Request microphone permission before audio capture starts

.changes/mic-permission-before-capture

@@ -0,0 +1 @@
+patch type="fixed" "iOS/macOS: request microphone permission before audio capture starts, failing fast with TrackCreateException while the app is not in the foreground"

.changes/preconnect-buffer-cleanup

@@ -0,0 +1 @@
+patch type="fixed" "Pre-connect audio buffer returns to a reusable state when recording fails to start, instead of ignoring retries and leaking the agent timeout"

lib/src/core/room_preconnect.dart

@@ -41,8 +41,12 @@ extension RoomPreConnect on Room {
   /// );
   /// ```
   ///
-  /// - Note: Ensure microphone permissions are granted early in your app
-  ///   lifecycle so pre-connect can start without additional prompts.
+  /// - Note: Requires microphone permission. On iOS/macOS the SDK requests it
+  ///   when recording starts, but only while the app is active, so call this
+  ///   once the app has become active and the system prompt can appear. At app
+  ///   launch the app may not be active yet, so when calling this early,
+  ///   request permission up front (for example with the permission_handler
+  ///   package). Otherwise it throws a [TrackCreateException].
   /// - SeeAlso: [PreConnectAudioBuffer]
   Future<T> withPreConnectAudio<T>(
     Future<T> Function() operation, {

lib/src/preconnect/pre_connect_audio_buffer.dart

@@ -105,8 +105,9 @@ class PreConnectAudioBuffer {
   /// [agentReadyFuture] completes with an error and callers should [reset] the
   /// buffer.
   ///
-  /// Ensure microphone permissions are granted before calling this.
-  /// Audio capture may fail without permissions.
+  /// Requires microphone permission. On iOS/macOS it is requested here while
+  /// the app is in the foreground. Throws a [TrackCreateException] when it is
+  /// denied or cannot be requested (app not in the foreground).
   Future<void> startRecording({
     Duration timeout = const Duration(seconds: 20),
   }) async {
@@ -119,7 +120,14 @@ class PreConnectAudioBuffer {
     // Set up timeout for agent readiness
     _agentReadyManager.setTimer(timeout, timeoutReason: 'Agent did not become ready within timeout');
 
-    _localTrack = await LocalAudioTrack.create();
+    try {
+      _localTrack = await LocalAudioTrack.create();
+    } catch (error) {
+      logger.severe('[Preconnect audio] failed to create local track: $error');
+      _notifyError(error);
+      await stopRecording(withError: error);
+      rethrow;
+    }
     logger.fine('[Preconnect audio] created local track ${_localTrack!.mediaStreamTrack.id}');
 
     final rendererId = Uuid().v4();
@@ -137,7 +145,7 @@ class PreConnectAudioBuffer {
     if (!result) {
       final error = StateError('Failed to start audio renderer ($result)');
       logger.severe('[Preconnect audio] $error');
-      _onError?.call(error);
+      _notifyError(error);
       await stopRecording(withError: error);
       await _localTrack?.stop();
       _localTrack = null;
@@ -149,7 +157,7 @@ class PreConnectAudioBuffer {
       _nativeRecordingStarted = lkPlatformSupportsExplicitAudioRecordingStart();
     } catch (error) {
       logger.severe('[Preconnect audio] failed to start local recording: $error');
-      _onError?.call(error);
+      _notifyError(error);
       await stopRecording(withError: error);
       await _localTrack?.stop();
       _localTrack = null;
@@ -183,7 +191,7 @@ class PreConnectAudioBuffer {
           _agentReadyManager.complete();
         } catch (error) {
           _agentReadyManager.completeError(error);
-          _onError?.call(error);
+          _notifyError(error);
         }
       },
     );
@@ -345,4 +353,15 @@ class PreConnectAudioBuffer {
   void setErrorHandler(PreConnectOnError? onError) {
     _onError = onError;
   }
+
+  /// Invokes the app-provided error callback without letting a throwing
+  /// callback derail the failure path it is called from: cleanup must still
+  /// run and the original error must stay the one callers see.
+  void _notifyError(Object error) {
+    try {
+      _onError?.call(error);
+    } catch (callbackError) {
+      logger.warning('[Preconnect audio] onError callback threw: $callbackError');
+    }
+  }
 }

lib/src/support/native.dart

@@ -266,12 +266,39 @@ class Native {
     }
   }
 
+  /// Requests microphone permission before audio capture starts (iOS/macOS).
+  ///
+  /// The WebRTC audio device only checks the permission and fails when it is
+  /// missing, so the SDK requests it here. On iOS the prompt is only shown while
+  /// the app is active. Throws a [PlatformException] with code
+  /// `deviceAccessDenied` when permission is denied, restricted, or could not be
+  /// requested. A no-op where the platform does not implement it, or while the
+  /// engine's input availability is disabled via [setEngineAvailability] (the
+  /// audio device defers opening input there, so no permission is needed yet).
+  @internal
+  static Future<void> ensureMicrophoneAccess() async {
+    try {
+      await channel.invokeMethod<void>('ensureMicrophoneAccess', <String, dynamic>{});
+    } on PlatformException catch (error) {
+      if (error.code == 'Unimplemented') return;
+      rethrow;
+    } on MissingPluginException {
+      return;
+    }
+  }
+
   /// Sets whether the WebRTC audio engine is allowed to run (iOS/macOS).
   ///
   /// Unlike most methods in this class this deliberately does not swallow
   /// platform errors: a failed availability change means the engine may run
   /// outside the window the caller intended (e.g. CallKit's
   /// didActivate/didDeactivate), so the error must reach the caller.
+  ///
+  /// Microphone permission is not requested here. A recording requested while
+  /// input was unavailable is honored on re-enable, but the audio device only
+  /// passively checks permission at that point, so it must be granted before
+  /// input availability is restored. Otherwise this throws a
+  /// [PlatformException] with code `deviceAccessDenied`.
   @internal
   static Future<void> setEngineAvailability({
     required bool isInputAvailable,

lib/src/support/reusable_completer.dart

@@ -72,6 +72,14 @@ class ReusableCompleter<T> {
       return false;
     }
 
+    if (!_hasPendingListener) {
+      // No one can observe this error: [future] creates a fresh completer once
+      // completed, so delivering it would only surface an unhandled async
+      // error. Mark completed silently, like reset() and dispose() do.
+      _markCompletedWithoutNotify();
+      return true;
+    }
+
     _completeCurrent((completer) => completer.completeError(error, stackTrace));
     return true;
   }

lib/src/track/local/local.dart

@@ -16,17 +16,20 @@ import 'dart:async';
 
 import 'package:flutter/foundation.dart' show kIsWeb;
 import 'package:flutter/material.dart';
+import 'package:flutter/services.dart' show PlatformException;
 
 import 'package:flutter_webrtc/flutter_webrtc.dart' as rtc;
 import 'package:meta/meta.dart';
 
+import '../../audio/audio_engine_error.dart';
 import '../../audio/audio_frame_capture.dart';
 import '../../events.dart';
 import '../../exceptions.dart';
 import '../../extensions.dart';
 import '../../internal/events.dart';
 import '../../logger.dart';
 import '../../participant/remote.dart';
+import '../../support/native.dart';
 import '../../support/platform.dart';
 import '../../types/other.dart';
 import '../options.dart';
@@ -254,6 +257,20 @@ abstract class LocalTrack extends Track {
       'video': options is VideoCaptureOptions ? options.toMediaConstraintsMap() : false,
     };
 
+    if (options is AudioCaptureOptions && lkPlatformIsApple()) {
+      // The WebRTC audio device only checks microphone permission and fails
+      // when it is missing, so the SDK requests it before opening the mic. On
+      // iOS this fails fast while the app is not in the foreground instead of
+      // suspending getUserMedia (and the publish queue behind it) on a prompt
+      // the system cannot show yet.
+      try {
+        await Native.ensureMicrophoneAccess();
+      } on PlatformException catch (error) {
+        throw audioEngineExceptionFrom(error) ??
+            TrackCreateException(error.message ?? 'Microphone permission is not granted');
+      }
+    }
+
     final rtc.MediaStream stream;
     if (options is ScreenShareCaptureOptions) {
       if (kIsWeb) {

shared_swift/LiveKitPlugin.swift

@@ -542,6 +542,63 @@ public class LiveKitPlugin: NSObject, FlutterPlugin {
         }
     }
 
+    // MARK: - Microphone permission
+
+    /// Ensures microphone access is granted before audio capture starts.
+    ///
+    /// The WebRTC audio device does not request microphone permission itself. It
+    /// only checks it and fails with kAudioEngineErrorInsufficientDevicePermission,
+    /// so requesting is the SDK's job. On iOS the request is only made while the
+    /// app is active: while inactive or in the background the system defers the
+    /// alert, and waiting on it would suspend the caller, and the publish queue
+    /// behind it, for as long as the app stays there. Failing fast lets the next
+    /// attempt prompt normally. macOS can present the prompt regardless.
+    ///
+    /// Method channel handlers run on the main thread, which UIApplication needs.
+    public func handleEnsureMicrophoneAccess(result: @escaping FlutterResult) {
+        // With engine input availability disabled (the CallKit flow, see
+        // setEngineAvailability) the audio device module defers opening input
+        // entirely and runs no permission check, so gating here would turn a
+        // working background connect into a deviceAccessDenied failure. The
+        // last-set value is tracked by both the channel and native static
+        // paths, so it covers gating done before the Flutter engine exists.
+        LiveKitPlugin.engineAvailabilityLock.lock()
+        let pendingAvailability = LiveKitPlugin.pendingEngineAvailability
+        LiveKitPlugin.engineAvailabilityLock.unlock()
+        if let pendingAvailability, !pendingAvailability.isInputAvailable.boolValue {
+            result(nil)
+            return
+        }
+
+        let denied = { (message: String) in
+            result(FlutterError(code: LiveKitPlugin.deviceAccessDeniedErrorCode, message: message, details: nil))
+        }
+        switch AVCaptureDevice.authorizationStatus(for: .audio) {
+        case .authorized:
+            result(nil)
+        case .notDetermined:
+            #if !os(macOS)
+            guard UIApplication.shared.applicationState == .active else {
+                denied("Microphone permission could not be requested because the app is not in the foreground. Request it while the app is active before enabling recording.")
+                return
+            }
+            #endif
+            AVCaptureDevice.requestAccess(for: .audio) { granted in
+                DispatchQueue.main.async {
+                    if granted {
+                        result(nil)
+                    } else {
+                        denied("Microphone permission was denied.")
+                    }
+                }
+            }
+        case .denied, .restricted:
+            denied("Microphone permission is not granted.")
+        @unknown default:
+            denied("Microphone permission is not granted.")
+        }
+    }
+
     // MARK: - Microphone mute mode
 
     static func muteModeString(_ mode: RTCAudioEngineMuteMode) -> String {
@@ -768,6 +825,8 @@ public class LiveKitPlugin: NSObject, FlutterPlugin {
             handleStopLocalRecording(result: result)
         case "setEngineAvailability":
             handleSetEngineAvailability(args: args, result: result)
+        case "ensureMicrophoneAccess":
+            handleEnsureMicrophoneAccess(result: result)
         case "setAudioProcessingOptions":
             handleSetAudioProcessingOptions(args: args, result: result)
         case "getAudioProcessingState":
@@ -800,14 +859,18 @@ extension LiveKitPlugin {
     static let kAudioEngineErrorInsufficientDevicePermission = -9000
     static let kAudioEngineErrorAudioSessionInvalidCategory = -9001
 
+    /// FlutterError code for missing microphone permission. Dart maps it to
+    /// TrackCreateException (see audio_engine_error.dart).
+    static let deviceAccessDeniedErrorCode = "deviceAccessDenied"
+
     /// Maps a non-zero audio device module result to a `FlutterError` whose code
     /// the Dart side can act on. Codes with a known cause get their own error
     /// code, mirroring client-sdk-swift's `checkAdmResult`. Anything else falls
     /// back to `fallbackCode` with the raw value in the message.
     static func flutterError(forAudioEngineResult result: Int, fallbackCode: String) -> FlutterError {
         switch result {
         case kAudioEngineErrorInsufficientDevicePermission:
-            return FlutterError(code: "deviceAccessDenied",
+            return FlutterError(code: deviceAccessDeniedErrorCode,
                                 message: "Microphone permission is not granted (audio engine error \(result))",
                                 details: result)
         case kAudioEngineErrorAudioSessionInvalidCategory:

test/audio/audio_session_test.dart

@@ -876,6 +876,37 @@ void main() {
     });
   });
 
+  group('Native.ensureMicrophoneAccess', () {
+    test('is a no-op when the platform does not implement it', () async {
+      TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(
+        Native.channel,
+        (call) async => throw PlatformException(code: 'Unimplemented'),
+      );
+      await expectLater(Native.ensureMicrophoneAccess(), completes);
+
+      TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(
+        Native.channel,
+        null,
+      );
+      await expectLater(Native.ensureMicrophoneAccess(), completes);
+    });
+
+    test('propagates a denied permission so callers can map it', () async {
+      TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(
+        Native.channel,
+        (call) async {
+          expect(call.method, 'ensureMicrophoneAccess');
+          throw PlatformException(code: audioEngineErrorCodeDeviceAccessDenied, message: 'denied');
+        },
+      );
+
+      await expectLater(
+        Native.ensureMicrophoneAccess(),
+        throwsA(isA<PlatformException>().having((error) => error.code, 'code', audioEngineErrorCodeDeviceAccessDenied)),
+      );
+    });
+  });
+
   group('audioEngineExceptionFrom', () {
     test('maps missing microphone permission to TrackCreateException', () {
       final error = audioEngineExceptionFrom(