test: cover 4K format selector in buildYtdlpArgs

src/lib/__tests__/ytdlp.test.ts

@@ -40,6 +40,13 @@ describe('buildYtdlpArgs', () => {
     expect(args[idx + 1]).toContain('height<=?1080')
   })
 
+  it('adds a height filter to -f for 4K quality', () => {
+    const args = buildYtdlpArgs({ ...base, quality: '2160p' })
+    const idx = args.indexOf('-f')
+    expect(idx).toBeGreaterThan(-1)
+    expect(args[idx + 1]).toContain('height<=?2160')
+  })
+
   it('does not add a height filter when quality is "best"', () => {
     const args = buildYtdlpArgs(base)
     const idx = args.indexOf('-f')