feat: add focus trap to modal dialogs

src/App.tsx

@@ -241,6 +241,77 @@ function setupKineticScroll(
   };
 }
 
+function useFocusTrap(isOpen: boolean, containerRef: React.RefObject<HTMLElement | null>) {
+  const triggerRef = useRef<HTMLElement | null>(null);
+
+  useEffect(() => {
+    if (!isOpen) return;
+
+    // Save the element that had focus before the modal opened
+    triggerRef.current = document.activeElement as HTMLElement;
+
+    // Wait for AnimatePresence to render the modal
+    const raf = requestAnimationFrame(() => {
+      const container = containerRef.current;
+      if (!container) return;
+
+      const focusable = container.querySelectorAll<HTMLElement>(
+        'button, [href], input, select, textarea, [tabindex]:not([tabindex="-1"])'
+      );
+      if (focusable.length > 0) focusable[0].focus();
+    });
+
+    return () => {
+      cancelAnimationFrame(raf);
+      // Restore focus to trigger element when modal closes
+      triggerRef.current?.focus();
+      triggerRef.current = null;
+    };
+  }, [isOpen, containerRef]);
+
+  useEffect(() => {
+    if (!isOpen) return;
+
+    const container = containerRef.current;
+    if (!container) return;
+
+    const handleKeyDown = (e: KeyboardEvent) => {
+      if (e.key === 'Escape') {
+        e.preventDefault();
+        e.stopPropagation();
+        // The modal's own close handler will be called separately
+        return;
+      }
+
+      if (e.key !== 'Tab') return;
+
+      const focusable = container.querySelectorAll<HTMLElement>(
+        'button, [href], input, select, textarea, [tabindex]:not([tabindex="-1"])'
+      );
+      if (focusable.length === 0) return;
+
+      const first = focusable[0];
+      const last = focusable[focusable.length - 1];
+
+      if (e.shiftKey) {
+        if (document.activeElement === first) {
+          e.preventDefault();
+          last.focus();
+        }
+      } else {
+        if (document.activeElement === last) {
+          e.preventDefault();
+          first.focus();
+        }
+      }
+    };
+
+    // Use capture to intercept Tab before anything else
+    document.addEventListener('keydown', handleKeyDown, true);
+    return () => document.removeEventListener('keydown', handleKeyDown, true);
+  }, [isOpen, containerRef]);
+}
+
 function App() {
   const [tabs, setTabs] = useState<Tab[]>([]);
   const [activeTabId, setActiveTabId] = useState<string | null>(null);
@@ -287,6 +358,11 @@ function App() {
   const [tabScrollState, setTabScrollState] = useState({ canLeft: false, canRight: false });
   const tabsRef = useRef(tabs);
   tabsRef.current = tabs;
+  const shortcutsModalRef = useRef<HTMLDivElement>(null);
+  const aboutModalRef = useRef<HTMLDivElement>(null);
+
+  useFocusTrap(showShortcutsModal, shortcutsModalRef);
+  useFocusTrap(showAboutModal, aboutModalRef);
 
   const [appWindow, setAppWindow] = useState<ReturnType<typeof getCurrentWindow> | null>(null);
   const activeTab = tabs.find(t => t.id === activeTabId) || null;
@@ -1147,8 +1223,8 @@ function App() {
 
       <AnimatePresence>
         {showShortcutsModal && (
-          <motion.div className="modal-overlay" initial={{ opacity: 0 }} animate={{ opacity: 1 }} exit={{ opacity: 0 }} transition={smoothTransition} onClick={() => setShowShortcutsModal(false)}>
-            <motion.div className="shortcuts-dialog" role="dialog" aria-modal="true" aria-labelledby="shortcuts-title" initial={{ opacity: 0, scale: 0.95 }} animate={{ opacity: 1, scale: 1 }} exit={{ opacity: 0, scale: 0.95 }} transition={smoothTransition} onClick={e => e.stopPropagation()}>
+          <motion.div className="modal-overlay" initial={{ opacity: 0 }} animate={{ opacity: 1 }} exit={{ opacity: 0 }} transition={smoothTransition} onClick={() => setShowShortcutsModal(false)} onKeyDown={(e) => { if (e.key === 'Escape') setShowShortcutsModal(false); }}>
+            <motion.div ref={shortcutsModalRef} className="shortcuts-dialog" role="dialog" aria-modal="true" aria-labelledby="shortcuts-title" initial={{ opacity: 0, scale: 0.95 }} animate={{ opacity: 1, scale: 1 }} exit={{ opacity: 0, scale: 0.95 }} transition={smoothTransition} onClick={e => e.stopPropagation()}>
               <div className="shortcuts-dialog-header">
                 <h2 className="shortcuts-dialog-title" id="shortcuts-title">Keyboard Shortcuts</h2>
                 <button className="shortcuts-dialog-close" aria-label="Close dialog" onClick={() => setShowShortcutsModal(false)}><X size={16} /></button>
@@ -1179,8 +1255,8 @@ function App() {
           </motion.div>
         )}
         {showAboutModal && (
-          <motion.div className="modal-overlay" initial={{ opacity: 0 }} animate={{ opacity: 1 }} exit={{ opacity: 0 }} transition={smoothTransition} onClick={() => setShowAboutModal(false)}>
-            <motion.div className="modal" role="dialog" aria-modal="true" aria-labelledby="about-title" initial={{ opacity: 0, scale: 0.95 }} animate={{ opacity: 1, scale: 1 }} exit={{ opacity: 0, scale: 0.95 }} transition={smoothTransition} onClick={e => e.stopPropagation()}>
+          <motion.div className="modal-overlay" initial={{ opacity: 0 }} animate={{ opacity: 1 }} exit={{ opacity: 0 }} transition={smoothTransition} onClick={() => setShowAboutModal(false)} onKeyDown={(e) => { if (e.key === 'Escape') setShowAboutModal(false); }}>
+            <motion.div ref={aboutModalRef} className="modal" role="dialog" aria-modal="true" aria-labelledby="about-title" initial={{ opacity: 0, scale: 0.95 }} animate={{ opacity: 1, scale: 1 }} exit={{ opacity: 0, scale: 0.95 }} transition={smoothTransition} onClick={e => e.stopPropagation()}>
               <div className="modal-header">
                 <h2 className="modal-title" id="about-title">About Vesper</h2>
                 <button className="modal-close" aria-label="Close dialog" onClick={() => setShowAboutModal(false)}><X size={16} /></button>