feat: add favorites — sidebar section, star button, frontmatter-backed, drag-to-reorder

FAVORITES section in sidebar (hidden when empty) with drag-to-reorder
via dnd-kit. Star button in breadcrumb bar toggles _favorite frontmatter.
_favorite_index controls display order, updated on reorder. Both keys
hidden from Properties panel via SKIP_KEYS.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src-tauri/src/vault/mod_tests.rs

@@ -1117,6 +1117,26 @@ fn test_parse_underscore_archived_canonical() {
     );
 }
 
+// --- favorite field tests ---
+
+#[test]
+fn test_parse_favorite_true() {
+    let dir = TempDir::new().unwrap();
+    let content = "---\n_favorite: true\n_favorite_index: 3\n---\n# Fav\n";
+    let entry = parse_test_entry(&dir, "fav.md", content);
+    assert!(entry.favorite, "'_favorite: true' must be parsed as favorite");
+    assert_eq!(entry.favorite_index, Some(3));
+}
+
+#[test]
+fn test_parse_favorite_absent_defaults_false() {
+    let dir = TempDir::new().unwrap();
+    let content = "---\ntype: Note\n---\n# Not Fav\n";
+    let entry = parse_test_entry(&dir, "not-fav.md", content);
+    assert!(!entry.favorite, "absent _favorite must default to false");
+    assert_eq!(entry.favorite_index, None);
+}
+
 // --- visible field tests ---
 
 #[test]

src/hooks/useEntryActions.test.ts

@@ -521,6 +521,94 @@ describe('useEntryActions', () => {
     })
   })
 
+  describe('handleToggleFavorite', () => {
+    it('favorites a note: writes _favorite and _favorite_index', async () => {
+      const entry = makeEntry({ path: '/vault/note/test.md', favorite: false, favoriteIndex: null })
+      const { result } = setup([entry])
+
+      await act(async () => {
+        await result.current.handleToggleFavorite('/vault/note/test.md')
+      })
+
+      expect(handleUpdateFrontmatter).toHaveBeenCalledWith('/vault/note/test.md', '_favorite', true, { silent: true })
+      expect(handleUpdateFrontmatter).toHaveBeenCalledWith('/vault/note/test.md', '_favorite_index', 1, { silent: true })
+      expect(updateEntry).toHaveBeenCalledWith('/vault/note/test.md', { favorite: true, favoriteIndex: 1 })
+      expect(onFrontmatterPersisted).toHaveBeenCalledTimes(1)
+    })
+
+    it('unfavorites a note: deletes _favorite and _favorite_index', async () => {
+      const entry = makeEntry({ path: '/vault/note/test.md', favorite: true, favoriteIndex: 0 })
+      const { result } = setup([entry])
+
+      await act(async () => {
+        await result.current.handleToggleFavorite('/vault/note/test.md')
+      })
+
+      expect(handleDeleteProperty).toHaveBeenCalledWith('/vault/note/test.md', '_favorite', { silent: true })
+      expect(handleDeleteProperty).toHaveBeenCalledWith('/vault/note/test.md', '_favorite_index', { silent: true })
+      expect(updateEntry).toHaveBeenCalledWith('/vault/note/test.md', { favorite: false, favoriteIndex: null })
+    })
+
+    it('assigns next available index when favoriting', async () => {
+      const entries = [
+        makeEntry({ path: '/vault/a.md', favorite: true, favoriteIndex: 3 }),
+        makeEntry({ path: '/vault/b.md', favorite: true, favoriteIndex: 5 }),
+        makeEntry({ path: '/vault/c.md', favorite: false, favoriteIndex: null }),
+      ]
+      const { result } = setup(entries)
+
+      await act(async () => {
+        await result.current.handleToggleFavorite('/vault/c.md')
+      })
+
+      expect(handleUpdateFrontmatter).toHaveBeenCalledWith('/vault/c.md', '_favorite_index', 6, { silent: true })
+    })
+
+    it('rolls back on failure', async () => {
+      const entry = makeEntry({ path: '/vault/note/test.md', favorite: false, favoriteIndex: null })
+      handleUpdateFrontmatter.mockRejectedValueOnce(new Error('disk full'))
+      const errorSpy = vi.spyOn(console, 'error').mockImplementation(() => {})
+      const { result } = setup([entry])
+
+      await act(async () => {
+        await result.current.handleToggleFavorite('/vault/note/test.md')
+      })
+
+      expect(updateEntry).toHaveBeenCalledWith('/vault/note/test.md', { favorite: false, favoriteIndex: null })
+      expect(setToastMessage).toHaveBeenCalledWith('Failed to favorite — rolled back')
+      errorSpy.mockRestore()
+    })
+
+    it('does nothing if entry not found', async () => {
+      const { result } = setup([])
+
+      await act(async () => {
+        await result.current.handleToggleFavorite('/vault/nonexistent.md')
+      })
+
+      expect(handleUpdateFrontmatter).not.toHaveBeenCalled()
+      expect(handleDeleteProperty).not.toHaveBeenCalled()
+    })
+  })
+
+  describe('handleReorderFavorites', () => {
+    it('updates _favorite_index for all reordered paths', async () => {
+      const { result } = setup()
+
+      await act(async () => {
+        await result.current.handleReorderFavorites(['/vault/a.md', '/vault/b.md', '/vault/c.md'])
+      })
+
+      expect(handleUpdateFrontmatter).toHaveBeenCalledWith('/vault/a.md', '_favorite_index', 0, { silent: true })
+      expect(handleUpdateFrontmatter).toHaveBeenCalledWith('/vault/b.md', '_favorite_index', 1, { silent: true })
+      expect(handleUpdateFrontmatter).toHaveBeenCalledWith('/vault/c.md', '_favorite_index', 2, { silent: true })
+      expect(updateEntry).toHaveBeenCalledWith('/vault/a.md', { favoriteIndex: 0 })
+      expect(updateEntry).toHaveBeenCalledWith('/vault/b.md', { favoriteIndex: 1 })
+      expect(updateEntry).toHaveBeenCalledWith('/vault/c.md', { favoriteIndex: 2 })
+      expect(onFrontmatterPersisted).toHaveBeenCalledTimes(1)
+    })
+  })
+
   describe('onBeforeAction callback', () => {
     function setupWithBeforeAction(onBeforeAction: ReturnType<typeof vi.fn>) {
       return renderHook(() =>

src/hooks/usePropertyPanelState.ts

@@ -12,7 +12,7 @@ import { containsWikilinks } from '../components/DynamicPropertiesPanel'
 
 // Keys to skip showing in Properties (handled by dedicated UI or internal)
 // Compared case-insensitively via isVisibleProperty()
-const SKIP_KEYS = new Set(['aliases', 'workspace', 'title', 'type', 'is_a', 'is a', '_trashed', 'trashed', '_trashed_at', 'trashed_at', 'trashed at', '_archived', 'archived', 'archived_at', 'icon'])
+const SKIP_KEYS = new Set(['aliases', 'workspace', 'title', 'type', 'is_a', 'is a', '_trashed', 'trashed', '_trashed_at', 'trashed_at', 'trashed at', '_archived', 'archived', 'archived_at', 'icon', '_favorite', '_favorite_index'])
 
 function coerceValue(raw: string): FrontmatterValue {
   if (raw.toLowerCase() === 'true') return true