Improved the Capturing protocol in the Recording package target to capture interruptions and pause any active capture process.

Packages/Features/Sources/Recording/Protocols/Capturing.swift

@@ -6,6 +6,13 @@ import Foundation
 /// state machine — for example, with a real microphone backend in the app, or with a mock in unit tests.
 public protocol Capturing: Sendable {
 
+    // MARK: Properties
+
+    /// The stream of events the service emits outside its method calls.
+    ///
+    /// Defaults to an empty stream that finishes immediately, for services that emit no events.
+    var events: AsyncStream<CapturingEvent> { get }
+
     // MARK: Methods
 
     /// Starts a new audio recording from the microphone.
@@ -23,3 +30,24 @@ public protocol Capturing: Sendable {
     func stop() async throws -> URL
 
 }
+
+// MARK: - Implementations
+
+public extension Capturing {
+
+    /// The empty stream of events, which finishes immediately, for services that emit no events.
+    var events: AsyncStream<CapturingEvent> {
+        AsyncStream { continuation in
+            continuation.finish()
+        }
+    }
+
+}
+
+// MARK: - Events
+
+/// An event emitted by a ``Capturing`` service outside its method calls.
+public enum CapturingEvent: Sendable {
+    /// The system interrupted the ongoing capture, pausing it.
+    case interrupted
+}

Packages/Features/Sources/Recording/Services/AudioCapturing.swift

@@ -4,24 +4,66 @@ import AVFoundation
 ///
 /// The service records into a temporary `.m4a` file through an `AVAudioRecorder`, and returns the file's location when the recording stops.
 /// The user's permission to record is requested before a recording starts and, on the platforms that require it, the shared audio session is
-/// configured for recording while the capture is in progress.
+/// configured for recording while the capture is in progress. When the system interrupts the session while a recording is in progress —
+/// because of a phone call or Siri, for example — the service emits ``CapturingEvent/interrupted`` through ``events``.
 @MainActor
 public final class AudioCapturing: Capturing {
 
     // MARK: Properties
 
+    /// The stream of events the service emits outside its method calls.
+    public let events: AsyncStream<CapturingEvent>
+
+    /// The continuation that feeds ``events``.
+    private let continuation: AsyncStream<CapturingEvent>.Continuation
+
     /// The recorder that captures the audio from the microphone into a temporary file.
     private var recorder: AVAudioRecorder?
 
+    #if os(iOS) || os(visionOS)
+    /// The task that observes the interruptions of the audio session while the service lives.
+    private var taskInterruptions: Task<Void, Never>?
+    #endif
+
     // MARK: Initializers
 
     /// Creates an audio recording service.
-    public init() {}
+    public init() {
+        (events, continuation) = AsyncStream.makeStream(of: CapturingEvent.self)
+
+        #if os(iOS) || os(visionOS)
+        taskInterruptions = Task { [weak self] in
+            let notifications = NotificationCenter.default.notifications(
+                named: AVAudioSession.interruptionNotification,
+                object: AVAudioSession.sharedInstance()
+            )
+
+            for await notification in notifications {
+                guard let self else {
+                    return
+                }
+
+                self.handleInterruption(notification)
+            }
+        }
+        #endif
+    }
+
+    deinit {
+        #if os(iOS) || os(visionOS)
+        taskInterruptions?.cancel()
+        #endif
+
+        continuation.finish()
+    }
 
     // MARK: Methods
 
     /// Starts a new audio recording from the microphone.
     ///
+    /// On the platforms that require an audio session, the session is deactivated again when the recorder fails to start after
+    /// the session was activated.
+    ///
     /// - Throws: ``AudioCapturingError/permissionNotGranted`` when the user denies the app access to the microphone,
     /// ``AudioCapturingError/captureNotStarted`` when the recorder fails to start, or any error thrown while configuring
     /// the audio session or creating the recorder.
@@ -37,16 +79,24 @@ public final class AudioCapturing: Capturing {
         try session.setActive(true)
         #endif
 
-        let recorder = try AVAudioRecorder(
-            url: Constant.File.url,
-            settings: Constant.Audio.settings
-        )
+        do {
+            let recorder = try AVAudioRecorder(
+                url: Constant.File.url,
+                settings: Constant.Audio.settings
+            )
 
-        guard recorder.record() else {
-            throw AudioCapturingError.captureNotStarted
+            guard recorder.record() else {
+                throw AudioCapturingError.captureNotStarted
+            }
+
+            self.recorder = recorder
+        } catch {
+            #if os(iOS) || os(visionOS)
+            try? AVAudioSession.sharedInstance().setActive(false)
+            #endif
+
+            throw error
         }
-
-        self.recorder = recorder
     }
 
     /// Pauses the ongoing recording.
@@ -95,6 +145,33 @@ public final class AudioCapturing: Capturing {
 
 }
 
+#if os(iOS) || os(visionOS)
+// MARK: - Helpers
+
+private extension AudioCapturing {
+
+    /// Handles an interruption notification of the audio session, emitting ``CapturingEvent/interrupted`` through ``events``
+    /// when the system began interrupting an ongoing recording. The end of an interruption is deliberately ignored: the capture is
+    /// never resumed without the user asking for it.
+    ///
+    /// - Parameter notification: The interruption notification posted by the audio session.
+    func handleInterruption(
+        _ notification: Notification
+    ) {
+        guard
+            recorder != nil,
+            let typeValue = notification.userInfo?[AVAudioSessionInterruptionTypeKey] as? UInt,
+            AVAudioSession.InterruptionType(rawValue: typeValue) == .began
+        else {
+            return
+        }
+
+        continuation.yield(.interrupted)
+    }
+
+}
+#endif
+
 // MARK: - Errors
 
 /// The errors thrown by ``AudioCapturing``.

Packages/Features/Sources/Recording/View Models/RecordingViewModel.swift

@@ -47,6 +47,10 @@ extension RecordingView {
         @ObservationIgnored
         private var taskCapturer: Task<Void, Never>?
 
+        /// The task that listens to the events emitted by the capturing service, or `nil` until the first recording starts.
+        @ObservationIgnored
+        private var taskEvents: Task<Void, Never>?
+
         /// The task that updates ``elapsedSeconds`` from the measured recording time once per second while recording.
         @ObservationIgnored
         private var taskTimer: Task<Void, Never>?
@@ -130,16 +134,11 @@ extension RecordingView {
             case .notRecording:
                 state = .recording
 
+                listenToEvents()
                 startTimer(true)
                 startCapturer(true)
             case .recording:
-                state = .paused
-
-                stopTimer()
-
-                enqueueCapturer {
-                    try? await self.capturer.pause()
-                }
+                pauseRecording()
             case .paused:
                 state = .recording
 
@@ -224,6 +223,40 @@ private extension RecordingView.Model {
         }
     }
 
+    /// Starts listening to the events emitted by the capturing service, unless already listening: an interruption of the capture pauses
+    /// an ongoing recording, exactly like a press of the main button would.
+    func listenToEvents() {
+        guard taskEvents == nil else {
+            return
+        }
+
+        taskEvents = Task { [weak self, events = capturer.events] in
+            for await event in events {
+                guard let self else {
+                    return
+                }
+
+                switch event {
+                case .interrupted:
+                    if state == .recording {
+                        pauseRecording()
+                    }
+                }
+            }
+        }
+    }
+
+    /// Pauses the ongoing recording: it stops the timer and pauses the audio capture.
+    func pauseRecording() {
+        state = .paused
+
+        stopTimer()
+
+        enqueueCapturer {
+            try? await self.capturer.pause()
+        }
+    }
+
     /// Starts the audio capture through the attached ``Capturing``, falling back to the not-recording state when the service fails.
     ///
     /// - Parameter isNewRecording: Whether a new recording should be started, as opposed to a paused one being resumed.

Packages/Features/Tests/Recording/Mocks/CapturingMock.swift

@@ -6,6 +6,9 @@ import Recording
 @MainActor
 final class CapturingMock: Capturing {
 
+    /// The stream of events the service emits outside its method calls.
+    let events: AsyncStream<CapturingEvent>
+
     /// The duration every method takes before returning, simulating slow capture work.
     var delay: Duration = .zero
 
@@ -15,6 +18,18 @@ final class CapturingMock: Capturing {
     /// The names of the methods called on the service, in call order.
     private(set) var calls: [String] = []
 
+    /// The continuation that feeds ``events``.
+    private let continuation: AsyncStream<CapturingEvent>.Continuation
+
+    init() {
+        (events, continuation) = AsyncStream.makeStream(of: CapturingEvent.self)
+    }
+
+    /// Emits an interruption of the ongoing capture through ``events``.
+    func interrupt() {
+        continuation.yield(.interrupted)
+    }
+
     func start() async throws {
         try await called("start")
     }

Packages/Features/Tests/Recording/View Models/RecordingViewModelTests.swift

@@ -342,6 +342,47 @@ struct RecordingViewModelTests {
 
     }
 
+    // MARK: Interruptions
+
+    @MainActor
+    @Suite("Interruptions")
+    struct Interruptions {
+
+        @Test func `pauses an ongoing recording when the capture is interrupted`() async throws {
+            let capturer = CapturingMock()
+            let model = Model(capturer: capturer)
+
+            model.pressedMain()
+
+            try await Task.sleep(for: .seconds(0.1))
+
+            capturer.interrupt()
+
+            try await Task.sleep(for: .seconds(0.1))
+
+            #expect(model.state == .paused)
+            #expect(capturer.calls == ["start", "pause"])
+        }
+
+        @Test func `changes nothing when the capture is interrupted while paused`() async throws {
+            let capturer = CapturingMock()
+            let model = Model(capturer: capturer)
+
+            model.pressedMain()
+            model.pressedMain()
+
+            try await Task.sleep(for: .seconds(0.1))
+
+            capturer.interrupt()
+
+            try await Task.sleep(for: .seconds(0.1))
+
+            #expect(model.state == .paused)
+            #expect(capturer.calls == ["start", "pause"])
+        }
+
+    }
+
     // MARK: Processing
 
     @MainActor