feat: add PiP, fullscreen, and playbackRate helpers to playback module

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/lib/transport/playback.test.ts

@@ -0,0 +1,129 @@
+import { describe, it, expect, vi, beforeEach } from 'vitest';
+
+// Mock the videoSession store (playback.ts imports it)
+vi.mock('$lib/stores/videoSession.svelte', () => ({
+  session: {
+    duration: 120,
+    currentTime: 0,
+    fps: 30,
+    isPlaying: false,
+    keyframePositions: [],
+  },
+}));
+
+import {
+  setVideoElement,
+  togglePiP,
+  isPiPActive,
+  toggleFullscreen,
+  isFullscreenActive,
+  setPlaybackRate,
+  getPlaybackRate,
+} from '$lib/transport/playback';
+
+function createMockVideoElement(): HTMLVideoElement {
+  const el = document.createElement('video');
+  // PiP
+  (el as any).requestPictureInPicture = vi.fn().mockResolvedValue({});
+  // Fullscreen
+  el.requestFullscreen = vi.fn().mockResolvedValue(undefined);
+  return el;
+}
+
+describe('playback — PiP helpers', () => {
+  let mockVideo: HTMLVideoElement;
+
+  beforeEach(() => {
+    mockVideo = createMockVideoElement();
+    setVideoElement(mockVideo);
+    // Reset PiP state
+    Object.defineProperty(document, 'pictureInPictureElement', {
+      value: null,
+      writable: true,
+      configurable: true,
+    });
+    Object.defineProperty(document, 'pictureInPictureEnabled', {
+      value: true,
+      writable: true,
+      configurable: true,
+    });
+  });
+
+  it('isPiPActive returns false when no PiP element', () => {
+    expect(isPiPActive()).toBe(false);
+  });
+
+  it('togglePiP calls requestPictureInPicture', () => {
+    togglePiP();
+    expect((mockVideo as any).requestPictureInPicture).toHaveBeenCalled();
+  });
+
+  it('isPiPActive returns true when PiP element exists', () => {
+    Object.defineProperty(document, 'pictureInPictureElement', {
+      value: mockVideo,
+      writable: true,
+      configurable: true,
+    });
+    expect(isPiPActive()).toBe(true);
+  });
+});
+
+describe('playback — fullscreen helpers', () => {
+  let mockVideo: HTMLVideoElement;
+
+  beforeEach(() => {
+    mockVideo = createMockVideoElement();
+    setVideoElement(mockVideo);
+    Object.defineProperty(document, 'fullscreenElement', {
+      value: null,
+      writable: true,
+      configurable: true,
+    });
+  });
+
+  it('isFullscreenActive returns false when not fullscreen', () => {
+    expect(isFullscreenActive()).toBe(false);
+  });
+
+  it('toggleFullscreen calls requestFullscreen when not fullscreen', () => {
+    toggleFullscreen();
+    expect(mockVideo.requestFullscreen).toHaveBeenCalled();
+  });
+
+  it('isFullscreenActive returns true when fullscreen element exists', () => {
+    Object.defineProperty(document, 'fullscreenElement', {
+      value: mockVideo,
+      writable: true,
+      configurable: true,
+    });
+    expect(isFullscreenActive()).toBe(true);
+  });
+});
+
+describe('playback — playback rate helpers', () => {
+  let mockVideo: HTMLVideoElement;
+
+  beforeEach(() => {
+    mockVideo = createMockVideoElement();
+    setVideoElement(mockVideo);
+  });
+
+  it('getPlaybackRate returns 1 by default', () => {
+    expect(getPlaybackRate()).toBe(1);
+  });
+
+  it('setPlaybackRate changes the video playback rate', () => {
+    setPlaybackRate(1.5);
+    expect(mockVideo.playbackRate).toBe(1.5);
+  });
+
+  it('getPlaybackRate returns the current rate', () => {
+    setPlaybackRate(2);
+    expect(getPlaybackRate()).toBe(2);
+  });
+
+  it('getPlaybackRate returns 1 when no video element', () => {
+    setVideoElement(null);
+    expect(getPlaybackRate()).toBe(1);
+  });
+});