Generics, Generated Types, and Erasure

Generated archetypes such as Points3D give callers concrete constructors, builders, descriptors, and documentation. Components implement serialization traits that map typed Rust values into Arrow arrays. The generic RecordingStream::log<AS: AsComponents + ?Sized> accepts built-ins, custom bundles, and trait objects through the same API.

AsComponents is deliberately object-safe. Arrays, Vec<AS>, references, and Box<dyn AsComponents> flatten into Vec<SerializedComponentBatch>. That is the erasure point: semantic identity remains in each ComponentDescriptor, while concrete bundle shape no longer matters to batching or transport.

The viewer returns to strong types. Generic query and visualization helpers such as process_archetype::<Points3D, _, _> use descriptors to request required and optional components, then typed Arrow slicing exposes values like [f32; 3], u32, or String.

Trait objects handle open runtime sets: Box<dyn LogSink>, visualizer systems, data sources, and registries. Generics handle repeated algorithms whose concrete types improve inference or representation. Code generation handles the large, cross-language product schema that hand-written generic abstractions alone would not keep consistent.