Stabilize iOS reconnect and screen audio sessions

PROGRESS.md

@@ -45,6 +45,15 @@ because the voice-processing IO unit only stays up while the input is in the ren
 changes no longer force a rebuild; media-services resets still do, and the stall watchdog now
 backs off and stops after four failed attempts instead of rebuilding without end.
 
+An explicit disconnect now pauses the prepared iOS graph and releases the audio session; the
+next connection resumes that graph before attempting a rebuild. A signed iOS 26 simulator gate
+verified guest-to-account editing, saved-password login after a process restart, two voice joins,
+and a screen-audio stream started before the microphone. Screen sharing no longer forces a graph
+rebuild, and its pump subscribes before announcing the stream. An idle shared broadcast ring is
+no longer held mapped through suspension. A TestFlight report from build 2026092504 was an iOS
+`0xdead10cc` shared-file-lock termination; physical-device validation of that mitigation remains
+open.
+
 Voice-chat capture is not yet reliable on the first attempt: a graph with voice processing still
 sometimes fails to start and is only recovered by a watchdog rebuild, which costs seconds before
 audio appears. Speaker output is an explicit choice that no longer changes the preset. Every
@@ -75,6 +84,10 @@ cap the applied Opus hint at 30%, and feed it back over TLS.
 
 - Find why an iOS graph with voice processing intermittently starts and then stops within a
   second, so voice-chat capture comes up on the first attempt rather than after a watchdog rebuild.
+- On physical iOS 27 hardware, repeat account login after app restart, explicit disconnect and
+  reconnect, microphone permission denial, ReplayKit and ScreenCaptureKit sharing with and
+  without a joined microphone, and background/foreground transitions. Confirm the graph keeps
+  rendering and that `0xdead10cc` does not recur.
 - Run real multi-person calls on Windows, macOS, and physical iOS hardware, including adaptive
   20/40/60 ms buffering, duration-aware DRED/FEC, automatic packet-loss feedback, and mismatched
   input/output endpoints.

clients/apple/VoiceCat.iOS/AppDelegate.cs

@@ -9,6 +9,9 @@ internal sealed class AppDelegate : UIApplicationDelegate
     public override bool FinishedLaunching(UIApplication application, NSDictionary? launchOptions)
     {
         AppModel.Shared.Load();
+#if DEBUG
+        SimulatorSmoke.RunIfRequested();
+#endif
         return true;
     }
 

clients/apple/VoiceCat.iOS/AppModel.cs

@@ -51,6 +51,9 @@ internal sealed class AppModel
     internal bool IsConnecting { get; private set; }
     internal bool VoiceJoined => microphoneStream != 0;
     internal bool ScreenSharing => broadcast?.IsActive == true;
+#if DEBUG
+    internal bool ScreenRingMapped => broadcast?.IsMappingOpen == true;
+#endif
     internal bool IsBackgrounded => backgrounded;
     internal float MicrophoneLevel { get; private set; }
     internal string Status { get; private set; } = "Not connected";
@@ -162,7 +165,7 @@ internal sealed class AppModel
         }
         catch (Exception exception)
         {
-            System.Diagnostics.Debug.WriteLine($"Connection failed: {exception}");
+            Console.Error.WriteLine($"VoiceCat connection setup failed: {exception}");
             IsConnecting = false; Status = exception.Message;
             if (ReferenceEquals(client, next)) { client = null; await StopSessionResourcesAsync(releaseAudio: !restoring); }
             await next.DisposeAsync();
@@ -270,15 +273,35 @@ internal sealed class AppModel
         if (microphoneStream != 0)
         {
             IosAudioEngine.Shared.StopMicrophone(); active.StopStream(microphoneStream); microphoneStream = 0;
-            await active.SubscribeVoiceAsync(false); MicrophoneLevel = 0; feedback.Play(SoundEvent.VoiceOff); Notify(); return;
+            if (!ScreenSharing) await active.SubscribeVoiceAsync(false);
+            MicrophoneLevel = 0; feedback.Play(SoundEvent.VoiceOff); Notify(); return;
         }
-        if (AVFoundation.AVCaptureDevice.GetAuthorizationStatus(AVFoundation.AVAuthorizationMediaType.Audio) == AVFoundation.AVAuthorizationStatus.NotDetermined)
+        AVFoundation.AVAuthorizationStatus authorization = AVFoundation.AVCaptureDevice.GetAuthorizationStatus(AVFoundation.AVAuthorizationMediaType.Audio);
-            await AVFoundation.AVCaptureDevice.RequestAccessForMediaTypeAsync(AVFoundation.AVAuthorizationMediaType.Audio);
+        if (authorization == AVFoundation.AVAuthorizationStatus.NotDetermined)
+            authorization = await AVFoundation.AVCaptureDevice.RequestAccessForMediaTypeAsync(AVFoundation.AVAuthorizationMediaType.Audio)
+                ? AVFoundation.AVAuthorizationStatus.Authorized : AVFoundation.AVAuthorizationStatus.Denied;
+        if (authorization != AVFoundation.AVAuthorizationStatus.Authorized)
+            throw new InvalidOperationException("Microphone access is required to join voice. Allow it in iOS Settings.");
         VoiceSubscriptionResult subscribed = await active.SubscribeVoiceAsync();
         if (!subscribed.Ok) throw new InvalidOperationException(subscribed.Error);
+        uint startedStream = 0;
+        try
+        {
             int channels = IosAudioRouter.Shared.CaptureChannels;
             StreamInfo stream = await active.StartStreamAsync(StreamKind.StreamMic, "Microphone", channels);
-        microphoneStream = stream.StreamId; IosAudioEngine.Shared.StartMicrophone(stream.StreamId, channels); feedback.Play(SoundEvent.VoiceOn); Notify();
+            startedStream = stream.StreamId;
+            IosAudioEngine.Shared.StartMicrophone(stream.StreamId, channels);
+            microphoneStream = stream.StreamId; feedback.Play(SoundEvent.VoiceOn); Notify();
+        }
+        catch
+        {
+            IosAudioEngine.Shared.StopMicrophone();
+            if (startedStream != 0)
+                try { active.StopStream(startedStream); } catch (Exception exception) when (exception is IOException or InvalidOperationException or ObjectDisposedException) { }
+            if (!ScreenSharing)
+                try { await active.SubscribeVoiceAsync(false); } catch (Exception exception) when (exception is IOException or InvalidOperationException or ObjectDisposedException) { }
+            throw;
+        }
     }
 
     internal void ToggleScreenAudio()
@@ -390,10 +413,9 @@ internal sealed class AppModel
     {
         UIApplication.SharedApplication.BeginInvokeOnMainThread(() =>
         {
-            // Presenting either system picker can replace or interrupt the app's audio session.
+            // Presenting either picker can change the audio route. Keep a healthy graph; if the
-            // Rebuild after the producer becomes active so playback and an existing mic tap are
+            // picker stopped it, Recover resumes the same graph or rebuilds for changed hardware.
-            // attached to the session that will remain in use for the broadcast.
+            IosAudioRouter.Shared.Recover(ScreenSharing ? "screen sharing started" : "screen sharing stopped", force: false);
-            if (ScreenSharing) IosAudioRouter.Shared.Recover("screen sharing started");
             Notify();
         });
     }

clients/apple/VoiceCat.iOS/BroadcastAudioPump.cs

@@ -18,9 +18,15 @@ internal sealed class BroadcastAudioPump : IAsyncDisposable
     private uint streamId;
     private bool active;
     private int generation;
+    private ulong observedWrite;
+    private ulong idleWrite;
+    private bool idleWriteSeen;
 
     internal event Action? Changed;
     internal bool IsActive => active;
+#if DEBUG
+    internal bool IsMappingOpen => view is not null;
+#endif
 
     internal void Start(VoiceCatClient owner)
     {
@@ -37,8 +43,17 @@ internal sealed class BroadcastAudioPump : IAsyncDisposable
             while (!token.IsCancellationRequested)
             {
                 try { DrainAsync(token).GetAwaiter().GetResult(); }
-                catch (Exception exception) when (exception is IOException or UnauthorizedAccessException or InvalidDataException or OperationCanceledException) { CloseMapping(); }
+                catch (OperationCanceledException) when (token.IsCancellationRequested) { break; }
-                if (!token.IsCancellationRequested) Thread.Sleep(5);
+                catch (Exception exception)
+                {
+                    // A rejected screen stream is a session error, not an unhandled exception on
+                    // this background Thread. Keep the app and microphone call alive.
+                    Console.Error.WriteLine($"VoiceCat screen audio pump failed: {exception}");
+                    CloseMapping(); StopStream(); SetActive(false);
+                    if (!token.IsCancellationRequested) Thread.Sleep(1000);
+                }
+                // The shared file must not remain mapped while the app is idle or suspending.
+                if (!token.IsCancellationRequested) Thread.Sleep(view is null ? 100 : 5);
             }
         }
         finally { CloseMapping(); }
@@ -49,11 +64,18 @@ internal sealed class BroadcastAudioPump : IAsyncDisposable
         if (!OpenMapping()) return;
         MemoryMappedViewAccessor pages = view!;
         bool active = pages.ReadUInt32(16) != 0;
-        if (!active) { StopStream(); SetActive(false); return; }
+        if (!active) { StopStream(); SetActive(false); CloseMapping(); return; }
         VoiceCatClient owner = client ?? throw new IOException("Client disconnected.");
         if (streamId == 0)
         {
+            // A ring left marked active by a killed extension must not start a phantom stream.
+            // Wait for a fresh producer write after this connection opened the mapping.
+            ulong currentWrite = pages.ReadUInt64(24);
+            if (currentWrite == observedWrite) return;
+            observedWrite = currentWrite;
             int startGeneration = Volatile.Read(ref generation);
+            VoiceSubscriptionResult subscription = await owner.SubscribeVoiceAsync(cancellationToken: token).ConfigureAwait(false);
+            if (!subscription.Ok) throw new InvalidOperationException(subscription.Error);
             StreamInfo stream = await owner.StartStreamAsync(StreamKind.StreamScreenAudio, "Screen audio", 2, token).ConfigureAwait(false);
             if (startGeneration != Volatile.Read(ref generation) || pages.ReadUInt32(16) == 0 || !ReferenceEquals(client, owner))
             {
@@ -77,11 +99,10 @@ internal sealed class BroadcastAudioPump : IAsyncDisposable
         }
     }
 
-    // The producer opens the ring with O_CREAT and never replaces it, so one mapping covers the
+    // Keep a mapping only while a broadcast is active. An inactive mapping holds an open handle
-    // pump's whole life. Creating and disposing a mapping (plus its container lookup and path
+    // into the shared App Group container through suspension, which iOS may terminate as a shared
-    // strings) every 5 ms tick allocated steadily at 200 Hz and churned the GC under long calls;
+    // file lock (0xdead10cc). Poll the small header with a short-lived read when idle, then map
-    // the mapping is now built on the ring's transitions and reused until the file disappears or
+    // once for the active broadcast's high-rate drain.
-    // a drain fails.
     private bool OpenMapping()
     {
         path ??= ResolvePath();
@@ -92,7 +113,28 @@ internal sealed class BroadcastAudioPump : IAsyncDisposable
             if (present) return true;
             CloseMapping(); return false;
         }
-        if (!present) return false;
+        if (!present) { idleWriteSeen = false; return false; }
+        using (var file = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.ReadWrite | FileShare.Delete))
+        {
+            if (file.Length < Header) { idleWriteSeen = false; return false; }
+            Span<byte> header = stackalloc byte[32];
+            file.ReadExactly(header);
+            if (System.Buffers.Binary.BinaryPrimitives.ReadUInt32LittleEndian(header) != Magic ||
+                System.Buffers.Binary.BinaryPrimitives.ReadUInt32LittleEndian(header[4..]) != Version ||
+                System.Buffers.Binary.BinaryPrimitives.ReadUInt32LittleEndian(header[16..]) == 0)
+            {
+                idleWriteSeen = false;
+                return false;
+            }
+            ulong currentWrite = System.Buffers.Binary.BinaryPrimitives.ReadUInt64LittleEndian(header[24..]);
+            if (!idleWriteSeen)
+            {
+                idleWrite = currentWrite;
+                idleWriteSeen = true;
+                return false;
+            }
+            if (currentWrite == idleWrite) return false;
+        }
         MemoryMappedFile candidate = MemoryMappedFile.CreateFromFile(path, FileMode.Open, null, Header + Capacity * sizeof(short), MemoryMappedFileAccess.ReadWrite);
         try
         {
@@ -101,7 +143,7 @@ internal sealed class BroadcastAudioPump : IAsyncDisposable
             {
                 pages.Dispose(); throw new InvalidDataException("Unsupported broadcast ring.");
             }
-            map = candidate; view = pages; return true;
+            map = candidate; view = pages; observedWrite = idleWrite; return true;
         }
         catch { candidate.Dispose(); throw; }
     }
@@ -116,12 +158,14 @@ internal sealed class BroadcastAudioPump : IAsyncDisposable
     {
         view?.Dispose(); view = null;
         map?.Dispose(); map = null;
+        observedWrite = 0;
+        idleWriteSeen = false;
     }
 
     private void StopStream()
     {
         uint id = streamId; streamId = 0; if (id == 0 || client?.State != ClientConnectionState.Connected) return;
-        try { client.StopStream(id); } catch (Exception exception) when (exception is IOException or InvalidOperationException) { }
+        try { client.StopStream(id); } catch (Exception exception) when (exception is IOException or InvalidOperationException or ObjectDisposedException) { }
     }
 
     internal void RequestStop() { Interlocked.Increment(ref generation); SetActive(false); }

clients/apple/VoiceCat.iOS/IosAudioEngine.cs

@@ -88,6 +88,7 @@ internal sealed class IosAudioEngine
         // right hardware. Rebuilding it there would release an HFP headset and pay a Bluetooth
         // profile renegotiation for a transport blip that changed no audio configuration.
         if (engine?.Running == true) { playbackRing.Resynchronize(); return; }
+        if (ResumeStoppedGraph()) return;
         Volatile.Write(ref microphone, null); Rebuild();
     }
 
@@ -134,6 +135,7 @@ internal sealed class IosAudioEngine
         int channels = IosAudioRouter.Shared.CaptureChannels;
         if (!force && engine?.Running == true && tapInstalled && builtCaptureChannels == channels
             && voiceProcessing == IosAudioRouter.Shared.UsesVoiceProcessing && !HardwareChanged()) return;
+        if (!force && ResumeStoppedGraph()) return;
         if (current is not null)
         {
             // Stop the old tap before publishing a route with a different sample width. Otherwise
@@ -155,9 +157,30 @@ internal sealed class IosAudioEngine
         // Still starting: report it as running rather than replacing it, since that is what it is
         // about to be, and a rebuild here would start the cycle over.
         if (Settling) return true;
+        if (ResumeStoppedGraph()) return true;
         Rebuild(); return engine?.Running == true;
     }
 
+    private bool ResumeStoppedGraph()
+    {
+        if (engine is not { } paused || !tapInstalled ||
+            builtCaptureChannels != IosAudioRouter.Shared.CaptureChannels ||
+            voiceProcessing != IosAudioRouter.Shared.UsesVoiceProcessing || HardwareChanged()) return false;
+        IosAudioRouter.Shared.Apply(true);
+        bool started = paused.StartAndReturnError(out NSError? error);
+        if (started)
+        {
+            playbackRing.Resynchronize();
+            // Voice-processing IO may still be starting when Start returns. Give the existing
+            // graph its settling window before a watchdog judges it, just as a fresh graph gets.
+            Volatile.Write(ref lastRebuildAt, Environment.TickCount64);
+            Console.Error.WriteLine($"VC_RESUME running={paused.Running}");
+            return true;
+        }
+        Console.Error.WriteLine($"VC_RESUME running={paused.Running} error={error?.LocalizedDescription ?? "none"}");
+        return false;
+    }
+
     private void Rebuild([System.Runtime.CompilerServices.CallerMemberName] string cause = "")
     {
         Console.Error.WriteLine($"VC_REBUILD cause={cause} running={engine?.Running == true} callbacks={RenderCallbacks}");
@@ -182,7 +205,7 @@ internal sealed class IosAudioEngine
             // formats are queried or nodes are connected so the graph is built from the final IO.
             input = next.InputNode;
             if (!input.SetVoiceProcessingEnabled(IosAudioRouter.Shared.UsesVoiceProcessing, out NSError? processingError))
-                throw new InvalidOperationException(processingError.LocalizedDescription);
+                throw new InvalidOperationException(processingError?.LocalizedDescription ?? "Could not configure voice processing.");
             if (IosAudioRouter.Shared.UsesVoiceProcessing) input.VoiceProcessingAgcEnabled = IosAudioRouter.Shared.AutomaticGainControl;
         }
         outputFormat = new(AVAudioCommonFormat.PCMFloat32, 48_000, 2, false);
@@ -195,6 +218,8 @@ internal sealed class IosAudioEngine
         if (captures)
         {
             AVAudioFormat inputFormat = input!.GetBusOutputFormat(0);
+            if (inputFormat.SampleRate <= 0 || inputFormat.ChannelCount == 0)
+                throw new InvalidOperationException("No usable microphone input is available on the current audio route.");
             Console.Error.WriteLine($"VC_GRAPH vpio={IosAudioRouter.Shared.UsesVoiceProcessing} requestedCh={captureChannels} " +
                 $"inputCh={inputFormat.ChannelCount} inputRate={inputFormat.SampleRate}");
             builtInputRate = inputFormat.SampleRate; builtInputChannels = inputFormat.ChannelCount;
@@ -231,15 +256,15 @@ internal sealed class IosAudioEngine
             captureSink.OutputVolume = 0f;
         }
         next.Prepare();
-        if (!next.StartAndReturnError(out NSError? error)) { next.Dispose(); throw new InvalidOperationException(error.LocalizedDescription); }
+        if (!next.StartAndReturnError(out NSError? error)) { next.Dispose(); throw new InvalidOperationException(error?.LocalizedDescription ?? "The iOS audio graph could not start."); }
         engine = next;
         {
             AVAudioSession live = AVAudioSession.SharedInstance();
             Console.Error.WriteLine($"VC_START running={next.Running} builtCh={builtInputChannels} sessionRate={live.SampleRate} " +
                 $"sessionInCh={live.InputNumberOfChannels} sessionOutCh={live.OutputNumberOfChannels} inputAvailable={live.InputAvailable} " +
                 $"other={live.OtherAudioPlaying} mode={live.Mode} options={live.CategoryOptions} io={live.IOBufferDuration:F4} " +
-                $"out={string.Join(',', live.CurrentRoute.Outputs.Select(value => value.PortType.ToString()))} " +
+                $"out={string.Join(',', live.CurrentRoute?.Outputs?.Select(value => value.PortType.ToString()) ?? [])} " +
-                $"in={string.Join(',', live.CurrentRoute.Inputs.Select(value => value.PortType.ToString()))}");
+                $"in={string.Join(',', live.CurrentRoute?.Inputs?.Select(value => value.PortType.ToString()) ?? [])}");
             // A graph that starts and then stops on its own is the failure that matters, and it is
             // invisible at start: check again once the IO has had time to come up.
             AVAudioEngine started = next;
@@ -380,7 +405,7 @@ internal sealed class IosAudioEngine
     {
         IsConnected = false; Volatile.Write(ref microphone, null);
         if (client is { } owner) owner.Audio.MixedPcm -= ReceiveMixedPcm;
-        DestroyGraph(); client = null; IosAudioRouter.Shared.Deactivate();
+        engine?.Pause(); client = null; IosAudioRouter.Shared.Deactivate();
     }
 
     private void DestroyGraph()

clients/apple/VoiceCat.iOS/IosAudioRouter.cs

@@ -127,7 +127,7 @@ internal sealed class IosAudioRouter
     {
         AVAudioSession session = AVAudioSession.SharedInstance();
         Inputs = session.AvailableInputs?.Select(value => new IosAudioPort(value.UID, value.PortName, value.PortType.ToString())).ToArray() ?? [];
-        Outputs = session.CurrentRoute.Outputs.Select(value => new IosAudioPort(value.UID, value.PortName, value.PortType.ToString())).ToArray();
+        Outputs = session.CurrentRoute?.Outputs?.Select(value => new IosAudioPort(value.UID, value.PortName, value.PortType.ToString())).ToArray() ?? [];
         // A route reported by iOS is not an explicit user input choice. Capturing it here
         // can pin the built-in mic after a speaker fallback and displace a Bluetooth HFP route
         // on the next graph rebuild.
@@ -145,10 +145,10 @@ internal sealed class IosAudioRouter
             if (BluetoothMode == IosBluetoothMode.BuiltInMicSpeaker || ForceSpeaker && BluetoothMode != IosBluetoothMode.BuiltInMicA2dp) options |= AVAudioSessionCategoryOptions.DefaultToSpeaker;
             AVAudioSessionMode mode = CaptureChannels == 2 ? AVAudioSessionMode.Default : MicMode == IosMicMode.Raw ? AVAudioSessionMode.Measurement
                 : BluetoothMode == IosBluetoothMode.BuiltInMicA2dp ? AVAudioSessionMode.VideoRecording : AVAudioSessionMode.VoiceChat;
-            if (!session.SetCategory(AVAudioSessionCategory.PlayAndRecord, mode, options, out NSError? categoryError)) throw new InvalidOperationException(categoryError.LocalizedDescription);
+            if (!session.SetCategory(AVAudioSessionCategory.PlayAndRecord, mode, options, out NSError? categoryError)) throw new InvalidOperationException(categoryError?.LocalizedDescription ?? "Could not configure the iOS audio session.");
             session.SetPreferredSampleRate(48_000, out _); session.SetPreferredIOBufferDuration(0.02, out _);
             if (configureInput) ApplyInputSelection(session);
-            if (!session.SetActive(true, AVAudioSessionSetActiveOptions.NotifyOthersOnDeactivation, out NSError? activeError)) throw new InvalidOperationException(activeError.LocalizedDescription);
+            if (!session.SetActive(true, AVAudioSessionSetActiveOptions.NotifyOthersOnDeactivation, out NSError? activeError)) throw new InvalidOperationException(activeError?.LocalizedDescription ?? "Could not activate the iOS audio session.");
             Console.Error.WriteLine($"VC_ROUTE preset={Preset} requestedCh={CaptureChannels} sessionCh={session.InputNumberOfChannels} " +
                 $"preferred={session.PreferredInput?.PortName ?? "default"} dataSource={session.InputDataSource?.DataSourceName ?? "default"} " +
                 $"pattern={session.InputDataSource?.SelectedPolarPattern.ToString() ?? "default"}");
@@ -189,19 +189,19 @@ internal sealed class IosAudioRouter
         if (CaptureChannels == 1 && source is null && stereoApplied) ClearStereo(session);
         if (source is not null)
         {
-            if (!port.SetPreferredDataSource(source, out NSError? portError)) throw new InvalidOperationException(portError.LocalizedDescription);
+            if (!port.SetPreferredDataSource(source, out NSError? portError)) throw new InvalidOperationException(portError?.LocalizedDescription ?? "Could not select the microphone data source.");
             if (CaptureChannels == 2) SetStereoPolarPattern(source);
             else if (SelectedPolarPattern != AVAudioDataSourcePolarPattern.Unknown &&
                 !source.SetPreferredPolarPattern(SelectedPolarPattern, out NSError? patternError))
-                throw new InvalidOperationException(patternError.LocalizedDescription);
+                throw new InvalidOperationException(patternError?.LocalizedDescription ?? "Could not select the microphone polar pattern.");
         }
-        if (!session.SetPreferredInput(port, out NSError? inputError)) throw new InvalidOperationException(inputError.LocalizedDescription);
+        if (!session.SetPreferredInput(port, out NSError? inputError)) throw new InvalidOperationException(inputError?.LocalizedDescription ?? "Could not select the microphone input.");
         // The working Swift client deliberately does not call
         // SetPreferredInputNumberOfChannels: doing so disrupts stereo + A2DP routing. The stereo
         // capsule and polar pattern above cause the input node to expose its two-channel format.
         if (CaptureChannels == 2 && source is not null &&
             !session.SetInputDataSource(source, out NSError? sourceError))
-            throw new InvalidOperationException(sourceError.LocalizedDescription);
+            throw new InvalidOperationException(sourceError?.LocalizedDescription ?? "Could not activate the stereo microphone source.");
         Console.Error.WriteLine($"VC_ROUTE_SELECT port={port.PortName} source={source?.DataSourceName ?? "none"} " +
             $"stereoPattern={source is not null && SupportsStereoPolarPattern(source)} " +
             $"patterns={string.Join(',', source?.SupportedPolarPatterns?.Select(value => value.ToString()) ?? [])}");
@@ -265,7 +265,9 @@ internal sealed class IosAudioRouter
     {
         // A released session has no route the next graph can be compared against.
         watchdog?.Dispose(); watchdog = null; ResetWatchdog(); ResetWatchdogAttempts();
-        AVAudioSession.SharedInstance().SetActive(false, AVAudioSessionSetActiveOptions.NotifyOthersOnDeactivation, out _);
+        if (!AVAudioSession.SharedInstance().SetActive(false, AVAudioSessionSetActiveOptions.NotifyOthersOnDeactivation, out NSError? error))
+            Console.Error.WriteLine($"VC_DEACTIVATE failed: {error?.LocalizedDescription ?? "no system error"}");
+        else Console.Error.WriteLine("VC_DEACTIVATE succeeded");
     }
     internal void EnsureAudio(string reason)
     {

clients/apple/VoiceCat.iOS/SimulatorSmoke.cs

@@ -0,0 +1,144 @@
+#if DEBUG
+using System.Buffers.Binary;
+using System.Runtime.InteropServices;
+using Foundation;
+using UIKit;
+using VoiceCat.Core;
+
+namespace VoiceCat.iOS;
+
+// An opt-in simulator gate for the real UIKit model and audio graph. Local development only.
+internal static class SimulatorSmoke
+{
+    internal static void RunIfRequested()
+    {
+        string? endpoint = Environment.GetEnvironmentVariable("VOICECAT_SIM_SMOKE");
+        if (endpoint is null || !RuntimeInformation.RuntimeIdentifier.StartsWith("iossimulator", StringComparison.Ordinal)) return;
+        UIApplication.SharedApplication.BeginInvokeOnMainThread(async () =>
+        {
+            try
+            {
+                string[] parts = endpoint.Split(':', 3);
+                Guid id = Guid.Parse("959da92f-f088-452d-a870-4c15007a6fd3");
+                ServerProfile guest = ServerProfile.Create(parts[0], ushort.Parse(parts[1]), ServerAuthentication.Guest, nickname: "smoke", id: id);
+                ServerProfile profile = ServerProfile.Create(parts[0], ushort.Parse(parts[1]), ServerAuthentication.Account, "smoke", id: id);
+                AppModel model = AppModel.Shared;
+                bool share = Environment.GetEnvironmentVariable("VOICECAT_SIM_SMOKE_MODE") == "share";
+                string? ring = share ? PrepareRing() : null;
+                model.IdentityRequested += _ => model.ResolveIdentity(true);
+                if (Environment.GetEnvironmentVariable("VOICECAT_SIM_SMOKE_MODE") != "resume")
+                {
+                    model.UpsertProfile(guest, null);
+                    model.UpsertProfile(profile, parts[2]);
+                }
+                model.Load();
+                profile = model.Profiles.Single(value => value.Id == id);
+                Console.Error.WriteLine("VC_SIM phase=connect");
+                await model.ConnectAsync(profile);
+                Console.Error.WriteLine($"VC_SIM phase=connected audioRunning={IosAudioEngine.Shared.IsRunning}");
+                Require(model.IsConnected, "Account login did not connect.");
+                if (ring is not null)
+                {
+                    // Start a synthetic producer while the microphone is off. This exercises
+                    // screen-only subscription and the real BroadcastChanged audio recovery.
+                    await Task.Delay(300);
+                    Require(!model.ScreenRingMapped && !model.ScreenSharing,
+                        "An unchanged ring from a previous broadcast remained mapped.");
+                    WriteRing(ring, active: true, write: 3840);
+                    await WaitUntil(() => model.ScreenSharing, "Screen stream did not start.");
+                    Require(IosAudioEngine.Shared.IsRunning, "Screen sharing stopped the audio graph.");
+                    WriteRing(ring, active: false, write: 3840);
+                    await WaitUntil(() => !model.ScreenSharing, "Screen stream did not stop.");
+                    Require(!model.ScreenRingMapped, "The stopped screen ring remained mapped.");
+                    Console.Error.WriteLine("VC_SIM phase=screenSharePassed");
+                }
+                await model.ToggleVoiceAsync();
+                Console.Error.WriteLine($"VC_SIM phase=joined audioRunning={IosAudioEngine.Shared.IsRunning}");
+                await Task.Delay(2500);
+                Require(model.VoiceJoined && IosAudioEngine.Shared.IsRunning, "The first voice graph stopped.");
+                long beforeShare = IosAudioEngine.Shared.RenderCallbacks;
+                IosAudioRouter.Shared.Recover("simulated screen sharing start", force: false);
+                await Task.Delay(1000);
+                Require(IosAudioEngine.Shared.IsRunning && IosAudioEngine.Shared.RenderCallbacks > beforeShare,
+                    "Screen sharing recovery stopped the live audio graph.");
+                if (ring is not null)
+                {
+                    WriteRing(ring, active: true, write: 3840);
+                    await Task.Delay(300);
+                    WriteRing(ring, active: true, write: 5760);
+                    await WaitUntil(() => model.ScreenSharing, "Screen stream did not start during a voice call.");
+                    Require(IosAudioEngine.Shared.IsRunning, "Starting screen sharing stopped the voice graph.");
+                }
+                await model.ToggleVoiceAsync();
+                if (ring is not null)
+                {
+                    Require(model.ScreenSharing, "Leaving the microphone call unsubscribed active screen audio.");
+                    WriteRing(ring, active: false, write: 5760);
+                    await WaitUntil(() => !model.ScreenSharing, "The second screen stream did not stop.");
+                }
+                await model.DisconnectAsync();
+                await Task.Delay(3000);
+                model.Load();
+                profile = model.Profiles.Single(value => value.Id == id);
+                Console.Error.WriteLine("VC_SIM phase=reconnect");
+                await model.ConnectAsync(profile);
+                Console.Error.WriteLine($"VC_SIM phase=reconnected audioRunning={IosAudioEngine.Shared.IsRunning}");
+                Require(model.IsConnected, "Saved account login did not reconnect.");
+                await Task.Delay(2500);
+                Console.Error.WriteLine($"VC_SIM phase=reconnectedSettled audioRunning={IosAudioEngine.Shared.IsRunning}");
+                Require(IosAudioEngine.Shared.IsRunning, "The reconnect audio graph stopped.");
+                await model.ToggleVoiceAsync();
+                Console.Error.WriteLine($"VC_SIM phase=rejoined audioRunning={IosAudioEngine.Shared.IsRunning}");
+                await Task.Delay(2500);
+                Console.Error.WriteLine($"VC_SIM phase=rejoinedSettled audioRunning={IosAudioEngine.Shared.IsRunning}");
+                Require(model.VoiceJoined && IosAudioEngine.Shared.IsRunning, "The rejoined voice graph stopped.");
+                await model.DisconnectAsync();
+                Console.Error.WriteLine("VC_SIM phase=passed");
+            }
+            catch (Exception exception) { Console.Error.WriteLine($"VC_SIM phase=failed exception={exception}"); }
+        });
+    }
+
+    private static void Require(bool condition, string message)
+    {
+        if (!condition) throw new InvalidOperationException(message);
+    }
+
+    private static string PrepareRing()
+    {
+        string root = NSFileManager.DefaultManager.GetContainerUrl(IosConstants.AppGroup)?.Path
+            ?? throw new InvalidOperationException("Simulator App Group is unavailable.");
+        string path = Path.Combine(root, "voicecat", "broadcast_audio.ring");
+        Directory.CreateDirectory(Path.GetDirectoryName(path)!);
+        using var file = new FileStream(path, FileMode.Create, FileAccess.Write, FileShare.ReadWrite);
+        file.SetLength(64 + 96_000 * sizeof(short));
+        byte[] header = new byte[20];
+        BinaryPrimitives.WriteUInt32LittleEndian(header, 0x56434252);
+        BinaryPrimitives.WriteUInt32LittleEndian(header.AsSpan(4), 1);
+        file.Write(header);
+        file.Dispose();
+        WriteRing(path, active: true, write: 1920);
+        return path;
+    }
+
+    private static void WriteRing(string path, bool active, ulong write)
+    {
+        using var file = new FileStream(path, FileMode.Open, FileAccess.Write, FileShare.ReadWrite);
+        byte[] value = new byte[8];
+        BinaryPrimitives.WriteUInt64LittleEndian(value, write);
+        file.Position = 24; file.Write(value);
+        BinaryPrimitives.WriteUInt32LittleEndian(value, active ? 1u : 0u);
+        file.Position = 16; file.Write(value, 0, 4);
+    }
+
+    private static async Task WaitUntil(Func<bool> condition, string error)
+    {
+        for (int attempt = 0; attempt < 30; attempt++)
+        {
+            if (condition()) return;
+            await Task.Delay(100);
+        }
+        throw new InvalidOperationException(error);
+    }
+}
+#endif

docs/ios-deploy.md

@@ -133,6 +133,42 @@ CoreDevice can also install the app successfully and then reject only the launch
 deployment; rebuilding is unnecessary. Occasional CoreDeviceService initialization timeouts while
 listing devices or processes do not imply that an already-confirmed install or launch failed.
 
+## Simulator connection and audio gate
+
+The Debug app has an opt-in simulator smoke gate. Start a local VoiceCat server and create an
+account named `smoke`, then build the `iossimulator-arm64` app. The simulator build needs an
+App Group entitlement for the saved-password and screen-ring checks; sign the built app
+ad hoc with `clients/apple/VoiceCat.iOS/Entitlements.plist` before installing it. A clean
+build avoids stale simulator AOT modules after managed code changes.
+
+```bash
+dotnet restore clients/apple/VoiceCat.iOS/VoiceCat.iOS.csproj \
+  -p:RuntimeIdentifier=iossimulator-arm64 -p:VoiceCatIosStatic=true --force-evaluate
+dotnet clean clients/apple/VoiceCat.iOS/VoiceCat.iOS.csproj -c Debug \
+  -p:RuntimeIdentifier=iossimulator-arm64
+dotnet build clients/apple/VoiceCat.iOS/VoiceCat.iOS.csproj -c Debug --no-restore \
+  -p:RuntimeIdentifier=iossimulator-arm64
+codesign --force --sign - --entitlements clients/apple/VoiceCat.iOS/Entitlements.plist \
+  clients/apple/VoiceCat.iOS/bin/Debug/net10.0-ios27.0/iossimulator-arm64/VoiceCat.iOS.app
+xcrun simctl install booted \
+  clients/apple/VoiceCat.iOS/bin/Debug/net10.0-ios27.0/iossimulator-arm64/VoiceCat.iOS.app
+```
+
+Grant microphone access with `xcrun simctl privacy booted grant microphone
+me.iamtalon.voicecat`. Launch with `SIMCTL_CHILD_VOICECAT_SIM_SMOKE` set to
+`127.0.0.1:<port>:<smoke-account-password>` and
+`SIMCTL_CHILD_VOICECAT_SIM_SMOKE_MODE=share` using `xcrun simctl launch --console-pty booted
+me.iamtalon.voicecat`. The `share` mode checks that a stale ring stays unmapped, then exercises
+synthetic screen audio with the microphone off and during a voice call, voice join, disconnect,
+and reconnect. Look for
+`VC_SIM phase=screenSharePassed` and `VC_SIM phase=passed`. Terminate the app, then launch
+again with mode `resume` to verify the saved account after a process restart. The simulator
+does not validate Bluetooth hardware, the iOS 27 ScreenCaptureKit picker, or suspension on
+a physical device.
+
+The simulator restore can rewrite `packages.ios.lock.json`; retain both checked-in iOS
+runtime entries when reviewing the diff.
+
 ## Verified hardware result
 
 On 2026-09-22, the Debug build completed with .NET 10.0.401 and Xcode 27.0. The host and

src/VoiceCat.Core/VoiceCatClient.cs

@@ -264,6 +264,7 @@ public sealed partial class VoiceCatClient : IAsyncDisposable
         }
         // A liveness failure has already recorded the real cause and cancelled this read, so do
         // not replace it with the cancellation it produced.
+        catch (OperationCanceledException) when (cancellationToken.IsCancellationRequested) { }
         catch (Exception exception) { failure = exception; ConnectionFailure ??= exception; }
         finally
         {

tests/VoiceCat.Tests/ManagedClientTests.cs

@@ -39,6 +39,7 @@ public class ManagedClientTests
         await Assert.ThrowsAsync<InvalidOperationException>(() => Connect(alice, fixture));
         Assert.Equal(ClientConnectionState.Connected, alice.State);
         await alice.DisconnectAsync();
+        Assert.Null(alice.ConnectionFailure);
         await Event(bob, e => e.UserEvent?.Kind == UserEvent.Types.Kind.Left);
         await Connect(alice, fixture); Assert.True((await alice.AuthenticateGuestAsync("Returned")).Ok);
     }

tests/VoiceCat.Tests/PublishServerScriptTests.cs

@@ -131,7 +131,7 @@ public class PublishServerScriptTests
         Assert.Single(Regex.Matches(pump, "MemoryMappedFile.CreateFromFile"));
         Assert.Contains("private bool OpenMapping()", pump);
         Assert.Contains("private void CloseMapping()", pump);
-        Assert.Contains("Thread.Sleep(5)", pump);
+        Assert.Contains("Thread.Sleep(view is null ? 100 : 5)", pump);
         Assert.Contains("File.Exists(path)", pump);
         Assert.DoesNotContain("using MemoryMappedFile", pump);
         Assert.DoesNotContain("using MemoryMappedViewAccessor", pump);