diff --git a/src/lib/transport/playback.ts b/src/lib/transport/playback.ts
index 34c7c83..25a45cd 100644
--- a/src/lib/transport/playback.ts
+++ b/src/lib/transport/playback.ts
@@ -96,6 +96,58 @@ export function adjustShuttle(dir: 1 | -1, shuttleRate: number): number {
   return nextRate;
 }
 
+export function togglePiP(): void {
+  if (document.pictureInPictureElement) {
+    document.exitPictureInPicture().catch((e) => {
+      console.error('Exit PiP failed:', e);
+    });
+  } else {
+    const videoEl = getVideo();
+    if (videoEl && document.pictureInPictureEnabled) {
+      videoEl.requestPictureInPicture().catch((e) => {
+        console.error('PiP request failed:', e);
+      });
+    }
+  }
+}
+
+export function isPiPActive(): boolean {
+  return !!document.pictureInPictureElement;
+}
+
+export function toggleFullscreen(): void {
+  if (document.fullscreenElement) {
+    document.exitFullscreen().catch((e) => {
+      console.error('Exit fullscreen failed:', e);
+    });
+  } else {
+    const videoEl = getVideo();
+    if (!videoEl) return;
+    if (videoEl.requestFullscreen) {
+      videoEl.requestFullscreen().catch((e) => {
+        console.error('Fullscreen request failed:', e);
+      });
+    } else if ((videoEl as HTMLVideoElement & { webkitEnterFullscreen?: () => void }).webkitEnterFullscreen) {
+      (videoEl as HTMLVideoElement & { webkitEnterFullscreen: () => void }).webkitEnterFullscreen();
+    }
+  }
+}
+
+export function isFullscreenActive(): boolean {
+  return !!document.fullscreenElement;
+}
+
+export function setPlaybackRate(rate: number): void {
+  const videoEl = getVideo();
+  if (videoEl) {
+    videoEl.playbackRate = rate;
+  }
+}
+
+export function getPlaybackRate(): number {
+  return getVideo()?.playbackRate ?? 1;
+}
+
 export type TransportKeyAction =
   | 'play-pause'
   | 'frame-back'
diff --git a/tests/lib/transport/playback.test.ts b/tests/lib/transport/playback.test.ts
new file mode 100644
index 0000000..7436cc0
--- /dev/null
+++ b/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);
+  });
+});