Island
Islands are client-hydratable components embedded within server-rendered content; they enable interactive UI sections without hydrating the entire page. Island components are defined by the site application, not plugins.
Island pattern
Islands allow interactive components (e.g., widgets, charts) to be rendered on the server and hydrated only on the client where needed. This reduces JavaScript payload and improves time-to-interactive.
Site responsibility
The site application owns island placement, routing, and hydration. Plugins may expose server-rendered components, but island logic resides in the app layer.