Item: hyperframes-core
Rating: 4.2
Author: Implexa
The HyperFrames composition contract — build one renderable project. Use for composition structure, the `data-*` timing attributes, `class="clip"`, tracks,…
SKILL.md

HyperFrames Core

HyperFrames renders video from HTML. A composition is an HTML file whose DOM declares timing with data-* attributes, whose animation runtime is seekable, and whose media playback is owned by the framework.

This skill is the technical contract — how to build one hyperframes project. The body below is the build guide; per-topic detail lives in references/ (index next), read on demand. Other concerns live in the sibling domain skills — hyperframes-animation, hyperframes-creative, media-use, hyperframes-cli, hyperframes-registry. The capability map in /hyperframes says what each one covers.

References

File
Read it to…

references/minimal-composition.md
start from the smallest renderable composition skeleton

references/composition-patterns.md
choose monolithic vs modular; structure a modular index.html; pick a sub-comp archetype

references/data-attributes.md
look up any data-* (root / clip / sub-comp host / legacy aliases); use class="clip"

references/tracks-and-clips.md
pick data-track-index, handle same-track overlap / z-index, time a clip relative to another

references/sub-compositions.md
wire a sub-composition (host attrs, <template>, per-instance vars) and animate inside it

references/variables-and-media.md
declare variables; place <video>/<audio>, set volume, trim

references/determinism-rules.md
build a seekable timeline; determinism bans; the animatable-property allowlist; layout / text fit

references/full-screen-motion.md
author full-frame motion with shared backgrounds

references/storyboard-format.md
author a STORYBOARD.md plan (+ the parsed manifest)

references/review-loop.md
run the plan → sketch → build review passes on a live board — shared by every storyboard-planning workflow

references/production-loop.md
take an approved plan to a delivered video — the stage dependencies (audio, frames, assembly, transitions, captions, verify, deliver) a freeform build follows directly

references/brief-contract.md
the brief's ground rules — mode derivation (collaborative / autonomous), shared field registry, question invariants (the asking itself lives in /hyperframes → the intent layer)

references/brief-format.md
author BRIEF.md — the confirmed intent document a workflow's Setup writes and every later step reads

references/script-format.md
author the optional SCRIPT.md locked narration

references/subagent-dispatch.md
map subagent dispatch verbs (parallel fan-out / background / wait) to your harness

references/frame-worker-core.md
the shared frame-worker role contract — each narrative workflow's packet builder prepends it to that workflow's sub-agents/frame-worker.md delta

references/tailwind.md
work in a Tailwind v4 project (init --tailwind; runtime contract differs from Studio's v3)

For animation runtime specifics (GSAP API, Lottie, Three.js, etc.) go to hyperframes-animation → adapters/<runtime>.md.

Building a composition

Two root forms (not interchangeable)

Standalone (top-level index.html) — root <div data-composition-id="…"> sits directly in <body>, no <template> wrapper (wrapping it hides all content and breaks rendering).

Sub-composition (loaded via data-composition-src) — root must be wrapped in <template>.

⚠ Transport rule: the runtime only clones <template> contents; everything outside (incl. <head> styles/scripts) is discarded — put <style>/<script> inside the template.
⚠ Host-id rule: the host slot's data-composition-id must exactly equal the inner template's data-composition-id and the window.__timelines["<id>"] key — no -mount/-slot/-host suffix.

File shape, host wiring, and the pre-render checklist → references/sub-compositions.md.

Root must be sized (silent layout bug)

The standalone root needs an explicit sized box (width/height in px), and every ancestor down to a height:100% element must have a resolved height — otherwise a flex/100% child collapses to ~0 and content piles into the top-left corner. Do not rely on automated gates alone to catch this; inspect a snapshot. Skeleton → references/minimal-composition.md.

One paused timeline

Each composition registers exactly one gsap.timeline({ paused: true }) at window.__timelines["<id>"] (key = root data-composition-id), built synchronously at page load. Render duration = root data-duration, not timeline length. Don't manually nest sub-timelines into the host. Full contract (incl. non-GSAP runtimes) → references/determinism-rules.md + hyperframes-animation/adapters/.

First-pass lint gotchas (a guaranteed first build failure)

Two rules that lint does catch, but only after the fact — write them right the first time:

The root composition element must carry data-start="0" (alongside data-composition-id/data-width/data-height); omitting it fails lint with root_composition_missing_data_start.

Never pair a CSS initial transform with a GSAP tween on the same property — the CSS value and the tween's start fight and lint rejects it with gsap_css_transform_conflict. Set the initial state inside the tween with gsap.fromTo(el, { x: -40 }, { x: 0 }) instead of a CSS transform: translateX(-40px).

Non-negotiable rules (silent bugs automated gates may miss)

Surfaced here; full rationale in the linked reference. Do not violate:

No render-time clocks / unseeded Math.random / network / input-state; no repeat: -1 (use a finite count). → determinism-rules.md

Animate only the visual-property allowlist; never tween display or raw visibility. GSAP autoAlpha and zero-duration timeline boundary sets are the only visibility exceptions, and only on non-clip elements or wrappers inside a clip. The framework alone controls .clip visibility. Do not gsap.set later-scene clips at page load. → determinism-rules.md

No <br> in body text; transformed elements must be block-level + sized; pulsing absolute decoratives need peak clearance. → determinism-rules.md

<video>/<audio> work at any nesting depth (including inside a sub-comp <template> or wrapper); the framework owns playback and seeks/decodes media wherever it lives. The one caveat is timelines, not placement: a sub-comp timeline can't animate host-root elements. → variables-and-media.md

Every id must be unique across the assembled page; inside a sub-comp, prefix ids with the composition id (#<id>-hero). Duplicate <video>/<img> ids render blank — the producer injects frames by getElementById, and cross-file dupes slip past lint. → composition-patterns.md

A full-screen scene fill goes on a full-bleed child (position:absolute; inset:0), never on the composition root itself — the producer's frame compositing can drop the root element's own background (the frame renders black) even though preview/snapshot show it correctly. → composition-patterns.md

Editing existing compositions

Read the files first. Preserve unrelated timing, tracks, IDs, variables, media paths.

Match existing composition IDs and timeline keys.

Adding a clip: pick a non-overlapping data-track-index or adjust surrounding timing intentionally.

data-hidden on any composition element hides it in BOTH preview and render, overriding its time window; it is non-destructive/reversible and toggled by Studio's timeline eye icon.

Adding a sub-composition: verify its internal data-composition-id before wiring the host.

Validation

Use hyperframes-cli for command details

 npx hyperframes check passes (0 findings across lint, runtime, layout, motion, and contrast)

 Projects with sub-compositions: npx hyperframes snapshot --at <midpoints> and eyeball each frame

 npx hyperframes preview for review (the user can edit anything in Studio's timeline)

 npx hyperframes render only after the user approves