feat: add AI voice transcription fallback for domestic Android ROMs

kouyu_english/lib/core/voice_service.dart

@@ -19,6 +19,9 @@ class VoiceService {
   bool _speechReady = false;
   bool _ttsInitialized = false;
 
+  void Function(String status)? _statusListener;
+  void Function(String error)? _errorListener;
+
   Future<void> _initTts() async {
     if (_ttsInitialized) return;
     try {
@@ -65,6 +68,8 @@ class VoiceService {
     } catch (_) {}
   }
 
+  Future<bool> hasRecordPermission() => _recorder.hasPermission();
+
   Future<bool> startRecording() async {
     if (!await _recorder.hasPermission()) return false;
     final directory = await getApplicationDocumentsDirectory();
@@ -125,27 +130,70 @@ class VoiceService {
     await _player.dispose();
   }
 
-  Future<bool> initializeSpeech() async {
-    _speechReady = await _stt.initialize();
-    return _speechReady;
+  Future<bool> initializeSpeech({
+    void Function(String status)? onStatus,
+    void Function(String error)? onError,
+  }) async {
+    _statusListener = onStatus;
+    _errorListener = onError;
+    try {
+      _speechReady = await _stt.initialize(
+        onError: (val) {
+          _errorListener?.call(val.errorMsg);
+        },
+        onStatus: (val) {
+          _statusListener?.call(val);
+        },
+        debugLogging: false,
+      );
+      return _speechReady;
+    } catch (_) {
+      _speechReady = false;
+      return false;
+    }
   }
 
   Future<bool> startListening(
-    void Function(String text, bool finalResult) onResult,
-  ) async {
-    if (!_speechReady && !await initializeSpeech()) {
+    void Function(String text, bool finalResult) onResult, {
+    void Function(String status)? onStatus,
+    void Function(String error)? onError,
+  }) async {
+    _statusListener = onStatus;
+    _errorListener = onError;
+    try {
+      if (!_speechReady || !_stt.isAvailable) {
+        final ready = await initializeSpeech(onStatus: onStatus, onError: onError);
+        if (!ready) return false;
+      }
+
+      String? targetLocaleId = 'en_US';
+      try {
+        final locales = await _stt.locales();
+        if (locales.isNotEmpty) {
+          final enLocale = locales.firstWhere(
+            (l) => l.localeId.toLowerCase().startsWith('en'),
+            orElse: () => locales.first,
+          );
+          targetLocaleId = enLocale.localeId;
+        }
+      } catch (_) {}
+
+      await _stt.listen(
+        onResult: (result) =>
+            onResult(result.recognizedWords, result.finalResult),
+        listenOptions: SpeechListenOptions(
+          localeId: targetLocaleId,
+          listenFor: const Duration(seconds: 30),
+          pauseFor: const Duration(seconds: 4),
+          partialResults: true,
+          cancelOnError: false,
+        ),
+      );
+      return _stt.isListening;
+    } catch (e) {
+      if (onError != null) onError(e.toString());
       return false;
     }
-    await _stt.listen(
-      onResult: (result) =>
-          onResult(result.recognizedWords, result.finalResult),
-      listenOptions: SpeechListenOptions(
-        localeId: 'en_US',
-        listenFor: const Duration(seconds: 30),
-        pauseFor: const Duration(seconds: 4),
-      ),
-    );
-    return true;
   }
 
   Future<void> stopListening() => _stt.stop();