Native Flutter integration

Is your feature request related to a problem? Please describe. OpenUI currently focuses on JavaScript/TypeScript runtimes and examples. Teams building Flutter apps do not have a native way to define OpenUI component libraries, generate OpenUI Lang prompts, parse streamed OpenUI Lang output, or render generated UI directly as Flutter widgets.

This means Flutter integrations would likely need to rely on a WebView, a custom bridge to the web runtime, or an app-specific parser/renderer. That adds friction for Flutter teams and makes OpenUI harder to adopt in mobile products that are otherwise fully Dart/Flutter.

Describe the solution you'd like Add native Flutter/Dart support for OpenUI.

The integration should make it possible to:

• Define OpenUI component libraries in Dart with typed props.
• Generate system prompts from those component definitions.
• Parse OpenUI Lang output, including streamed/incremental output.
• Render parsed OpenUI Lang into Flutter widgets.
• Support common OpenUI primitives such as layout, text, forms, buttons, lists, tables, and charts where feasible.
• Expose action/event callbacks so generated UI can trigger app behavior.
• Provide a minimal Flutter sample app showing an end-to-end streaming chat flow.

A good first version could focus on the core Dart runtime and Flutter renderer, with parity for the most common OpenUI Lang features before expanding to the full component surface.

Describe alternatives you've considered

• Use a WebView and render the existing React runtime inside Flutter.
• Keep OpenUI rendering on the server and send pre-rendered UI to the app.
• Build a custom app-specific Dart parser for a limited subset of OpenUI Lang.
• Use React Native instead of Flutter for mobile OpenUI experiences.

These options work around the gap, but they either reduce native integration quality or create duplicated protocol/rendering work.

Additional context This would make OpenUI more useful for teams building cross-platform mobile apps with Flutter. It would also help position OpenUI Lang as a portable UI generation protocol that can target native mobile frameworks, not only web runtimes.

Potential package/module shape:

• openui_lang for parsing, validation, prompt generation, and streaming state.
• openui_flutter for Flutter widget rendering.
• examples/flutter_chat for an end-to-end demo.