Prior Art

json-render is an alternative that predates this library. It provides React and React Native integration and works with the AI SDK. Its design:

• The LLM streams the UI in a predefined format; a stream parser consumes the output.
• A long system prompt describes that format and includes examples.

That works well for large language models (such as cloud APIs). For on-device, small models (such as Apple Foundation Models, with limited context), you run into:

1. Context size — Small models often have 4K-token windows (such as Apple Foundation having a 4096 token limit). A long system prompt plus conversation leaves little room; you end up summarizing or truncating, if you even fit into the window at all.
2. Task complexity — json-render supports rich actions and state. For small models (around 3B parameters), generating a correct static UI is already hard; a simpler, tool-based flow is more reliable.

How this package differs

• Tool calling instead of streaming UI — The model emits small JSON payloads by calling tools (add node, set props, etc.). Each step is small and easier for the model to get right.
• Narrower feature set — Focus on static UI building first, so smaller models can complete the task. More features will be added later.

Choose @react-native-ai/json-ui when you run small models on-device; consider json-render when using cloud providers or larger models.