useUpdateModelContext

sunpeak API

Overview

Returns a function to send model context updates to the host. Unlike useAppState (which automatically syncs structured state), this hook gives direct control over when and what is sent to the model context — including text content blocks. Each call overwrites the previous context. The host includes the last update in the model’s next turn.

Wraps updateModelContext

MCP Apps SDK reference

Import

import { useUpdateModelContext } from 'sunpeak';

Signature

function useUpdateModelContext(): (params: UpdateModelContextParams) => Promise<void>

UpdateModelContextParams

content

ContentBlock[]

Array of content blocks to include in model context.

structuredContent

Record<string, unknown>

Structured data to include in model context. Serialized as JSON.

Returns

updateModelContext

(params: UpdateModelContextParams) => Promise<void>

Function to push context updates to the host. Each call replaces the previous context.

Usage

Structured Content

import { useUpdateModelContext } from 'sunpeak';

function MapResource() {
  const updateModelContext = useUpdateModelContext();

  const handleSelect = (place: Place) => {
    updateModelContext({
      structuredContent: { selectedPlace: place },
    });
  };

  return <PlaceList onSelect={handleSelect} />;
}

Text Content

import { useUpdateModelContext } from 'sunpeak';

function EditorResource() {
  const updateModelContext = useUpdateModelContext();

  const handleChange = (text: string) => {
    updateModelContext({
      content: [{ type: 'text', text }],
    });
  };

  return <textarea onChange={(e) => handleChange(e.target.value)} />;
}

Comparison with useAppState

Feature	`useAppState`	`useUpdateModelContext`
Automatic sync	Yes — syncs on every state change	No — you call it explicitly
Content types	Structured data only	Text blocks + structured data
State management	Built-in (like `useState`)	Bring your own
Use case	Simple persistent state	Custom sync logic, text content

useAppState

Automatic state persistence and sync.

​Overview

Wraps updateModelContext

​Import

​Signature

​UpdateModelContextParams

​Returns

​Usage

​Structured Content

​Text Content

​Comparison with useAppState

​See Also