Vance Ingalls 229538c622 fix: add media rendering guardrails to prevent silent failures (#112)
## Summary

- **Lint rules** catch media elements missing `id` (renderer silently skips them), missing `src`, `preload="none"` (blocks renderer), and video nested in timed divs (freezes playback). Upgraded `video_nested_in_timed_element` from warning to error.
- **Compiler** strips `preload="none"` from media during compilation. Runs parallel, cached keyframe interval analysis via ffprobe — warns on sparse keyframes (>2s) that cause seek failures and audio/video desync. Suggested ffmpeg command preserves audio (`-c:a copy`).
- **Pre-render lint** lints `index.html` + all `compositions/*.html` sub-compositions before render via shared `lintProject()` helper. Warns by default; `--strict` blocks on errors, `--strict-all` blocks on errors + warnings.
- **Render orchestrator** logs a hint to retry with `--workers 1` when parallel capture times out on video-heavy compositions.
- **Refactor**: extracted `runFfprobe()` + `parseProbeJson()` helpers to deduplicate ~80 lines of spawn boilerplate across 3 ffprobe functions. Extracted `shouldBlockRender()` so strict flag tests exercise production code. Shared `lintProject()` used by both `lint` and `render` commands.

## Context

Discovered during a real composition build session where:
1. `<audio>` without `id` rendered silently (preview worked fine because runtime queries `[data-start]`, but renderer queries `[id][src]`)
2. `<video>` inside timed `<div>` froze on first frame
3. `preload="none"` caused 45s renderer timeout
4. YouTube clips with sparse keyframes from `yt-dlp --download-sections` caused audio/video desync
5. Parallel workers timed out on video-heavy compositions

## Test plan

- [x] Core: 365/365 tests passing (5 new lint tests)
- [x] Engine: 24/24 tests passing
- [x] CLI: 14/14 tests passing (7 lintProject + 7 shouldBlockRender)
- [x] Lint + format hooks pass
- [ ] Manual: create a composition with `<audio data-start="0" src="test.wav">` (no id) — verify `npx hyperframes lint` catches it
- [ ] Manual: run `npx hyperframes render --strict` with lint errors — verify it blocks
- [ ] Manual: run `npx hyperframes render --strict-all` with lint warnings — verify it blocks
2026-03-30 11:07:19 -07:00
2026-03-21 22:43:56 -07:00
2026-03-21 22:43:56 -07:00

Hyperframes

Node.js

Write HTML. Render video. Built for agents.

Hyperframes is an open-source video rendering framework that lets you create, preview, and render HTML-based video compositions — with first-class support for AI agents via MCP.

Why Hyperframes?

  • HTML-native — AI agents already speak HTML. No React required.
  • Frame Adapter pattern — bring your own animation runtime (GSAP, Lottie, CSS, Three.js).
  • Deterministic rendering — same input = identical output. Built for automated pipelines.
  • AI-first design — not a bolted-on afterthought.

Quick Start

npx hyperframes init my-video
cd my-video

Then open the project with your AI coding agent (Claude Code, Cursor, etc.) — it has HyperFrames skills installed and knows how to create and edit compositions.

npx hyperframes dev      # preview in browser (live reload)
npx hyperframes render   # render to MP4

Requirements: Node.js >= 22, FFmpeg

How It Works

Define your video as HTML with data attributes:

<div id="stage" data-composition-id="my-video" data-start="0" data-width="1920" data-height="1080">
  <video
    id="clip-1"
    data-start="0"
    data-duration="5"
    data-track="0"
    src="intro.mp4"
    muted
    playsinline
  ></video>
  <img id="overlay" data-start="2" data-duration="3" data-track="1" src="logo.png" />
  <audio
    id="bg-music"
    data-start="0"
    data-duration="9"
    data-track="2"
    data-volume="0.5"
    src="music.wav"
  ></audio>
</div>

Preview instantly in the browser. Render to MP4 locally. Let AI agents compose videos using tools they already understand.

Packages

Package Description
hyperframes CLI — create, preview, lint, and render compositions
@hyperframes/core Types, parsers, generators, linter, runtime, frame adapters
@hyperframes/engine Seekable page-to-video capture engine (Puppeteer + FFmpeg)
@hyperframes/producer Full rendering pipeline (capture + encode + audio mix)
@hyperframes/studio Browser-based composition editor UI

AI Agent Skills

HyperFrames ships skills that teach AI coding agents (Claude Code, Gemini CLI, Codex, Cursor) how to write correct compositions and GSAP animations. Use these instead of writing from scratch — they encode framework-specific patterns that generic docs don't cover.

# Install all skills (HyperFrames + GSAP) — runs automatically during `hyperframes init`
npx hyperframes skills

# Or install to a specific agent
npx hyperframes skills --claude
npx hyperframes skills --cursor

Or via npx skills add

# HyperFrames skills (hyperframes-compose, hyperframes-captions)
npx skills add heygen-com/hyperframes

# GSAP skills (gsap-core, gsap-timeline, gsap-scrolltrigger, gsap-plugins, gsap-performance, gsap-utils, gsap-react, gsap-frameworks)
npx skills add greensock/gsap-skills

Installed Skills

Source Skills What they teach
HyperFrames hyperframes-compose, hyperframes-captions HTML composition structure, class="clip" rules, data-* attributes, timeline registration, rendering constraints
GSAP gsap-core, gsap-timeline, gsap-performance, gsap-plugins, gsap-scrolltrigger, gsap-utils, gsap-react, gsap-frameworks Core API, timeline sequencing, ScrollTrigger, plugin usage, performance best practices

In Claude Code, invoke with /hyperframes-compose, /hyperframes-captions, /gsap-core, etc.

Documentation

Full docs at hyperframes.heygen.com — includes guides, concepts, API reference, and package documentation.

Contributing

See CONTRIBUTING.md for guidelines on how to contribute.

License

See LICENSE for details.

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Description
Write HTML. Render video. Built for agents.
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