OpenUI and JSON-render are some other players in this space. I’m building an agentic commerce chat that uses MCP-UI and want to start using these new implementations instead of MCP-UI but can’t wrap my head around how button on click and actions work? MCP-UI allows onClick events to work since you’re “hard coding” the UI from the get-go vs relying on AI generating undertemistic JSON and turning that into UI that migh…
In my approach, callbacks are first-class. The agent defines server-side functions and passes them to the UI:
const onRefresh = async () => {
data.loading = true;
data.messages = await loadMessages();
data.loading = false;
};
mount({
data,
callbacks: { onRefresh },
ui: ({ data, callbacks }) => (
Refresh
)
});
So the UI is generated dynamically by the LLM, but the interactions are real server-side code, not just display. Forms work the same way — "await form.result" pauses execution until the user submits.
The article has a full walkthrough of the four data flow patterns (forms, live updates, streaming data, callbacks) with demos.