svelte dependency bypasses entry points and optimizes any package with svelte as a dependency

[gregroyal]

Describe the bug

I noticed this because in my monorepo, i moved svelte from a devDependency to a dependency. This plugin caused my vite dev and vite build commands to drastically increase (30s to 7min). Its because for my entire monorepo, if a package has svelte a dependency, the plugin added it to optimize deps. Instead of just using my entry points to treeshake packages. I posted a ? in discord and got no response

this is the offending line
https://github.com/sveltejs/vite-plugin-svelte/blame/main/packages/vite-plugin-svelte/src/utils/options.js#L466

https://discord.com/channels/457912077277855764/1060332203571151019/threads/1461112660254003354
is this a bug? is there a right way to turn this off without just making svelte a devDep over a dep

Reproduction URL

NA

Reproduction

No response

Logs

System Info

System:
    OS: Linux 4.18 Red Hat Enterprise Linux 8.10 (Ootpa)
    CPU: (32) x64 Intel(R) Xeon(R) Platinum 8375C CPU @ 2.90GHz
    Memory: 27.97 GB / 61.63 GB
    Container: Yes
    Shell: 4.4.20 - /bin/bash
  Binaries:
    Node: 22.15.0
    npm: 11.6.2
    pnpm: 10.18.0
  Browsers:
    Chrome: 142.0.7444.162
    Firefox: 140.7.0esr
    Firefox Developer Edition: 140.7.0esr
  npmPackages:
    vite: ^7.3.1 => 7.3.1

[gregroyal]

I think the line moved, its this

		isSemiFrameworkPkgByJson(pkgJson) {
			return !!pkgJson.dependencies?.svelte || !!pkgJson.peerDependencies?.svelte;
		},

[dominikg]

please provide a link to a repository containing a full reproduction. In general there are only few cases where svelte needs to be added to dependencies rather than as a peer dependency or devDependency.

You can exclude your package from prebundling by explicitly adding it to optimizeDeps.exclude in your vite config. In general you want libraries your applications depend on to be prebundled, otherwise the dev server can end up requesting thousands of modules separately instead of one bundle.

[gregroyal]

I'll have to carve out some time to create a reproduction repo. So is your guidance is svelte should be a devDependency then? I think the lines are a little gray, since upgrading svelte can change your final build, that seems like it would fall under a dependency to me. We create packages daily so adding each one to exclude isn't maintainable.

If i include entry points, shouldn't it just use those entrypoints for its optimizations and not via inspection of my monorepo's packages?

[dominikg]

rule of thumb is svelte goes into devDependencies of your application and into peerDependencies of svelte libraries that are imported into your application.

Happy to look at the reproduction, but please keep in mind that this is an issue tracker, for general help how to structure your repository or app, svelte discord is the right place. If people don't respond you can either try to rephrase your question or even bump it after a while.