Markup is the handoff.

The server emits the island host, inert data, and fallback content. The client reads that contract without creating a second DOM tree.

Island host

<taipa-island data-taipa-component="Counter" data-taipa-hydrate="load" data-taipa-version="1">
<button data-taipa-ref="increment">Increment</button>
<output data-taipa-ref="count">0</output>
<script type="application/json" data-taipa-props>
  {}
</script>
</taipa-island>

Preflight before attachment

Before attaching effects or listeners, hydration validates the component version, payload shapes, and every singular ref declared through bind() and on(). Missing or duplicated singular refs leave the island inert and report one error.