Prevent note switching when there are unsaved changes

- Added hasUnsavedChanges state tracking in App.tsx
- NoteEditor now notifies parent via onUnsavedChanges callback
- NotesList receives hasUnsavedChanges prop
- Clicking on other notes is prevented when current note has unsaved changes
- Visual feedback: other notes become semi-transparent with cursor-not-allowed
- Tooltip shows 'Save current note before switching' on disabled notes
- Much simpler and more reliable than trying to auto-save on switch

src/App.tsx

@@ -16,6 +16,7 @@ function App() {
   const [username, setUsername] = useState('');
   const [theme, setTheme] = useState<'light' | 'dark' | 'system'>('system');
   const [effectiveTheme, setEffectiveTheme] = useState<'light' | 'dark'>('light');
+  const [hasUnsavedChanges, setHasUnsavedChanges] = useState(false);
 
   useEffect(() => {
     const savedServer = localStorage.getItem('serverURL');
@@ -193,11 +194,13 @@ function App() {
         onSearchChange={setSearchText}
         showFavoritesOnly={showFavoritesOnly}
         onToggleFavorites={() => setShowFavoritesOnly(!showFavoritesOnly)}
+        hasUnsavedChanges={hasUnsavedChanges}
       />
       <NoteEditor
         note={selectedNote}
         onUpdateNote={handleUpdateNote}
         fontSize={fontSize}
+        onUnsavedChanges={setHasUnsavedChanges}
       />
     </div>
   );

src/components/NoteEditor.tsx

@@ -11,6 +11,7 @@ interface NoteEditorProps {
   note: Note | null;
   onUpdateNote: (note: Note) => void;
   fontSize: number;
+  onUnsavedChanges?: (hasChanges: boolean) => void;
 }
 
 const turndownService = new TurndownService({
@@ -18,7 +19,7 @@ const turndownService = new TurndownService({
   codeBlockStyle: 'fenced',
 });
 
-export function NoteEditor({ note, onUpdateNote, fontSize }: NoteEditorProps) {
+export function NoteEditor({ note, onUpdateNote, fontSize, onUnsavedChanges }: NoteEditorProps) {
   const [localTitle, setLocalTitle] = useState('');
   const [localFavorite, setLocalFavorite] = useState(false);
   const [isSaving, setIsSaving] = useState(false);
@@ -26,6 +27,11 @@ export function NoteEditor({ note, onUpdateNote, fontSize }: NoteEditorProps) {
   const [titleManuallyEdited, setTitleManuallyEdited] = useState(false);
   const previousNoteIdRef = useRef<number | null>(null);
 
+  // Notify parent component when unsaved changes state changes
+  useEffect(() => {
+    onUnsavedChanges?.(hasUnsavedChanges);
+  }, [hasUnsavedChanges, onUnsavedChanges]);
+
   const editor = useEditor({
     extensions: [
       StarterKit,

src/components/NotesList.tsx

@@ -16,6 +16,7 @@ interface NotesListProps {
   onSearchChange: (text: string) => void;
   showFavoritesOnly: boolean;
   onToggleFavorites: () => void;
+  hasUnsavedChanges: boolean;
 }
 
 export function NotesList({
@@ -33,6 +34,7 @@ export function NotesList({
   onSearchChange,
   showFavoritesOnly,
   onToggleFavorites,
+  hasUnsavedChanges,
 }: NotesListProps) {
   const [isSyncing, setIsSyncing] = React.useState(false);
   const [deleteClickedId, setDeleteClickedId] = React.useState<number | null>(null);
@@ -144,10 +146,21 @@ export function NotesList({
           notes.map((note) => (
             <div
               key={note.id}
-              onClick={() => onSelectNote(note.id)}
-              className={`p-3 border-b border-gray-200 dark:border-gray-700 cursor-pointer hover:bg-gray-100 dark:hover:bg-gray-800 transition-colors group ${
-                note.id === selectedNoteId ? 'bg-blue-50 dark:bg-gray-800 border-l-4 border-l-blue-500' : ''
+              onClick={() => {
+                // Prevent switching if current note has unsaved changes
+                if (hasUnsavedChanges && note.id !== selectedNoteId) {
+                  return;
+                }
+                onSelectNote(note.id);
+              }}
+              className={`p-3 border-b border-gray-200 dark:border-gray-700 transition-colors group ${
+                note.id === selectedNoteId 
+                  ? 'bg-blue-50 dark:bg-gray-800 border-l-4 border-l-blue-500' 
+                  : hasUnsavedChanges 
+                    ? 'cursor-not-allowed opacity-50' 
+                    : 'cursor-pointer hover:bg-gray-100 dark:hover:bg-gray-800'
               }`}
+              title={hasUnsavedChanges && note.id !== selectedNoteId ? 'Save current note before switching' : ''}
             >
               <div className="flex items-start justify-between mb-1">
                 <div className="flex items-center flex-1 min-w-0">