fix(chat): do not hijack ctrl/cmd+digit while typing in an input

The numbered context-surface switcher (mod+digit) fired even while focus was
in an editable target, stealing the browser's own tab-switching chord and
opening the changes pane mid-typing (issue #2503). Guard the digit branch
with an editable-target check (input/textarea/contenteditable, covering the
CodeMirror composer) so the chord keeps its normal meaning while the user
types; surface switching still works from any non-editable focus, and the
shortcut remains rebindable/unassignable in Settings.

Fixes #2503

packages/ui/src/hooks/keyboard-shortcut-dom.test.ts

@@ -1,6 +1,6 @@
 import { expect, test } from 'bun:test';
 
-import { hasOpenDropdown } from './keyboard-shortcut-dom';
+import { hasOpenDropdown, isTypingInEditableTarget } from './keyboard-shortcut-dom';
 
 test('does not treat an unrelated visible listbox as an open dropdown', () => {
   const promptNavigator = {} as Element;
@@ -28,3 +28,27 @@ test('detects an open select popup', () => {
 
   expect(hasOpenDropdown(root)).toBe(true);
 });
+
+// isTypingInEditableTarget — the mod+digit surface switcher guard (issue
+// #2503): while the user is typing in an editable target, ctrl/cmd+digit
+// must keep its normal meaning (browser tab switching, in-input chords)
+// instead of switching the context panel surface.
+const targetWithClosest = (result: Element | null): EventTarget =>
+  ({ closest: (selector: string) => (selector === 'input, textarea, [contenteditable="true"]' ? result : null) }) as unknown as EventTarget;
+
+test('editable guard is false for a null target', () => {
+  expect(isTypingInEditableTarget(null)).toBe(false);
+});
+
+test('editable guard is false for a target without closest', () => {
+  expect(isTypingInEditableTarget({} as EventTarget)).toBe(false);
+});
+
+test('editable guard is true inside an input, textarea or contenteditable', () => {
+  const editable = {} as Element;
+  expect(isTypingInEditableTarget(targetWithClosest(editable))).toBe(true);
+});
+
+test('editable guard is false outside editable surfaces', () => {
+  expect(isTypingInEditableTarget(targetWithClosest(null))).toBe(false);
+});

packages/ui/src/hooks/keyboard-shortcut-dom.ts

@@ -6,3 +6,17 @@ const OPEN_DROPDOWN_SELECTOR = [
 export function hasOpenDropdown(root: ParentNode = document): boolean {
   return Boolean(root.querySelector(OPEN_DROPDOWN_SELECTOR));
 }
+
+// Editable surfaces (the chat composer is a contenteditable CodeMirror view;
+// CommitInput, searches and dialogs use textareas/inputs). Global shortcuts
+// must not hijack keystrokes while the user is typing in one of these —
+// mod+digit in particular is the browser's own tab-switching chord.
+const EDITABLE_TARGET_SELECTOR = 'input, textarea, [contenteditable="true"]';
+
+export function isTypingInEditableTarget(target: EventTarget | null): boolean {
+  const element = target as Element | null;
+  if (!element || typeof element.closest !== 'function') {
+    return false;
+  }
+  return Boolean(element.closest(EDITABLE_TARGET_SELECTOR));
+}

packages/ui/src/hooks/useKeyboardShortcuts.ts

@@ -26,7 +26,7 @@ import { useEffectiveDirectory } from '@/hooks/useEffectiveDirectory';
 import { getCycledPrimaryAgentName } from '@/components/chat/mobileControlsUtils';
 import { focusChatInput } from '@/components/chat/composer/editor/dom';
 import { addSelectionToChat } from '@/lib/addSelectionToChat';
-import { hasOpenDropdown } from './keyboard-shortcut-dom';
+import { hasOpenDropdown, isTypingInEditableTarget } from './keyboard-shortcut-dom';
 
 export const useKeyboardShortcuts = () => {
   const openNewSessionDraft = useSessionUIStore((s) => s.openNewSessionDraft);
@@ -493,6 +493,13 @@ export const useKeyboardShortcuts = () => {
       if (switchSurfaceDigit !== null
         && !e.repeat
         && eventMatchesShortcutPrefix(e, switchSurfacePrefix, heldKeysRef.current)) {
+        // mod+digit is the browser's own tab-switching chord and a common
+        // in-input chord; never hijack it while the user is typing (the chat
+        // composer, CommitInput, searches, dialogs). Surface switching still
+        // works from anywhere that is not an editable target.
+        if (isTypingInEditableTarget(e.target)) {
+          return;
+        }
         const state = useUIStore.getState();
         if (state.isMobile || !effectiveDirectory) {
           return;