svelte-package does not take into account exports entry points

[x0k]

Describe the bug

I have a base package which exports ComponentProps interface.
This package also have a subpath export ./extension which extends ComponentProps via module augmentation and interfaces merging.

export interface WidgetProps<V> {
  value: V
}

declare module './index.js' {
  interface ComponentProps {
    text: WidgetProps<string>
  }
}

In another package impl i use augmented ComponentProps type to define properties type for the text-widget.svelte component.

  const { value }: ComponentProps["text"] = $props();

After building the packages the impl/dist/text-widget.svelte.d.ts file contains a definition of TextWidget with type any as props.

declare const TextWidget: import("svelte").Component<any, {}, "">;

Expected

TextWidget must be defined with the correct props type, possibly with import('base/extension').WidgetProps<string> type.

Reproduction

https://github.com/x0k/svelte-props-type-inlining-issue

Run npm i && npm run build -ws to build packages

Logs

System Info

System:
    OS: Linux 6.6 cpe:/o:nixos:nixos:24.11 24.11 (Vicuna)
    CPU: (12) x64 Intel(R) Core(TM) i5-10400F CPU @ 2.90GHz
    Memory: 5.88 GB / 15.56 GB
    Container: Yes
    Shell: 5.2.37 - /run/current-system/sw/bin/bash
  Binaries:
    Node: 22.10.0 - /nix/store/hnkyz55vndmvwhg6nzpliv86gh6sxg7h-nodejs-22.10.0/bin/node
    npm: 10.9.0 - /nix/store/hnkyz55vndmvwhg6nzpliv86gh6sxg7h-nodejs-22.10.0/bin/npm
    pnpm: 9.15.3 - /nix/store/by7hqplbckljzzsq6jpmcjp1w4jzvxpg-pnpm-9.15.3/bin/pnpm
  Browsers:
    Brave Browser: 132.1.74.51
  npmPackages:
    @sveltejs/package: catalog: => 2.3.10 
    @sveltejs/vite-plugin-svelte: catalog: => 5.0.3 
    svelte: catalog: => 5.19.7 
    vite: catalog: => 6.0.11

Severity

annoyance

Additional Information

My original project had a slightly different problem: svelte-package could correctly identify the type of the props, but was inserting the wrong path to the type defined in the subpath entrypoint.

I've been getting this type

declare const TextWidget: import("svelte").Component<import("base/dist/extension").WidgetProps<...

instead of

declare const TextWidget: import("svelte").Component<import("base/extension").WidgetProps<...

[x0k]

The problem I have been able to reproduce is not related to exports. I recently tried to work around this problem and extracted the extension into a separate package, but the props type is still missing (any).
So I think the main cause of this problem is the module augmentation + interfaces merging.

[x0k]

I made a mistake in the previous comment, after extracting the code into separate packages I was still using the exports functionality

  "exports": {
    ".": {
      "types": "./dist/export.d.ts",
      "svelte": "./dist/export.js"
    },

So yes, the main problem is with exports.

While debugging, I found that svelte2tsx uses the NodeJs module resolution strategy (code) while the typescript SvelteKit project is generated with the NodeNext strategy by default. Patching this parameter in svelte2tsx package also solves the problem.