fix(shortcuts): address review on rebinding (gate holes, re-enable/Reset duplicates, labels, tests)

- isUserBoundShortcutEvent skips toggleSessionSidebar (it has its own gate) and an
  entry re-captured onto its own default, so ^L still reaches the CLI.
- Re-enabling a shortcut and Reset run the duplicate check and refuse when the
  chord was taken meanwhile; Ctrl/Shift+Enter and Ctrl/Cmd+V are reserved with
  Alt+1-9, and the Alt-digit check no longer excludes Cmd.
- Alt+[ / Alt+] keep their Alt/Option+[ labels via displayBindings.
- Behavioural tests (vm harness) replace the source-string test.
- Docs: wiki Rebinding / Why-chords-behave-oddly, architecture-invariants note.
- Small: _shortcutActions indentation, stale Alt-block comment, typeof check
  instead of Object.hasOwn, full-width parentheses in zh-CN.

src/web/public/app.js

@@ -532,8 +532,8 @@ const DEFAULT_SHORTCUTS = [
     group: 'Session',
     label: 'Toggle Session Sidebar',
     // Alt+B, not Ctrl+B: Ctrl+B must reach the terminal (tmux prefix,
-    // readline backward-char). The Alt block below claims only Digit1-9 and
-    // the brackets, and the registry claims Alt for KeyK and Slash only.
+    // readline backward-char). The Alt block below claims only Digit1-9; the
+    // brackets are registry entries, and the registry claims Alt for KeyK and Slash only.
     bindings: [{ modifiers: ['alt'], key: 'b', code: 'KeyB' }],
     action: 'toggleSessionSidebar',
   },
@@ -642,6 +642,7 @@ const DEFAULT_SHORTCUTS = [
     id: 'previous-session',
     group: 'Session',
     label: 'Previous Session',
+    displayBindings: ['Alt/Option+['],
     bindings: [{ modifiers: ['alt'], code: 'BracketLeft' }],
     action: 'previousSession',
   },
@@ -649,6 +650,7 @@ const DEFAULT_SHORTCUTS = [
     id: 'next-session-alt',
     group: 'Session',
     label: 'Next Session (alternate)',
+    displayBindings: ['Alt/Option+]'],
     bindings: [{ modifiers: ['alt'], code: 'BracketRight' }],
     action: 'nextSession',
   },
@@ -1450,7 +1452,8 @@ class CodemanApp {
       // Option/Alt session navigation uses physical key CODES, not e.key, so macOS
       // keyboard layouts that emit special characters under Option (Option+1 -> ¡,
       // Option+[ -> "“") still switch sessions. e.code is the physical key regardless
-      // of layout. Option+1-9 = switch by index. Option+[ / ] (prev / next) live in the shortcut registry, so they can be rebound.
+      // of layout. Option+1-9 = switch by index. Option+[ / ] (prev / next) live in the
+      // shortcut registry, so they can be rebound.
       if (e.altKey && !e.ctrlKey && !e.shiftKey) {
         const code = e.code || '';
         const digitMatch = code.match(/^Digit([1-9])$/);
@@ -10196,39 +10199,46 @@ class CodemanApp {
    * absent here (copy selection, the palette, the tile chords) have their own dispatch.
    */
   _shortcutActions() {
-  return {
-    showShortcutOverlay: () => this.showShortcutOverlay(),
-    killActiveSession: () => this.killActiveSession(),
-    nextSession: () => this.nextSession(),
-    previousSession: () => this.prevSession(),
-    clearTerminal: () => this.clearTerminal(),
-    restoreTerminalSize: () => this.restoreTerminalSize(),
-    increaseFontSize: () => this.increaseFontSize(),
-    decreaseFontSize: () => this.decreaseFontSize(),
-    toggleVoiceInput: () => VoiceInput.toggle(),
-    moveActiveTabLeft: () => this.moveActiveTabLeft(),
-    moveActiveTabRight: () => this.moveActiveTabRight(),
-    toggleSessionSidebar: () => this.toggleSessionSidebar(),
-  };
+    return {
+      showShortcutOverlay: () => this.showShortcutOverlay(),
+      killActiveSession: () => this.killActiveSession(),
+      nextSession: () => this.nextSession(),
+      previousSession: () => this.prevSession(),
+      clearTerminal: () => this.clearTerminal(),
+      restoreTerminalSize: () => this.restoreTerminalSize(),
+      increaseFontSize: () => this.increaseFontSize(),
+      decreaseFontSize: () => this.decreaseFontSize(),
+      toggleVoiceInput: () => VoiceInput.toggle(),
+      moveActiveTabLeft: () => this.moveActiveTabLeft(),
+      moveActiveTabRight: () => this.moveActiveTabRight(),
+      toggleSessionSidebar: () => this.toggleSessionSidebar(),
+    };
   }
 
   /**
    * True when `e` is a chord the USER rebound to a generically dispatched action.
    * The document handler has already run the action, but its preventDefault() does not
    * stop xterm, so without this gate a rebind to e.g. Alt+J would also type ESC j into the
-   * session. Defaults are not covered on purpose: several (Ctrl+L) rely on reaching the PTY.
+   * session. Defaults are not covered on purpose: several (Ctrl+L) rely on reaching the PTY,
+   * and neither is a chord that matches the entry's own default (a re-capture of it).
    */
   isUserBoundShortcutEvent(e) {
     if (!e.ctrlKey && !e.metaKey && !e.altKey) return false;
     const overrides = this.loadAppSettingsFromStorage().shortcutOverrides || {};
     const actions = this._shortcutActions();
-    return this.getShortcutRegistry().some(
-      (shortcut) =>
-        !shortcut.disabled &&
-        Array.isArray(overrides[shortcut.id]?.bindings) &&
-        Object.hasOwn(actions, shortcut.action) &&
-        this.matchesShortcutEvent(e, shortcut)
-    );
+    return this.getShortcutRegistry().some((shortcut) => {
+      if (shortcut.disabled || !Array.isArray(overrides[shortcut.id]?.bindings)) return false;
+      // toggleSessionSidebar has its own gate (shouldToggleSessionSidebarFromShortcut) that
+      // lets the chord through when the sidebar layout is off; swallowing it here would make a
+      // rebound sidebar key dead in the header layout.
+      if (shortcut.action === 'toggleSessionSidebar') return false;
+      if (typeof actions[shortcut.action] !== 'function') return false;
+      if (!this.matchesShortcutEvent(e, shortcut)) return false;
+      // Re-capturing the entry's own default (Ctrl+L for Clear Terminal) must keep reaching the
+      // CLI: clearTerminal() relies on ^L for the redraw.
+      const fallback = DEFAULT_SHORTCUTS.find((d) => d.id === shortcut.id);
+      return !this.matchesShortcutEvent(e, fallback);
+    });
   }
 
   // Returns the merged shortcut list: DEFAULT_SHORTCUTS with any per-shortcut

src/web/public/i18n.js

@@ -1141,7 +1141,7 @@
     'Previous / Next Session': '上一个 / 下一个会话',
     'Next Session': '下一个会话',
     'Previous Session': '上一个会话',
-    'Next Session (alternate)': '下一个会话(备用)',
+    'Next Session (alternate)': '下一个会话（备用）',
     'Switch to Tab N': '切换到第 N 个标签页',
     'Move Active Tab Left': '向左移动当前标签页',
     'Move Active Tab Right': '向右移动当前标签页',

src/web/public/settings-ui.js

@@ -4730,10 +4730,16 @@ Object.assign(CodemanApp.prototype, {
 
   /** Label of the action that already owns the chord in `e`, or '' when it is free. */
   findShortcutConflict(e, shortcutId) {
-    // Alt+1-9 switch tabs by index; they are fixed, not in the registry.
-    if (e.altKey && !e.ctrlKey && !e.metaKey && !e.shiftKey && /^Digit[1-9]$/.test(e.code || '')) {
+    // Chords the keydown handlers claim before (or outside) the registry: they are fixed, so a
+    // rebind onto one of them would be dead or would hijack it. Alt+1-9 switch tabs by index
+    // (the document handler does not exclude Cmd); Ctrl/Shift+Enter insert a newline and
+    // Ctrl/Cmd+V pastes, and the user-bound gate sits above those branches in the xterm handler.
+    if (e.altKey && !e.ctrlKey && !e.shiftKey && /^Digit[1-9]$/.test(e.code || '')) {
       return 'Switch to Tab N';
     }
+    // (Alt+Shift+Enter is the tile grid's Zoom chord, a registry entry, so Alt stays free.)
+    if (e.key === 'Enter' && !e.altKey && (e.ctrlKey || e.shiftKey)) return 'Insert Newline';
+    if ((e.ctrlKey || e.metaKey) && !e.altKey && !e.shiftKey && String(e.key).toLowerCase() === 'v') return 'Paste';
     if (typeof this.getShortcutRegistry !== 'function' || typeof this.matchesShortcutEvent !== 'function') return '';
     const other = this.getShortcutRegistry().find(
       (shortcut) =>
@@ -4742,6 +4748,30 @@ Object.assign(CodemanApp.prototype, {
     return other ? other.label : '';
   },
 
+  /**
+   * Label of the action that already owns a chord in `shortcut`'s bindings, or ''. Used when a
+   * binding comes back without a capture (re-enable, Reset), where the chord may have been
+   * given to another action in the meantime.
+   */
+  findShortcutBindingConflict(shortcut) {
+    for (const binding of shortcut?.bindings || []) {
+      const mods = binding.modifiers || [];
+      const taken = this.findShortcutConflict(
+        {
+          ctrlKey: mods.includes('ctrl'),
+          metaKey: mods.includes('meta'),
+          shiftKey: mods.includes('shift'),
+          altKey: mods.includes('alt'),
+          key: binding.key || '',
+          code: binding.code || '',
+        },
+        shortcut.id
+      );
+      if (taken) return taken;
+    }
+    return '';
+  },
+
   describeShortcutEvent(e) {
     const parts = [];
     if (e.ctrlKey) parts.push('Ctrl');
@@ -4753,6 +4783,15 @@ Object.assign(CodemanApp.prototype, {
   },
 
   resetShortcutOverride(shortcutId) {
+    // Reset puts the default chord back (and re-enables the row): refuse when another action
+    // has taken that chord since, instead of leaving two actions on one key.
+    const fallback = typeof DEFAULT_SHORTCUTS !== 'undefined' ? DEFAULT_SHORTCUTS.find((d) => d.id === shortcutId) : null;
+    const taken = fallback ? this.findShortcutBindingConflict(fallback) : '';
+    if (taken) {
+      this.renderShortcutSettingsList();
+      this.showToast?.(`The default chord is already used by ${taken}`, 'error');
+      return;
+    }
     const settings = this.loadAppSettingsFromStorage();
     const shortcutOverrides = { ...(settings.shortcutOverrides || {}) };
     delete shortcutOverrides[shortcutId];
@@ -4762,6 +4801,17 @@ Object.assign(CodemanApp.prototype, {
   },
 
   toggleShortcutEnabled(shortcutId, enabled) {
+    if (enabled) {
+      // Re-enabling brings the row's chord back into play: leave it disabled when another action
+      // has been bound to that chord while it was off.
+      const shortcut = this.getShortcutRegistry?.().find((s) => s.id === shortcutId);
+      const taken = this.findShortcutBindingConflict(shortcut);
+      if (taken) {
+        this.renderShortcutSettingsList();
+        this.showToast?.(`Its chord is already used by ${taken}`, 'error');
+        return;
+      }
+    }
     const settings = this.loadAppSettingsFromStorage();
     const shortcutOverrides = { ...(settings.shortcutOverrides || {}) };
     shortcutOverrides[shortcutId] = { ...(shortcutOverrides[shortcutId] || {}), disabled: !enabled };