feat(ui): modernize desktop interactions

src/utils/downloadActions.test.ts

@@ -0,0 +1,38 @@
+import { describe, expect, it } from 'vitest';
+import {
+  canPauseDownload,
+  canRedownload,
+  canStartDownload,
+  isIdentityLocked,
+  isTransferLocked,
+  startActionLabel,
+} from './downloadActions';
+
+describe('download action policy', () => {
+  it('keeps start and pause actions mutually exclusive', () => {
+    for (const status of ['ready', 'paused', 'failed'] as const) {
+      expect(canStartDownload(status)).toBe(true);
+      expect(canPauseDownload(status)).toBe(false);
+    }
+    for (const status of ['queued', 'downloading', 'processing', 'retrying'] as const) {
+      expect(canPauseDownload(status)).toBe(true);
+      expect(canStartDownload(status)).toBe(false);
+    }
+  });
+
+  it('limits redownload to terminal or paused states', () => {
+    expect(canRedownload('completed')).toBe(true);
+    expect(canRedownload('failed')).toBe(true);
+    expect(canRedownload('paused')).toBe(true);
+    expect(canRedownload('downloading')).toBe(false);
+  });
+
+  it('provides consistent labels and edit locks', () => {
+    expect(startActionLabel('ready')).toBe('Start');
+    expect(startActionLabel('failed')).toBe('Start');
+    expect(startActionLabel('paused')).toBe('Resume');
+    expect(isTransferLocked('processing')).toBe(true);
+    expect(isIdentityLocked('completed')).toBe(true);
+    expect(isTransferLocked('completed')).toBe(false);
+  });
+});