NativeCanvasPresentation

Detached read-only result of final native canvas preparation for one GUI batch.

The original runtime frame is never changed. This object retains only immutable commands, tokens, and optional CPU snapshots, never native storage or a producer. An uncommitted Canvas remains transparent in the native display list, but immutable readiness metadata prevents an incomplete portable capture. Read access and portable capture are safe from any thread; native submission and consumption remain device-thread operations. Retaining this object cannot keep a native target alive after its device has retired the generation.