fix(settings): harden audited state synchronization

src/utils/dockBadge.test.ts

@@ -0,0 +1,36 @@
+import { beforeEach, describe, expect, it, vi } from 'vitest';
+import * as ipc from '../ipc';
+import { updateDockBadge } from './dockBadge';
+
+vi.mock('../ipc', () => ({
+  invokeCommand: vi.fn()
+}));
+
+describe('dock badge synchronization', () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+    vi.mocked(ipc.invokeCommand).mockImplementation(async command => (
+      command === 'begin_dock_badge_session' ? 1 : undefined
+    ));
+  });
+
+  it('attaches increasing generations to concurrent updates', async () => {
+    await Promise.all([updateDockBadge(3), updateDockBadge(0)]);
+
+    const calls = vi.mocked(ipc.invokeCommand).mock.calls;
+    expect(calls).toHaveLength(3);
+    expect(calls[0]).toEqual(['begin_dock_badge_session']);
+    const badgeCalls = calls.slice(1);
+    expect(badgeCalls[0]).toEqual([
+      'update_dock_badge',
+      { count: 3, generation: expect.any(Number), session: 1 }
+    ]);
+    expect(badgeCalls[1]).toEqual([
+      'update_dock_badge',
+      { count: 0, generation: expect.any(Number), session: 1 }
+    ]);
+    const firstBadgeArgs = badgeCalls[0][1] as { generation: number };
+    const secondBadgeArgs = badgeCalls[1][1] as { generation: number };
+    expect(secondBadgeArgs.generation).toBe(firstBadgeArgs.generation + 1);
+  });
+});

src/utils/dockBadge.ts

@@ -0,0 +1,25 @@
+import { invokeCommand } from '../ipc';
+
+let dockBadgeGeneration = 0;
+let dockBadgeSessionRequest: Promise<number> | null = null;
+
+const getDockBadgeSession = (): Promise<number> => {
+  if (!dockBadgeSessionRequest) {
+    const request = invokeCommand('begin_dock_badge_session');
+    dockBadgeSessionRequest = request.catch(error => {
+      dockBadgeSessionRequest = null;
+      throw error;
+    });
+  }
+  return dockBadgeSessionRequest;
+};
+
+/**
+ * Attach the backend session and a per-session generation to every badge
+ * update so stale main-thread callbacks cannot overwrite a newer session.
+ */
+export const updateDockBadge = async (count: number): Promise<void> => {
+  const session = await getDockBadgeSession();
+  const generation = ++dockBadgeGeneration;
+  await invokeCommand('update_dock_badge', { count, generation, session });
+};