feat: mini player bar with expandable track list

web/test/player.test.tsx

@@ -1,7 +1,7 @@
 import { describe, it, expect, vi, beforeEach } from 'vitest'
 import { render, screen, waitFor, act } from '@testing-library/react'
 import userEvent from '@testing-library/user-event'
-import { PlayerProvider, usePlayer } from '../src/player/PlayerContext.js'
+import { PlayerProvider, usePlayer, playerReducer, type PlayerState } from '../src/player/PlayerContext.js'
 import type { Track } from '../src/types.js'
 
 vi.mock('../src/api.js', async (importOriginal) => {
@@ -106,3 +106,30 @@ describe('PlayerProvider', () => {
     await waitFor(() => expect(screen.getByText('track:Theme de Yoyo')).toBeTruthy())
   })
 })
+
+const twoTracks: Track[] = [
+  { id: 's1', title: 'Overture', duration: 200, track: 1 },
+  { id: 's2', title: 'Theme de Yoyo', duration: 300, track: 2 },
+]
+
+describe('playerReducer edges', () => {
+  const loaded: PlayerState = playerReducer(
+    { album: null, tracks: [], index: 0, playing: false, failed: [] },
+    { type: 'LOAD', album: { id: 'a1', title: 'Motion', artist: 'TCO' }, tracks: twoTracks }
+  )
+
+  it('LOAD with empty tracks does not play', () => {
+    const s = playerReducer(loaded, { type: 'LOAD', album: loaded.album!, tracks: [] })
+    expect(s.playing).toBe(false)
+  })
+
+  it('TRACK_ERROR at last track pauses without advancing, records failure once', () => {
+    const atLast = playerReducer(loaded, { type: 'NEXT' })
+    const err = playerReducer(atLast, { type: 'TRACK_ERROR' })
+    expect(err.index).toBe(1)
+    expect(err.playing).toBe(false)
+    expect(err.failed).toEqual([1])
+    const again = playerReducer(err, { type: 'TRACK_ERROR' })
+    expect(again.failed).toEqual([1])
+  })
+})