Xb Context

xb-context — agent-facing scene context

xb.context.scene summarizes the XR scene for agents. It is not DOM-based: it

traverses XR Blocks, UIBlocks, and meaningful Three.js objects, omitting internal

helpers such as XRSystems descendants and depth meshes.

Enable Context

const options = new xb.Options();
options.enableContext(); // semantic tree + visible objects + SOM

For narrower streams:

options.enableSceneContext(); // semantic tree only
options.enableVisibleObjectsContext(); // semantic tree + view visibility
options.enableSetOfMarkContext(); // semantic tree + visible objects + SOM image
options.context.scene.pollingIntervalMs = 3000;

Disabled modules match the xb.world shape: xb.context.scene is undefined

unless context is enabled before xb.init(options).

One-Off Snapshot

Use one scene context call when you need multiple streams from the same snapshot:

const context = await xb.context.scene.runContextDetection({
  semanticTree: true,
  visibleObjects: true,
  setOfMark: true,
});

console.log(context.semanticTree.nodes);
console.log(context.visibleObjects.nodes);
console.log(context.setOfMark.marks);

Each semantic node has a stable ctx_* id, role, name, parent/children

relationships, object id, visibility flags, and optional view state. SOM marks

reuse stable labels so labels do not realign between app snapshots.

Continuous Polling

const client = {};
xb.context.scene.start(client);
// read xb.context.scene.tree / visibleObjects / setOfMark after polling
xb.context.scene.stop(client);

Continuous detection uses options.context.scene.pollingIntervalMs and shares a

single poll across enabled context streams.

Acting On Context Ids

Remote/embodied action tools can target context nodes with the structured target:

{"type": "contextNode", "id": "ctx_7"}

The scene detector resolves that id through its current semantic snapshot, so do

not infer targets from the ctx_ prefix yourself.