waapi

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SKILL.md as published, 90 lines.

# Web Animations API for HyperFrames

HyperFrames can seek Web Animations API animations through its `waapi` runtime adapter. WAAPI is useful when you want native browser keyframes with JavaScript-created timing and no GSAP dependency.

## Contract

- Create animations synchronously during composition initialization.
- Use `element.animate(...)` with finite `duration` and `iterations`.
- Use `fill: "both"` so seeked states persist.
- Pause animations after creation or let the adapter pause them on first seek.
- Avoid callbacks and promises for render-critical state.

The adapter calls `document.getAnimations()`, sets each animation's `currentTime` to HyperFrames time in milliseconds, then pauses it.

## Basic Pattern

```html
<div id="orb" class="clip orb" data-start="2" data-duration="3" data-track-index="2"></div>

<script>
  const orb = document.getElementById("orb");
  const animation = orb.animate(
    [
      { transform: "translate3d(-160px, 0, 0) scale(0.8)", opacity: 0 },
      { transform: "translate3d(0, 0, 0) scale(1)", opacity: 1, offset: 0.35 },
      { transform: "translate3d(120px, 0, 0) scale(1.08)", opacity: 1 },
    ],
    {
      duration: 3000,
      delay: 2000,
      easing: "cubic-bezier(0.2, 0, 0, 1)",
      fill: "both",
      iterations: 1,
    },
  );

  animation.pause();
</script>
```

## Stagger Pattern

```js
document.querySelectorAll(".token").forEach((token, index) => {
  const animation = token.animate(
    [
      { transform: "translateY(24px)", opacity: 0 },
      { transform: "translateY(0)", opacity: 1 },
    ],
    {
      duration: 620,
      delay: index * 80,
      easing: "cubic-bezier(0.2, 0, 0, 1)",
      fill: "both",
      iterations: 1,
    },
  );
  animation.pause();
});
```

## Good Uses

- Lightweight DOM motion where CSS keyframes are too rigid and GSAP is unnecessary.
- Generated animations from structured data.
- Simple timelines that can be represented as keyframes, delays, and offsets.

## Avoid

- Infinite `iterations`.
- Depending on `animation.finished` to mutate render-critical DOM.
- Running separate clocks with `requestAnimationFrame`, timers, or `performance.now()`.
- Animating layout properties when transforms and opacity can express the motion.
- Assuming clip-local start time is automatic. WAAPI adapter seeks document-level animation time; model clip offsets with `delay` or create the animation on an element whose visibility is controlled by HyperFrames timing.

## Validation

After editing a WAAPI composition:

```bash
npx hyperframes lint
npx hyperframes validate
```

## Credits And References

- HyperFrames adapter source: `packages/core/src/runtime/adapters/waapi.ts`.
- MDN Web Animations API guide: https://developer.mozilla.org/docs/Web/API/Web_Animations_API/Using_the_Web_Animations_API
- MDN `Animation.currentTime`: https://developer.mozilla.org/en-US/docs/Web/API/Animation/currentTime