// background engine ([KeepAlive], [BackgroundHold], [PepoTasks]).
+/// Everything else answers "not implemented", which the Dart side treats as
+/// a no-op.
 final class PepoNativeChannel: NSObject, AVAudioPlayerDelegate {
   private let channel: FlutterMethodChannel
   private var players: [AVAudioPlayer] = []
@@ -45,12 +50,69 @@ final class PepoNativeChannel: NSObject, AVAudioPlayerDelegate {
           return
         }
         result(self.play(wav.data))
+      case "keepAliveStart":
+        result(KeepAlive.shared.start())
+      case "keepAliveStop":
+        KeepAlive.shared.stop()
+        result(nil)
+      case "backgroundHold":
+        let on = (call.arguments as? [String: Any])?["on"] as? Bool ?? false
+        BackgroundHold.shared.set(on)
+        result(BackgroundHold.shared.isHeld)
+      case "backgroundStatus":
+        result(self.status())
+      case "backgroundReady":
+        // Native → Dart calls made before the Dart handler exists sit in the
+        // channel buffer unanswered, so nothing is pushed until this arrives.
+        self.listenForTasks()
+        result(nil)
+      case "openAppSettings":
+        if let url = URL(string: UIApplication.openSettingsURLString) {
+          UIApplication.shared.open(url)
+        }
+        result(nil)
+      case "backgroundTaskDone":
+        let args = call.arguments as? [String: Any]
+        let identifier = args?["id"] as? String ?? ""
+        let ok = args?["ok"] as? Bool ?? true
+        PepoTasks.shared.complete(identifier, success: ok)
+        result(nil)
       default:
         result(FlutterMethodNotImplemented)
       }
     }
   }
 
+  private func listenForTasks() {
+    PepoTasks.shared.onTask = { [weak self] identifier in
+      self?.channel.invokeMethod("backgroundTask", arguments: ["id": identifier])
+    }
+    PepoTasks.shared.flush()
+  }
+
+  private func status() -> [String: Any] {
+    let engine = KeepAlive.shared
+    var out: [String: Any] = [
+      "running": engine.running,
+      "playing": engine.isPlaying,
+      "held": BackgroundHold.shared.isHeld,
+      "refresh": PepoNativeChannel.refreshState(),
+    ]
+    if let started = engine.startedAt {
+      out["startedAt"] = Int(started.timeIntervalSince1970 * 1000)
+    }
+    return out
+  }
+
+  private static func refreshState() -> String {
+    switch UIApplication.shared.backgroundRefreshStatus {
+    case .available: return "available"
+    case .denied: return "denied"
+    case .restricted: return "restricted"
+    @unknown default: return "unknown"
+    }
+  }
+
   private func play(_ data: Data) -> Bool {
     do {
       let player = try AVAudioPlayer(data: data, fileTypeHint: AVFileType.wav.rawValue)
@@ -65,5 +127,7 @@ final class PepoNativeChannel: NSObject, AVAudioPlayerDelegate {
 
   func audioPlayerDidFinishPlaying(_ player: AVAudioPlayer, successfully flag: Bool) {
     players.removeAll { $0 === player }
+    // Never deactivate the session here: the chime shares it with the
+    // keep-alive loop, and tearing it down would suspend the app.
   }
 }

ios/Runner/Info.plist

@@ -2,6 +2,11 @@
 <!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>org.pepoconnect.app.refresh</string>
+		<string>org.pepoconnect.app.sync</string>
+	</array>
 	<key>CADisableMinimumFrameDurationOnPhone</key>
 	<true/>
 	<key>CFBundleDevelopmentRegion</key>
@@ -80,6 +85,8 @@
 	<true/>
 	<key>UIBackgroundModes</key>
 	<array>
+		<string>audio</string>
+		<string>fetch</string>
 		<string>processing</string>
 	</array>
 	<key>UIFileSharingEnabled</key>