Use recorder amplitude for web voice meter

lib/screens/mapflow_shell.dart

@@ -730,6 +730,7 @@ class _AddExperienceFlowState extends ConsumerState<AddExperienceFlow> {
   Future<List<PlaceRecommendation>>? _nearbyPlacesFuture;
   Timer? _timer;
   Timer? _visualTimer;
+  Timer? _amplitudeTimer;
   StreamSubscription<Uint8List>? _audioStreamSub;
   var _step = 0;
   var _seconds = 0;
@@ -741,6 +742,7 @@ class _AddExperienceFlowState extends ConsumerState<AddExperienceFlow> {
   var _voiceCeiling = 0.045;
   var _visualPhase = 0.0;
   DateTime? _lastAudioChunkAt;
+  DateTime? _lastInformationAt;
 
   @override
   void initState() {
@@ -751,6 +753,7 @@ class _AddExperienceFlowState extends ConsumerState<AddExperienceFlow> {
   void dispose() {
     _timer?.cancel();
     _visualTimer?.cancel();
+    _amplitudeTimer?.cancel();
     _audioStreamSub?.cancel();
     _recorder.dispose();
     super.dispose();
@@ -796,7 +799,9 @@ class _AddExperienceFlowState extends ConsumerState<AddExperienceFlow> {
     );
     _audioStreamSub = stream.listen(_handleAudioChunk);
     _lastAudioChunkAt = DateTime.now();
+    _lastInformationAt = _lastAudioChunkAt;
     _startIdleWave();
+    _startAmplitudePolling();
     _timer = Timer.periodic(const Duration(seconds: 1), (_) {
       if (!mounted) {
         return;
@@ -816,10 +821,12 @@ class _AddExperienceFlowState extends ConsumerState<AddExperienceFlow> {
   Future<void> _stopRecording() async {
     _timer?.cancel();
     _visualTimer?.cancel();
+    _amplitudeTimer?.cancel();
     await _audioStreamSub?.cancel();
     _audioStreamSub = null;
     await _recorder.stop();
     _lastAudioChunkAt = null;
+    _lastInformationAt = null;
     if (!mounted) {
       return;
     }
@@ -855,6 +862,57 @@ class _AddExperienceFlowState extends ConsumerState<AddExperienceFlow> {
     });
   }
 
+  void _startAmplitudePolling() {
+    _amplitudeTimer?.cancel();
+    _amplitudeTimer = Timer.periodic(const Duration(milliseconds: 90), (
+      _,
+    ) async {
+      if (!mounted || !_recording) {
+        return;
+      }
+
+      final amplitude = await _recorder.getAmplitude();
+      if (!mounted || !_recording) {
+        return;
+      }
+
+      _handleAmplitude(amplitude.current);
+    });
+  }
+
+  void _handleAmplitude(double currentDb) {
+    final now = DateTime.now();
+    final normalized = ((currentDb + 54) / 54).clamp(0.0, 1.0);
+    final voicedAmount = math.pow(normalized, 0.72).toDouble();
+    final informationDelta = _consumeInformationDelta(voicedAmount, now);
+    _visualPhase += 0.38;
+    final samples = List<double>.generate(8, (index) {
+      final wave = math.sin(_visualPhase + index * 0.68) * 0.5 + 0.5;
+      return (0.10 + voicedAmount * 0.68 + wave * voicedAmount * 0.22).clamp(
+        0.0,
+        1.0,
+      );
+    });
+
+    setState(() {
+      _waveSamples
+        ..removeRange(0, samples.length)
+        ..addAll(samples);
+      _informationUnits = math.min(
+        _minimumInformationUnits,
+        _informationUnits + informationDelta,
+      );
+    });
+  }
+
+  double _consumeInformationDelta(double voicedAmount, DateTime now) {
+    final previous = _lastInformationAt ?? now;
+    _lastInformationAt = now;
+    final deltaSeconds =
+        now.difference(previous).inMilliseconds.clamp(20, 180) / 1000;
+    return voicedAmount.clamp(0.0, 1.0) * deltaSeconds;
+  }
+
   void _handleAudioChunk(Uint8List chunk) {
     if (chunk.length < 2) {
       return;
@@ -896,8 +954,6 @@ class _AddExperienceFlowState extends ConsumerState<AddExperienceFlow> {
     final now = DateTime.now();
     final previousChunkAt = _lastAudioChunkAt ?? now;
     _lastAudioChunkAt = now;
-    final deltaSeconds =
-        now.difference(previousChunkAt).inMilliseconds.clamp(20, 300) / 1000;
     final currentRms = totalRms / peaks.length;
     _ambientLevel = currentRms < _ambientLevel
         ? (_ambientLevel * 0.86 + currentRms * 0.14)
@@ -913,7 +969,11 @@ class _AddExperienceFlowState extends ConsumerState<AddExperienceFlow> {
     final voicedAmount =
         normalizedPeaks.fold<double>(0, (sum, value) => sum + value) /
         normalizedPeaks.length;
-    final informationDelta = voicedAmount * deltaSeconds;
+    final hasRecentAmplitude =
+        now.difference(previousChunkAt).inMilliseconds < 120;
+    final informationDelta = hasRecentAmplitude
+        ? 0.0
+        : _consumeInformationDelta(voicedAmount, now);
 
     if (!mounted) {
       return;
@@ -1465,6 +1525,24 @@ class _VoiceInformationPainter extends CustomPainter {
         canvas.drawRRect(rect, backgroundPaint);
         canvas.drawRRect(rect, borderPaint);
 
+        final centerDistance = (row - (rows - 1) / 2).abs();
+        final waveReach = 0.55 + signal * rows * 0.52;
+        final inWave = centerDistance <= waveReach;
+        if (inWave) {
+          final waveAlpha = active
+              ? 0.14 + signal * 0.26
+              : 0.07 + signal * 0.08;
+          final wavePaint = Paint()
+            ..shader = LinearGradient(
+              colors: [
+                const Color(0xFF38F5D3).withValues(alpha: waveAlpha),
+                const Color(0xFFFF2D75).withValues(alpha: waveAlpha * 0.92),
+              ],
+            ).createShader(rect.outerRect)
+            ..style = PaintingStyle.fill;
+          canvas.drawRRect(rect, wavePaint);
+        }
+
         if (filled) {
           final warmth = (0.38 + signal * 0.62).clamp(0.0, 1.0);
           final paint = Paint()