App structure: a swipe-in menu shell; pages/, link/, actions/; Settings

The shell (shell.dart): a drawer from the left edge or each page's menu button.
Dash, Signals, Captures; Tools (Camera, Link test, Orin power options), the
rarely used ones, after pirate-station-aide; Settings (gateway address, dark/bright,
build-time theme and landing). Landing view at build time: YUKART_HOME=dash|signals,
signals for now. Dash, Signals and Captures stay alive while hidden; Captures has its
own navigator, so a run survives switching views. Back goes inside Captures, then to
the landing view, then out. The mock banner sits over every page.

main.dart is startup only; the old home screen is pages/signals.dart; dialogs and
sheets moved to actions/; the protocol client, USB binding and Reading to link/.
lib/README.md catalogues it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DDwfd6Ki8UfG4hK6W5YpJz

docs/impl/reports/LINK-TEST-2026-10-11.md

@@ -6,7 +6,7 @@ date: 2026-10-11
 
 Does the PD hub degrade the tablet ⇄ Orin USB (NCM) link? Measured from the app
 (the only place on the tablet whose sockets use the link) with the link test,
-`lib/linktest.dart` + `tool/linktest_server.py`.
+`lib/linktest.dart` (now `lib/pages/link_test.dart`) + `tool/linktest_server.py`.
 
 ## Short version
 

lib/README.md

@@ -3,15 +3,21 @@ type: reference
 ---
 # The app's code: a catalogue
 
-Laid out like smart-serow's HUD (`pi/ui/lib/`), which several pieces come from.
+Laid out like smart-serow's HUD (`pi/ui/lib/`), which several pieces come from; the menu follows
+pirate-station-aide's (main views, then the rarely used ones grouped as Tools).
 
 ## Folders
 
 | Where | Holds |
 |---|---|
-| `lib/*.dart` | Pages (`dash`, `checklist`, `camview`, `linktest`), the boundary client (`boundary`), the USB network binding (`net`), and `reading`, one signal's state as a display needs it |
+| `main.dart` | Startup: the link to the Orin, the theme, then the shell |
-| `theme/` | `palette.dart`: the palette and `hudFont` |
+| `shell.dart` | The shell: a menu that swipes in from the left; Dash, Signals, Captures, then Tools (Camera, Link test, Orin power options), then Settings. Dash, Signals and Captures stay alive while hidden |
-| `widgets/` | Reusable display widgets, one per file, each fed values, never the boundary |
+| `shell_scope.dart` | What a page needs from the shell: `MenuButton`, `ShellView`, the landing view (`--dart-define=YUKART_HOME=dash\|signals`, `signals` for now) |
+| `pages/` | One file per view: `dash`, `signals` (values and raw traffic), `checklist` (Captures), `camera`, `link_test`, `settings` |
+| `actions/` | Things done from anywhere, as dialogs and sheets: `marks` (free-form mark), `orin_power` (power off / reboot), `server_url` (gateway address) |
+| `link/` | Talking to the Orin: `boundary` (the protocol client), `net` (binding to the USB link), `reading` (one signal's state as a display needs it) |
+| `theme/` | `palette.dart`: the palette roles and `hudFont` |
+| `widgets/` | Reusable display widgets, one per file, each fed values, never the boundary (`link_status` takes it whole: it shows the link) |
 
 ## Widgets
 
@@ -22,6 +28,8 @@ Laid out like smart-serow's HUD (`pi/ui/lib/`), which several pieces come from.
 | `WhiskeyMark` | `widgets/whiskey_mark.dart` | Attitude: a horizon tilting with roll, ladder moving with pitch | smart-serow |
 | `AccelGraph` | `widgets/accel_graph.dart` | G-meter: a dot for lateral/longitudinal g, a trace and a peak marker over a window | smart-serow |
 | `GpsCompass` | `widgets/gps_compass.dart` | Heading arrow and bearing; "ACQ" while acquiring, "N/A" without | smart-serow, from gps-speedo |
+| `LinkChip`, `LinkDetails` | `widgets/link_status.dart` | The link's state in good / caution / alarm; address, last-message age, clock offset, USB link | Yukart |
+| `MockBanner` | `widgets/mock_banner.dart` | "MOCK DATA — NOT FROM THE CAR" in caution, over every page while the gateway is mocking | Yukart |
 
 ## Conventions
 

lib/actions/marks.dart

@@ -0,0 +1,72 @@
+// The free-form mark: stamped into the open recording from anywhere, beside the
+// checklist's structured ones.
+
+import 'dart:math';
+
+import 'package:flutter/material.dart';
+
+import '../link/boundary.dart';
+
+const quickMarks = [
+  'cold start',
+  'engine start',
+  'indicator left',
+  'indicator right',
+  'brake',
+  'headlights',
+  'something odd',
+];
+
+Future<void> showMarkSheet(BuildContext context, Boundary b) {
+  final custom = TextEditingController();
+  return showModalBottomSheet(
+    context: context,
+    isScrollControlled: true,
+    useSafeArea: true,
+    builder: (ctx) {
+      void send(String text) {
+        if (text.trim().isEmpty) return;
+        b.command('mark', {'text': text.trim()});
+        Navigator.pop(ctx);
+      }
+
+      return Padding(
+        // Clear the keyboard when it is up, the navigation bar when it is not.
+        padding: EdgeInsets.fromLTRB(
+          16,
+          16,
+          16,
+          16 +
+              max(
+                MediaQuery.of(ctx).viewInsets.bottom,
+                MediaQuery.of(ctx).viewPadding.bottom,
+              ),
+        ),
+        child: Column(
+          mainAxisSize: MainAxisSize.min,
+          crossAxisAlignment: CrossAxisAlignment.stretch,
+          children: [
+            Text(
+              'Stamp into the recording',
+              style: Theme.of(ctx).textTheme.titleMedium,
+            ),
+            const SizedBox(height: 8),
+            Wrap(
+              spacing: 8,
+              runSpacing: 8,
+              children: [
+                for (final q in quickMarks)
+                  ActionChip(label: Text(q), onPressed: () => send(q)),
+              ],
+            ),
+            TextField(
+              controller: custom,
+              decoration: const InputDecoration(labelText: 'Other'),
+              onSubmitted: send,
+            ),
+          ],
+        ),
+      );
+    },
+  );
+}

lib/actions/orin_power.dart

@@ -0,0 +1,67 @@
+import 'package:flutter/material.dart';
+
+import '../link/boundary.dart';
+import '../theme/palette.dart';
+
+/// Power off or reboot the Orin: one confirmation that is also the choice. Sent once,
+/// never resent (contracts BOUNDARY.md: the ack cache does not survive the restart).
+Future<void> orinPowerOptions(BuildContext context, Boundary b) async {
+  final host = b.hello?['host'] ?? 'the Orin';
+  final verb = await showDialog<String>(
+    context: context,
+    builder: (context) => AlertDialog(
+      title: Text('Power options: $host'),
+      content: const Text(
+        'Either way, recording stops and the session is closed cleanly.\n\n'
+        'Power off: the Orin stays off until its power button is pressed.\n'
+        'Reboot: it is back in about a minute; this screen reconnects by itself.',
+      ),
+      actions: [
+        TextButton(
+          onPressed: () => Navigator.of(context).pop(),
+          child: const Text('Cancel'),
+        ),
+        OutlinedButton.icon(
+          onPressed: () => Navigator.of(context).pop('reboot'),
+          icon: const Icon(Icons.restart_alt),
+          label: const Text('Reboot'),
+        ),
+        FilledButton.icon(
+          style: FilledButton.styleFrom(
+            backgroundColor: AppTheme.of(context).alarm,
+            foregroundColor: AppTheme.of(context)
+                .onFill(AppTheme.of(context).alarm),
+          ),
+          onPressed: () => Navigator.of(context).pop('poweroff'),
+          icon: const Icon(Icons.power_settings_new),
+          label: const Text('Power off'),
+        ),
+      ],
+    ),
+  );
+  if (verb == null || !context.mounted) return;
+  final messenger = ScaffoldMessenger.of(context);
+  final id = b.commandOnce(verb, {
+    'confirm': verb,
+    'boot_id': b.hello?['boot_id'],
+  });
+  if (id == null) {
+    messenger.showSnackBar(
+      const SnackBar(content: Text('Not sent: no link to the Orin')),
+    );
+    return;
+  }
+  final ack = await b.ackFor(id);
+  final what = verb == 'reboot' ? 'rebooting' : 'shutting down';
+  messenger.showSnackBar(
+    SnackBar(
+      content: Text(
+        ack == null
+            ? 'No reply: the Orin may or may not be $what'
+            : ack.ok
+            ? 'Orin: ${ack.detail}'
+            : 'Refused: ${ack.detail}',
+      ),
+    ),
+  );
+}

lib/actions/server_url.dart

@@ -0,0 +1,29 @@
+import 'package:flutter/material.dart';
+
+import '../link/boundary.dart';
+import '../link/net.dart';
+
+/// Ask for the gateway's address and reconnect there, binding to the USB link when it is on it.
+Future<void> editUrl(BuildContext context, Boundary b, UsbLink usb) async {
+  final c = TextEditingController(text: b.url);
+  final url = await showDialog<String>(
+    context: context,
+    builder: (ctx) => AlertDialog(
+      title: const Text('Gateway address'),
+      content: TextField(controller: c, autofocus: true),
+      actions: [
+        TextButton(
+          onPressed: () => Navigator.pop(ctx),
+          child: const Text('Cancel'),
+        ),
+        TextButton(
+          onPressed: () => Navigator.pop(ctx, c.text.trim()),
+          child: const Text('Connect'),
+        ),
+      ],
+    ),
+  );
+  if (url == null || url.isEmpty) return;
+  await usb.bindFor(Uri.parse(url));
+  b.retarget(url);
+}

lib/main.dart

@@ -1,16 +1,13 @@
-// Yukart display — starter. A text readout of whatever svc-gw sends, proving the
+// Yukart display: the tablet app. Starts the link to the Orin and hands the screen to
-// boundary contract before anything is drawn (initial plan, step 1).
+// the shell (lib/shell.dart). Code layout: lib/README.md.
-
-import 'dart:math';
 
 import 'package:flutter/material.dart';
 
-import 'boundary.dart';
+import 'link/boundary.dart';
-import 'camview.dart';
+import 'link/net.dart';
-import 'checklist.dart';
+import 'pages/link_test.dart';
-import 'dash.dart';
+import 'shell.dart';
-import 'linktest.dart';
+import 'shell_scope.dart';
-import 'net.dart';
 import 'theme/palette.dart';
 
 /// Override for development, e.g. `--dart-define=YUKART_GW=ws://halogen.local:7700/`.
@@ -21,7 +18,7 @@ const defaultUrl = String.fromEnvironment(
 
 Future<void> main() async {
   WidgetsFlutterBinding.ensureInitialized();
-  themes = await Themes.load();
+  final themes = await Themes.load();
   final usb = UsbLink();
   await usb.bindFor(Uri.parse(defaultUrl));
   final boundary = Boundary(defaultUrl)..start();
@@ -38,11 +35,7 @@ Future<void> main() async {
     final host = at < 0
         ? Uri.parse(boundary.url).host
         : request.substring(at + 1);
-    navigatorKey.currentState?.push(
+    shellView.value = ShellView.linkTest;
-      MaterialPageRoute<void>(
-        builder: (_) => linkTestPage(boundary, linkTest, usb),
-      ),
-    );
     await switch (mode) {
       'dl' => linkTest.runDownload(host, label),
       'bi' => linkTest.runBurstIdle(host, label),
@@ -52,34 +45,27 @@ Future<void> main() async {
   }
 
   usb.onLinkTest = runLinkTest;
-  runApp(YukartApp(boundary: boundary, usb: usb, linkTest: linkTest));
+  runApp(
+    YukartApp(boundary: boundary, usb: usb, linkTest: linkTest, themes: themes),
+  );
   final pending = await usb.takeLinkTest();
   if (pending != null) {
     WidgetsBinding.instance.addPostFrameCallback((_) => runLinkTest(pending));
   }
 }
 
-final navigatorKey = GlobalKey<NavigatorState>();
-
-/// The palette (lib/theme/palette.dart), loaded before the first frame.
-late final Themes themes;
-
-Widget linkTestPage(Boundary b, LinkTest t, UsbLink usb) => LinkTestPage(
-  test: t,
-  host: Uri.parse(b.url).host,
-  restoreBinding: () => usb.bindFor(Uri.parse(b.url)),
-);
-
 class YukartApp extends StatelessWidget {
   const YukartApp({
     super.key,
     required this.boundary,
     required this.usb,
     required this.linkTest,
+    required this.themes,
   });
   final Boundary boundary;
   final UsbLink usb;
   final LinkTest linkTest;
+  final Themes themes;
 
   @override
   Widget build(BuildContext context) {
@@ -88,519 +74,17 @@ class YukartApp extends StatelessWidget {
       listenable: themes,
       builder: (context, _) => MaterialApp(
         title: 'Yukart',
-        navigatorKey: navigatorKey,
         debugShowCheckedModeBanner: false,
         theme: themes.material(),
         builder: (context, child) =>
             AppTheme(palette: themes.current, child: child!),
-        home: ListenableBuilder(
+        home: AppShell(
-          listenable: Listenable.merge([boundary, usb]),
+          boundary: boundary,
-          builder: (context, _) =>
+          usb: usb,
-              Readout(boundary: boundary, usb: usb, linkTest: linkTest),
+          linkTest: linkTest,
+          themes: themes,
         ),
       ),
     );
   }
 }
-
-class Readout extends StatelessWidget {
-  const Readout({
-    super.key,
-    required this.boundary,
-    required this.usb,
-    required this.linkTest,
-  });
-  final Boundary boundary;
-  final UsbLink usb;
-  final LinkTest linkTest;
-
-  @override
-  Widget build(BuildContext context) {
-    final b = boundary;
-    return Scaffold(
-      body: SafeArea(
-        child: Column(
-          crossAxisAlignment: CrossAxisAlignment.stretch,
-          children: [
-            // Mock data must look like mock data: on the surface, not in a menu.
-            if (b.mock) const MockBanner(),
-            LinkBar(boundary: b, usb: usb, linkTest: linkTest),
-            Expanded(
-              child: LayoutBuilder(
-                builder: (context, c) {
-                  final wide = c.maxWidth > 800;
-                  final signals = SignalList(boundary: b);
-                  final raw = RawLog(boundary: b);
-                  return wide
-                      ? Row(
-                          crossAxisAlignment: CrossAxisAlignment.stretch,
-                          children: [
-                            Expanded(flex: 3, child: signals),
-                            const VerticalDivider(width: 1),
-                            Expanded(flex: 2, child: raw),
-                          ],
-                        )
-                      : Column(
-                          children: [
-                            Expanded(child: signals),
-                            const Divider(height: 1),
-                            Expanded(child: raw),
-                          ],
-                        );
-                },
-              ),
-            ),
-          ],
-        ),
-      ),
-      floatingActionButton: FloatingActionButton.extended(
-        onPressed: () => showMarkSheet(context, b),
-        icon: const Icon(Icons.flag),
-        label: Text(
-          b.pending.isEmpty ? 'Mark' : 'Mark (${b.pending.length} pending)',
-        ),
-      ),
-    );
-  }
-}
-
-class MockBanner extends StatelessWidget {
-  const MockBanner({super.key});
-
-  @override
-  Widget build(BuildContext context) {
-    final p = AppTheme.of(context);
-    return Container(
-      color: p.caution,
-      padding: const EdgeInsets.symmetric(vertical: 6),
-      child: Text(
-        'MOCK DATA — NOT FROM THE CAR',
-        textAlign: TextAlign.center,
-        style: TextStyle(
-          color: p.onFill(p.caution),
-          fontWeight: FontWeight.w900,
-          fontSize: 20,
-          letterSpacing: 2,
-        ),
-      ),
-    );
-  }
-}
-
-class LinkBar extends StatelessWidget {
-  const LinkBar({
-    super.key,
-    required this.boundary,
-    required this.usb,
-    required this.linkTest,
-  });
-  final Boundary boundary;
-  final UsbLink usb;
-  final LinkTest linkTest;
-
-  @override
-  Widget build(BuildContext context) {
-    final b = boundary;
-    final p = AppTheme.of(context);
-    final (color, label) = switch (b.state) {
-      LinkState.up => (p.good, 'CONNECTED'),
-      LinkState.connecting => (p.caution, 'CONNECTING'),
-      LinkState.down => (p.alarm, 'DOWN'),
-    };
-    // Fixed-width numbers, padded with figure spaces (U+2007, digit-wide): the bar must
-    // not reflow every time a value gains a digit.
-    String pad(String v, int n) => v.padLeft(n, '\u2007');
-    final age = b.lastMessage == null
-        ? pad('—', 4)
-        : pad(
-            '${DateTime.now().difference(b.lastMessage!).inMilliseconds.clamp(0, 9999)}',
-            4,
-          );
-    final offset = b.clockOffset == null
-        ? pad('—', 6)
-        : pad((b.clockOffset!.inMilliseconds / 1000).toStringAsFixed(1), 6);
-    const fixed = TextStyle(fontFeatures: [FontFeature.tabularFigures()]);
-    return Material(
-      color: Theme.of(context).colorScheme.surfaceContainerHigh,
-      child: InkWell(
-        onTap: () => editUrl(context, b, usb),
-        child: Padding(
-          padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 8),
-          child: Wrap(
-            spacing: 16,
-            runSpacing: 4,
-            crossAxisAlignment: WrapCrossAlignment.center,
-            children: [
-              Chip(
-                label: Text(
-                  label,
-                  style: TextStyle(color: color, fontWeight: FontWeight.w600),
-                ),
-                backgroundColor: color.withValues(alpha: 0.3),
-              ),
-              Text(b.url, style: const TextStyle(fontFamily: 'monospace')),
-              Text(b.detail),
-              Text('last msg $age ms', style: fixed),
-              Text('Orin−tablet clock $offset s', style: fixed),
-              if (usb.supported)
-                Text(
-                  'USB link ${usb.up ? 'up' : 'absent'}${usb.bound ? ', bound' : ''}',
-                ),
-              TextButton.icon(
-                onPressed: () => Navigator.of(context).push(
-                  MaterialPageRoute<void>(
-                    builder: (_) => DashPage(boundary: b, themes: themes),
-                  ),
-                ),
-                icon: const Icon(Icons.dashboard),
-                label: const Text('Dash'),
-              ),
-              TextButton.icon(
-                onPressed: () => Navigator.of(context).push(
-                  MaterialPageRoute<void>(
-                    builder: (_) => linkTestPage(b, linkTest, usb),
-                  ),
-                ),
-                icon: const Icon(Icons.speed),
-                label: const Text('Link test'),
-              ),
-              TextButton.icon(
-                onPressed: () => Navigator.of(context).push(
-                  MaterialPageRoute<void>(
-                    builder: (_) => CamViewPage(host: Uri.parse(b.url).host),
-                  ),
-                ),
-                icon: const Icon(Icons.videocam),
-                label: const Text('Camera'),
-              ),
-              TextButton.icon(
-                onPressed: () => Navigator.of(context).push(
-                  MaterialPageRoute<void>(
-                    builder: (_) => ChecklistsPage(boundary: b),
-                  ),
-                ),
-                icon: const Icon(Icons.checklist),
-                label: const Text('Captures'),
-              ),
-              if (b.state == LinkState.up && b.hello?['boot_id'] is String)
-                TextButton.icon(
-                  onPressed: () => orinPowerOptions(context, b),
-                  icon: const Icon(Icons.power_settings_new),
-                  label: const Text('Orin power options'),
-                ),
-            ],
-          ),
-        ),
-      ),
-    );
-  }
-}
-
-/// Confirm, then send `poweroff` once (contracts BOUNDARY.md): it carries this
-/// connection's boot id, so it can never take effect on a later boot.
-/// Power off or reboot the Orin: one confirmation that is also the choice. Sent once,
-/// never resent (contracts BOUNDARY.md: the ack cache does not survive the restart).
-Future<void> orinPowerOptions(BuildContext context, Boundary b) async {
-  final host = b.hello?['host'] ?? 'the Orin';
-  final verb = await showDialog<String>(
-    context: context,
-    builder: (context) => AlertDialog(
-      title: Text('Power options: $host'),
-      content: const Text(
-        'Either way, recording stops and the session is closed cleanly.\n\n'
-        'Power off: the Orin stays off until its power button is pressed.\n'
-        'Reboot: it is back in about a minute; this screen reconnects by itself.',
-      ),
-      actions: [
-        TextButton(
-          onPressed: () => Navigator.of(context).pop(),
-          child: const Text('Cancel'),
-        ),
-        OutlinedButton.icon(
-          onPressed: () => Navigator.of(context).pop('reboot'),
-          icon: const Icon(Icons.restart_alt),
-          label: const Text('Reboot'),
-        ),
-        FilledButton.icon(
-          style: FilledButton.styleFrom(
-            backgroundColor: AppTheme.of(context).alarm,
-            foregroundColor: AppTheme.of(context).onFill(AppTheme.of(context).alarm),
-          ),
-          onPressed: () => Navigator.of(context).pop('poweroff'),
-          icon: const Icon(Icons.power_settings_new),
-          label: const Text('Power off'),
-        ),
-      ],
-    ),
-  );
-  if (verb == null || !context.mounted) return;
-  final messenger = ScaffoldMessenger.of(context);
-  final id = b.commandOnce(verb, {
-    'confirm': verb,
-    'boot_id': b.hello?['boot_id'],
-  });
-  if (id == null) {
-    messenger.showSnackBar(
-      const SnackBar(content: Text('Not sent: no link to the Orin')),
-    );
-    return;
-  }
-  final ack = await b.ackFor(id);
-  final what = verb == 'reboot' ? 'rebooting' : 'shutting down';
-  messenger.showSnackBar(
-    SnackBar(
-      content: Text(
-        ack == null
-            ? 'No reply: the Orin may or may not be $what'
-            : ack.ok
-            ? 'Orin: ${ack.detail}'
-            : 'Refused: ${ack.detail}',
-      ),
-    ),
-  );
-}
-
-class SignalList extends StatelessWidget {
-  const SignalList({super.key, required this.boundary});
-  final Boundary boundary;
-
-  @override
-  Widget build(BuildContext context) {
-    final b = boundary;
-    if (b.state != LinkState.up) {
-      return const Center(child: Text('No link to the Orin'));
-    }
-    if (b.seen.isEmpty) {
-      return Center(
-        child: Text(
-          'Connected — the Orin is sending no vehicle state\n(source: ${b.hello?['source'] ?? '?'})',
-          textAlign: TextAlign.center,
-        ),
-      );
-    }
-    // Rows stay put: a signal that drops out is shown as missing, not removed.
-    final names = b.seen.keys.toList()..sort();
-    return ListView(
-      padding: const EdgeInsets.all(12),
-      children: [
-        for (final n in names)
-          b.signals[n] is Map
-              ? SignalTile(
-                  name: n,
-                  envelope: Map<String, dynamic>.from(b.signals[n] as Map),
-                )
-              : SignalTile(name: n, envelope: b.seen[n]!, missing: true),
-      ],
-    );
-  }
-}
-
-/// Missing, known-without-value, stale and fresh each look different: all four are normal in a car.
-class SignalTile extends StatelessWidget {
-  const SignalTile({
-    super.key,
-    required this.name,
-    required this.envelope,
-    this.missing = false,
-  });
-  final String name;
-
-  /// The current envelope, or the last one seen when [missing] (only its unit is used then).
-  final Map<String, dynamic> envelope;
-  final bool missing;
-
-  @override
-  Widget build(BuildContext context) {
-    final p = AppTheme.of(context);
-    if (missing) {
-      return ListTile(
-        title: Text(
-          name,
-          style: TextStyle(fontFamily: 'monospace', color: p.subdued),
-        ),
-        subtitle: Text(
-          'MISSING · not in the latest state',
-          style: TextStyle(color: p.alarm),
-        ),
-        trailing: Text.rich(
-          TextSpan(
-            children: [
-              TextSpan(
-                text: '?',
-                style: TextStyle(fontSize: 34, color: p.subdued),
-              ),
-              TextSpan(
-                text: '  ${envelope['unit'] ?? ''}',
-                style: TextStyle(fontSize: 16, color: p.subdued),
-              ),
-            ],
-          ),
-        ),
-      );
-    }
-    final v = envelope['value'];
-    final quality = envelope['quality'] as String? ?? 'ok';
-    final stale = quality != 'ok';
-    final text = v == null
-        ? '—'
-        : (v is double && v == v.roundToDouble() ? v.toInt().toString() : '$v');
-    final style = TextStyle(
-      fontSize: 34,
-      fontWeight: FontWeight.w600,
-      fontFeatures: const [FontFeature.tabularFigures()],
-      color: stale || v == null ? p.subdued : p.foreground,
-      fontStyle: stale ? FontStyle.italic : null,
-    );
-    return ListTile(
-      title: Text(name, style: const TextStyle(fontFamily: 'monospace')),
-      subtitle: Text(
-        style: stale ? TextStyle(color: p.caution) : null,
-        [
-          if (stale) quality.toUpperCase(),
-          if (v == null) 'no value',
-          if (envelope['mock'] == true) 'mock',
-        ].join(' · '),
-      ),
-      trailing: Text.rich(
-        TextSpan(
-          children: [
-            TextSpan(text: text, style: style),
-            TextSpan(
-              text: '  ${envelope['unit'] ?? ''}',
-              style: const TextStyle(fontSize: 16),
-            ),
-          ],
-        ),
-      ),
-    );
-  }
-}
-
-class RawLog extends StatelessWidget {
-  const RawLog({super.key, required this.boundary});
-  final Boundary boundary;
-
-  @override
-  Widget build(BuildContext context) {
-    final b = boundary;
-    return ListView(
-      padding: const EdgeInsets.all(8),
-      children: [
-        if (b.pending.isNotEmpty || b.acks.isNotEmpty) ...[
-          Text('Commands', style: Theme.of(context).textTheme.titleSmall),
-          for (final p in b.pending)
-            Text(
-              '… ${p.cmd} ${p.args['text'] ?? ''} (unacked)',
-              style: TextStyle(color: AppTheme.of(context).caution),
-            ),
-          for (final a in b.acks)
-            Text(
-              '${a.ok ? '✓' : '✗'} ${a.detail}',
-              style: TextStyle(color: a.ok ? AppTheme.of(context).good : AppTheme.of(context).alarm),
-            ),
-          const Divider(),
-        ],
-        Text(
-          'Raw messages, newest first',
-          style: Theme.of(context).textTheme.titleSmall,
-        ),
-        for (final r in b.recent)
-          Padding(
-            padding: const EdgeInsets.symmetric(vertical: 2),
-            child: Text(
-              r,
-              style: const TextStyle(fontFamily: 'monospace', fontSize: 11),
-            ),
-          ),
-      ],
-    );
-  }
-}
-
-const quickMarks = [
-  'cold start',
-  'engine start',
-  'indicator left',
-  'indicator right',
-  'brake',
-  'headlights',
-  'something odd',
-];
-
-Future<void> showMarkSheet(BuildContext context, Boundary b) {
-  final custom = TextEditingController();
-  return showModalBottomSheet(
-    context: context,
-    isScrollControlled: true,
-    useSafeArea: true,
-    builder: (ctx) {
-      void send(String text) {
-        if (text.trim().isEmpty) return;
-        b.command('mark', {'text': text.trim()});
-        Navigator.pop(ctx);
-      }
-
-      return Padding(
-        // Clear the keyboard when it is up, the navigation bar when it is not.
-        padding: EdgeInsets.fromLTRB(
-          16,
-          16,
-          16,
-          16 +
-              max(
-                MediaQuery.of(ctx).viewInsets.bottom,
-                MediaQuery.of(ctx).viewPadding.bottom,
-              ),
-        ),
-        child: Column(
-          mainAxisSize: MainAxisSize.min,
-          crossAxisAlignment: CrossAxisAlignment.stretch,
-          children: [
-            Text(
-              'Stamp into the recording',
-              style: Theme.of(ctx).textTheme.titleMedium,
-            ),
-            const SizedBox(height: 8),
-            Wrap(
-              spacing: 8,
-              runSpacing: 8,
-              children: [
-                for (final q in quickMarks)
-                  ActionChip(label: Text(q), onPressed: () => send(q)),
-              ],
-            ),
-            TextField(
-              controller: custom,
-              decoration: const InputDecoration(labelText: 'Other'),
-              onSubmitted: send,
-            ),
-          ],
-        ),
-      );
-    },
-  );
-}
-
-Future<void> editUrl(BuildContext context, Boundary b, UsbLink usb) async {
-  final c = TextEditingController(text: b.url);
-  final url = await showDialog<String>(
-    context: context,
-    builder: (ctx) => AlertDialog(
-      title: const Text('Gateway address'),
-      content: TextField(controller: c, autofocus: true),
-      actions: [
-        TextButton(
-          onPressed: () => Navigator.pop(ctx),
-          child: const Text('Cancel'),
-        ),
-        TextButton(
-          onPressed: () => Navigator.pop(ctx, c.text.trim()),
-          child: const Text('Connect'),
-        ),
-      ],
-    ),
-  );
-  if (url == null || url.isEmpty) return;
-  await usb.bindFor(Uri.parse(url));
-  b.retarget(url);
-}

lib/pages/camera.dart

@@ -10,7 +10,8 @@ import 'dart:typed_data';
 
 import 'package:flutter/material.dart';
 
-import 'theme/palette.dart';
+import '../shell_scope.dart';
+import '../theme/palette.dart';
 
 const camviewPort = 7710;
 
@@ -168,7 +169,7 @@ class _CamViewPageState extends State<CamViewPage> {
   Widget build(BuildContext context) {
     return Scaffold(
       backgroundColor: AppTheme.of(context).background,
-      appBar: AppBar(title: const Text('Camera (test)')),
+      appBar: AppBar(leading: const MenuButton(), title: const Text('Camera (test)')),
       body: SafeArea(
         child: ListenableBuilder(
           listenable: cam,

lib/pages/checklist.dart

@@ -17,8 +17,9 @@ import 'dart:convert';
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 
-import 'boundary.dart';
+import '../link/boundary.dart';
-import 'theme/palette.dart';
+import '../shell_scope.dart';
+import '../theme/palette.dart';
 
 const checklistAssets = 'assets/contracts/checklists/';
 
@@ -197,13 +198,13 @@ class ChecklistsPage extends StatelessWidget {
       future: loadChecklists(),
       builder: (context, snap) {
         if (snap.hasError) {
-          return Scaffold(appBar: AppBar(title: const Text('Captures')), body: Center(child: Text('${snap.error}')));
+          return Scaffold(appBar: AppBar(leading: const MenuButton(), title: const Text('Captures')), body: Center(child: Text('${snap.error}')));
         }
         final lists = snap.data;
         if (lists == null) return const Scaffold(body: Center(child: CircularProgressIndicator()));
         if (lists.length == 1) return ChecklistPage(boundary: boundary, checklist: lists.single);
         return Scaffold(
-          appBar: AppBar(title: const Text('Captures')),
+          appBar: AppBar(leading: const MenuButton(), title: const Text('Captures')),
           body: ListView(
             children: [
               if (lists.isEmpty) const ListTile(title: Text('No checklists in this build')),

lib/pages/dash.dart

@@ -5,14 +5,15 @@
 
 import 'package:flutter/material.dart';
 
-import 'boundary.dart';
+import '../link/boundary.dart';
-import 'reading.dart';
+import '../shell_scope.dart';
-import 'theme/palette.dart';
+import '../link/reading.dart';
-import 'widgets/accel_graph.dart';
+import '../theme/palette.dart';
-import 'widgets/gps_compass.dart';
+import '../widgets/accel_graph.dart';
-import 'widgets/stat_box.dart';
+import '../widgets/gps_compass.dart';
-import 'widgets/telltale.dart';
+import '../widgets/stat_box.dart';
-import 'widgets/whiskey_mark.dart';
+import '../widgets/telltale.dart';
+import '../widgets/whiskey_mark.dart';
 
 class DashPage extends StatelessWidget {
   const DashPage({super.key, required this.boundary, required this.themes});
@@ -47,20 +48,6 @@ class DashPage extends StatelessWidget {
             child: Column(
               crossAxisAlignment: CrossAxisAlignment.stretch,
               children: [
-                if (b.mock)
-                  Container(
-                    color: p.caution,
-                    padding: const EdgeInsets.symmetric(vertical: 4),
-                    child: Text(
-                      'MOCK DATA — NOT FROM THE CAR',
-                      textAlign: TextAlign.center,
-                      style: TextStyle(
-                        color: p.onFill(p.caution),
-                        fontWeight: FontWeight.w900,
-                        letterSpacing: 2,
-                      ),
-                    ),
-                  ),
                 _DashBar(boundary: b, themes: themes),
                 Expanded(
                   child: Padding(
@@ -175,7 +162,7 @@ class DashPage extends StatelessWidget {
   }
 }
 
-/// The dash's own thin top line: link state, back, and the dark/bright switch.
+/// The dash's own thin top line: the menu, link state, and the dark/bright switch.
 class _DashBar extends StatelessWidget {
   const _DashBar({required this.boundary, required this.themes});
   final Boundary boundary;
@@ -193,10 +180,7 @@ class _DashBar extends StatelessWidget {
       height: 40,
       child: Row(
         children: [
-          IconButton(
+          MenuButton(color: p.subdued),
-            onPressed: () => Navigator.of(context).maybePop(),
-            icon: Icon(Icons.arrow_back, color: p.subdued),
-          ),
           Text(text, style: TextStyle(color: color, letterSpacing: 2)),
           const Spacer(),
           IconButton(

lib/pages/link_test.dart

@@ -11,7 +11,8 @@ import 'dart:typed_data';
 
 import 'package:flutter/material.dart';
 
-import 'net.dart';
+import '../link/net.dart';
+import '../shell_scope.dart';
 
 const _down = 7791, _up = 7792, _echo = 7793, _results = 7794;
 
@@ -419,7 +420,7 @@ class _LinkTestPageState extends State<LinkTestPage> {
   @override
   Widget build(BuildContext context) {
     return Scaffold(
-      appBar: AppBar(title: const Text('Link test')),
+      appBar: AppBar(leading: const MenuButton(), title: const Text('Link test')),
       body: ListenableBuilder(
         listenable: widget.test,
         builder: (context, _) {

lib/pages/settings.dart

@@ -0,0 +1,83 @@
+// Settings: the few things that are chosen, gathered in one place. Build-time choices
+// are shown so it is clear where they come from, not edited here.
+
+import 'package:flutter/material.dart';
+
+import '../actions/server_url.dart';
+import '../link/boundary.dart';
+import '../link/net.dart';
+import '../shell_scope.dart';
+import '../theme/palette.dart';
+
+class SettingsPage extends StatelessWidget {
+  const SettingsPage({
+    super.key,
+    required this.boundary,
+    required this.usb,
+    required this.themes,
+  });
+  final Boundary boundary;
+  final UsbLink usb;
+  final Themes themes;
+
+  @override
+  Widget build(BuildContext context) {
+    final p = AppTheme.of(context);
+    Widget section(String t) => Padding(
+      padding: const EdgeInsets.fromLTRB(16, 20, 16, 4),
+      child: Text(
+        t,
+        style: Theme.of(context).textTheme.labelLarge
+            ?.copyWith(color: p.subdued),
+      ),
+    );
+    return ListenableBuilder(
+      listenable: Listenable.merge([boundary, themes]),
+      builder: (context, _) => Scaffold(
+        appBar: AppBar(
+          leading: const MenuButton(),
+          title: const Text('Settings'),
+        ),
+        body: ListView(
+          children: [
+            section('Connection'),
+            ListTile(
+              leading: const Icon(Icons.lan),
+              title: const Text('Gateway address'),
+              subtitle: Text(
+                boundary.url,
+                style: const TextStyle(fontFamily: 'monospace'),
+              ),
+              trailing: const Icon(Icons.edit),
+              onTap: () => editUrl(context, boundary, usb),
+            ),
+            section('Display'),
+            SwitchListTile(
+              secondary: Icon(
+                themes.isDark ? Icons.dark_mode : Icons.light_mode,
+              ),
+              title: const Text('Dark variant'),
+              subtitle: const Text('Bright for daylight, dark for night'),
+              value: themes.isDark,
+              onChanged: (v) => themes.isDark = v,
+            ),
+            ListTile(
+              leading: const Icon(Icons.palette),
+              title: const Text('Theme'),
+              subtitle: Text(
+                '${themes.name} · set at build time: --dart-define=YUKART_THEME=<name>',
+              ),
+            ),
+            ListTile(
+              leading: const Icon(Icons.home),
+              title: const Text('Landing view'),
+              subtitle: Text(
+                '${landingView.name} · set at build time: --dart-define=YUKART_HOME=dash|signals',
+              ),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}

lib/pages/signals.dart

@@ -0,0 +1,247 @@
+// Signals: every value the gateway sends, as a list, beside the raw traffic. The
+// development landing view (lib/shell_scope.dart).
+
+import 'package:flutter/material.dart';
+
+import '../actions/marks.dart';
+import '../actions/server_url.dart';
+import '../link/boundary.dart';
+import '../link/net.dart';
+import '../shell_scope.dart';
+import '../theme/palette.dart';
+import '../widgets/link_status.dart';
+
+class SignalsPage extends StatelessWidget {
+  const SignalsPage({super.key, required this.boundary, required this.usb});
+  final Boundary boundary;
+  final UsbLink usb;
+
+  @override
+  Widget build(BuildContext context) {
+    final b = boundary;
+    return ListenableBuilder(
+      listenable: Listenable.merge([boundary, usb]),
+      builder: (context, _) => Scaffold(
+        appBar: AppBar(
+          leading: const MenuButton(),
+          title: const Text('Signals'),
+          actions: [
+            LinkChip(boundary: b),
+            const SizedBox(width: 12),
+          ],
+        ),
+        body: Column(
+          crossAxisAlignment: CrossAxisAlignment.stretch,
+          children: [
+            Material(
+              color: AppTheme.of(context).surface,
+              child: InkWell(
+                onTap: () => editUrl(context, b, usb),
+                child: Padding(
+                  padding: const EdgeInsets.symmetric(
+                    horizontal: 16,
+                    vertical: 8,
+                  ),
+                  child: LinkDetails(boundary: b, usb: usb),
+                ),
+              ),
+            ),
+            Expanded(
+              child: LayoutBuilder(
+                builder: (context, c) {
+                  final wide = c.maxWidth > 800;
+                  final signals = SignalList(boundary: b);
+                  final raw = RawLog(boundary: b);
+                  return wide
+                      ? Row(
+                          crossAxisAlignment: CrossAxisAlignment.stretch,
+                          children: [
+                            Expanded(flex: 3, child: signals),
+                            const VerticalDivider(width: 1),
+                            Expanded(flex: 2, child: raw),
+                          ],
+                        )
+                      : Column(
+                          children: [
+                            Expanded(child: signals),
+                            const Divider(height: 1),
+                            Expanded(child: raw),
+                          ],
+                        );
+                },
+              ),
+            ),
+          ],
+        ),
+        floatingActionButton: FloatingActionButton.extended(
+          onPressed: () => showMarkSheet(context, b),
+          icon: const Icon(Icons.flag),
+          label: Text(
+            b.pending.isEmpty ? 'Mark' : 'Mark (${b.pending.length} pending)',
+          ),
+        ),
+      ),
+    );
+  }
+}
+
+class SignalList extends StatelessWidget {
+  const SignalList({super.key, required this.boundary});
+  final Boundary boundary;
+
+  @override
+  Widget build(BuildContext context) {
+    final b = boundary;
+    if (b.state != LinkState.up) {
+      return const Center(child: Text('No link to the Orin'));
+    }
+    if (b.seen.isEmpty) {
+      return Center(
+        child: Text(
+          'Connected — the Orin is sending no vehicle state\n(source: ${b.hello?['source'] ?? '?'})',
+          textAlign: TextAlign.center,
+        ),
+      );
+    }
+    // Rows stay put: a signal that drops out is shown as missing, not removed.
+    final names = b.seen.keys.toList()..sort();
+    return ListView(
+      padding: const EdgeInsets.all(12),
+      children: [
+        for (final n in names)
+          b.signals[n] is Map
+              ? SignalTile(
+                  name: n,
+                  envelope: Map<String, dynamic>.from(b.signals[n] as Map),
+                )
+              : SignalTile(name: n, envelope: b.seen[n]!, missing: true),
+      ],
+    );
+  }
+}
+
+/// Missing, known-without-value, stale and fresh each look different: all four are normal in a car.
+class SignalTile extends StatelessWidget {
+  const SignalTile({
+    super.key,
+    required this.name,
+    required this.envelope,
+    this.missing = false,
+  });
+  final String name;
+
+  /// The current envelope, or the last one seen when [missing] (only its unit is used then).
+  final Map<String, dynamic> envelope;
+  final bool missing;
+
+  @override
+  Widget build(BuildContext context) {
+    final p = AppTheme.of(context);
+    if (missing) {
+      return ListTile(
+        title: Text(
+          name,
+          style: TextStyle(fontFamily: 'monospace', color: p.subdued),
+        ),
+        subtitle: Text(
+          'MISSING · not in the latest state',
+          style: TextStyle(color: p.alarm),
+        ),
+        trailing: Text.rich(
+          TextSpan(
+            children: [
+              TextSpan(
+                text: '?',
+                style: TextStyle(fontSize: 34, color: p.subdued),
+              ),
+              TextSpan(
+                text: '  ${envelope['unit'] ?? ''}',
+                style: TextStyle(fontSize: 16, color: p.subdued),
+              ),
+            ],
+          ),
+        ),
+      );
+    }
+    final v = envelope['value'];
+    final quality = envelope['quality'] as String? ?? 'ok';
+    final stale = quality != 'ok';
+    final text = v == null
+        ? '—'
+        : (v is double && v == v.roundToDouble() ? v.toInt().toString() : '$v');
+    final style = TextStyle(
+      fontSize: 34,
+      fontWeight: FontWeight.w600,
+      fontFeatures: const [FontFeature.tabularFigures()],
+      color: stale || v == null ? p.subdued : p.foreground,
+      fontStyle: stale ? FontStyle.italic : null,
+    );
+    return ListTile(
+      title: Text(name, style: const TextStyle(fontFamily: 'monospace')),
+      subtitle: Text(
+        style: stale ? TextStyle(color: p.caution) : null,
+        [
+          if (stale) quality.toUpperCase(),
+          if (v == null) 'no value',
+          if (envelope['mock'] == true) 'mock',
+        ].join(' · '),
+      ),
+      trailing: Text.rich(
+        TextSpan(
+          children: [
+            TextSpan(text: text, style: style),
+            TextSpan(
+              text: '  ${envelope['unit'] ?? ''}',
+              style: const TextStyle(fontSize: 16),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}
+
+class RawLog extends StatelessWidget {
+  const RawLog({super.key, required this.boundary});
+  final Boundary boundary;
+
+  @override
+  Widget build(BuildContext context) {
+    final b = boundary;
+    return ListView(
+      padding: const EdgeInsets.all(8),
+      children: [
+        if (b.pending.isNotEmpty || b.acks.isNotEmpty) ...[
+          Text('Commands', style: Theme.of(context).textTheme.titleSmall),
+          for (final p in b.pending)
+            Text(
+              '… ${p.cmd} ${p.args['text'] ?? ''} (unacked)',
+              style: TextStyle(color: AppTheme.of(context).caution),
+            ),
+          for (final a in b.acks)
+            Text(
+              '${a.ok ? '✓' : '✗'} ${a.detail}',
+              style: TextStyle(
+                color: a.ok
+                    ? AppTheme.of(context).good
+                    : AppTheme.of(context).alarm,
+              ),
+            ),
+          const Divider(),
+        ],
+        Text(
+          'Raw messages, newest first',
+          style: Theme.of(context).textTheme.titleSmall,
+        ),
+        for (final r in b.recent)
+          Padding(
+            padding: const EdgeInsets.symmetric(vertical: 2),
+            child: Text(
+              r,
+              style: const TextStyle(fontFamily: 'monospace', fontSize: 11),
+            ),
+          ),
+      ],
+    );
+  }
+}

lib/shell.dart

@@ -0,0 +1,239 @@
+// The shell: one page at a time, chosen from a menu that swipes in from the left
+// (or opens from each page's menu button). Main views first, then Tools, the rarely
+// used ones (pirate-station-aide's pattern), then Settings.
+//
+// Dash, Signals and Captures stay alive while hidden, so a capture run survives a look
+// at the dash; Camera and Link test are built only while shown (the camera holds a stream).
+
+import 'package:flutter/material.dart';
+
+import 'actions/orin_power.dart';
+import 'link/boundary.dart';
+import 'link/net.dart';
+import 'pages/camera.dart';
+import 'pages/checklist.dart';
+import 'pages/dash.dart';
+import 'pages/link_test.dart';
+import 'pages/settings.dart';
+import 'pages/signals.dart';
+import 'shell_scope.dart';
+import 'theme/palette.dart';
+import 'widgets/link_status.dart';
+import 'widgets/mock_banner.dart';
+
+class AppShell extends StatefulWidget {
+  const AppShell({
+    super.key,
+    required this.boundary,
+    required this.usb,
+    required this.linkTest,
+    required this.themes,
+  });
+  final Boundary boundary;
+  final UsbLink usb;
+  final LinkTest linkTest;
+  final Themes themes;
+
+  @override
+  State<AppShell> createState() => _AppShellState();
+}
+
+class _AppShellState extends State<AppShell> {
+  final _scaffold = GlobalKey<ScaffoldState>();
+  // Captures runs its own navigator (list → checklist), so the menu stays reachable
+  // inside it and the run survives switching views.
+  final _captures = GlobalKey<NavigatorState>();
+  final Set<ShellView> _built = {shellView.value};
+
+  void _go(ShellView v) {
+    shellView.value = v;
+    _scaffold.currentState?.closeDrawer();
+  }
+
+  Widget _page(ShellView v) {
+    final b = widget.boundary;
+    return switch (v) {
+      ShellView.dash => DashPage(boundary: b, themes: widget.themes),
+      ShellView.signals => SignalsPage(boundary: b, usb: widget.usb),
+      ShellView.captures => Navigator(
+        key: _captures,
+        onGenerateRoute: (_) => MaterialPageRoute<void>(
+          builder: (_) => ChecklistsPage(boundary: b),
+        ),
+      ),
+      ShellView.camera => CamViewPage(host: Uri.parse(b.url).host),
+      ShellView.linkTest => LinkTestPage(
+        test: widget.linkTest,
+        host: Uri.parse(b.url).host,
+        restoreBinding: () => widget.usb.bindFor(Uri.parse(b.url)),
+      ),
+      ShellView.settings => SettingsPage(
+        boundary: b,
+        usb: widget.usb,
+        themes: widget.themes,
+      ),
+    };
+  }
+
+  static const _kept = {ShellView.dash, ShellView.signals, ShellView.captures};
+
+  @override
+  Widget build(BuildContext context) {
+    return ValueListenableBuilder(
+      valueListenable: shellView,
+      builder: (context, current, _) {
+        _built.add(current);
+        return PopScope(
+          // Back: inside Captures first, then to the landing view, then out of the app.
+          canPop:
+              current == landingView &&
+              !(_captures.currentState?.canPop() ?? false),
+          onPopInvokedWithResult: (didPop, _) {
+            if (didPop) return;
+            if (current == ShellView.captures &&
+                (_captures.currentState?.canPop() ?? false)) {
+              _captures.currentState!.pop();
+            } else {
+              shellView.value = landingView;
+            }
+          },
+          child: ShellScope(
+            openMenu: () => _scaffold.currentState?.openDrawer(),
+            child: Scaffold(
+              key: _scaffold,
+              drawerEdgeDragWidth: 32,
+              drawer: _Menu(
+                boundary: widget.boundary,
+                current: current,
+                go: _go,
+                // From the shell's context: the drawer's is gone once it closes.
+                power: () {
+                  _scaffold.currentState?.closeDrawer();
+                  orinPowerOptions(context, widget.boundary);
+                },
+              ),
+              body: ListenableBuilder(
+                listenable: widget.boundary,
+                builder: (context, child) => Column(
+                  crossAxisAlignment: CrossAxisAlignment.stretch,
+                  children: [
+                    if (widget.boundary.mock)
+                      const SafeArea(bottom: false, child: MockBanner()),
+                    // Pages draw their own top (app bars); keep every bottom clear of the system bar.
+                    Expanded(child: SafeArea(top: false, child: child!)),
+                  ],
+                ),
+                child: IndexedStack(
+                  index: ShellView.values.indexOf(current),
+                  children: [
+                    for (final v in ShellView.values)
+                      // Kept views, once built, stay built; the rest exist only while shown.
+                      if ((_kept.contains(v) && _built.contains(v)) ||
+                          v == current)
+                        _page(v)
+                      else
+                        const SizedBox.shrink(),
+                  ],
+                ),
+              ),
+            ),
+          ),
+        );
+      },
+    );
+  }
+}
+
+class _Menu extends StatelessWidget {
+  const _Menu({
+    required this.boundary,
+    required this.current,
+    required this.go,
+    required this.power,
+  });
+  final Boundary boundary;
+  final ShellView current;
+  final void Function(ShellView) go;
+  final VoidCallback power;
+
+  @override
+  Widget build(BuildContext context) {
+    final p = AppTheme.of(context);
+    Widget item(ShellView v, IconData icon, String label) => ListTile(
+      leading: Icon(icon),
+      title: Text(label),
+      selected: v == current,
+      selectedColor: p.accent,
+      selectedTileColor: p.accent.withValues(alpha: 0.12),
+      onTap: () => go(v),
+    );
+    Widget heading(String t) => Padding(
+      padding: const EdgeInsets.fromLTRB(16, 16, 16, 4),
+      child: Text(
+        t,
+        style: Theme.of(context).textTheme.labelLarge
+            ?.copyWith(color: p.subdued),
+      ),
+    );
+    return Drawer(
+      backgroundColor: p.surface,
+      child: SafeArea(
+        child: ListenableBuilder(
+          listenable: boundary,
+          builder: (context, _) {
+            final b = boundary;
+            final host = b.hello?['host'] as String?;
+            return ListView(
+              children: [
+                // The link, always: tapping it goes to Settings, where the address is.
+                InkWell(
+                  onTap: () => go(ShellView.settings),
+                  child: Padding(
+                    padding: const EdgeInsets.fromLTRB(16, 24, 16, 12),
+                    child: Column(
+                      crossAxisAlignment: CrossAxisAlignment.start,
+                      children: [
+                        Text(
+                          'Yukart',
+                          style: Theme.of(context).textTheme.headlineSmall,
+                        ),
+                        const SizedBox(height: 8),
+                        LinkChip(boundary: b),
+                        const SizedBox(height: 4),
+                        Text(host ?? b.url, style: TextStyle(color: p.subdued)),
+                      ],
+                    ),
+                  ),
+                ),
+                const Divider(),
+                item(ShellView.dash, Icons.speed, 'Dash'),
+                item(ShellView.signals, Icons.list_alt, 'Signals'),
+                item(ShellView.captures, Icons.checklist, 'Captures'),
+                const Divider(),
+                heading('Tools'),
+                item(ShellView.camera, Icons.videocam, 'Camera'),
+                item(ShellView.linkTest, Icons.network_check, 'Link test'),
+                ListTile(
+                  leading: const Icon(Icons.power_settings_new),
+                  title: const Text('Orin power options'),
+                  subtitle:
+                      b.state == LinkState.up && b.hello?['boot_id'] is String
+                      ? null
+                      : Text(
+                          'needs the link up',
+                          style: TextStyle(color: p.subdued),
+                        ),
+                  enabled:
+                      b.state == LinkState.up && b.hello?['boot_id'] is String,
+                  onTap: power,
+                ),
+                const Divider(),
+                item(ShellView.settings, Icons.settings, 'Settings'),
+              ],
+            );
+          },
+        ),
+      ),
+    );
+  }
+}

lib/shell_scope.dart

@@ -0,0 +1,47 @@
+// What a page needs from the shell (lib/shell.dart), without importing it: open the
+// menu, switch view. Pages import this; the shell imports the pages.
+
+import 'package:flutter/material.dart';
+
+/// Every view the menu offers. Tools are the rarely used ones (pirate-station-aide's pattern).
+enum ShellView { dash, signals, captures, camera, linkTest, settings }
+
+/// The landing view, set at build time: `--dart-define=YUKART_HOME=dash` for the car,
+/// `signals` (the default, for now) while developing.
+ShellView get landingView => switch (const String.fromEnvironment(
+  'YUKART_HOME',
+  defaultValue: 'signals',
+)) {
+  'dash' => ShellView.dash,
+  _ => ShellView.signals,
+};
+
+/// The view on screen. The shell listens to it; anything may set it (the link-test hook does).
+final shellView = ValueNotifier<ShellView>(landingView);
+
+class ShellScope extends InheritedWidget {
+  const ShellScope({super.key, required this.openMenu, required super.child});
+
+  final VoidCallback openMenu;
+
+  static ShellScope? maybeOf(BuildContext context) =>
+      context.dependOnInheritedWidgetOfExactType<ShellScope>();
+
+  @override
+  bool updateShouldNotify(ShellScope old) => false;
+}
+
+/// The menu button every page puts where a back arrow would be. The menu also opens
+/// with a swipe in from the left edge.
+class MenuButton extends StatelessWidget {
+  const MenuButton({super.key, this.color});
+
+  final Color? color;
+
+  @override
+  Widget build(BuildContext context) => IconButton(
+    tooltip: 'Menu',
+    icon: Icon(Icons.menu, color: color),
+    onPressed: ShellScope.maybeOf(context)?.openMenu,
+  );
+}

lib/widgets/link_status.dart

@@ -0,0 +1,71 @@
+// The link to the Orin at a glance: the state chip, and the details behind it.
+
+import 'package:flutter/material.dart';
+
+import '../link/boundary.dart';
+import '../link/net.dart';
+import '../theme/palette.dart';
+
+/// CONNECTED / CONNECTING / DOWN in good / caution / alarm.
+class LinkChip extends StatelessWidget {
+  const LinkChip({super.key, required this.boundary});
+  final Boundary boundary;
+
+  @override
+  Widget build(BuildContext context) {
+    final p = AppTheme.of(context);
+    final (color, label) = switch (boundary.state) {
+      LinkState.up => (p.good, 'CONNECTED'),
+      LinkState.connecting => (p.caution, 'CONNECTING'),
+      LinkState.down => (p.alarm, 'DOWN'),
+    };
+    return Chip(
+      label: Text(
+        label,
+        style: TextStyle(color: color, fontWeight: FontWeight.w600),
+      ),
+      backgroundColor: color.withValues(alpha: 0.3),
+      side: BorderSide.none,
+      visualDensity: VisualDensity.compact,
+    );
+  }
+}
+
+/// Address, gateway, last-message age, clock offset, USB link. Fixed-width numbers,
+/// padded with figure spaces (U+2007, digit-wide): nothing reflows as a value gains a digit.
+class LinkDetails extends StatelessWidget {
+  const LinkDetails({super.key, required this.boundary, required this.usb});
+  final Boundary boundary;
+  final UsbLink usb;
+
+  @override
+  Widget build(BuildContext context) {
+    final b = boundary;
+    String pad(String v, int n) => v.padLeft(n, ' ');
+    final age = b.lastMessage == null
+        ? pad('—', 4)
+        : pad(
+            '${DateTime.now().difference(b.lastMessage!).inMilliseconds.clamp(0, 9999)}',
+            4,
+          );
+    final offset = b.clockOffset == null
+        ? pad('—', 6)
+        : pad((b.clockOffset!.inMilliseconds / 1000).toStringAsFixed(1), 6);
+    const fixed = TextStyle(fontFeatures: [FontFeature.tabularFigures()]);
+    return Wrap(
+      spacing: 16,
+      runSpacing: 4,
+      crossAxisAlignment: WrapCrossAlignment.center,
+      children: [
+        Text(b.url, style: const TextStyle(fontFamily: 'monospace')),
+        Text(b.detail),
+        Text('last msg $age ms', style: fixed),
+        Text('Orin−tablet clock $offset s', style: fixed),
+        if (usb.supported)
+          Text(
+            'USB link ${usb.up ? 'up' : 'absent'}${usb.bound ? ', bound' : ''}',
+          ),
+      ],
+    );
+  }
+}

lib/widgets/mock_banner.dart

@@ -0,0 +1,28 @@
+// Mock data must look like mock data: on the surface of every page, not in a menu.
+
+import 'package:flutter/material.dart';
+
+import '../theme/palette.dart';
+
+class MockBanner extends StatelessWidget {
+  const MockBanner({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    final p = AppTheme.of(context);
+    return Container(
+      color: p.caution,
+      padding: const EdgeInsets.symmetric(vertical: 6),
+      child: Text(
+        'MOCK DATA — NOT FROM THE CAR',
+        textAlign: TextAlign.center,
+        style: TextStyle(
+          color: p.onFill(p.caution),
+          fontWeight: FontWeight.w900,
+          fontSize: 20,
+          letterSpacing: 2,
+        ),
+      ),
+    );
+  }
+}

lib/widgets/telltale.dart

@@ -1,9 +1,9 @@
 // An on/off lamp in the boxed pattern (lib/widgets/stat_box.dart): the label is the
-// lamp. Takes a [Reading] (lib/reading.dart) so missing and stale draw as they do elsewhere.
+// lamp. Takes a [Reading] (lib/link/reading.dart) so missing and stale draw as they do elsewhere.
 
 import 'package:flutter/material.dart';
 
-import '../reading.dart';
+import '../link/reading.dart';
 import '../theme/palette.dart';
 
 /// An on/off lamp in the boxed pattern: the label is the lamp. Lit in foreground

test/boundary_test.dart

@@ -2,7 +2,7 @@ import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
 
-import 'package:display/boundary.dart';
+import 'package:display/link/boundary.dart';
 import 'package:flutter_test/flutter_test.dart';
 
 /// A minimal stand-in for svc-gw: hello, then whatever the test sends.

test/checklist_test.dart

@@ -1,7 +1,7 @@
 import 'dart:convert';
 import 'dart:io';
 
-import 'package:display/checklist.dart';
+import 'package:display/pages/checklist.dart';
 import 'package:flutter_test/flutter_test.dart';
 
 Checklist sample() => Checklist.fromJson({