fix(ios): keep voice chat on Bluetooth headset

clients/apple/VoiceCat.iOS/IosAudioRouter.cs

@@ -52,10 +52,14 @@ internal sealed class IosAudioRouter
         if (Enum.TryParse(defaults.StringForKey("cat.voice.audio.bluetoothMode"), true, out IosBluetoothMode bluetooth)) BluetoothMode = bluetooth;
         if (Enum.TryParse(defaults.StringForKey("cat.voice.audio.micMode"), true, out IosMicMode mic)) MicMode = mic;
         ForceSpeaker = defaults.BoolForKey("cat.voice.audio.forceSpeaker");
+        // Older voice-chat selections saved an automatic speaker override. Drop that
+        // preference for the named preset so an existing install can follow HFP again.
+        if (Preset == IosAudioPreset.VoiceChat) ForceSpeaker = false;
         VoiceProcessing = defaults.ValueForKey(new NSString("cat.voice.audio.voiceProcessing")) is null || defaults.BoolForKey("cat.voice.audio.voiceProcessing");
         AutomaticGainControl = defaults.ValueForKey(new NSString("cat.voice.audio.agc")) is null || defaults.BoolForKey("cat.voice.audio.agc");
         CaptureChannels = defaults.IntForKey("cat.voice.audio.captureChannels") == 2 ? 2 : Preset == IosAudioPreset.StereoMicrophone ? 2 : 1;
         SelectedInputId = defaults.StringForKey("cat.voice.audio.inputPortId"); SelectedDataSourceId = defaults.StringForKey("cat.voice.audio.dataSourceId");
+        if (Preset == IosAudioPreset.VoiceChat) { SelectedInputId = null; SelectedDataSourceId = null; }
         if (Enum.TryParse(defaults.StringForKey("cat.voice.audio.polarPattern"), true, out AVAudioDataSourcePolarPattern pattern)) SelectedPolarPattern = pattern;
         RefreshRoutes();
     }
@@ -73,12 +77,14 @@ internal sealed class IosAudioRouter
             // Named presets never carry an Advanced capsule selection across transitions.
             // Stereo derives its data source below; mono/voice chat must clear a stale stereo one.
             SelectedDataSourceId = null; SelectedPolarPattern = AVAudioDataSourcePolarPattern.Unknown;
-            if (preset == IosAudioPreset.VoiceChat) ForceSpeaker = true;
+            // HFP needs to remain free to follow a connected headset. A speaker route can
+            // still be requested explicitly with the Speaker output control.
+            if (preset == IosAudioPreset.VoiceChat) ForceSpeaker = false;
         }
         SaveAndReconfigure();
     }
 
-    internal void SetForceSpeaker(bool value) { ForceSpeaker = value; SaveAndReconfigure(); }
+    internal void SetForceSpeaker(bool value) { ForceSpeaker = value; Preset = IosAudioPreset.Advanced; SaveAndReconfigure(); }
     internal void SetVoiceProcessing(bool value) { VoiceProcessing = value; SaveAndReconfigure(); }
     internal void SetAutomaticGainControl(bool value) { AutomaticGainControl = value; SaveAndReconfigure(); }
     internal void SetCaptureChannels(int value) { CaptureChannels = value == 2 ? 2 : 1; Preset = IosAudioPreset.Advanced; SaveAndReconfigure(); }
@@ -100,7 +106,10 @@ 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();
-        SelectedInputId ??= session.PreferredInput?.UID; Changed?.Invoke();
+        // 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.
+        Changed?.Invoke();
     }
 
     internal void Apply(bool configureInput)
@@ -121,7 +130,10 @@ internal sealed class IosAudioRouter
             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"}");
-            session.OverrideOutputAudioPort(ForceSpeaker && BluetoothMode != IosBluetoothMode.BuiltInMicA2dp ? AVAudioSessionPortOverride.Speaker : AVAudioSessionPortOverride.None, out _); RefreshRoutes();
+            // The speaker port override forces both input and output to built-in hardware,
+            // even with a headset connected. DefaultToSpeaker is an explicit speaker choice
+            // only; the voice-chat preset leaves it off so HFP can follow the headset.
+            RefreshRoutes();
             ResetWatchdog(); EnsureWatchdog();
         }
         finally { applying = false; }