feat(voice): integrate voice mode into Chat screen

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/screens/chat/chat_screen.dart

@@ -2,8 +2,11 @@ import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 
 import '../../core/exceptions.dart';
+import '../../data/models/message.dart';
 import '../../providers/chat_provider.dart';
+import '../../providers/voice_provider.dart';
 import '../../widgets/chat_message_bubble.dart';
+import '../../widgets/voice_mic_button.dart';
 
 class ChatScreen extends ConsumerStatefulWidget {
   final int conversationId;
@@ -21,6 +24,8 @@ class _ChatScreenState extends ConsumerState<ChatScreen> {
   void dispose() {
     _controller.dispose();
     _scrollController.dispose();
+    // Exit voice mode if the user navigates away mid-session.
+    ref.read(voiceProvider.notifier).exitVoiceMode();
     super.dispose();
   }
 
@@ -58,16 +63,52 @@ class _ChatScreenState extends ConsumerState<ChatScreen> {
     }
   }
 
+  Future<void> _toggleVoiceMode() async {
+    final voice = ref.read(voiceProvider);
+    if (voice.voiceModeActive) {
+      ref.read(voiceProvider.notifier).exitVoiceMode();
+      return;
+    }
+    await ref.read(voiceProvider.notifier).enterVoiceMode(
+      onTranscript: (transcript) async {
+        await ref
+            .read(messagesProvider(widget.conversationId).notifier)
+            .sendMessage(transcript);
+      },
+      enableTts: true,
+      onError: (msg) {
+        if (mounted) {
+          ScaffoldMessenger.of(context)
+              .showSnackBar(SnackBar(content: Text(msg)));
+        }
+      },
+    );
+  }
+
   @override
   Widget build(BuildContext context) {
     final messagesAsync = ref.watch(messagesProvider(widget.conversationId));
     final isStreaming = ref.watch(isStreamingProvider(widget.conversationId));
+    final voiceState = ref.watch(voiceProvider);
 
-    // Scroll when messages change
+    // Scroll when messages change.
-    ref.listen(messagesProvider(widget.conversationId), (_, _) {
+    ref.listen(messagesProvider(widget.conversationId), (prev, next) {
       _scrollToBottom();
     });
 
+    // Feed streaming content to VoiceNotifier for TTS.
+    ref.listen(messagesProvider(widget.conversationId), (prev, next) {
+      if (!voiceState.voiceModeActive) return;
+      final messages = next.value;
+      if (messages == null || messages.isEmpty) return;
+      final last = messages.last;
+      if (last.role != MessageRole.assistant) return;
+      final isComplete = last.status != 'generating';
+      ref
+          .read(voiceProvider.notifier)
+          .feedContent(last.content, isComplete: isComplete);
+    });
+
     final convTitle = ref
         .watch(conversationsProvider)
         .value
@@ -85,7 +126,7 @@ class _ChatScreenState extends ConsumerState<ChatScreen> {
             child: messagesAsync.when(
               loading: () =>
                   const Center(child: CircularProgressIndicator()),
-              error: (_, _) => const Center(
+              error: (err, stack) => const Center(
                 child: Text('Could not load messages.'),
               ),
               data: (messages) {
@@ -104,6 +145,21 @@ class _ChatScreenState extends ConsumerState<ChatScreen> {
               },
             ),
           ),
+          // Voice mode banner
+          if (voiceState.voiceModeActive)
+            Container(
+              width: double.infinity,
+              color: const Color(0xFFEF4444).withValues(alpha: 0.12),
+              padding:
+                  const EdgeInsets.symmetric(horizontal: 16, vertical: 6),
+              child: const Text(
+                '🎤 Listening… tap mic to exit voice mode',
+                style: TextStyle(
+                  fontSize: 12,
+                  color: Color(0xFFF87171),
+                ),
+              ),
+            ),
           const Divider(height: 1),
           SafeArea(
             child: Padding(
@@ -114,23 +170,36 @@ class _ChatScreenState extends ConsumerState<ChatScreen> {
                   Expanded(
                     child: TextField(
                       controller: _controller,
-                      decoration: const InputDecoration(
+                      decoration: InputDecoration(
-                        hintText: 'Message...',
+                        hintText: voiceState.voiceModeActive
-                        border: OutlineInputBorder(),
+                            ? 'Listening…'
+                            : 'Message…',
+                        hintStyle: voiceState.voiceModeActive
+                            ? const TextStyle(fontStyle: FontStyle.italic)
+                            : null,
+                        border: const OutlineInputBorder(),
                         isDense: true,
-                        contentPadding: EdgeInsets.symmetric(
+                        contentPadding: const EdgeInsets.symmetric(
                             horizontal: 12, vertical: 10),
                       ),
                       maxLines:
                           MediaQuery.of(context).size.width >= 600 ? 2 : 4,
                       minLines: 1,
                       textInputAction: TextInputAction.newline,
-                      enabled: !isStreaming,
+                      enabled: !isStreaming && !voiceState.voiceModeActive,
                     ),
                   ),
                   const SizedBox(width: 8),
+                  VoiceMicButton(
+                    mode: voiceState.mode,
+                    voiceModeActive: voiceState.voiceModeActive,
+                    onTap: _toggleVoiceMode,
+                  ),
+                  const SizedBox(width: 6),
                   IconButton.filled(
-                    onPressed: isStreaming ? null : _send,
+                    onPressed: (isStreaming || voiceState.voiceModeActive)
+                        ? null
+                        : _send,
                     icon: isStreaming
                         ? const SizedBox(
                             width: 20,
@@ -149,4 +218,3 @@ class _ChatScreenState extends ConsumerState<ChatScreen> {
     );
   }
 }
-