Whether the active session exposes light estimation (feature granted).
Request the light probe. Resolves once the runtime provides it.
Drive a DirectionalLight from the latest estimate (no-op if there
is none this frame). Sets direction, color, and intensity; leaves
shadow settings untouched.
Stop listening (does not end the session).
WebXR lighting estimation helper: reads the AR runtime's estimate of the real environment's lighting so virtual objects are lit to match the room — a dominant directional term (sun/lamp) plus an order-2 spherical-harmonics ambient. Pipe the directional term into a
DirectionalLightvia applyToDirectional, and the SH into an ambient/IBL probe.Requires a session created with the
'light-estimation'feature. Call start once (async), then update everyXRFrame.Part of the AR half of the WebXR integration — see TODO/webxr-integration.md.