---
id: T02
parent: S01
milestone: M020
provides: []
requires: []
affects: []
key_files: ["frontend/src/hooks/useMediaSync.ts", "frontend/src/components/VideoPlayer.tsx", "frontend/src/components/PlayerControls.tsx", "frontend/src/App.css", "frontend/package.json"]
key_decisions: ["Cast videoRef to RefObject<HTMLVideoElement> at JSX site to satisfy React 18 strict ref typing"]
patterns_established: []
drill_down_paths: []
observability_surfaces: []
duration: ""
verification_result: "npx tsc --noEmit passes with zero errors. npm run build succeeds producing production bundle. hls.js is dynamically imported (lazy-loaded), not in main bundle."
completed_at: 2026-04-03T23:45:50.331Z
blocker_discovered: false
---

# T02: Built useMediaSync hook, VideoPlayer with HLS lazy-loading and native fallback, and PlayerControls with speed/volume/seek/fullscreen/keyboard shortcuts

> Built useMediaSync hook, VideoPlayer with HLS lazy-loading and native fallback, and PlayerControls with speed/volume/seek/fullscreen/keyboard shortcuts

## What Happened
---
id: T02
parent: S01
milestone: M020
key_files:
  - frontend/src/hooks/useMediaSync.ts
  - frontend/src/components/VideoPlayer.tsx
  - frontend/src/components/PlayerControls.tsx
  - frontend/src/App.css
  - frontend/package.json
key_decisions:
  - Cast videoRef to RefObject<HTMLVideoElement> at JSX site to satisfy React 18 strict ref typing
duration: ""
verification_result: passed
completed_at: 2026-04-03T23:45:50.331Z
blocker_discovered: false
---

# T02: Built useMediaSync hook, VideoPlayer with HLS lazy-loading and native fallback, and PlayerControls with speed/volume/seek/fullscreen/keyboard shortcuts

**Built useMediaSync hook, VideoPlayer with HLS lazy-loading and native fallback, and PlayerControls with speed/volume/seek/fullscreen/keyboard shortcuts**

## What Happened

Installed hls.js. Created useMediaSync hook managing shared playback state via video element event listeners. Created VideoPlayer with three source paths (HLS via lazy-loaded hls.js, Safari native HLS, direct mp4), null-src placeholder, and fatal error state. Created PlayerControls with play/pause, seek bar, time display, 6-option speed selector (0.5–2x), volume + mute, fullscreen, and keyboard shortcuts. Added ~180 lines of themed CSS with responsive stacking. Fixed React 18 ref type mismatch for video element.

## Verification

npx tsc --noEmit passes with zero errors. npm run build succeeds producing production bundle. hls.js is dynamically imported (lazy-loaded), not in main bundle.

## Verification Evidence

| # | Command | Exit Code | Verdict | Duration |
|---|---------|-----------|---------|----------|
| 1 | `cd frontend && npx tsc --noEmit` | 0 | ✅ pass | 2800ms |
| 2 | `cd frontend && npm run build` | 0 | ✅ pass | 3600ms |


## Deviations

Added RefObject cast at JSX ref site for React 18 strict ref typing compatibility.

## Known Issues

None.

## Files Created/Modified

- `frontend/src/hooks/useMediaSync.ts`
- `frontend/src/components/VideoPlayer.tsx`
- `frontend/src/components/PlayerControls.tsx`
- `frontend/src/App.css`
- `frontend/package.json`


## Deviations
Added RefObject cast at JSX ref site for React 18 strict ref typing compatibility.

## Known Issues
None.
