feat: expose voice input spike

flutter_app/lib/src/app_router.dart

@@ -15,6 +15,7 @@ import 'views/profile_edit_view.dart';
 import 'views/schedule_view.dart';
 import 'views/settings_view.dart';
 import 'views/shell_scaffold.dart';
+import 'views/voice_assist_view.dart';
 
 class AuthRouterState extends ChangeNotifier {
   AuthRouterState({
@@ -179,8 +180,9 @@ GoRouter buildAppRouter({
       ),
       GoRoute(
         path: '/voice',
-        builder: (context, state) => const Scaffold(
-          body: Center(child: Text('Voice assist coming soon')),
+        builder: (context, state) => _ScopedAppRoute(
+          controller: shellController(),
+          child: const VoiceAssistView(),
         ),
       ),
     ],

flutter_app/lib/src/views/shell_scaffold.dart

@@ -30,9 +30,7 @@ class _ShellScaffoldState extends State<ShellScaffold> {
           drawer: const SecondaryDestinationsDrawer(),
           floatingActionButton: AskFab(
             onPressed: () => context.push('/chat'),
-            onLongPress: () {
-              // TODO(voice): route to /voice when push-to-talk is implemented.
-            },
+            onLongPress: () => context.go('/voice'),
           ),
           floatingActionButtonLocation:
               FloatingActionButtonLocation.centerDocked,

flutter_app/lib/src/views/voice_assist_view.dart

@@ -0,0 +1,254 @@
+import 'package:flutter/material.dart';
+import 'package:go_router/go_router.dart';
+
+import '../app_shell_scope.dart';
+import '../studyos_theme.dart';
+import '../voice_controller.dart';
+import '../widgets/voice_listening_overlay.dart';
+
+class VoiceAssistView extends StatelessWidget {
+  const VoiceAssistView({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    final controller = AppShellScope.of(context);
+    return ListenableBuilder(
+      listenable: controller.voice,
+      builder: (context, _) {
+        final voice = controller.voice;
+        return Scaffold(
+          body: SafeArea(
+            child: Center(
+              child: ConstrainedBox(
+                constraints: const BoxConstraints(maxWidth: 760),
+                child: Padding(
+                  padding: const EdgeInsets.symmetric(
+                    horizontal: StudyOsSpacing.lg,
+                  ),
+                  child: ListView(
+                    padding: const EdgeInsets.only(
+                      top: StudyOsSpacing.lg,
+                      bottom: 96,
+                    ),
+                    children: <Widget>[
+                      _VoiceHeader(onBack: () => context.go('/home')),
+                      const SizedBox(height: StudyOsSpacing.lg),
+                      VoiceListeningOverlay(voice: voice),
+                      _VoiceControlCard(voice: voice),
+                      const SizedBox(height: StudyOsSpacing.lg),
+                      const _VoiceFeasibilityMatrix(),
+                      const SizedBox(height: StudyOsSpacing.lg),
+                      OutlinedButton.icon(
+                        onPressed: () => context.push('/chat'),
+                        icon: const Icon(Icons.chat_bubble_outline_rounded),
+                        label: const Text('Open chat'),
+                      ),
+                    ],
+                  ),
+                ),
+              ),
+            ),
+          ),
+        );
+      },
+    );
+  }
+}
+
+class _VoiceHeader extends StatelessWidget {
+  const _VoiceHeader({required this.onBack});
+
+  final VoidCallback onBack;
+
+  @override
+  Widget build(BuildContext context) {
+    return Row(
+      children: <Widget>[
+        IconButton(
+          tooltip: 'Back',
+          onPressed: onBack,
+          icon: const Icon(Icons.arrow_back_ios_new_rounded),
+        ),
+        const SizedBox(width: StudyOsSpacing.sm),
+        Expanded(
+          child: Text(
+            'Voice input spike',
+            style: Theme.of(context).textTheme.headlineSmall,
+          ),
+        ),
+      ],
+    );
+  }
+}
+
+class _VoiceControlCard extends StatelessWidget {
+  const _VoiceControlCard({required this.voice});
+
+  final VoiceController voice;
+
+  @override
+  Widget build(BuildContext context) {
+    final available = voice.available;
+    return Material(
+      color: StudyOsColors.surface,
+      shape: RoundedRectangleBorder(
+        side: const BorderSide(color: StudyOsColors.border),
+        borderRadius: BorderRadius.circular(StudyOsRadii.md),
+      ),
+      child: Padding(
+        padding: const EdgeInsets.all(StudyOsSpacing.lg),
+        child: Column(
+          crossAxisAlignment: CrossAxisAlignment.start,
+          children: <Widget>[
+            Text(
+              available ? 'Ready for local voice input' : 'Voice unavailable',
+              style: Theme.of(context).textTheme.titleMedium,
+            ),
+            const SizedBox(height: StudyOsSpacing.sm),
+            Text(
+              available
+                  ? 'Hold to dictate one request, or toggle conversation mode for repeated turns.'
+                  : 'Speech recognition is unavailable or permission was denied on this platform.',
+              style: Theme.of(context).textTheme.bodyMedium,
+            ),
+            const SizedBox(height: StudyOsSpacing.lg),
+            Row(
+              children: <Widget>[
+                Expanded(
+                  child: GestureDetector(
+                    onLongPressStart: available
+                        ? (_) => voice.startHold()
+                        : null,
+                    onLongPressEnd: available ? (_) => voice.stopHold() : null,
+                    child: FilledButton.icon(
+                      onPressed: available ? () {} : null,
+                      icon: const Icon(Icons.mic_rounded),
+                      label: const Text('Hold to talk'),
+                    ),
+                  ),
+                ),
+                const SizedBox(width: StudyOsSpacing.md),
+                Expanded(
+                  child: OutlinedButton.icon(
+                    onPressed: available ? voice.toggleConversation : null,
+                    icon: const Icon(Icons.graphic_eq_rounded),
+                    label: Text(
+                      voice.conversationMode ? 'Stop loop' : 'Conversation',
+                    ),
+                  ),
+                ),
+              ],
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}
+
+class _VoiceFeasibilityMatrix extends StatelessWidget {
+  const _VoiceFeasibilityMatrix();
+
+  @override
+  Widget build(BuildContext context) {
+    const rows = <_VoiceFeasibilityRow>[
+      _VoiceFeasibilityRow(
+        title: 'Push-to-talk',
+        status: 'Prototype path',
+        body:
+            'Lowest battery risk. Reuses the existing chat pipeline and only records while the user presses the mic.',
+      ),
+      _VoiceFeasibilityRow(
+        title: 'Conversation mode',
+        status: 'Optional demo',
+        body:
+            'Hands-free after explicit opt-in. Good for testing turn-taking, but should stay foreground-only.',
+      ),
+      _VoiceFeasibilityRow(
+        title: 'Custom hotword',
+        status: 'Research gate',
+        body:
+            'Needs platform-specific checks for background mic access, battery, model size, and offline wake-word support.',
+      ),
+      _VoiceFeasibilityRow(
+        title: 'Passive listener',
+        status: 'Defer',
+        body:
+            'High battery and permission risk. Do not make it the default prototype path.',
+      ),
+    ];
+    return Column(
+      crossAxisAlignment: CrossAxisAlignment.start,
+      children: <Widget>[
+        Text(
+          'Feasibility gates',
+          style: Theme.of(context).textTheme.titleMedium,
+        ),
+        const SizedBox(height: StudyOsSpacing.md),
+        for (final row in rows) ...<Widget>[
+          _FeasibilityTile(row: row),
+          if (row != rows.last) const SizedBox(height: StudyOsSpacing.sm),
+        ],
+      ],
+    );
+  }
+}
+
+class _VoiceFeasibilityRow {
+  const _VoiceFeasibilityRow({
+    required this.title,
+    required this.status,
+    required this.body,
+  });
+
+  final String title;
+  final String status;
+  final String body;
+}
+
+class _FeasibilityTile extends StatelessWidget {
+  const _FeasibilityTile({required this.row});
+
+  final _VoiceFeasibilityRow row;
+
+  @override
+  Widget build(BuildContext context) {
+    return Material(
+      color: StudyOsColors.surface,
+      shape: RoundedRectangleBorder(
+        side: const BorderSide(color: StudyOsColors.border),
+        borderRadius: BorderRadius.circular(StudyOsRadii.md),
+      ),
+      child: Padding(
+        padding: const EdgeInsets.all(StudyOsSpacing.md),
+        child: Row(
+          crossAxisAlignment: CrossAxisAlignment.start,
+          children: <Widget>[
+            const Icon(Icons.check_circle_outline, color: StudyOsColors.accent),
+            const SizedBox(width: StudyOsSpacing.md),
+            Expanded(
+              child: Column(
+                crossAxisAlignment: CrossAxisAlignment.start,
+                children: <Widget>[
+                  Text(
+                    row.title,
+                    style: Theme.of(context).textTheme.labelLarge,
+                  ),
+                  const SizedBox(height: StudyOsSpacing.xs),
+                  Text(row.body, style: Theme.of(context).textTheme.bodyMedium),
+                ],
+              ),
+            ),
+            const SizedBox(width: StudyOsSpacing.sm),
+            Text(
+              row.status,
+              style: Theme.of(
+                context,
+              ).textTheme.bodyMedium?.copyWith(color: StudyOsColors.success),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}

flutter_app/lib/src/widgets/study_bottom_bar.dart

@@ -81,12 +81,33 @@ class AskFab extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     return GestureDetector(
+      key: const ValueKey<String>('ask-fab-surface'),
+      behavior: HitTestBehavior.opaque,
+      onTap: onPressed,
       onLongPress: onLongPress,
-      child: FloatingActionButton.extended(
-        tooltip: 'Ask StudyOS',
-        onPressed: onPressed,
-        icon: const Icon(Icons.auto_awesome),
-        label: const Text('Ask'),
+      child: Semantics(
+        button: true,
+        label: 'Ask StudyOS',
+        child: Material(
+          elevation: 6,
+          color: StudyOsColors.accentStrong,
+          borderRadius: BorderRadius.circular(StudyOsRadii.lg),
+          clipBehavior: Clip.antiAlias,
+          child: const SizedBox(
+            height: 56,
+            child: Padding(
+              padding: EdgeInsets.symmetric(horizontal: StudyOsSpacing.lg),
+              child: Row(
+                mainAxisSize: MainAxisSize.min,
+                children: <Widget>[
+                  Icon(Icons.auto_awesome),
+                  SizedBox(width: StudyOsSpacing.sm),
+                  Text('Ask'),
+                ],
+              ),
+            ),
+          ),
+        ),
       ),
     );
   }