fix: refresh magic notes after external updates

Subscribe the open Magic Notes workspace to committed database changes from desktop and Agent/MCP writes. Preserve selections and unsaved drafts during refresh and external deletion.

File-level commit includes existing runtime edits in shared files; their remaining dependencies are still in the working tree.

Release note: Magic Notes now updates automatically after Agent/MCP edits while preserving your selection and unsaved drafts.

src/preload/index.ts

@@ -1604,6 +1604,12 @@ const desktopApi: DesktopApi = {
           handler
         )
     },
+    onChanged: (listener) => {
+      const handler = (): void => listener()
+      ipcRenderer.on(ipcChannels.magicNotesChanged, handler)
+      return () =>
+        ipcRenderer.removeListener(ipcChannels.magicNotesChanged, handler)
+    },
     onTodoStatusChanged: (listener) => {
       const handler = (): void => listener()
       ipcRenderer.on(ipcChannels.magicTodosStatusChanged, handler)

src/preload/magic-notes-events.test.ts

@@ -0,0 +1,25 @@
+import { describe, expect, it, vi } from 'vitest'
+import type { DesktopApi } from '../shared/contracts'
+import { ipcChannels } from '../shared/ipc-channels'
+
+const electron = vi.hoisted(() => ({
+  contextBridge: { exposeInMainWorld: vi.fn() },
+  ipcRenderer: { on: vi.fn(), removeListener: vi.fn() },
+  webUtils: {}
+}))
+vi.mock('electron', () => electron)
+
+describe('Magic Notes preload events', () => {
+  it('forwards change notifications without exposing the Electron event and removes the same listener', async () => {
+    await import('./index')
+    const api = electron.contextBridge.exposeInMainWorld.mock.calls[0]![1] as DesktopApi
+    const listener = vi.fn()
+    const unsubscribe = api.magicNotes.onChanged(listener)
+    const [channel, handler] = electron.ipcRenderer.on.mock.calls[0]!
+    expect(channel).toBe(ipcChannels.magicNotesChanged)
+    handler({ sender: 'must stay in preload' })
+    expect(listener).toHaveBeenCalledExactlyOnceWith()
+    unsubscribe()
+    expect(electron.ipcRenderer.removeListener).toHaveBeenCalledExactlyOnceWith(channel, handler)
+  })
+})