This reference separates three related but different concerns: keeping an interactive tree current, selecting a presentation for a target, and describing a device-level scene.
Render first; patch a known tree
An interactive session starts from a rendered AUP tree. Later changes can be sent as patches against a tree version. The current patch vocabulary includes create, update, remove, and reorder operations. That is a renderer/session synchronization mechanism, not a request for application authors to edit arbitrary transport messages.
When a state change is simple, express it as state/event intent in DSL or AUP source. Let the runtime determine the resulting tree update. A target that misses or rejects an update must not be assumed to have applied the author's intended state merely because a source file validated.
Capabilities are reported by the target
The AUP model contains shared degradation rules; the actual device capability set (DeviceCaps) is reported during handshake and the renderer applies target presentation. Current primitive support values are:
native | webview | partial | unsupportedThose values describe a target’s relation to a primitive, not a universal quality score for the whole app.
The current shared degradation contract is deliberately small. The canonical list of its nine chains is in Device capabilities and degradation; keep that target-specific acceptance guidance next to the chain list rather than copying it into every reference page.
A custom or unknown type without a chain passes through unchanged; it is not automatically converted to text. This is why a cross-device claim requires a concrete primitive and target check.
Scene is not a generic UI escape hatch
The runtime has scene-oriented delivery surfaces, but their lower-level transport details are not a stable shortcut around node/event/state authoring. Use a scene only when the relevant target contract and acceptance test are known. Do not use a frame, bridge, or embedded surface to bypass capability or data-scope review.
For the current primitive inventory, see Primitive taxonomy and evidence. For safe authoring of state changes, see Events, state, and bindings.