rolldown: preserveEntrySignatures: "strict" adds exports to an entry chunk

npm install
npm start

Reproduction

Three ESM files, no CommonJS, no plugins:

// src/main.js
import { lib } from "./lib.js";

export default async function main() {
  const { load } = await import("./adapter.js");
  return lib() + (await load());
}

// src/adapter.js
export async function load() {
  const { lib } = await import("./lib.js");
  return lib();
}

// src/lib.js
export function lib() {
  return "lib";
}

src/main.js statically imports lib.js. It also dynamically imports adapter.js, which dynamically imports lib.js again.

build.mjs builds with preserveEntrySignatures: "strict" and "exports-only". It also builds once with Rollup for comparison. run.mjs imports each built entry and prints its export names.

What is expected?

src/main.js exports only default, so the built main.js should export only default. Rollup does this:

rollup-strict          Object.keys(entry) = ["default"]  default() = "liblib"

What is actually happening?

Rolldown adds t, the namespace of src/lib.js, as an export of the entry chunk. The adapter chunk imports it from the entry:

rolldown-strict        Object.keys(entry) = ["default","t"]  default() = "liblib"
rolldown-exports-only  Object.keys(entry) = ["default","t"]  default() = "liblib"

// dist/rolldown-strict/main.js
var lib_exports = /* @__PURE__ */ __exportAll({ lib: () => lib });
// ...
export { main as default, lib_exports as t };

// dist/rolldown-strict/adapter-*.js
const { lib } = await import("./main.js").then((n) => n.t);

Rolldown changes the entry's export signature with "strict". It doesn't emit an error or warning, and it doesn't create a facade chunk the way Rollup does.

Variations I tested:

• If main.js does import("./lib.js") directly, without the intermediate adapter.js chunk, the entry keeps only default.
• A re-exporting barrel or a CommonJS module isn't needed. This is different from #10015, which needs CJS require.

Real-world impact

This breaks Cloudflare Workers built with @cloudflare/vite-plugin with Vite 8 and React Router. workerd treats every named export of the main module as an entrypoint, so the Worker fails to start:

service core:user:<worker>: Uncaught TypeError: Incorrect type for map entry 'at':
the provided value is not of type 'function or ExportedHandler'.

In our app the dynamic chain is hono-openapi → @standard-community/standard-json (lazy zod.js adapter) → await import("zod/v4/core"). The worker also imports zod statically. About 180 zod internals were added as exports of the worker entry, including INVALID (a Symbol) exported as at.

@cloudflare/vite-plugin sets preserveEntrySignatures: "strict" for the worker entry. That doesn't help, because Rolldown ignores it in this case.

Workaround: put the shared module in its own chunk so the entry doesn't need to re-export it:

output: { codeSplitting: { groups: [{ name: "zod", test: /[\\/]node_modules[\\/](\.pnpm[\\/])?zod@?/ }] } }

System info

• rolldown 1.2.13. Also seen with 1.2.12 via Vite 8.3.2.
• rollup 4.64.2, for comparison.
• Node 24, macOS.