feat(nav): discoverable sidebar — instant tooltips, shortcuts made visible, pinnable rail

The icon-only rail forced first-time users to guess (usertest:
Senior, a11y, UX personas). Three changes:
- Nav tooltips appear instantly and carry the page shortcut
  (Cmd+1..9, Ctrl on non-mac — Ctrl activators added); expanded
  labels show the same hint. Explicit button semantics for
  screen readers on every destination.
- A visible 'Search & commands' row above the footer opens the
  existing Cmd+K palette, which nothing in the UI advertised.
- Settings -> Appearance gains 'Keep the navigation expanded':
  pins the rail with permanent labels (persisted preference).
Footer strip and pillar toggle made overflow-safe for the
animating rail; responsive test scrolls the by-design scrollable
destinations list.

Signed-off-by: flemming-it <stefan.a.flemming@googlemail.com>

lib/data/sidebar_prefs.dart

@@ -0,0 +1,23 @@
+// Operator preference: keep the sidebar permanently expanded so
+// every destination shows its text label without hovering. Off by
+// default (hover-expand rail); a11y/senior operators flip it in
+// Settings → Appearance.
+
+import 'package:flutter/foundation.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+
+class SidebarPrefs {
+  static const _kPinnedKey = 'sidebar.pinned';
+  static final ValueNotifier<bool> pinned = ValueNotifier(false);
+
+  static Future<void> load() async {
+    final prefs = await SharedPreferences.getInstance();
+    pinned.value = prefs.getBool(_kPinnedKey) ?? false;
+  }
+
+  static Future<void> setPinned(bool value) async {
+    pinned.value = value;
+    final prefs = await SharedPreferences.getInstance();
+    await prefs.setBool(_kPinnedKey, value);
+  }
+}

lib/l10n/app_de.arb

@@ -1549,6 +1549,9 @@
   "doctorPathStudioErrors": "Studio-Fehler",
   "settingsCategoryGeneral": "Allgemein",
   "settingsCategoryAppearance": "Darstellung",
+  "sidebarSearchLabel": "Suchen & Befehle",
+  "settingsSidebarPinnedTitle": "Navigation immer ausgeklappt",
+  "settingsSidebarPinnedBody": "Zeigt die Beschriftungen der Seitenleiste dauerhaft an, statt sie nur beim Überfahren mit der Maus einzublenden.",
   "settingsCategoryAi": "System-KI",
   "settingsCategoryIntegrations": "Integrationen",
   "settingsCategorySecurity": "Sicherheit",

lib/l10n/app_en.arb

@@ -1573,6 +1573,9 @@
   "doctorPathStudioErrors": "Studio errors",
   "settingsCategoryGeneral": "General",
   "settingsCategoryAppearance": "Appearance",
+  "sidebarSearchLabel": "Search & commands",
+  "settingsSidebarPinnedTitle": "Keep the navigation expanded",
+  "settingsSidebarPinnedBody": "Shows the sidebar labels permanently instead of only while hovering with the mouse.",
   "settingsCategoryAi": "System AI",
   "settingsCategoryIntegrations": "Integrations",
   "settingsCategorySecurity": "Security",

lib/l10n/app_localizations.dart

@@ -4544,6 +4544,24 @@ abstract class AppLocalizations {
   /// **'Appearance'**
   String get settingsCategoryAppearance;
 
+  /// No description provided for @sidebarSearchLabel.
+  ///
+  /// In en, this message translates to:
+  /// **'Search & commands'**
+  String get sidebarSearchLabel;
+
+  /// No description provided for @settingsSidebarPinnedTitle.
+  ///
+  /// In en, this message translates to:
+  /// **'Keep the navigation expanded'**
+  String get settingsSidebarPinnedTitle;
+
+  /// No description provided for @settingsSidebarPinnedBody.
+  ///
+  /// In en, this message translates to:
+  /// **'Shows the sidebar labels permanently instead of only while hovering with the mouse.'**
+  String get settingsSidebarPinnedBody;
+
   /// No description provided for @settingsCategoryAi.
   ///
   /// In en, this message translates to:

lib/l10n/app_localizations_de.dart

@@ -2666,6 +2666,16 @@ class AppLocalizationsDe extends AppLocalizations {
   @override
   String get settingsCategoryAppearance => 'Darstellung';
 
+  @override
+  String get sidebarSearchLabel => 'Suchen & Befehle';
+
+  @override
+  String get settingsSidebarPinnedTitle => 'Navigation immer ausgeklappt';
+
+  @override
+  String get settingsSidebarPinnedBody =>
+      'Zeigt die Beschriftungen der Seitenleiste dauerhaft an, statt sie nur beim Überfahren mit der Maus einzublenden.';
+
   @override
   String get settingsCategoryAi => 'System-KI';
 

lib/l10n/app_localizations_en.dart

@@ -2668,6 +2668,16 @@ class AppLocalizationsEn extends AppLocalizations {
   @override
   String get settingsCategoryAppearance => 'Appearance';
 
+  @override
+  String get sidebarSearchLabel => 'Search & commands';
+
+  @override
+  String get settingsSidebarPinnedTitle => 'Keep the navigation expanded';
+
+  @override
+  String get settingsSidebarPinnedBody =>
+      'Shows the sidebar labels permanently instead of only while hovering with the mouse.';
+
   @override
   String get settingsCategoryAi => 'System AI';
 

lib/main.dart

@@ -6,12 +6,14 @@
 import 'dart:async';
 
 import 'package:chain_client_sdk/chain_client_sdk.dart';
+import 'package:flutter/foundation.dart' show defaultTargetPlatform;
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 
 import 'data/chain_log.dart';
 import 'data/error_presentation.dart';
 import 'data/hub.dart';
+import 'data/sidebar_prefs.dart';
 import 'data/workspace.dart';
 import 'data/system_actions.dart';
 import 'data/theme_plugin.dart';
@@ -74,6 +76,10 @@ Future<void> main() async {
     () => HubService.instance.loadLocale(),
   );
   final themePlugin = await _restoreOr(null, loadActiveThemePlugin);
+  await _restoreOr(null, () async {
+    await SidebarPrefs.load();
+    return null;
+  });
   runApp(
     StudioApp(
       initialThemeMode: themeMode,
@@ -608,8 +614,9 @@ class StudioShellState extends State<StudioShell> {
     final theme = Theme.of(context);
     return Shortcuts(
       shortcuts: <ShortcutActivator, Intent>{
-        // Cmd+1..6 jumps to the matching destination. Numbered
+        // Cmd+1..9 (Ctrl on non-mac) jumps to the matching
-        // 1-based to match the visual order in the sidebar.
+        // destination. Numbered 1-based to match the visual
+        // order in the sidebar.
         for (var i = 0; i < _pages.length; i++)
           SingleActivator(
             LogicalKeyboardKey(LogicalKeyboardKey.digit1.keyId + i),
@@ -617,6 +624,13 @@ class StudioShellState extends State<StudioShell> {
           ): _GoToPageIntent(
             i,
           ),
+        for (var i = 0; i < _pages.length; i++)
+          SingleActivator(
+            LogicalKeyboardKey(LogicalKeyboardKey.digit1.keyId + i),
+            control: true,
+          ): _GoToPageIntent(
+            i,
+          ),
         // Settings dialog. macOS reserves Cmd+, for the native
         // app-Preferences menu item, which Flutter Desktop
         // doesn't wire up — the keystroke is captured by the OS
@@ -661,15 +675,19 @@ class StudioShellState extends State<StudioShell> {
           child: Scaffold(
             body: Row(
               children: [
-                _Sidebar(
+                ValueListenableBuilder<bool>(
-                  selectedIndex: _selectedIndex,
+                  valueListenable: SidebarPrefs.pinned,
-                  onSelect: (i) => setState(() => _selectedIndex = i),
+                  builder: (context, pinned, _) => _Sidebar(
-                  pages: _pages,
+                    selectedIndex: _selectedIndex,
-                  connected: _connected,
+                    onSelect: (i) => setState(() => _selectedIndex = i),
-                  endpointLabel: HubService.instance.endpointLabel,
+                    pages: _pages,
-                  activeChannel: _activeChannel,
+                    connected: _connected,
-                  pendingApprovals: _pendingApprovals,
+                    endpointLabel: HubService.instance.endpointLabel,
-                  forceExpanded: widget.startSidebarExpanded,
+                    activeChannel: _activeChannel,
+                    pendingApprovals: _pendingApprovals,
+                    forceExpanded: widget.startSidebarExpanded || pinned,
+                    onOpenSearch: _openSearchPalette,
+                  ),
                 ),
                 Container(width: 1, color: theme.colorScheme.outlineVariant),
                 Expanded(
@@ -787,6 +805,11 @@ class _OpenSearchIntent extends Intent {
   const _OpenSearchIntent();
 }
 
+/// Platform-truthful label for the app's primary-modifier
+/// shortcuts (the activators bind ⌘ on macOS and Ctrl elsewhere).
+String _metaShortcut(String key) =>
+    defaultTargetPlatform == TargetPlatform.macOS ? '⌘$key' : 'Ctrl+$key';
+
 class _Sidebar extends StatefulWidget {
   final int selectedIndex;
   final ValueChanged<int> onSelect;
@@ -804,11 +827,17 @@ class _Sidebar extends StatefulWidget {
   /// without polling the page.
   final int pendingApprovals;
 
-  /// Test-only: start fully expanded (controller at 1.0) and disable
+  /// Keep the rail fully expanded and disable hover-collapse.
-  /// hover, so a widget test can measure the expanded layout without a
+  /// True when the operator pins the sidebar (Settings →
-  /// hover gesture. Always false in production.
+  /// Appearance) and in widget tests measuring the expanded
+  /// layout.
   final bool forceExpanded;
 
+  /// Opens the Cmd+K command palette — the sidebar carries a
+  /// visible search row so the palette is discoverable without
+  /// knowing the shortcut.
+  final VoidCallback? onOpenSearch;
+
   const _Sidebar({
     required this.selectedIndex,
     required this.onSelect,
@@ -818,6 +847,7 @@ class _Sidebar extends StatefulWidget {
     required this.activeChannel,
     this.pendingApprovals = 0,
     this.forceExpanded = false,
+    this.onOpenSearch,
   });
 
   @override
@@ -863,6 +893,16 @@ class _SidebarState extends State<_Sidebar>
     );
   }
 
+  @override
+  void didUpdateWidget(covariant _Sidebar old) {
+    super.didUpdateWidget(old);
+    // The pin toggle flips at runtime (Settings → Appearance):
+    // animate to the new resting state instead of jumping.
+    if (widget.forceExpanded != old.forceExpanded) {
+      widget.forceExpanded ? _ctrl.forward() : _ctrl.reverse();
+    }
+  }
+
   @override
   void dispose() {
     _ctrl.dispose();
@@ -1026,11 +1066,33 @@ class _SidebarState extends State<_Sidebar>
                                     widget.pendingApprovals > 0
                                 ? widget.pendingApprovals
                                 : null,
+                            // Cmd+1..9 jump to the destination; the
+                            // hint rides in tooltip + expanded label
+                            // so the shortcut is discoverable.
+                            shortcutHint: i < 9 ? _metaShortcut('${i + 1}') : null,
                             onTap: () => widget.onSelect(i),
                           ),
                       ],
                     ),
                   ),
+                  // Visible entry point for the Cmd+K palette — the
+                  // shortcut exists since 0.3x but nothing in the UI
+                  // said so (usertest: "no shortcuts anywhere").
+                  if (widget.onOpenSearch != null)
+                    Builder(
+                      builder: (context) {
+                        final l = AppLocalizations.of(context)!;
+                        return _SidebarActionRow(
+                          icon: Icons.search,
+                          label: l.sidebarSearchLabel,
+                          shortcutHint: _metaShortcut('K'),
+                          t: t,
+                          labelsInteractive: labelsInteractive,
+                          iconColumnWidth: _collapsedWidth,
+                          onTap: widget.onOpenSearch!,
+                        );
+                      },
+                    ),
                   _Footer(
                     t: t,
                     labelsInteractive: labelsInteractive,
@@ -1535,6 +1597,11 @@ class _SidebarItem extends StatefulWidget {
   /// Approvals item for pending count.
   final int? badge;
 
+  /// Keyboard shortcut ('⌘2') shown in the tooltip and, subtly,
+  /// next to the expanded label — discoverability for the
+  /// existing Cmd+1..9 navigation.
+  final String? shortcutHint;
+
   const _SidebarItem({
     super.key,
     required this.page,
@@ -1544,6 +1611,7 @@ class _SidebarItem extends StatefulWidget {
     required this.iconColumnWidth,
     required this.onTap,
     this.badge,
+    this.shortcutHint,
   });
 
   @override
@@ -1627,13 +1695,33 @@ class _SidebarItemState extends State<_SidebarItem> {
                     opacity: widget.t,
                     child: Padding(
                       padding: const EdgeInsets.only(right: ChainSpace.md),
-                      child: Text(
+                      child: Row(
-                        label,
+                        children: [
-                        overflow: TextOverflow.fade,
+                          Expanded(
-                        softWrap: false,
+                            child: Text(
-                        style: theme.textTheme.labelMedium?.copyWith(
+                              label,
-                          color: color,
+                              overflow: TextOverflow.fade,
-                        ),
+                              softWrap: false,
+                              style: theme.textTheme.labelMedium?.copyWith(
+                                color: color,
+                              ),
+                            ),
+                          ),
+                          if (widget.shortcutHint != null)
+                            Flexible(
+                              child: Text(
+                                widget.shortcutHint!,
+                                overflow: TextOverflow.clip,
+                                softWrap: false,
+                                maxLines: 1,
+                                style: theme.textTheme.labelSmall?.copyWith(
+                                  color: theme.colorScheme.onSurfaceVariant
+                                      .withValues(alpha: 0.7),
+                                  fontSize: 10,
+                                ),
+                              ),
+                            ),
+                        ],
                       ),
                     ),
                   ),
@@ -1674,10 +1762,156 @@ class _SidebarItemState extends State<_SidebarItem> {
       ),
     );
 
+    // Explicit button semantics: the collapsed rail is icon-only,
+    // so a screen reader needs the destination name + role from
+    // here, not from a hover-only tooltip.
+    final semantic = Semantics(
+      button: true,
+      selected: widget.selected,
+      label: widget.shortcutHint == null
+          ? label
+          : '$label (${widget.shortcutHint})',
+      child: ExcludeSemantics(child: inner),
+    );
+
     // Tooltip only while the label is hidden — once the label
     // is visible inline the tooltip becomes redundant noise.
-    if (widget.t > 0.5) return inner;
+    // waitDuration zero: a first-time user hunting through
-    return Tooltip(message: label, preferBelow: false, child: inner);
+    // unlabeled icons should not have to linger per icon.
+    if (widget.t > 0.5) return semantic;
+    return Tooltip(
+      message: widget.shortcutHint == null
+          ? label
+          : '$label · ${widget.shortcutHint}',
+      preferBelow: false,
+      waitDuration: Duration.zero,
+      child: semantic,
+    );
+  }
+}
+
+/// Sidebar utility row (search/palette) — same geometry and
+/// hover behaviour as a destination item, minus selection state.
+class _SidebarActionRow extends StatefulWidget {
+  final IconData icon;
+  final String label;
+  final String? shortcutHint;
+  final double t;
+  final bool labelsInteractive;
+  final double iconColumnWidth;
+  final VoidCallback onTap;
+
+  const _SidebarActionRow({
+    required this.icon,
+    required this.label,
+    required this.shortcutHint,
+    required this.t,
+    required this.labelsInteractive,
+    required this.iconColumnWidth,
+    required this.onTap,
+  });
+
+  @override
+  State<_SidebarActionRow> createState() => _SidebarActionRowState();
+}
+
+class _SidebarActionRowState extends State<_SidebarActionRow> {
+  bool _hovered = false;
+
+  @override
+  Widget build(BuildContext context) {
+    final theme = Theme.of(context);
+    final color = _hovered
+        ? theme.colorScheme.onSurface
+        : theme.colorScheme.onSurfaceVariant;
+    final content = Row(
+      children: [
+        SizedBox(
+          width: widget.iconColumnWidth,
+          child: Center(child: Icon(widget.icon, size: 18, color: color)),
+        ),
+        Expanded(
+          child: widget.t > 0
+              ? IgnorePointer(
+                  ignoring: !widget.labelsInteractive,
+                  child: Opacity(
+                    opacity: widget.t,
+                    child: Padding(
+                      padding: const EdgeInsets.only(right: ChainSpace.md),
+                      child: Row(
+                        children: [
+                          Expanded(
+                            child: Text(
+                              widget.label,
+                              overflow: TextOverflow.fade,
+                              softWrap: false,
+                              style: theme.textTheme.labelMedium?.copyWith(
+                                color: color,
+                              ),
+                            ),
+                          ),
+                          if (widget.shortcutHint != null)
+                            Flexible(
+                              child: Text(
+                                widget.shortcutHint!,
+                                overflow: TextOverflow.clip,
+                                softWrap: false,
+                                maxLines: 1,
+                                style: theme.textTheme.labelSmall?.copyWith(
+                                  color: theme.colorScheme.onSurfaceVariant
+                                      .withValues(alpha: 0.7),
+                                  fontSize: 10,
+                                ),
+                              ),
+                            ),
+                        ],
+                      ),
+                    ),
+                  ),
+                )
+              : const SizedBox.shrink(),
+        ),
+      ],
+    );
+    final inner = Padding(
+      padding: const EdgeInsets.symmetric(vertical: 2),
+      child: MouseRegion(
+        onEnter: (_) => setState(() => _hovered = true),
+        onExit: (_) => setState(() => _hovered = false),
+        cursor: SystemMouseCursors.click,
+        child: GestureDetector(
+          behavior: HitTestBehavior.opaque,
+          onTap: widget.onTap,
+          child: AnimatedContainer(
+            duration: ChainMotion.fast,
+            padding: const EdgeInsets.symmetric(vertical: ChainSpace.md),
+            decoration: BoxDecoration(
+              color: _hovered
+                  ? theme.colorScheme.surfaceContainerHigh
+                  : Colors.transparent,
+              borderRadius: BorderRadius.circular(ChainRadius.sm),
+            ),
+            child: content,
+          ),
+        ),
+      ),
+    );
+    final semantic = Semantics(
+      button: true,
+      label: widget.shortcutHint == null
+          ? widget.label
+          : '${widget.label} (${widget.shortcutHint})',
+      child: ExcludeSemantics(child: inner),
+    );
+    if (widget.t > 0.5) return semantic;
+    return Tooltip(
+      message: widget.shortcutHint == null
+          ? widget.label
+          : '${widget.label} · ${widget.shortcutHint}',
+      preferBelow: false,
+      waitDuration: Duration.zero,
+      child: semantic,
+    );
   }
 }
 
@@ -1724,10 +1958,14 @@ class _Footer extends StatelessWidget {
                     opacity: t,
                     child: Padding(
                       padding: const EdgeInsets.only(right: ChainSpace.sm),
+                      // Flexibles + clip: the strip lives inside the
+                      // animating rail, so a transient narrow width
+                      // must degrade gracefully instead of throwing
+                      // a RenderFlex overflow.
                       child: Row(
                         children: [
-                          _ThemeToggle(),
+                          Flexible(child: ClipRect(child: _ThemeToggle())),
-                          _LanguageToggle(),
+                          Flexible(child: ClipRect(child: _LanguageToggle())),
                           const Expanded(child: Center(child: _SidebarClock())),
                         ],
                       ),

lib/pages/welcome.dart

@@ -444,10 +444,13 @@ class _PillarState extends State<_Pillar> {
                     color: theme.colorScheme.primary,
                   ),
                   const SizedBox(width: 4),
-                  Text(
+                  Flexible(
-                    l.welcomePillarTechToggle,
+                    child: Text(
-                    style: theme.textTheme.labelMedium?.copyWith(
+                      l.welcomePillarTechToggle,
-                      color: theme.colorScheme.primary,
+                      overflow: TextOverflow.ellipsis,
+                      style: theme.textTheme.labelMedium?.copyWith(
+                        color: theme.colorScheme.primary,
+                      ),
                     ),
                   ),
                 ],

lib/widgets/chain_settings_dialog.dart

@@ -9,6 +9,7 @@ import '../data/error_presentation.dart';
 import '../data/hub.dart';
 import '../data/hub_auth_token.dart';
 import '../data/registry_token.dart';
+import '../data/sidebar_prefs.dart';
 import '../data/system_actions.dart';
 import '../l10n/app_localizations.dart';
 import '../pages/welcome.dart' show showFaiDoc;
@@ -604,6 +605,19 @@ class _FaiSettingsDialogState extends State<ChainSettingsDialog> {
         theme,
       ),
       const _ThemePluginPanel(),
+      const SizedBox(height: ChainSpace.xl),
+      // Pinned rail: permanent sidebar labels for operators who
+      // don't want (or can't use) the hover-expand gesture.
+      ValueListenableBuilder<bool>(
+        valueListenable: SidebarPrefs.pinned,
+        builder: (context, pinned, _) => SwitchListTile(
+          contentPadding: EdgeInsets.zero,
+          title: Text(l.settingsSidebarPinnedTitle),
+          subtitle: Text(l.settingsSidebarPinnedBody),
+          value: pinned,
+          onChanged: (v) => SidebarPrefs.setPinned(v),
+        ),
+      ),
     ];
   }
 

test/responsive_test.dart

@@ -48,7 +48,13 @@ void main() {
       await tester.pump(const Duration(milliseconds: 100));
 
       for (final id in _destinations) {
-        await tester.tap(find.byKey(ValueKey('sidebar-item-$id')));
+        // The destinations list scrolls by design: at 600-px-high
+        // windows the rail (destinations + search row + footer)
+        // exceeds the viewport, so bring the item into view first.
+        final item = find.byKey(ValueKey('sidebar-item-$id'));
+        await tester.scrollUntilVisible(item, 40,
+            scrollable: find.byType(Scrollable).first);
+        await tester.tap(item);
         await tester.pump(const Duration(milliseconds: 400));
         expect(
           tester.takeException(),

test/sidebar_test.dart

@@ -41,6 +41,12 @@ void main() {
   testWidgets(
     'sidebar destination Y positions are stable across rail expansion',
     (tester) async {
+      // Desktop-sized surface: the rail carries 8 destinations plus
+      // the search row and footer — the 600-px default viewport
+      // scrolls the last destination out of the ListView.
+      tester.view.physicalSize = const Size(1280, 900);
+      tester.view.devicePixelRatio = 1.0;
+      addTearDown(tester.view.reset);
       // Collapsed (default).
       await tester.pumpWidget(
         const StudioApp(