feat(settings): toggle gesture control + multi-monitor button (off by default)

Make the two experimental header features opt-in via App Settings instead of
forced on. Both default OFF.

- App Settings → Display → 'Header Displays' gains a 'Multi-monitor Button'
  toggle (setting: showMultiMonitorButton). The button is hidden in the template
  by default; the server reveals it at render when enabled, and
  applyHeaderVisibilitySettings handles live toggles from a save.
- App Settings → Display → new 'Input' section gains a 'Gesture Control' toggle
  (setting: gestureControlEnabled). The gesture overlay is injected at page
  render, so renderIndexHtml (now async) reads settings.json and injects the
  bundle only when enabled; toggling reloads the page. CODEMAN_GESTURE=1 stays
  the instance-level 'feature available' gate (CSP + assets) and exposes
  window.__codemanGestureAvailable so the Input section only shows when usable.
- The retired notification bell stays hidden regardless of notification state.

Both settings added to SettingsUpdateSchema and the mobile defaults.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/web/public/index.html

@@ -105,7 +105,7 @@
           </div>
         </div>
         <button class="btn-icon-header btn-response-viewer-header" onclick="app.toggleResponseViewer()" title="View last response" aria-label="View last response"><svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2"><path d="M1 12s4-8 11-8 11 8 11 8-4 8-11 8-11-8-11-8z"/><circle cx="12" cy="12" r="3"/></svg></button>
-        <button class="btn-icon-header btn-multimonitor" onclick="app.launchMultiMonitor()" title="Open Codeman across all displays" aria-label="Open Codeman across all displays"><svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" aria-hidden="true"><rect x="2" y="4" width="13" height="9" rx="1.5"/><rect x="11" y="9" width="11" height="8" rx="1.5"/></svg></button>
+        <button class="btn-icon-header btn-multimonitor" onclick="app.launchMultiMonitor()" title="Open Codeman across all displays" aria-label="Open Codeman across all displays" style="display:none;"><svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" aria-hidden="true"><rect x="2" y="4" width="13" height="9" rx="1.5"/><rect x="11" y="9" width="11" height="8" rx="1.5"/></svg></button>
         <button class="btn-icon-header btn-notifications" onclick="app.toggleNotifications()" title="Notifications" aria-label="Toggle notifications" style="display:none;">
           <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" aria-hidden="true"><path d="M18 8A6 6 0 0 0 6 8c0 7-3 9-3 9h18s-3-2-3-9"/><path d="M13.73 21a2 2 0 0 1-3.46 0"/></svg>
           <span class="notification-badge" id="notifBadge" style="display:none;">0</span>
@@ -969,6 +969,25 @@
                   <span class="slider"></span>
                 </label>
               </div>
+              <div class="settings-item" title="Show the multi-monitor button in the header (opens Codeman spanned across all displays)">
+                <span class="settings-item-label">Multi-monitor Button</span>
+                <label class="switch switch-sm">
+                  <input type="checkbox" id="appSettingsShowMultiMonitorButton">
+                  <span class="slider"></span>
+                </label>
+              </div>
+
+              <!-- Input Section -->
+              <div id="appSettingsInputSection">
+                <div class="settings-section-header">Input</div>
+                <div class="settings-item" title="Enable the camera hand-tracking gesture overlay (applied on reload). The instance must run with CODEMAN_GESTURE=1.">
+                  <span class="settings-item-label">Gesture Control</span>
+                  <label class="switch switch-sm">
+                    <input type="checkbox" id="appSettingsGestureControl">
+                    <span class="slider"></span>
+                  </label>
+                </div>
+              </div>
 
               <!-- Tab Bar Section -->
               <div class="settings-section-header">Tab Bar</div>

src/web/public/settings-ui.js

@@ -312,6 +312,13 @@ Object.assign(CodemanApp.prototype, {
     document.getElementById('appSettingsShowProjectInsights').checked = settings.showProjectInsights ?? defaults.showProjectInsights ?? false;
     document.getElementById('appSettingsShowFileBrowser').checked = settings.showFileBrowser ?? defaults.showFileBrowser ?? false;
     document.getElementById('appSettingsShowSubagents').checked = settings.showSubagents ?? defaults.showSubagents ?? false;
+    document.getElementById('appSettingsShowMultiMonitorButton').checked = settings.showMultiMonitorButton ?? defaults.showMultiMonitorButton ?? false;
+    // Input section: gesture control is only available when the instance runs with
+    // CODEMAN_GESTURE=1 (server sets window.__codemanGestureAvailable). Hide the
+    // whole section otherwise so the toggle can't promise something that won't work.
+    const inputSection = document.getElementById('appSettingsInputSection');
+    if (inputSection) inputSection.style.display = window.__codemanGestureAvailable ? '' : 'none';
+    document.getElementById('appSettingsGestureControl').checked = settings.gestureControlEnabled ?? defaults.gestureControlEnabled ?? false;
     document.getElementById('appSettingsSubagentTracking').checked = settings.subagentTrackingEnabled ?? defaults.subagentTrackingEnabled ?? true;
     document.getElementById('appSettingsSubagentActiveTabOnly').checked = settings.subagentActiveTabOnly ?? defaults.subagentActiveTabOnly ?? true;
     document.getElementById('appSettingsImageWatcherEnabled').checked = settings.imageWatcherEnabled ?? defaults.imageWatcherEnabled ?? false;
@@ -1107,6 +1114,9 @@ Object.assign(CodemanApp.prototype, {
   },
 
   async saveAppSettings() {
+    // Gesture overlay is injected at page render (server-side), so a change to it
+    // only takes effect on reload — remember the prior value to decide below.
+    const _prevGestureEnabled = (this.loadAppSettingsFromStorage().gestureControlEnabled ?? false) === true;
     const settings = {
       defaultClaudeMdPath: document.getElementById('appSettingsClaudeMdPath').value.trim(),
       defaultWorkingDir: document.getElementById('appSettingsDefaultDir').value.trim(),
@@ -1121,6 +1131,8 @@ Object.assign(CodemanApp.prototype, {
       showProjectInsights: document.getElementById('appSettingsShowProjectInsights').checked,
       showFileBrowser: document.getElementById('appSettingsShowFileBrowser').checked,
       showSubagents: document.getElementById('appSettingsShowSubagents').checked,
+      showMultiMonitorButton: document.getElementById('appSettingsShowMultiMonitorButton').checked,
+      gestureControlEnabled: document.getElementById('appSettingsGestureControl').checked,
       subagentTrackingEnabled: document.getElementById('appSettingsSubagentTracking').checked,
       subagentActiveTabOnly: document.getElementById('appSettingsSubagentActiveTabOnly').checked,
       imageWatcherEnabled: document.getElementById('appSettingsImageWatcherEnabled').checked,
@@ -1273,6 +1285,18 @@ Object.assign(CodemanApp.prototype, {
     }
 
     this.closeAppSettings();
+
+    // The gesture overlay is injected at page render (server reads
+    // gestureControlEnabled from settings.json), so a change only takes effect on
+    // reload. Reload when it actually changed — the server PUT above already
+    // persisted the new value.
+    if (settings.gestureControlEnabled !== _prevGestureEnabled) {
+      this.showToast(
+        settings.gestureControlEnabled ? 'Enabling gesture control — reloading…' : 'Disabling gesture control — reloading…',
+        'info'
+      );
+      setTimeout(() => location.reload(), 400);
+    }
   },
 
   // Load model configuration from server for the settings modal
@@ -1374,6 +1398,9 @@ Object.assign(CodemanApp.prototype, {
         showProjectInsights: false,
         showFileBrowser: false,
         showSubagents: false,
+        showMultiMonitorButton: false,
+        // Input
+        gestureControlEnabled: false,
         // Feature toggles - keep tracking on even on mobile
         subagentTrackingEnabled: true,
         subagentActiveTabOnly: true, // Only show subagents for active tab
@@ -1445,13 +1472,23 @@ Object.assign(CodemanApp.prototype, {
       lifecycleBtn.style.display = showLifecycleLog ? '' : 'none';
     }
 
-    // Hide notification bell when notifications are disabled
-    const notifEnabled = this.notificationManager?.preferences?.enabled ?? true;
+    // Multi-monitor button — hidden by default (App Settings → Display → "Header
+    // Displays"). The server renders the correct initial state on every reload;
+    // this handles a live toggle from a settings save (no reload).
+    const showMultiMonitorButton = settings.showMultiMonitorButton ?? defaults.showMultiMonitorButton ?? false;
+    const multiMonitorBtn = document.querySelector('.btn-multimonitor');
+    if (multiMonitorBtn) {
+      multiMonitorBtn.style.display = showMultiMonitorButton ? '' : 'none';
+    }
+
+    // Notification bell is retired (notifications live in Settings → Notifications
+    // + the drawer); keep it hidden regardless of the notification-enabled state.
     const notifBtn = document.querySelector('.btn-notifications');
     if (notifBtn) {
-      notifBtn.style.display = notifEnabled ? '' : 'none';
+      notifBtn.style.display = 'none';
     }
     // Close the drawer if notifications got disabled while it's open
+    const notifEnabled = this.notificationManager?.preferences?.enabled ?? true;
     if (!notifEnabled) {
       const drawer = document.getElementById('notifDrawer');
       if (drawer) drawer.classList.remove('open');