IWSDK 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.

1. Find the three stable identities

Every scene-authored panel has three different identities:

1. the manifest asset ID, which names the reusable UIKitML definition;
2. the scene node ID, which names one placed instance;
3. 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, type AssetManifest } from '@iwsdk/core';

const assets = {
  'welcome-panel': {
    name: 'Welcome panel',
    type: AssetType.UIKitML,
    url: '/ui/welcome.uikitml',
  },
} satisfies AssetManifest;

export default assets;

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 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. Confirm supported elements and properties from the installed IWSDK reference before assuming browser behavior.

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.

After each edit:

1. rerender with ui render-preview and inspect the image;
2. rerender the scene when placement or scale matters;
3. 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 { UIKit, UIKitMLAsset } from '@iwsdk/core';

const panel = await world.assets.instantiate<UIKitMLAsset>('welcome-panel');
const entity = world.createTransformEntity(panel);
const button = panel.requireElementById<UIKit.Text>('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<UIKit.Text>('xr-button');
button.setProperties({ text: 'Enter XR' });

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.

For immersive XR, default to a world-space panel or attach contextual UI to the object it controls. Use a thresholded Follower targeting world.player.head only when compact global UI must remain discoverable. Do not head-lock menus, reading surfaces, or persistent panels; reserve direct world.playerHeadEntity parenting for tiny, transient, non-interactive markers that require exact view alignment. Do not use ScreenSpace expecting it to remain camera-attached in XR. See docs/concepts/spatial-ui/hud.md for the placement guidance.

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.