feat(downloads): add media quality and queue reordering

src/utils/queueOrdering.test.ts

@@ -0,0 +1,32 @@
+import { describe, expect, it } from 'vitest';
+import {
+  moveSelectedBlockToIndex,
+  targetIndexForBoundary,
+  targetIndexForDesiredOrder
+} from './queueOrdering';
+
+const items = ['a', 'b', 'c', 'd'].map(id => ({ id }));
+
+describe('queue ordering', () => {
+  it('moves discontiguous selection as one block', () => {
+    expect(moveSelectedBlockToIndex(items, ['b', 'd'], 1).map(item => item.id))
+      .toEqual(['a', 'b', 'd', 'c']);
+  });
+
+  it('translates pointer boundaries after selected rows are removed', () => {
+    expect(targetIndexForBoundary(items, ['b', 'd'], 2)).toBe(1);
+    expect(targetIndexForBoundary(items, ['b', 'd'], 3)).toBe(2);
+  });
+
+  it('computes a registered-only backend target from the desired local order', () => {
+    const current = [{ id: 'a' }, { id: 'staged' }, { id: 'b' }, { id: 'c' }];
+    const desired = [{ id: 'a' }, { id: 'b' }, { id: 'c' }, { id: 'staged' }];
+    expect(targetIndexForDesiredOrder(current, ['c'], desired)).toBe(2);
+
+    expect(targetIndexForDesiredOrder(
+      [{ id: 'a' }, { id: 'c' }],
+      ['c'],
+      [{ id: 'a' }, { id: 'staged' }, { id: 'c' }]
+    )).toBe(1);
+  });
+});