State Sync — App ↔ DataModel Coordination #638
Description
Is your feature request related to a problem? Please describe.
In collaboration interfaces (not chat-style UIs), state must flow both ways: app → surface and surface → app. Today, app state (Provider/Bloc/Riverpod) and GenUI DataModel (per surface in A2uiMessageProcessor) are disconnected, which causes drift (stale UI, reset mismatches, and validation failures not reflected in the surface). Cross-surface views of the same entity can also drift.
Describe the solution you'd like
A supported, opt-in way to keep app state and DataModel in sync (both directions), with the ability to flag which app state changes should trigger UI regeneration. Ideally the LLM can access current state without prompt stuffing.
Describe alternatives you've considered
Manual syncing on each change, stuffing state into prompts, or wrapping widgets to push changes back. These work but are boilerplate-heavy and easy to miss, and prompt stuffing is costly and can go stale.
Additional context
Discussion: #609