fix: Always calc correct file extension for voice messages

lib/pages/chat/chat.dart

@@ -34,6 +34,7 @@ import 'package:flutter/services.dart';
 import 'package:go_router/go_router.dart';
 import 'package:image_picker/image_picker.dart';
 import 'package:matrix/matrix.dart';
+import 'package:mime/mime.dart';
 import 'package:scroll_to_index/scroll_to_index.dart';
 
 import '../../utils/account_bundles.dart';
@@ -700,7 +701,7 @@ class ChatController extends State<ChatPageWithRoom>
     String path,
     int duration,
     List<int> waveform,
-    String? fileName,
+    String fileName,
   ) async {
     final scaffoldMessenger = ScaffoldMessenger.of(context);
     final audioFile = XFile(path);
@@ -712,9 +713,17 @@ class ChatController extends State<ChatPageWithRoom>
     final bytes = bytesResult.result;
     if (bytes == null) return;
 
+    final mimeType = lookupMimeType(fileName, headerBytes: bytes);
+    final extension = mimeType == null ? null : extensionFromMime(mimeType);
+    if (extension != null) {
+      fileName =
+          'voice_message_${DateTime.now().millisecondsSinceEpoch}.$extension';
+    }
+
     final file = MatrixAudioFile(
       bytes: bytes,
-      name: fileName ?? audioFile.path,
+      name: fileName,
+      mimeType: mimeType,
     );
 
     room

lib/pages/chat/recording_input_row.dart

@@ -6,7 +6,7 @@ import 'package:flutter/material.dart';
 
 class RecordingInputRow extends StatelessWidget {
   final RecordingViewModelState state;
-  final Future<void> Function(String, int, List<int>, String?) onSend;
+  final Future<void> Function(String, int, List<int>, String) onSend;
   const RecordingInputRow({
     required this.state,
     required this.onSend,

lib/pages/chat/recording_view_model.dart

@@ -67,7 +67,7 @@ class RecordingViewModelState extends State<RecordingViewModel> {
           ? AudioEncoder.opus
           : AudioEncoder.aacLc;
       fileName =
-          'recording${DateTime.now().microsecondsSinceEpoch}.${codec.fileExtension}';
+          'voice_message_${DateTime.now().millisecondsSinceEpoch}.${codec.fileExtension}';
       String? path;
       if (!kIsWeb) {
         final tempDir = await getTemporaryDirectory();
@@ -168,7 +168,7 @@ class RecordingViewModelState extends State<RecordingViewModel> {
       String path,
       int duration,
       List<int> waveform,
-      String? fileName,
+      String fileName,
     )
     onSend,
   ) async {
@@ -189,7 +189,7 @@ class RecordingViewModelState extends State<RecordingViewModel> {
       isSending = true;
     });
     try {
-      await onSend(path, duration.inMilliseconds, waveform, fileName);
+      await onSend(path, duration.inMilliseconds, waveform, fileName!);
     } catch (e, s) {
       Logs().e('Unable to send voice message', e, s);
       setState(() {