Prerender

Use Prerender for data that can be known at build time or generated as static output. It keeps static pages fast while still letting the code use Effect services.

When to use this

Use it for docs indexes, product catalogs, marketing content, generated navigation, and other data that changes through deploys rather than per request.

Minimal working example

import { Prerender } from "svelte-effect-runtime/server";
import { Effect, Schema } from "effect";

const DocsIndexInput = Schema.Struct({
  section: Schema.String,
});

export const get_docs_index = Prerender(
  DocsIndexInput,
  ({ section }) =>
    Effect.succeed([
      { section, title: "Install" },
      { section, title: "Mental model" },
    ]),
);

Realistic variant

Allow dynamic fallback only when the data can safely be computed at request time:

export const get_product = Prerender(
  Schema.Struct({ slug: Schema.String }),
  ({ slug }) =>
    Effect.succeed({ slug, name: "Starter Kit" }),
  { dynamic: true },
);

When not to use it

Do not use Prerender for authenticated data, cookies, rapidly changing records, or mutations. Use Query for request-time reads and Command or Form for writes.

Common mistakes

• Reading request-only values while expecting static output.
• Turning on dynamic: true to hide that data should really be a query.
• Using prerendered data for permissions or account-specific UI.
• Forgetting that build-time failures can break deployment.

Related pages

• Query
• Server runtime
• Remote function overview