Iwsdk UI Agent Skill

UIKitML Asset Workflow

Treat UIKitML as a first-class renderable asset. Use the managed editor's isolated

renderer for layout, the scene editor for placement, and the application runtime for

behavior. Do not change the scene, camera, or component model merely to inspect a

panel.

User request is in $ARGUMENTS.

1. Find the three stable identities

Every scene-authored panel has three different identities:

• the manifest asset ID, which names the reusable UIKitML definition;
• the scene node ID, which names one placed instance;
• element id attributes, which name fields and controls inside the document.

Find or add the manifest entry in src/assets.ts and keep the source under

public/ui/:

import { AssetType, defineAssets } from '@iwsdk/core';

const publicAssetUrl = (path: string) =>
  `${import.meta.env.BASE_URL}${path.replace(/^\/+/u, '')}`;

export default defineAssets({
  'welcome-panel': {
    name: 'Welcome panel',
    type: AssetType.UIKitML,
    url: publicAssetUrl('ui/welcome.uikitml'),
  },
});

A file under public/ui/ is not placeable until it is registered. The .uikitml

file is the runtime source of truth; never generate an intermediate JSON file.

2. Reuse the managed editor

Run commands from the application directory. Reuse a command-ready session instead

of starting a second server or browser:

npx iwsdk dev status
npx iwsdk dev up --timeout 60000
npx iwsdk ui assets --raw

dev up owns the managed headed browser. Do not launch a second Playwright browser,

enable Vite's independent opener, or implement a custom UIKit renderer.

3. Render the panel in isolation

Use the editor-backed isolated renderer before debugging scene placement:

npx iwsdk ui render-preview \
  --input-json '{"assetId":"welcome-panel","width":800,"height":600}' \
  --output-file artifacts/welcome-panel.png

This renders the real manifest entry through the real UIKitML parser, fonts, layout,

and WebGL path on a neutral background. It waits for UIKit render and resource

signals; do not add fixed frame delays. Re-run the command after every layout change.

Same-URL sources are reloaded without restarting the server.

4. Place and inspect it in the scene editor

For a human-authored placement, open the scene and add the UIKitML asset from the

asset drawer. For file authoring, use the same asset-only node contract:

{
  "id": "welcome-panel-instance",
  "name": "Welcome panel",
  "content": { "type": "asset", "asset": "welcome-panel" },
  "transform": {
    "position": [0, 1.4, -1.5],
    "rotationDeg": [0, 180, 0],
    "scale": 0.5
  }
}

npx iwsdk scene render-file \
  --input-json '{"path":"public/scenes/main.iwsdk.scene.json","view":"quarter"}' \
  --output-file artifacts/main-editor.png
npx iwsdk scene open \
  --input-json '{"path":"public/scenes/main.iwsdk.scene.json"}' --raw

UIKitML surfaces are single-sided. If the isolated preview works but the placed panel

is invisible, inspect its rotation first. Size a world-space panel with its ordinary

entity transform scale. There is no maxWidth/maxHeight fitting layer and no

editor-visible legacy PanelUI component to configure.

Use scene screenshot for editor/scene evidence. browser screenshot is intentionally

runtime-only and switches the managed workspace to runtime before capturing.

5. Edit UIKitML

UIKitML is HTML/CSS-shaped, but it is not a browser engine. Before assuming browser

behavior, use npx iwsdk reference search or the connected IWSDK reference tools to

confirm supported elements and properties.

Key rules:

• numeric UIKit sizes are centimeters (100 = 100 cm = 1 m);
• use stable id attributes for elements application code must manipulate;
• prefer explicit supported declarations over CSS shorthand;
• parser errors include source locations;
• relative and remote font URLs are supported, but font completion can change layout;
• the managed preview settles from UIKit render/font/texture signals, so inspect logs

instead of compensating with arbitrary waits.

Reuse built-in kits, icons, and remote fonts

IWSDK bundles the UIKitML Horizon component kit and Lucide icon set. Select the

Horizon kit explicitly in iwsdk.config.json so the choice is visible to both the

runtime and editor:

{
  "world": {
    "features": {
      "spatialUI": { "kit": "horizon" }
    }
  }
}

Horizon tags such as <Panel>, <Button>, <ButtonIcon>, and <ButtonLabel>

can then be combined directly with Lucide tags such as <RectangleGoggles> or

<LogIn>. Do not install or register either component set in application code.

UIKitML also accepts remote TTF declarations. The starter's

public/ui/welcome.uikitml demonstrates multiple DM Sans weights loaded from

fonts.gstatic.com with @font-face; apply the declared family to a root class so

all descendants inherit it. Keep a local font under public/ when offline or

cross-origin availability is a product requirement.

After each edit:

• rerender with ui render-preview and inspect the image;
• rerender the scene when placement or scale matters;
• inspect browser logs for parser, font, texture, or runtime failures.

6. Connect runtime behavior

For a code-owned instance, keep the UIKitMLAsset returned by the asset manager:

import { UIKitMLAsset } from '@iwsdk/core';

const panel = await world.assets.instantiate<UIKitMLAsset>('welcome-panel');
const entity = world.createTransformEntity(panel);
const button = panel.requireElementById('xr-button');
button.addEventListener('click', () => world.launchXR());

For a scene-authored instance, resolve it by stable scene node ID after the level has

loaded:

const panel = world.requireSceneObject<UIKitMLAsset>('welcome-panel-instance');
const button = panel.requireElementById('xr-button');
button.setProperties({ display: 'none' });

Do not locate a panel by transient ECS index, manifest URL, or a scan for an internal

PanelDocument. Use the scene node ID and element IDs.

ScreenSpace is product behavior

Add ScreenSpace only when the experience genuinely needs a browser-camera HUD:

entity.addComponent(ScreenSpace, {
  width: '420px',
  height: '240px',
  top: '20px',
  right: '20px',
  zOffset: 0.2,
});

Position and size values are CSS strings. In immersive mode the document returns to

its authored world transform. Do not add ScreenSpace, a backdrop, or a temporary

camera pose merely to make a panel easier to inspect—the editor already provides the

correct isolated and in-scene render paths.

Completion checklist

• Manifest ID resolves and ui assets lists it.
• Isolated preview is nonblank, correctly laid out, and uses the intended fonts.
• Scene preview has correct facing, transform scale, and lighting-independent color.
• Runtime behavior resolves the placed node and required element IDs.
• Browser logs contain no UIKitML parser, resource, or font errors.
• No generated UI JSON, temporary ScreenSpace component, backdrop, or camera hack

remains.