refactor: remove tab bar — single note open at a time

Replace the multi-tab model with single-note navigation. One note is
open at a time; clicking any note (sidebar, wikilink, relationship)
replaces the current note in the editor. Back/Forward history still
works via Cmd+[/].

Removed: TabBar component, useClosedTabHistory, tab reorder/close/
reopen logic, Cmd+W/Cmd+Shift+T shortcuts, Close Tab and Reopen
Closed Tab menu items, tabLayout utility, and all related tests.

Simplified: useTabManagement (single-note), useAppNavigation (no tab
lookup), useKeyboardNavigation (note nav only), useNoteCreation (no
close-tab cleanup), useDeleteActions (deselect instead of close tab),
Editor (no TabBar render), Rust menu (removed 2 menu items).

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

src/hooks/useKeyboardNavigation.test.ts

@@ -34,13 +34,7 @@ const makeEntry = (overrides: Partial<VaultEntry> = {}): VaultEntry => ({
   ...overrides,
 })
 
-interface Tab {
-  entry: VaultEntry
-  content: string
-}
-
 describe('useKeyboardNavigation', () => {
-  const onSwitchTab = vi.fn()
   const onReplaceActiveTab = vi.fn()
   const onSelectNote = vi.fn()
 
@@ -50,12 +44,6 @@ describe('useKeyboardNavigation', () => {
     makeEntry({ path: '/vault/c.md', title: 'C', modifiedAt: 1700000001 }),
   ]
 
-  const tabs: Tab[] = [
-    { entry: entries[0], content: '# A' },
-    { entry: entries[1], content: '# B' },
-    { entry: entries[2], content: '# C' },
-  ]
-
   const selection: SidebarSelection = { kind: 'filter', filter: 'all' }
   let addedListeners: { type: string; handler: EventListenerOrEventListenerObject }[] = []
 
@@ -81,70 +69,19 @@ describe('useKeyboardNavigation', () => {
   it('registers keydown listener on mount', () => {
     renderHook(() =>
       useKeyboardNavigation({
-        tabs, activeTabPath: '/vault/a.md', entries, selection,
-        onSwitchTab, onReplaceActiveTab, onSelectNote,
+        activeTabPath: '/vault/a.md', entries, selection,
+        onReplaceActiveTab, onSelectNote,
       })
     )
 
     expect(addedListeners.some(l => l.type === 'keydown')).toBe(true)
   })
 
-  it('switches to next tab on Cmd+Shift+ArrowRight (browser mode)', () => {
-    renderHook(() =>
-      useKeyboardNavigation({
-        tabs, activeTabPath: '/vault/a.md', entries, selection,
-        onSwitchTab, onReplaceActiveTab, onSelectNote,
-      })
-    )
-
-    act(() => {
-      window.dispatchEvent(new KeyboardEvent('keydown', {
-        key: 'ArrowRight', metaKey: true, shiftKey: true, bubbles: true,
-      }))
-    })
-
-    expect(onSwitchTab).toHaveBeenCalledWith('/vault/b.md')
-  })
-
-  it('switches to previous tab on Cmd+Shift+ArrowLeft (browser mode)', () => {
-    renderHook(() =>
-      useKeyboardNavigation({
-        tabs, activeTabPath: '/vault/b.md', entries, selection,
-        onSwitchTab, onReplaceActiveTab, onSelectNote,
-      })
-    )
-
-    act(() => {
-      window.dispatchEvent(new KeyboardEvent('keydown', {
-        key: 'ArrowLeft', metaKey: true, shiftKey: true, bubbles: true,
-      }))
-    })
-
-    expect(onSwitchTab).toHaveBeenCalledWith('/vault/a.md')
-  })
-
-  it('wraps around when navigating past last tab', () => {
-    renderHook(() =>
-      useKeyboardNavigation({
-        tabs, activeTabPath: '/vault/c.md', entries, selection,
-        onSwitchTab, onReplaceActiveTab, onSelectNote,
-      })
-    )
-
-    act(() => {
-      window.dispatchEvent(new KeyboardEvent('keydown', {
-        key: 'ArrowRight', metaKey: true, shiftKey: true, bubbles: true,
-      }))
-    })
-
-    expect(onSwitchTab).toHaveBeenCalledWith('/vault/a.md')
-  })
-
   it('navigates to next note on Cmd+Alt+ArrowDown', () => {
     renderHook(() =>
       useKeyboardNavigation({
-        tabs, activeTabPath: '/vault/a.md', entries, selection,
-        onSwitchTab, onReplaceActiveTab, onSelectNote,
+        activeTabPath: '/vault/a.md', entries, selection,
+        onReplaceActiveTab, onSelectNote,
       })
     )
 
@@ -160,8 +97,8 @@ describe('useKeyboardNavigation', () => {
   it('navigates to previous note on Cmd+Alt+ArrowUp', () => {
     renderHook(() =>
       useKeyboardNavigation({
-        tabs, activeTabPath: '/vault/b.md', entries, selection,
-        onSwitchTab, onReplaceActiveTab, onSelectNote,
+        activeTabPath: '/vault/b.md', entries, selection,
+        onReplaceActiveTab, onSelectNote,
       })
     )
 
@@ -177,8 +114,8 @@ describe('useKeyboardNavigation', () => {
   it('selects first note when no active tab', () => {
     renderHook(() =>
       useKeyboardNavigation({
-        tabs: [], activeTabPath: null, entries, selection,
-        onSwitchTab, onReplaceActiveTab, onSelectNote,
+        activeTabPath: null, entries, selection,
+        onReplaceActiveTab, onSelectNote,
       })
     )
 
@@ -194,8 +131,8 @@ describe('useKeyboardNavigation', () => {
   it('does nothing without modifier keys', () => {
     renderHook(() =>
       useKeyboardNavigation({
-        tabs, activeTabPath: '/vault/a.md', entries, selection,
-        onSwitchTab, onReplaceActiveTab, onSelectNote,
+        activeTabPath: '/vault/a.md', entries, selection,
+        onReplaceActiveTab, onSelectNote,
       })
     )
 
@@ -205,25 +142,7 @@ describe('useKeyboardNavigation', () => {
       }))
     })
 
-    expect(onSwitchTab).not.toHaveBeenCalled()
     expect(onReplaceActiveTab).not.toHaveBeenCalled()
     expect(onSelectNote).not.toHaveBeenCalled()
   })
-
-  it('does nothing with empty tabs for tab navigation', () => {
-    renderHook(() =>
-      useKeyboardNavigation({
-        tabs: [], activeTabPath: null, entries, selection,
-        onSwitchTab, onReplaceActiveTab, onSelectNote,
-      })
-    )
-
-    act(() => {
-      window.dispatchEvent(new KeyboardEvent('keydown', {
-        key: 'ArrowRight', metaKey: true, shiftKey: true, bubbles: true,
-      }))
-    })
-
-    expect(onSwitchTab).not.toHaveBeenCalled()
-  })
 })