A small A2UI v0.9.1 fixture for host-side validation and action gating

[IsaacZhaoo]

I put together a small, model-free fixture for exploring the boundary between A2UI message processing and application policy.

It pins @a2ui/web_core@0.10.6 and uses protocol v0.9.1 through the /v0_9 imports. The host checks message schemas and component admission, replays candidate batches in a temporary processor before changing live state, and checks action names before dispatch.

The repository includes seven deterministic Node tests covering this fixture only. They do not establish safety for other catalogs, renderers, URL handling, or application side effects. The staging behavior is synchronous host code, not a protocol rollback guarantee.

Pinned code and reproduction steps

I’d welcome feedback on the admission boundary: what additional checks would you require before letting a custom catalog’s components enter live surface state?