Partial Pre-Rendering (PPR)

Partial Pre-Rendering (PPR) is Rebask's rendering model. It renders and caches as much of the route as possible: a shell when part of the render depends on the current request, or complete HTML when the route can be resolved safely without postponed work.

A shell is server-rendered HTML together with the postponed state needed to resume work that could not be completed during prerendering. Shells can be broad and reusable or more specific to a route, depending on how much route context is known.

See Page Caching to learn how Rebask stores, upgrades, and selects shells.

PPR does not mean every request streams dynamic content. When complete HTML is available, Rebask serves it directly.

Suspense and dynamic work

Wrap dynamic work in <Suspense> so Rebask can capture the surrounding content as a PPR shell. The fallback is included in the initial shell and is replaced when the dynamic content resumes:

import { Suspense } from "react"
import { routeParams } from "@rebask/core/request"

export default function ProductPage() {
  return (
    <Suspense fallback={<ProductSkeleton />}>
      <ProductContent />
    </Suspense>
  )
}

async function ProductContent() {
  const { id } = await routeParams<{ id: string }>()
  const product = await getProduct(id)
  return <ProductDetail product={product} />
}

Server Runtime APIs such as headers(), cookies(), searchParam(), and unresolved routeParams() create dynamic work. Rebask stops capturing the shell when one of them is read. If the read is inside <Suspense>, the surrounding content becomes the shell and the rest resumes later. Outside <Suspense>, the route has no static shell and renders dynamically.

Async data that does not read a runtime API is not dynamic work. Rebask waits for it to finish and includes the result in the prerendered output.

See Server Runtime APIs for the request helpers and their effect on PPR.

On a cache hit, Rebask rerenders the RSC tree and uses the shell's postponed state to resume the HTML. See Advanced concepts for what a shell stores and why the tree is rerendered.