Remote functions errors when `rolldown-vite` is used

[sapphi-red]

Describe the bug

The following error happens when a remote function is called in a built application:

Cannot find module '/path/to/this/repository/packages/kit/test/apps/basics/.svelte-kit/output/server/assets/remote-entry-tMlqBMhW.js' imported from /path/to/this/repository/packages/kit/test/apps/basics/.svelte-kit/output/server/remote/1lldu3f.js (500 Internal Error)

Reproduction

1. add

"overrides": {
	"vite": "npm:rolldown-vite@^7.1.0-beta.0"
}

to package.json of this repository
2. run pnpm i && pnpm build && pnpm preview in /packages/kit/test/apps/basics
3. open http://localhost:4173/remote

Logs

System Info

System:
    OS: Linux 6.6 Ubuntu 24.04.2 LTS 24.04.2 LTS (Noble Numbat)
    CPU: (32) x64 AMD Ryzen 9 9950X 16-Core Processor
    Memory: 15.87 GB / 23.46 GB
    Container: Yes
    Shell: 5.2.21 - /bin/bash
  Binaries:
    Node: 22.16.0 - ~/.local/share/asdf/data/installs/nodejs/22.16.0/bin/node
    npm: 10.9.2 - ~/.local/share/asdf/data/plugins/nodejs/shims/npm
    pnpm: 10.14.0 - ~/.local/share/asdf/data/installs/nodejs/22.16.0/bin/pnpm
    bun: 1.2.17 - ~/.local/share/asdf/data/shims/bun
  npmPackages:
    @sveltejs/kit: workspace:^ => 2.27.0 
    @sveltejs/vite-plugin-svelte: catalog: => 6.0.0-next.3 
    rolldown-vite:  7.1.0-beta.0 
    svelte: ^5.35.5 => 5.35.5

Severity

serious, but I can work around it

Additional Information

It is probably because the remote functions feature relies on an optimization that is implemented in Rollup but not yet in Rolldown (rolldown/rolldown#4812).

I didn't trace down in details, but my guess is that this import is the one affecting the chunking.

kit/packages/kit/src/exports/vite/index.js

Line 673 in 0b05a95

code: `import * as ${namespace} from '__sveltekit/remote';\n\n${exports.join('\n')}\n`

[sapphi-red]

Hmm, maybe that optimization is not related.
The output with rolldown-vite has a chunk like:

import { d as prerender } from "../assets/remote-entry-tMlqBMhW.js";
import "../chunks/false.js";
import "../chunks/pathname.js";
import "../chunks/exports.js";
import "../chunks/paths.js";
import "../chunks/event-state.js";
import "../chunks/shared.js";
import "../chunks/environment.js";
import "../chunks/remote.js";
import "../chunks/utils.js";
import "../chunks/server.js";
import "../chunks/server3.js";
import "../chunks/environment2.js";
import { c as prerendered_entries } from "../chunks/prerender.remote.js";
const prerendered = prerender("unchecked", () => {
	throw new Error("Unexpectedly called prerender function. Did you forget to set { dynamic: true } ?");
});
for (const [name, fn] of Object.entries({
	prerendered,
	prerendered_entries
})) fn.__.id = "hbmo38/" + name, fn.__.name = name;
export { prerendered, prerendered_entries };

But the output with rollup-vite has a chunk like:

import "../chunks/event.js";
import { c } from "../chunks/command.js";
import "../chunks/index.js";
import { p } from "../chunks/prerender.js";
import { q } from "../chunks/query.js";
import "../chunks/form.js";
const schema = (
  /** @type {import("@standard-schema/spec").StandardSchemaV1<string>} */
  {
    ["~standard"]: {
      validate: (value) => {
        if (typeof value !== "string") {
          return { issues: [{ message: "Input must be a string" }] };
        }
        return { value };
      }
    }
  }
);
const validated_query_no_args = q((arg) => arg === void 0 ? "success" : "failure");
const validated_query_with_arg = q(
  schema,
  (...arg) => typeof arg[0] === "string" && arg.length === 1 ? "success" : "failure"
);
p(
  (arg) => arg === void 0 ? "success" : "failure"
);
const validated_prerendered_query_with_arg = p(
  schema,
  (...arg) => typeof arg[0] === "string" && arg.length === 1 ? "success" : "failure",
  {
    inputs: () => ["a"],
    dynamic: true
  }
);
const validated_command_no_args = c(
  (arg) => arg === void 0 ? "success" : "failure"
);
const validated_command_with_arg = c(
  schema,
  (...arg) => typeof arg[0] === "string" && arg.length === 1 ? "success" : "failure"
);
const validated_prerendered_query_no_args = p("unchecked", () => {
  throw new Error("Unexpectedly called prerender function. Did you forget to set { dynamic: true } ?");
});
for (const [name, fn] of Object.entries({ validated_command_no_args, validated_command_with_arg, validated_prerendered_query_no_args, validated_prerendered_query_with_arg, validated_query_no_args, validated_query_with_arg })) {
  fn.__.id = "yx2lx0/" + name;
  fn.__.name = name;
}
export {
  validated_command_no_args,
  validated_command_with_arg,
  validated_prerendered_query_no_args,
  validated_prerendered_query_with_arg,
  validated_query_no_args,
  validated_query_with_arg
};

[teemingc]

This seems to be caused by the procedure that removes prerendered remote functions.

kit/packages/kit/src/exports/vite/build/build_remote.js

Line 51 in bfdb564

export async function treeshake_prerendered_remotes(out, manifest_data, metadata) {

Commenting out the line that executes the treeshaking makes the issue disappear. cc: @dummdidumm

kit/packages/kit/src/exports/vite/index.js

Lines 1114 to 1115 in 0b05a95

	// remove prerendered remote functions
	await treeshake_prerendered_remotes(out, manifest_data, metadata);

EDIT: This is the specific part that's not working cc: @sapphi-red is this is a known strategy, including a file as an entry point so that the bundler treeshakes its exports?

kit/packages/kit/src/exports/vite/build/build_remote.js

Lines 64 to 67 in bfdb564

	// include this file in the bundle, so that Rollup understands
	// that functions like `prerender` are side-effect free
	[path.basename(remote_entry.slice(0, -3))]: remote_entry
	};

Rolldown outputs the extra remote-entry chunk in addition to the entry point we set:

    {
      type: 'chunk',
      code: [Getter],
      fileName: 'remote-entry.js',
      name: 'remote-entry',
      modules: [Getter],
      imports: [Getter],
      dynamicImports: [Getter],
      exports: [ 'command', 'form', 'prerender', 'query' ],
      isEntry: true,
      facadeModuleId: '/home/chewteeming/git/sveltejs/kit-2/packages/kit/test/apps/basics/.svelte-kit/output/server/remote-entry.js',
      isDynamicEntry: false,
      moduleIds: [Getter],
      map: [Getter],
      sourcemapFileName: null,
      preliminaryFileName: 'remote-entry.js',
      viteMetadata: {
        importedAssets: Set(0) {},
        importedCss: Set(0) {},
        __modules: {}
      }
    },
    {
      type: 'chunk',
      code: [Getter],
      fileName: 'assets/remote-entry-jXSmQD9J.js',
      name: 'remote-entry',
      modules: [Getter],
      imports: [Getter],
      dynamicImports: [Getter],
      exports: [ 'b', 'c', 'd', 'e' ],
      isEntry: false,
      facadeModuleId: null,
      isDynamicEntry: false,
      moduleIds: [Getter],
      map: [Getter],
      sourcemapFileName: null,
      preliminaryFileName: 'assets/remote-entry-!~{000}~.js',
      viteMetadata: {
        importedAssets: Set(0) {},
        importedCss: Set(0) {},
        __modules: {
          '/home/chewteeming/git/sveltejs/kit-2/packages/kit/test/apps/basics/.svelte-kit/output/server/remote-entry.js': {
            code: [Getter],
            renderedLength: [Getter],
            renderedExports: [Getter]
          }
        }
      }
    }

Compared with Rollup which outputs just the one remote-entry we set:

    {
      exports: [ 'command', 'form', 'prerender', 'query' ],
      facadeModuleId: '/home/chewteeming/git/sveltejs/kit-2/packages/kit/test/apps/basics/.svelte-kit/output/server/remote-entry.js',
      isDynamicEntry: false,
      isEntry: true,
      isImplicitEntry: false,
      moduleIds: [
        '/home/chewteeming/git/sveltejs/kit-2/packages/kit/test/apps/basics/.svelte-kit/output/server/remote-entry.js'
      ],
      name: 'remote-entry',
      type: 'chunk',
      dynamicImports: [],
      fileName: 'remote-entry.js',
      implicitlyLoadedBefore: [],
      importedBindings: {
        'chunks/command.js': [ 'c' ],
        'chunks/form.js': [ 'f' ],
        'chunks/prerender.js': [ 'p' ],
        'chunks/query.js': [ 'q' ]
      },
      imports: [
        'chunks/command.js',
        'chunks/form.js',
        'chunks/prerender.js',
        'chunks/query.js'
      ],
      modules: [Object: null prototype] {
        '/home/chewteeming/git/sveltejs/kit-2/packages/kit/test/apps/basics/.svelte-kit/output/server/remote-entry.js': {
          code: [Getter],
          originalLength: 233,
          removedExports: [],
          renderedExports: [ 'command', 'form', 'prerender', 'query' ],
          renderedLength: 0
        }
      },
      referencedFiles: [],
      viteMetadata: { importedAssets: Set(0) {}, importedCss: Set(0) {} },
      code: 'import { c } from "./chunks/command.js";\n' +
        'import { f } from "./chunks/form.js";\n' +
        'import { p } from "./chunks/prerender.js";\n' +
        'import { q } from "./chunks/query.js";\n' +
        'export {\n' +
        '  c as command,\n' +
        '  f as form,\n' +
        '  p as prerender,\n' +
        '  q as query\n' +
        '};\n',
      map: null,
      preliminaryFileName: 'remote-entry.js',
      sourcemapFileName: null
    },

[teemingc]

I think this is related to rolldown/rolldown#3234 since we use the /*@__NO_SIDE_EFFECTS__*/ annotation for the prerender function and that's not being treeshaken currently.

[sapphi-red]

is this is a known strategy, including a file as an entry point so that the bundler treeshakes its exports?

I don't think including a file as an entry point would mark its exports as side effect free. For example, this has a side effect regardless of whether this file is an entry point or not.

export const foo = console.log()

[sapphi-red]

I think this is related to rolldown/rolldown#3234 since we use the /*@__NO_SIDE_EFFECTS__*/ annotation for the prerender function and that's not being treeshaken currently.

If that's the reason, I guess we can unblock users if we add /* @__PURE__ */ to the prerender calls. Probably here:

kit/packages/kit/src/exports/vite/build/build_remote.js

Line 91 in bfdb564

${prerendered.map((name) => `export const ${name} = prerender('unchecked', () => { throw new Error('Unexpectedly called prerender function. Did you forget to set { dynamic: true } ?') });`).join('\n')}

export const ${name} = /* @__PURE__ */ prerender('unchecked', ...)
It would take a bit more time to fix that issue.

[teemingc]

Just a quick update: I've tried the solution above but it did not work (probably due to some other factors as well). I think we'll wait for Rolldown to be updated and rolldown-vite by extension so we can test again with the treeshaking fix added in rolldown/rolldown#5829

[sapphi-red]

It seems it now works with rolldown-vite@7.1.0-beta.0 && rolldown-vite@7.1.10.
Maybe this was fixed by #14293, #14418 indirectly.

[TheOnlyTails]

I'm still getting this error with rolldown-vite@7.1.13:

Error: ENOENT: no such file or directory, open '/home/theonlytails/IdeaProjects/igy/apps/site/.svelte-kit/output/server/chunks/remote-hue1ku.js'

[sapphi-red]

@TheOnlyTails Would you create an issue with a reproduction?

[vyconm]

these issues could be related to #14739 , which is a rolldown upstream issue that has been opened