feat(settings): wire session, away-digest, and cron button visibility toggles

Per-device App Settings > Header Displays toggles that show/hide the session
manager and away-digest header buttons (default OFF) and the cron footer
button (default ON). Adds the load/save/apply/default/displayKeys wiring in
settings-ui.js plus the marker CSS in styles.css. Client-only display keys,
stripped from the settings PUT so they never reach the strict server schema
(mirrors the showAttachmentsButton pattern); session/away stay hidden on
phones via the existing mobile.css rules. The button markup and checkbox
rows landed earlier in 5728b86.

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

src/web/public/settings-ui.js

@@ -324,6 +324,10 @@ Object.assign(CodemanApp.prototype, {
     document.getElementById('appSettingsShowMultiMonitorButton').checked = settings.showMultiMonitorButton ?? defaults.showMultiMonitorButton ?? false;
     document.getElementById('appSettingsShowPlanUsageLimits').checked = settings.showPlanUsageLimits ?? defaults.showPlanUsageLimits ?? false;
     document.getElementById('appSettingsShowRedrawButton').checked = settings.showRedrawButton ?? defaults.showRedrawButton ?? false;
+    // Session Manager + Away Digest buttons default OFF; Cron button defaults ON.
+    document.getElementById('appSettingsShowSessionButton').checked = settings.showSessionButton ?? defaults.showSessionButton ?? false;
+    document.getElementById('appSettingsShowAwayDigestButton').checked = settings.showAwayDigestButton ?? defaults.showAwayDigestButton ?? false;
+    document.getElementById('appSettingsShowCronButton').checked = settings.showCronButton ?? defaults.showCronButton ?? true;
     // Gesture control lives in the Input section (alongside Local Echo / CJK Input)
     // but is only available when the instance runs with CODEMAN_GESTURE=1 (server sets
     // window.__codemanGestureAvailable). Hide just this item otherwise so the toggle
@@ -1432,6 +1436,9 @@ Object.assign(CodemanApp.prototype, {
       showMultiMonitorButton: document.getElementById('appSettingsShowMultiMonitorButton').checked,
       showPlanUsageLimits: document.getElementById('appSettingsShowPlanUsageLimits').checked,
       showRedrawButton: document.getElementById('appSettingsShowRedrawButton').checked,
+      showSessionButton: document.getElementById('appSettingsShowSessionButton').checked,
+      showAwayDigestButton: document.getElementById('appSettingsShowAwayDigestButton').checked,
+      showCronButton: document.getElementById('appSettingsShowCronButton').checked,
       gestureControlEnabled: document.getElementById('appSettingsGestureControl').checked,
       subagentTrackingEnabled: document.getElementById('appSettingsSubagentTracking').checked,
       subagentActiveTabOnly: document.getElementById('appSettingsSubagentActiveTabOnly').checked,
@@ -1613,6 +1620,11 @@ Object.assign(CodemanApp.prototype, {
       showAttachmentsButton: _ahb,
       webglRendererEnabled: _wgl,
       terminalWheelLocalScrollback: _twls,
+      // Per-device header/toolbar button toggles — client-only, and absent from
+      // SettingsUpdateSchema (.strict()), so sending them would 400 the PUT.
+      showSessionButton: _ssb,
+      showAwayDigestButton: _adb,
+      showCronButton: _crb,
       ...serverSettings
     } = settings;
     try {
@@ -1770,6 +1782,9 @@ Object.assign(CodemanApp.prototype, {
         showPlanUsageLimits: false,
         showAttachmentsButton: false,
         showRedrawButton: false,
+        showSessionButton: false,
+        showAwayDigestButton: false,
+        showCronButton: true,
         // Input
         gestureControlEnabled: false,
         // Feature toggles - keep tracking on even on mobile
@@ -1917,6 +1932,29 @@ Object.assign(CodemanApp.prototype, {
       redrawBtn.classList.toggle('btn-redraw-terminal--hidden', !showRedrawButton);
     }
 
+    // Session Manager button — opt-in, hidden by default (App Settings → Display).
+    // Marker class (base is display:inline-flex !important); phones keep it hidden
+    // via mobile.css regardless. Sessions stay reachable via the Ctrl+K palette.
+    const showSessionButton = settings.showSessionButton ?? defaults.showSessionButton ?? false;
+    const sessionBtn = document.querySelector('.btn-session-manager');
+    if (sessionBtn) {
+      sessionBtn.classList.toggle('btn-session-manager--hidden', !showSessionButton);
+    }
+
+    // Away Digest button — opt-in, hidden by default. Same marker pattern.
+    const showAwayDigestButton = settings.showAwayDigestButton ?? defaults.showAwayDigestButton ?? false;
+    const awayDigestBtn = document.querySelector('.btn-away-digest');
+    if (awayDigestBtn) {
+      awayDigestBtn.classList.toggle('btn-away-digest--hidden', !showAwayDigestButton);
+    }
+
+    // Cron button (footer toolbar) — shown by default; hide when disabled.
+    const showCronButton = settings.showCronButton ?? defaults.showCronButton ?? true;
+    const cronBtn = document.querySelector('.btn-cron');
+    if (cronBtn) {
+      cronBtn.classList.toggle('btn-cron--hidden', !showCronButton);
+    }
+
     // 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');
@@ -2155,6 +2193,7 @@ Object.assign(CodemanApp.prototype, {
           'subagentActiveTabOnly', 'tabTwoRows', 'localEchoEnabled', 'cjkInputEnabled', 'extendedKeyboardBar',
           'skin', 'showPlanUsageLimits', 'showAttachmentsButton', 'webglRendererEnabled',
           'terminalWheelLocalScrollback',
+          'showSessionButton', 'showAwayDigestButton', 'showCronButton',
         ]);
         // The plan-usage chip is a PER-DEVICE display setting (default OFF): desktop
         // can show it while mobile stays hidden. It used to sync, so an older

src/web/public/styles.css

@@ -9471,6 +9471,31 @@ kbd {
   display: none !important;
 }
 
+/* "Session Manager" + "Away Digest" header buttons — opt-in (App Settings →
+   Display), hidden by default. Same marker pattern as the response viewer: a
+   base inline-flex !important so an inline style can't override it, and a
+   more-specific marker rule to hide. Phones keep them hidden regardless via the
+   higher-specificity mobile.css rule (.btn-icon-header.btn-...). */
+.btn-session-manager {
+  display: inline-flex !important;
+}
+.btn-session-manager.btn-session-manager--hidden {
+  display: none !important;
+}
+.btn-away-digest {
+  display: inline-flex !important;
+}
+.btn-away-digest.btn-away-digest--hidden {
+  display: none !important;
+}
+
+/* "Cron" footer-toolbar button — shown by default (App Settings → Display can
+   hide it). Toolbar button, not a header icon, so only the hide marker is
+   needed; out-specify any base .btn-toolbar display. */
+.btn-toolbar.btn-cron--hidden {
+  display: none !important;
+}
+
 /* "Ultracode Agents" header launcher — opt-in (App Settings → Display), hidden by
    default everywhere (so the mobile-header-buttons-policy guard auto-excludes it).
    Base inline-flex !important + a more-specific marker rule to hide. */