fix(calls): hotkey rebind denylist; ignore modifiers; keep Space on buttons

- useKeyBind refuses Tab/Enter/arrows/Home/End/Page*/Escape and bare
  modifier codes, and refuses a code equal to the other call key, with an
  inline message (isBindableCallKey, unit-tested).
- PTT and deafen handlers ignore events with Ctrl/Alt/Meta held (deafen
  also Shift), so Cmd+M / Ctrl+M no longer toggle deafen.
- PTT only preventDefault()s when the target is not an interactive
  control, so Space still activates focused buttons during a call.

Fixes #23

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPmy3tPq869XDW4njjVaKA

src/app/features/call/CallControls.tsx

@@ -171,6 +171,10 @@ export function CallControls({ callEmbed }: CallControlsProps) {
 
     const onKeyDown = (e: KeyboardEvent) => {
       if (e.code !== pttKey || e.repeat) return;
+      // [Gitea #23] Ignore the PTT key with Ctrl/Alt/Meta held so it doesn't
+      // hijack OS/app chords (e.g. Cmd+Space) that happen to share the code.
+      // Shift is allowed through — Shift+Space is a harmless combo for PTT.
+      if (e.ctrlKey || e.altKey || e.metaKey) return;
       const target = e.target as HTMLElement;
       // BUG-7: use ownerDocument.body so isEditable works inside the EC iframe
       const isEditable = (el: HTMLElement): boolean => {
@@ -185,7 +189,23 @@ export function CallControls({ callEmbed }: CallControlsProps) {
         return false;
       };
       if (isEditable(target)) return;
-      e.preventDefault();
+      // [Gitea #23] Don't swallow Space on a focused button/link/etc — PTT still
+      // engages the mic, but the key's default action (activating the control)
+      // is left alone so keyboard users can still Tab+Space the call buttons.
+      const isInteractive = (el: HTMLElement): boolean => {
+        const tag = el.tagName;
+        if (tag === 'BUTTON' || tag === 'A' || tag === 'SELECT') return true;
+        let node: HTMLElement | null = el;
+        while (node && node !== el.ownerDocument.body) {
+          const role = node.getAttribute('role');
+          if (role === 'button' || role === 'link' || role === 'menuitem' || role === 'tab') {
+            return true;
+          }
+          node = node.parentElement;
+        }
+        return false;
+      };
+      if (!isInteractive(target)) e.preventDefault();
       // C-M5: mark PTT active BEFORE unmuting so the mic echo (onMediaState)
       // doesn't treat this transient unmute as a user-initiated undeafen.
       callEmbed.control.pttActive = true;
@@ -256,6 +276,10 @@ export function CallControls({ callEmbed }: CallControlsProps) {
     const onKeyDown = (e: KeyboardEvent) => {
       if (e.code !== deafenKey) return;
       if (e.repeat) return;
+      // [Gitea #23] Ignore the deafen key with any modifier held — with the
+      // default 'KeyM', Ctrl+M / Alt+M / Cmd+M are common OS/app chords that
+      // shouldn't also toggle deafen (and previously got preventDefault()ed).
+      if (e.ctrlKey || e.altKey || e.metaKey || e.shiftKey) return;
       if (isEditable(e.target as HTMLElement)) return;
       e.preventDefault();
       callEmbed.control.toggleSound();

src/app/features/settings/general/General.tsx

@@ -117,6 +117,7 @@ import { playCallJoinSound } from '../../../utils/callSounds';
 import { previewRingtone, RINGTONE_OPTIONS } from '../../../utils/ringtones';
 import { DenoiseTester } from './DenoiseTester';
 import { SettingsSelect } from '../../../components/settings-select/SettingsSelect';
+import { isBindableCallKey } from '../../../utils/callKeybind';
 
 /**
  * P5-47 — opt-in TDS window chrome toggle (desktop only). Renders nothing in the
@@ -1474,8 +1475,12 @@ function Privacy() {
   );
 }
 
-function useKeyBind(setter: (code: string) => void) {
+// [Gitea #23] Denylist navigation-critical/modifier codes and reject a code that
+// collides with the other call key (`otherKey`), so a rebind can never trap
+// keyboard focus in-call or silently double-bind PTT and deafen to the same key.
+function useKeyBind(setter: (code: string) => void, otherKey?: string) {
   const [listening, setListening] = useState(false);
+  const [error, setError] = useState<string | null>(null);
   const listenerRef = useRef<((e: KeyboardEvent) => void) | null>(null);
 
   useEffect(
@@ -1487,19 +1492,28 @@ function useKeyBind(setter: (code: string) => void) {
 
   const startListening = useCallback(() => {
     if (listening) return;
+    setError(null);
     setListening(true);
     const onKey = (e: KeyboardEvent) => {
       e.preventDefault();
-      if (e.code !== 'Escape') setter(e.code);
+      if (e.code === 'Escape') {
+        // Escape always cancels the rebind without changing the key.
+      } else if (!isBindableCallKey(e.code)) {
+        setError('That key can’t be bound — it’s needed for keyboard navigation.');
+      } else if (otherKey && e.code === otherKey) {
+        setError('That key is already bound to the other call shortcut.');
+      } else {
+        setter(e.code);
+      }
       setListening(false);
       window.removeEventListener('keydown', onKey, true);
       listenerRef.current = null;
     };
     listenerRef.current = onKey;
     window.addEventListener('keydown', onKey, true);
-  }, [listening, setter]);
+  }, [listening, setter, otherKey]);
 
-  return { listening, startListening };
+  return { listening, startListening, error };
 }
 
 const keyLabel = (code: string) =>
@@ -1556,8 +1570,8 @@ function Calls() {
     previewRingtone(value, Math.max(0, Math.min(1, ringtoneVolume / 100)));
   };
 
-  const pttBind = useKeyBind(setPttKey);
+  const pttBind = useKeyBind(setPttKey, deafenKey);
-  const deafenBind = useKeyBind(setDeafenKey);
+  const deafenBind = useKeyBind(setDeafenKey, pttKey);
 
   const mlSupported = isMLDenoiseSupported();
   const selectedDenoiseModel = DENOISE_MODELS.find((m) => m.id === callDenoiseModel);
@@ -1823,7 +1837,7 @@ function Calls() {
         {pttMode && (
           <SettingTile
             title="PTT Key"
-            description="Press a key to bind it as your push-to-talk key."
+            description={pttBind.error ?? 'Press a key to bind it as your push-to-talk key.'}
             after={
               <Button
                 size="300"
@@ -1841,7 +1855,9 @@ function Calls() {
         )}
         <SettingTile
           title="Push to Deafen"
-          description="Toggle speaker mute during a call. Press Escape to cancel rebind."
+          description={
+            deafenBind.error ?? 'Toggle speaker mute during a call. Press Escape to cancel rebind.'
+          }
           after={
             <Button
               size="300"

src/app/utils/callKeybind.test.ts

@@ -0,0 +1,47 @@
+import { test } from 'node:test';
+import assert from 'node:assert/strict';
+import { isBindableCallKey } from './callKeybind';
+
+test('isBindableCallKey rejects navigation-critical codes', () => {
+  [
+    'Escape',
+    'Tab',
+    'Enter',
+    'NumpadEnter',
+    'ArrowUp',
+    'ArrowDown',
+    'ArrowLeft',
+    'ArrowRight',
+    'Home',
+    'End',
+    'PageUp',
+    'PageDown',
+  ].forEach((code) => {
+    assert.equal(isBindableCallKey(code), false, `${code} should be unbindable`);
+  });
+});
+
+test('isBindableCallKey rejects bare modifier codes', () => {
+  [
+    'ShiftLeft',
+    'ShiftRight',
+    'ControlLeft',
+    'ControlRight',
+    'AltLeft',
+    'AltRight',
+    'MetaLeft',
+    'MetaRight',
+  ].forEach((code) => {
+    assert.equal(isBindableCallKey(code), false, `${code} should be unbindable`);
+  });
+});
+
+test('isBindableCallKey accepts ordinary keys', () => {
+  ['Space', 'KeyM', 'KeyQ', 'Digit1', 'F13'].forEach((code) => {
+    assert.equal(isBindableCallKey(code), true, `${code} should be bindable`);
+  });
+});
+
+test('isBindableCallKey rejects the empty string', () => {
+  assert.equal(isBindableCallKey(''), false);
+});

src/app/utils/callKeybind.ts

@@ -0,0 +1,33 @@
+/**
+ * `KeyboardEvent.code` values the push-to-talk / push-to-deafen rebind must
+ * never accept. Binding one of these turns it into a keyboard trap (the call
+ * hotkey listener swallows the key everywhere outside an editable field for
+ * the rest of the call) or collides with a bare modifier chord.
+ */
+const UNBINDABLE_CALL_KEY_CODES = new Set<string>([
+  'Escape',
+  'Tab',
+  'Enter',
+  'NumpadEnter',
+  'ArrowUp',
+  'ArrowDown',
+  'ArrowLeft',
+  'ArrowRight',
+  'Home',
+  'End',
+  'PageUp',
+  'PageDown',
+  'ShiftLeft',
+  'ShiftRight',
+  'ControlLeft',
+  'ControlRight',
+  'AltLeft',
+  'AltRight',
+  'MetaLeft',
+  'MetaRight',
+]);
+
+/** Whether `code` is safe to bind as a call hotkey (PTT / push-to-deafen). */
+export function isBindableCallKey(code: string): boolean {
+  return code.length > 0 && !UNBINDABLE_CALL_KEY_CODES.has(code);
+}